part 5 electrical systems - files.repuloterek-civil

DOC 9157-AN/901 Part 5

AERODROME DESIGN

MANUAL

PART 5 ELECTRICAL SYSTEMS

FIRST EDITION - 1983

Approved by the Secretary General and published under his authority

INTERNATIONAL CIVIL AVIATION ORGANIZATION

Copyright International Civil Aviation Organization Provided by IHS under license with ICAO

Not for ResaleNo reproduction or networking permitted without license from IHS

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I C A O 9357 P A R T 8 5 ** = 484343b 0039920 630 W

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Aerodrome Design Manual

(DOC 9157-AN/901)

Part 5

Electrical Systems

First Edition - 1983



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I C A O 9357 PART*5 ** W 4B4L4Lh 0019922 403 W

AMENDMENTS

The issue of amendments is announced in the ICAO Bulletin and in the monthly supplements to the Catalogue of ICAO Publications, which holders of this publication should consult. These amendments are available free upon request.



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ICAO 9157 PART*5 ** m 4B4L4Lb 0019923 3 4 T m

FOREWORD

Proper design, installation and maintenance of electrical systems fo r nav i - ga t ion a ids , bo th v i sua l and non-visual, are p re requ i s i t e s fo r t he s a fe ty , r egu la r i ty , and ef f ic iency of c iv i l av ia t ion . To t h i s e n d , t h i s manual provides guidance on the design and i n s t a l l a t i o n of electrical systems f o r aerodrome l i g h t i n g and radio naviga- t i o n a i d s .

The electrical systems f o r aerodrome l i g h t i n g and rad io naviga t ion a ids inc lude fea tures which are not usual ly involved in other electrical in s t a l l a t ions . This manual therefore discusses not only the general features of electrical p rac t i ces and instal la t ions but a lso those features which are of spec ia l s ign i f i cance fo r aerodrome i n s t a l l a t i o n s . It is assumed tha t r eade r s of t h e manual w i l l be famil iar with elec- t r ica l c i r c u i t s and general design concepts, but may not be knowledgeable of c e r t a i n f ea tu res of aerodrome i n s t a l l a t i o n s which are less f requent ly encountered in o ther i n s t a l l a t ions . It is impor t an t t o no te t ha t t he material presented in t h i s manual is in tended to complement na t iona l s a fe ty codes r e l a t ed t o electrical i n s t a l l a t i o n s .

The nranual does not discuss electrical systems for bu i ld ings loca ted on a n a i rpo r t o the r t han t he e f f ec t of such buildings on t o t a l power requirements for primary and secondary power suppl ies . Similar ly , the manual does not deal with the maintenance of electrical systems. For guidance on t h i s latter i s sue t he r eade r i s - adv i sed t o r e f e r t o t he A i rpo r t Servgces Manual, (Doc 9137), Part 9, Airport Maintenance Pract ices .

Future ed i t ions o f th i s manual will be improved on the bas i s of experience gained and of comments and suggestions received from users of t h i s manual. Readers of t h i s manual are invi ted to g ive the i r v iews , comments and suggest ions to the Secretary General of ICAO.



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iCA0 9357 PART*5 ** - 4B4L4Lb 0039924 286 m

TABLEOFCONTENTS

Paee

Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-l

1.1 Purpose ............................................................ 5-l 1.2 Organization of the manual ......................................... 5-l

Chapter 2. Electricity Supplies a..........................................* 5-2

2.1 Sources of power ................................................... 5-2 2.1.1 General .......................... ..~.......*.o*- ............. 2.1.2 Primary power sources ....................................... 25; 2.1.3 Secondary power sources ..................................... 5-2 2.1.4 Distribution of intermediate power .......................... 5-3

2.2 Power transfer characteristics ..................................... 5-3 2.2.1 Transfer (switch-over) time requirements ................... .5-3 2.2.2 Continuous power sources .................................... 5-3 2.2.3 Methods of transfer ......................................... 5-5

2.3 Secondary power equipment .......................................... 5-7 2.3.1 Components '5-7 .................................................. 2.3.2 Engine-generator sets ....................................... 5-9 2.3.3 Power transfer switching .................................... 5-10 2.3.4 Uninterruptible power supplies .............................. 5-10 2,3.5 Special secondary power devices ............................. 5-11

2.4 Vaults and shelters for electrical equipment ..................... ..5-11 2.4.1 Shelters .................................................... 5-11 2.4.2 Iocation .................................................... 5-13 2.4.3 Special provisions .......................................... 5-13

2.5 Distribution of power .............................................. 5-14 2.5,1 General ..................................................... 5-14 2.5.2 Primary power feeder circuits ............................... 5-15 2.5.3 Above-ground (overhead) primary distribution systems ..... ,.*5-l 5 205.4 Line-voltage regulators ..................................... 5-15 2.5.5 Power lines ................................................. 5-16 2.5.6 Conductors ................................................... 5-16 2.5.7 Insulators .................................................. 5-17 2.5.8 Iocknuts .................................................... 5-18 2.5.9 Transformers ................................................ 5-18 2.5.10 Capacitors .................................................. 5-19 2.5.11 Circuit interruption devices ................................ 5-19 2.5.12 Lightning protection ........................................ 5-20 2.5.13 Clearances .................................................. 5-20 2.5.14 Grounding ................................................... 5-20 2.5.15 Underground distribution systems ............................ 5-21



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ICAO 9157 P A R T * 5 ** 484141b 0039925 112

(vi ) Aerodrome Design Manual

Page

Chapter 3 . Elec t r i ca l C i r cu i t s fo r Aerodrome Lighting and Radio Navigation Aids ........................................................... 5-23

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

Types of e l e c t r i c a l c i r c u i t s ....................................... 5-23 3.1.1 Elec t r i ca l cha rac t e r i s t i c s .................................. 5-23 3.1.2 Series c i r c u i t s ............................................. .- 23 3.1.3 P a r a l l e l c i r c u i t s ........................................... 5-24 3.1.4 Comparison of series and p a r a l l e l l i g h t i n g c i r c u i t s ......... 5-25 Series c i r c u i t r y f o r aerodrome l igh t ing ............................ 5-25 3.2.1 Factors to be considered .................................... 5-25 Para l le l (mul t ip le ) c i rcu i t ry ...................................... 5-41 3.3.1 Use of para l l e l (mu l t ip l e ) c i r cu i t ry in aerodrome l igh t ing .. 5-41 Control of aerodrome l igh t ing systems .............................. 5-42

3.4.2 Control panels .............................................. 5-43 3.4.3 &e of re lays ............................................... 5-44 3.4.4 Interconnection of controls ................................. 5-45 3.4.5 Automatic controls .......................................... 5-45 3.4.6 Radio remote controls ....................................... 5-46

3.5.1 Character is t ics of incandescent lamps ....................... 5-46 3.5.2 Character is t ics sf gaseousdischarge lamps .................. 5-48 Methods of ob ta in ing in tegr i ty and r e l i a b i l i t y f o r aerodrome

l igh t ing ......................................................... 5-49 3.6.1 Definit ion of term ......................................... 5-49 3.6.2 Summary of means of improving e l e c t r i c a l i n t e g r i t y

and r e l i a b i l i t y ........................................... 5-50 Monitoring of aerodrome l i g h t i n g c i r c u i t s .......................... 5-51 3.7.1 Methods of monitoring ....................................... 5-51

307.3 Classes: of monitors .......................................... 5-51 3-7.4 Monitor overr ide controls ................................... 5-52 Elec t r i ca l c i r cu i t s fo r r ad io nav iga t ion a ids ...................... 5-52 3.8.1 Types of radio navigat ion a ids .............................. 5-52 3.8.2 Elec t r i ca l cha rac t e r i s t i c s .................................. 5-52 3.8.3 Control c i rcui ts for radio navigat ion a ids .................. 5-53 3-8.4 Rel i ab i l i t y and i n t e g r i t y of radio navigat ion a ids .......... 5-54 3.8.5 Monitoring of radio navigation aids ......................... 5-54 Acceptance t e s t i n g of aerodrome e l e c t r i c a l c i r c u i t s ................ 5-54 3.9.2 Guarantee period ............................................ 5-55 3.9.3 Inspection procedures ....................................... 5-55 3.9.4 Elec t r i ca l test of ser ies -c i rcu i t equipment ................. 5-57 3.9.5 Elec t r i ca l tests of other cables ............................ 5-59 3.9.6 E l e c t r i c a l t e s t s of regulators .............................. 5-60

3.4.1 Control c i r c u i t r y .......................................... ~5-42

Lamps .............................................................. 5-46

3.7.2 Design of monitoring devices ................................ 5-51

3.9.1 Application ................................................. 5-54

3.9.7 Troubleshooting tests ................................ ......*5-61 3.9.8 E l e c t r i c a l t e s t s of o ther equipment ......................... .- 62 3.9.9 Tests of monitors ........................................... 5-62



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ICAO 9357 PART*5 ** - 4BrlL41rb 0039926 059 m.

Table of Contents (vii >

* Page

Chapter 4. Underground Electrical Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-63

8

4.1

4.2

4.3

4.4

4.5

Chapter

5.1

5.2

General requirements ............................................... 5-63 4.1.1 Initial considerations ...................................... 5-63 4.1.2 Preconstruction arrangements ................................ 5-63 4.1.3 Methods of installation ..................................... 5-63 Direct burial of cable ............................................. 5-63 4.2.1 Steps of installing ......................................... 5-63 4.2.2 Trenching ................................................... 5-63 4.2.3 Separation between cables ................................... 5-64 4.2.4 Installation of direct-burial cables ...................... ..5-6 5 Installation of ducts (conduit) .................................... 5-66 4.3.1 Installation techniques and procedures ............=.........5-6 6 Manholes and handholes ............................................. 5-67 4.4.1 Selection ................................................... 5-67 4.4.2 Location .................................................... 5-69 4.4.3 Stubs ....................................................... 5-69 4.4.4 hardware .................................................... 5-69 4.4.5 Two-section manholes ........................................ 5-69 Installation of underground cables ................................. 5-69 4.5.1 Preparation of ducts ........................................ 5-69 4.5.2 Cable pulling in ducts ...................................... 5-69 4.5.3 Installation of cable in manholes and handholes ........... ..5-7 1 4.5.4 Pressurized type coaxial cables ............................. 5-72 4.5.5 Cable installation in saw cuts ............................. 5-73 4.5.6 Cable marking ............................................... 5-74 4.5.7 Enclosures for connections .................................. 5-75

5. Cables for Underground Service at Aerodromes . . . . . . . . . . . . . . . . . ...5-77

Features of the cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-77 5.1.1 Characteristics of cables for underground service ......... ..5-7 7 5.1.2 Classes of service .......................................... 5-79 5.1.3 Causes of cable damage ...................................... 5-80 Cable connections .................................................. 5-82 5.2.1 Cable splices ............................................... 5-82 5.2.2 Taped splices ............................................... 5-83 5.2.3 Connector kits for aerodrome lighting ..................... ..5-8 5 5.2.4 Coaxial cables .............................................. 5-85 5.2.5 Connection of conductors .................................... 5-88



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ICAO 9357 PART*5 ** = 4 8 4 3 4 L b 0039927 T95 W

1.1 PURPOSE

1.1.1 To ensure the regular i ty and safe ty of av ia t ion , i t i s necessary that aerodrome l igh t ing and radio navigational aids have h igh in tegr i ty and r e l i a b i l i t y . It is considered that the probabi l i ty of f a i l u r e of well designed and maintained l i g h t i n g and radio a ids a t a c r i t i c a l moment i s extremely low.

1.1.2 The following material i s intended as a guide t o t h e recommended electrical engineer ing pract ices for design and i n s t a l l a t i o n of new systems and the modification of existing systems of aerodrome f ixed l i gh t ing and of d i s t r ibu t ion of power t o r a d i o navigation aids. It does not imply t h a t e x i s t i n g i n s t a l l a t i o n s , i f d i f f e r e n t , are wrong and should be changed automatically. It does mean t h a t some of the earlier designs adopted are not recommended for repe t i t ion s ince they have been superseded by later thinking. Because of the differences i n engineer ing s tyle and equipment i n d i f f e r e n t count r ies , th i s material es tabl ishes only basic design pr inciples . It i s not intended t o i l lustrate de ta i led des ign or par t icu lar p ieces of equipment o r systems unique t o any one State.

1.1 .3 The electrical systems f o r aerodrome v i s u a l a i d s and navigation systems require good q u a l i t y i n s t a l l a t i o n s and considerat ion for features which are not usually involved i n o t h e r e l e c t r i c a l i n s t a l l a t i o n s . This manual d i scusses the genera l fea tures of e l e c t r i c a l p r a c t i c e s and in s t a l l a t ions w i th emphasis on those features which are less commonly involved or have special s ign i f icance for aerodrome operations. It is assumed tha t those us ing th i s manual w i l l be famil iar with electrical circuits and general pract ices but may not be knowledgeable of cer ta in fea tures of aerodrome i n s t a l l a t i o n s which are less f requent ly encountered in other electrical sys t em. Some of these f e a t u r e s a r e t h a t mast e I e c t r i c a 1 c i r c u i t s are i n s t a l l e d underground, s e r i e s c i r c u i t s a r e used fo r most l ight ing systems, higher re l iabi l i ty i s required of the input power sources, and rapid, automatic transfer to secondary power i n case of power f a i lu re s . Each aerodrome i s unique, and i t s e l ec t r i ca l i n s t a l l a t ion shou ld be designed t o provide economically power and cont ro l which i s sa fe , r e l i ab le , and easily maintained.

1.2 ORGANIZATION OF THE MANUAL

1.2.1 This manual provides information on the E lec t r ic i ty Suppl ies in Chapter 2, Elec t r i ca l C i r cu i t s fo r Aerodrome Lighting and Navigation Aids i n Chapter 3, Underground Electrical Systems i n Chapter 4 , and Cables f o r Underground Service a t Aerodromes i n Chapter 5.

5- 1



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ICAO 9357 P A R T * 5 t t 4843416 0039928 921 m

cBlLpTEB2

ELECTRICITY SUPPLIES

2.1 SOURCES OF POWER

2.101 General

2.1.1.1 The primary sources of power f o r aerodromes should be determined before the designs of the aerodrome l igh t ing ins ta l la t ions and the rad io naviga t ion a ids are i n i t i a t e d . The electrical power f o r these i n s t a l l a t i o n s i s usua l ly on ly a small p a r t o f t h e electrical power used by the aerodrome. . Whether the visual and radio navigat ion a i d s b e i n g i n s t a l l e d are f o r a new aerodrome or for modernizat ion and expansion of a n exis t ing aerodrome, the sources of power should be a n a l y z e d f o r a v a i l a b i l i t y , c a p a c i t y , r e l i a b i l i t y , p r a c t i c a l i t y f o r t h e p r o p o s e d i n s t a l l a t i o n , and for fu ture expans ion . This analysis should include both the pr imary power source and the secondary power sou rce required by Annex 10, Volume I, 2.9 and Annex 14, 8.1 f o r u s e i n cases o f f a i l u r e o r malfunction of the primary power source.

2.1.2 Primary power sources

2.1.2.1 The primary sources of power f o r most aerodromes are feeders f rom a widely in te rconnec ted e lec t r ic i ty ne twork ou ts ide the aerodrome, usua l ly f rom e i ther a commer- c ia l o r a public mains supply. In some cases t h e power may come from a l o c a l g e n e r a t i n g p l an t o r f rom a l imi t ed d i s t r ibu t ion sys t em. Two independent incoming power sources are des i rab le for major aerodromes , ins tead of a s ingle p r imary power source. They should come from widely separated sections of the e l e c t r i c i t y n e t w o r k beyond the aerodrome with each supp ly ing s epa ra t e c i r cu i t s that would p r o v i d e i n t e g r i t y of f a c i l i t i e s i f one fa i led . Preferab ly , these sources w i l l have separa te feeders f rom separa te subs ta t ions and w i l l a lso be f rom different generators . Other supply arrangements may be used depending on the s e c u r i t y , r e l i a b i l i t y , statistics, or economics appl icable to a p a r t i c u l a r s i t u a t i o n .

2.1.2.2 This power i s usua l ly supp l i ed a t h igher vo l tage (over 5 000 v o l t s ) t o t h e aerodrome main power substat ion.

2.1.3 Secondary power sources

2.1.3.1 Most aerodromes with aerodrome l ight ing and radio navigat ion a ids should be provided with secondary electrical power f o r t h e a i d s r e q u i r e d as a minimum for opera- t ions . The circuits a n d f a c i l i t i e s t o be provided with secondary power va ry w i th t he most c r i t i ca l class o r ca t egory of f l i g h t o p e r a t i o n s . The aerodrome f a c i l i t i e s f o r which a secondary power supply i s recommended are i n d i c a t e d i n Annex 14, Chapter 8 f o r v i s u a l a i d s and i n Annex 10, Volume I, P a r t I, Chapter 2 f o r r a d i o n a v i g a t i o n a i d s . Those f a c i l i t i e s f o r which secondary power i s requi red should be a r ranged to au tomat ica l ly connec t to the secondary power supply on f a i l u r e of the pr imary source power . 2.1.3.2 Sources of secondary power. As recommended i n Annex 14 , Chapter 8, sou rces of secondary power may be independent public power sources or stand-by power u n i t s .

5- 2



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I C A O 9357 PARTS5 t t 48434Lb 0039929 868

P a r t 5.- Electrical Systems 5-3

2.1.3.3 Inde endent commercial o r u b l i c main ower source. For aerodromes with the primary SUPPLY o! e l e c t r i c i t y t r o m a s!ngle source: separate independent electrical transmission power l i n e s may be used to provide secondary power. These independent power sources are not usua l ly connec ted to the aerodrome l i g h t i n g and radio navigat ion a ids loads bu t can be au tomat ica l ly connec ted to these loads in case of f a i l u r e of t h e primary power source. These independent power sources may be i n a r e se rve s t a tus on ly o r may be supp ly ing e l ec t r i ca l power t o o t h e r f a c i l i t i e s o n the aerodrome. An independent source supplying power t o o t h e r f a c i l i t i e s s h o u l d have adequate capacity to provide the power f o r t h e more e s s e n t i a l aerodrome l igh t ing and r ad io nav iga t ion a ids i n addi t ion to the usual load or switching arrangements should be provided to disconnect from i t s usual load as i t i s connec ted to the l igh t ing and rad io a ids load . The improvement i n i n t e g r i t y of operations provided by independent power sources depends on the s epa ra t ion and independence of th i s source f rom the p r imary source . I f the two sources come from interconnected distribution networks, a f a i l u r e i n t h e n e t w o r k may cause bo th sources to fa i l . An independent power source may be used as a secondary power s o u r c e i f i t has the capac i ty to supply i ts own load. p lus the aerodrome l i g h t i n g and r ad io a ids l oad and is s o separa ted tha t any s ing le cause of power f a i l u r e of t h e primary source w i l l n o t i n t e r f e r e w i t h power from the other source. Unless the independent source is completely isolated from the primary source and will not be overloaded upon f a i l u r e of the primary source, local secondary power should be provided f o r t h e v i s u a l and r ad io nav iga t ion a ids e s sen t i a l t o t he ope ra t ions o f t he ae rodrome .

2.1.3.4 Independent local power source. Some aerodromes may h a v e t u r b o a l t e r n a t o r motor u n i t s which are used to supply power t o n o n - c r i t i c a l f a c i l i t i e s . These l o c a l power sources may be used as the secondary source of power f o r cr i t ical aerodrome l i g h t - i n g and rad io naviga t iona l a ids . If the primary power f a i l s , t h e c r i t i ca l l i g h t i n g and r ad io a ids are t r a n s f e r r e d a u t o m a t i c a l l y t o t h e l o c a l power source. If the l o c a l power source has adequate capacity, the l i g h t i n g and rad io a ids load may be i n a d d i t i o n t o t h e

source may need to d i sconnec t some of t he non-c r i t i ca l l oad be fo re connec t ing t o t he c r i t i ca l l i gh t ing and r ad io a ids l oad .

e usual load . I f the capac i ty of t h e l o c a l power source i s l i m i t e d , t h e l o c a l power

2.1.3.5 Local power to primary source. Another arrangement is t o s u p p l y t h e power f o r t h e aerodrome l i g h t i n g and rad io naviga t iona l a ids f rom turbo-a l te rna tor motor u n i t s which may also be supplying power t o o t h e r f a c i l i t i e s . I f t h i s s o u r c e of power f a i l s , t h e cr i t ical l i g h t i n g and r ad io a ids l oad may be t r ans fe r r ed au tomat i ca l ly t o t he primary power s o u r c e f o r t h e aerodrome.

2.1.3.6 Stand-by power sources. Secondary power sources may be engine-generator sets, or turbine generators from which electrical power can be obtained and which can be automatical ly connected to the f a c i l i t i e s r e q u i r i n g s e c o n d a r y power. The maximum load which can be connected should be within the capacity of the s tand-by uni ts . Stand-by uni ts with capaci t ies ranging f rom 50 t o more than 1 000 kilovolt-amperes are used as secondary power s o u r c e s f o r a i r p o r t s . The secondary power source should be capable of supplying power f o r a time per iod tha t exceeds the maximum time needed t o r e s t o r e power from the primary source. Engine-generator sets are o f t en expec ted t o ope ra t e fo r 2: t o 72 hours without refuel l ing. Other secondary power sou rces , u sua l ly fo r small loads , may be b a t t e r y u n i t s , f u e l cells , etc.

2.1.4 Dis t r ibu t ion of intermediate power

2.1.4.1 The vol tage from the primary power source i s usual ly reduced a t the aerodrome subs ta t ion to an in te rmedia te vo l tage (2 000 t o 5 500 v o l t s ) f o r d i s t r i b u t i o n



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ICAO 7357 P A R T 8 5 t t 484343b 0037730 5 8 T

5-4 Aerodrome Design Manual

Table 2-1. secadary P a m Supply &q&xem3 for Visual +s Radio Aide (From h x 14 and Amex 10)

IhaJay C l a s s i f i c a t i o n

Non-iImtnment

precisian approach category I1

SRe MR NB m facility



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ICAO 9157 P A R T * 5 ** 4841416 0039933 416 =

P a r t 5.- E l e c t r i c a l Systems 5-5

within the aerodrome. This power i s usua l ly d i s t r ibu ted by a "para l le l" sys tem to the var ious t ransformer s ta t ions for fur ther step-down of v o l t a g e t o match the input vol tage of the equipment. Two independent incoming electrical supplies taken from widely separated sect ions of t h e e l e c t r i c i t y network beyond the aerodrome are recommended. Wi th in the aerodrome, re l iab i l i ty in the supply of power t o the ind iv idua l s ta t ions can be improved by using a closed r ing high vol tage input c i rcui t wi th balanced vol tage pro tec t ion on the d i s t r ibu t ion t ransformers o r by using a double loop system from independent primary sources operating as open r ings feeding two transformers a t each s ta t ion. This l a t te r system i s i l l u s t r a t e d i n F i g u r e 2-1. If a centralized monitoring system of the loop switches a t each s t a t ion and of f a u l t c u r r e n t s l i k e l y t o o c c u r i n each sect ion are used practically complete el imination of power f a i l u r e s t o t h e t ransformer s ta t fons can be achieved. Simpler arrangements providing lesser r e l i a b i l i t y may be used a t smaller a i rpo r t s .

2.2 POWER TRANSFER CHARACTERISTICS

2.2.1 Transfer (switch-over) time requirements

2.2.1.1 When the primary power supply to the more cr i t ical v i s u a l a i d s , f a c i l i t i e s , and r ad io nav iga t ion a ids f a i l s , t he l oad must be t ransferred to the secondary power source. The secondary power source must be s t a r t e d and speed and voltage stabilized before the load i s t ransferred.

2.2.1.2 The t ransfer , o r swi tch-over , times permitted depend on the most cri t ical instrument classification of the aerodromes operation. Annex 14, Chapter 8, and Annex 10, Volume I, Part I, Attachment C l i s t t h e maximum permiss ib le t ransfer times f o r t h e components of aerodrome lighting systems and radio aids associated with non-instrument, non-precision, and precision approach runway categories I, 11, and 111. (See Table 2-1. )

2.2.2 Continuous Dower sources

2.2.2.1 Certain types of lamps cannot be res tar ted for several minutes i f there i s a break in the cur ren t th rough the lamp of more than a few t en ths of a second. Some types of radio navigation and computer devices allow no in t e r rup t ion of power. It i s necessary to provide an uninterrupt ible or near cont inuous source of power when the primary power s o u r c e f a i l s t o cater to such equipment. Some devices, such as some computers, are capable of accomodat ing on ly very l imi ted f luc tua t ions of frequency or voltage and requi re a t ru ly un in t e r rup t ib l e power supply.

2.2.3 Methods of t r a n s f e r

2.2.3.1 The following methods are suggested as poss ib le ways t o r e s t o r e t h e power Supply within the specified maximm t r ans fe r times. It i s advantageous t o group loads with similar l i m i t i n g t r a n s f e r times s o tha t they may be cont ro l led a t the t ransformer supply or a t the feeder dis t r ibut ion connect ions f rom the same secondary source.

a ) Z-minute t r a n s f e r time. Where a 21ninute t r a n s f e r time is permissible , local gasol ine or diesel engine-generator or gas turbine-generator sets with automatic or remote s tar t ing and switching are sa t i s f ac to ry . In th i s 2=inute per iod the engine o r tu rb ine can be s ta r ted and the speed and vol tage regula t ion can be s tab i l ized .



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5-6 Aerodrome Design Manual

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P a r t 5.- Electrical Systems 5-7

15-second t r a n s f e r time. Where a 15-second t r a n s f e r time is required, s tandby d iese l and gasoline engine-generator sets with rapid-s tar t c a p a b i l i t y and fast-acting automatic switching or an independent source with automatic t ransfer switching can be used.

10-second t r a n s f e r time. Where a 10-second t r a n s f e r time is required, secondary power u n i t s w i t h s u i t a b l e s t a r t i n g and switch-over capabili ty can be used.

One-second t r a n s f e r t i m e . Where a one second switch-over time is required, one of the fol lowing two methods are usua l ly used for th i s r ap id t r ans fe r of power. One method is t o start the s tand-by diesel engine or gas turbine-generator set as soon as the RVR is of the order of 600 m and operate the more c r i t i c a l l i g h t i n g and rad io a ids f rom th i s generator set with automatic t ransfer to the pr imary power source in case the secondary power fails. The cr i t ical load power should continue t o be furnished by the secondary power s o u r c e u n t i l an RVR of 800 m is reached on a f i rm t rend of improvements. The second method is t o automatically switch-over to a sa t i s fac tory independent power supply.

. .

Near ze ro t r ans fe r time. Very f a s t - ac t ing ( swi t ch ing i n 0.3 second o r less) automatic t ransfer devices which can switch the load from the operating stand-by generator to the primary source are r equ i r ed fo r l i g h t s u s i n g some types of discharge lamps in order to maintain the discharge. Another method of obtaining a near-zero t ransfer time is t o use an inertfa f lywheel-driven generator which is capable of maintainfng the power supply during the start-up of the secondary power source.

Zero t r a n s f e r time. For t hose f ac i l i t i e s r equ i r fng un in t e r rup t ib l e power and accept ing on ly l imi ted var ia t ions of voltage or frequency, battery-driven s ta t ic inve r t e r ( s ) o r gene ra to r ( s ) ( s ee F igu re 2-2) may be used. Although the secondary power t ransfer should usua l ly be accomplished in on ly severa l seconds , the b a t t e r y s e t ( s ) s h o u l d be capable of operat ing the f a c i l i t i e s f o r a minimum of 15 minutes wlthout recharging.

2.3 SECONDARY POWER EQUIPMENT

2.3.1 Components

2.3.1.1 Secondary electrical power should be of such qua l i t y t ha t i t w i l l provide t h e r e l i a b i l i t y , a v a i l a b i l i t y , and voltages and frequencies needed by the f a c i l i t y . The major items of secondary power equipment commonly used f o r aerodrome l ighting and rad io naviga t ion a ids are engine-generator sets, power-transfer switching devices, batteries, and ba t t e ry cha rge r s t o fu rn i sh power fo r s t a r t i ng t he eng ine gene ra to r s , and v a u l t s o r s h e l t e r s f o r t h i s equipment. Less o f t en u sed , u sua l ly fo r spec ia l f ac i l i t i e s , are u n i n t e r r u p t i b l e power (UPS) systems, standby battery-power systems, solar or wind

' generators with bat tery system, independent generat ing devices such as thermoelectr ic , n u c l e a r , o r f u e l c e l l s . The secondary power equipment should be located as close as is p r a c t i c a l t o t h e i n p u t of t h e f a c i l i t i e s s e r v e d .



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P a r t 5.- Elec t r i ca l Systems 5-9

a 2.3.2 Engine-generator sets

2.3.2.1 The basic secondary power engine-generator set cons is t s of a prime mover, a genera tor o r a l te rna tor , a s t a r t i ng dev ice , s t a r t i ng con t ro l s , and a fue l t ank o r supply. Engine-generator sets for secondary power u n i t s are u s u a l l y i n 100 t o 500 kilovalt-amperes capacities but may range from 50 t o 1 000 k i lovol tamperes i n capacity.

a ) Prime movers. The prime movers f o r most secondary power u n i t s are -

gasoline, diesel , or gas engines or turbines, the choice being based on cos t and a v a i l a b i l i t y of fue ls . These prime movers are usua l ly ava i lab le i n standardized s i z e s with adequate power to handle the ki lovol tampere ra t ing of the generator . The prime m v e r s f o r most major aerodromes are rapid-start types which can start automatically, s t ab i l i ze t he speed , and be connected to t he l oad w i th in 10 seconds.

Generators. The generator , usual ly an a l ternator , i s mechanically coupled t o the prime mover and provides secondary electrical power at the frequency, voltage, and power r a t i n g of t he un i t . These generators may be e i ther s ing le phase o r th ree phase. They should have high e f f ic iency in conver t ing mechanica l energy to electrical energy.

Star t ing devices . Most secondary power engine-generator sets use ba t t e ry packs t o s t o r e energy f o r s t a r t i n g . Because of the in f requent use , shor t opera t ing per iods , h igh s ta r t ing cur ren t demands, and cos t , lead-acid type bat ter ies are used most f r equen t ly fo r s t a r t i ng t hese uni t s . The b a t t e r y pack (of ten a set of ba t t e r i e s connec ted i n series and/or parallel) must be capable of providing the voltage and current needed to s t a r t t he eng ine w i th in t he r equ i r ed time limits and under the most severe conditions (usually a low temperature of -7°C) a t which the secondary power u n i t i s expected to operate. A battery charger with over-current and over-charge cont ro l i s permanently connected t o t h e e l c t r i c a l power to main ta in the s tored energy in the ba t te r ies . The ba t te ry pack should be well ventilated to prevent accumulation of hydrogen gas and should be protected from arcs, sparks, or flames which could cause an explosion of any accumulated gas. Nickel-cadmium b a t t e r i e s may be used where special conditions warrant their high init ial cost . Flywheels, pneumatic-pressure vessels, other-than-battery stored-energy devices are used infrequent ly for engine s tar t ing because of un re l i ab i l i t y o r cos t .

S ta r t ing cont ro ls . The cont ro ls for the engine-genera tor set are usually automatic start with the sensor for primary power f a i l u r e as par t of the t ranfer switching device. Manual o r remote controls are sometimes u s e d f o r f a c i l i t i e s w i t h low cri t ical requirements. Once i t i s s t a r t e d , speed and power are automatical ly regulated by the engine and the electrical load is connected by the t ransfer swi tch . The engine generator should operate automatically without adjustment or other a t tent ion. Transfer of power back t o the primary source and stopping the engine may be automatic or by remote control.

Fuel supply. Hquid fuel for secondary power is usua l ly s to red i n t anks near the engine generator location. The capaci ty of the fue l t anks should be adequate for the maximum operating time expected of t h e



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5-1 0 Aerodrome Design Manual

engine-generator. Some a u t h o r i t i e s r e q u i r e a minimum of 72 hours supply. Others design for a lesser time per iod , bu t the time period usual ly should be a t least twice t h e maximum durat ion expected of condi t ions that could require the use of secondary power. Fuel tanks and connections should meet a l l safety requirements and should provide convenient access fo r r e fue l l i ng . These t anks shou ld a l so p rov ide arrangements f o r t e s t i n g f o r c o n t a m i n a t i o n o f t h e f u e l , e s p e c i a l i y the accumulation of water i n t h e t a n k .

2.3.3 Power t ransfer swi tch ing

2.3.3.1 A s u i t a b l e t r a n s f e r d e v i c e is needed f o r t r a n s f e r r i n g power frcim the pr imary source to the secondary source . For manual s t a r t i n g a n d c o n t r o l t h i s may be a s i m p l e swi t ch o r r e l ay t ha t d i sconnec t s t he l oad f rom one power source and connects i t t o t h e o ther . Addi t iona l cont ro ls are needed fo r au tomat i c t r ans fe r . These a r e u sua l ly combined i n t o a s ing le con t ro l un i t o r cub ic l e . Such a u n i t should be capable of sens ing the fa i lure o f p r imary power, i n i t i a t i n g t h e s t a r t i n g of t h e pr ime mover of the secondary generator set, determining that the vol tage and f requency of the generator have s tab i l ized adequate ly , and connec t ing the load to the genera tor . This un i t may a l so d i sconnec t non-es sen t i a l l oads and f ac i l i t i e s wh ich are n o t t o be energized by t h e secondary source and t ransfer these loads back t o t h e p r i m a r y s o u r c e a f t e r t h a t power has been restored. The swi tches o r re lays for d i sconnec t ing and connec t ing the load should have the capaci ty to handle the r a t ed l oad of the generator . The func t ioning of t hese swi t ches o r r e l ays i s similar f o r e i t h e r 2 d n u t e , 15-second, or l s e c o n d t r a n s f e r times, although more rap id-ac t ing re lays may be needed f o r t h e s h o r t e s t t r a n s f e r time. For a 2-minute t r a n s f e r , t h e power f a i l u r e s e n s o r s may delay a few seconds i n d e t e r - mining i f t h e p r i m a r y power h a s f a i l e d o r i s o n l y f l u c t u a t i n g and a l s o t o d e t e r m i n e 22 the secondary power has s t ab i l i zed . Fo r a lfi-second t r a n s f e r , t h e s e n s o r s must respond i n less than 3 seconds each because the quick s tar t ing engines need 10 seconds to start and t o s t a b i l i z e . F o r t r a n s f e r times of 1 second or less, time i s t o o s h o r t t o start the engine , bu t the load can be switched from one power sou rce t o ano the r ope ra t ing source w i th in t h i s time limit; however, the power f a i l u r e s e n s o r must respond within a few cycles.

2.3.4 Uninterrupt ible power s u p p l i e s (UPS) systems

2.3.4.1 An u n i n t e r r u p t i b l e electric power supply i s n e c e s s a r y f o r e l e c t r o n i c o r other equipment that performs a cr i t ica l func t ion and requires cont inuous, d is turbance- f r e e electric power to ope ra t e p rope r ly .

2.3.4.2 UPS equipment. The u n i n t e r r u p t i b l e power supply (UPS) sys tem cons is t s o f one or more UPS modules, an energy-storage battery, and accesso r i e s as r e q u i r e d t o provide a r e l i a b l e a n d h i g h q u a l i t y power supply. The UPS sys t em i so l a t e s t he l oad f rom the pr imary and secondary sources and i n t h e e v e n t of a power in t e r rup t ion p rov ides regulated power t o t h e c r i t i ca l l o a d f o r a spec i f i ed pe r iod . (The b a t t e r y t y p i c a l l y h a s a 151ninute capaci ty when operat ing a t fu l l load . ) (See F igure 2-2.)

a ) UPS module. A UPS module is t h e s ta t ic power convers ion por t ion of t h e UPS system and consis ts of a r e c t i f i e r , an inver te r , and assoc ia ted cont ro ls a long w i t h synchroniz ing , p ro tec t ive , and auxi l ia ry devices . UPS modules may be designed t o o p e r a t e either i n d i v i d u a l l y o r i n parallel.



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P a r t 5.- E l e c t r i c a l Systems 5-1 1 - b) Redundancy. A nonredundant UPS system is s u i t a b l e f o r most operat ions.

However, i f t h e e x p e n s e i s j u s t i f i e d , a redundant UPS conf igura t ion (see Figure 2-3) may be used t o p r o t e c t a g a i n s t module f a i l u r e o r v e r y frequent primary power f a i l u r e s .

c) UPS ba t te ry . The bat tery should be a heavy-du ty i ndus t r i a l un i t of t h e lead-cadmium type having an ampere-hour r a t i n g s u f f i c i e n t t o s u p p l y d i r e c t c u r r e n t t o t h e i n v e r t e r as required by t h e UPS system manufac tu re r ' s i n s t a l l a t ion i n s t ruc t i0ns . r The b a t t e r y i s usua l ly furnished with two-t ier racks; however, where space is l imi t ed t h ree - tier racks may be necessary.

d ) Remote alarms. The UPS equipment should be supplied with a remote-alarm p a n e l t o be i n s t a l l e d i n the opera t ing space se rved by t h e UPS u n i t o r in another cont inuously occupied room, such as a guard off ice . Since UPS equipment rooms are usua l ly una t tended; addi t iona l remote ind ica t ing devices should be provided to monitor the environmental control and f i re alarm system of UPS module and b a t t e r y rooms.

e) UPS and b a t t e r y room requirements. The UPS modules and t h e i r a s s o c i a t e d b a t t e r y set s h o u l d b e i n s t a l l e d i n s e p a r a t e rooms. Construct ion should be of a permanent type. The wa l l s epa ra t ing t he UPS module room from t h e b a t t e r y room should be f ireproof (1-hour r a t i n g ) . When f e a s i b l e , space should be provided i n t h e UPS module and ba t t e ry rooms f o r t h e add i t ion o f fu tu re UPS equipment.

f ) Environmental control. Both t h e UPS module and ba t te ry rooms should be provided wi th an envi ronmenta l cont ro l sys tem to main ta in the p rescr ibed room condi t ions. Each environmental control system should 'consis t of a primary system with a secondary system capabi l i ty . Upon f a i l u r e of the pr imary environmental control system, automatic t ransfer to the secondary system should occur and should sound an alarm ind ica t ing t he need for maintenance.

2.3.5 Special secondary power devices

203.5.1 Other secondary power devices which may b e u s e d f o r s p e c i a l f a c i l i t i e s are' s tandby ba t te ry power sys tems, wi th o r wi thout dc to ac inve r t e r s ; pho tovo l t a i c or wind generators with battery systems and with or without dc t o ac inver te rs ; independent generat ing devices , such as thermoelec t r ic , nuc lear , o r chemica l fue l cells; and iner t ia-f lywheel generators . The manufacturer 's information should explain the func t ion ing and i n s t a l l a t ions fo r u s ing t hese dev ices .

2.4 VAULTS AND SHELTERS FOR ELECTRICAL EQUIPMENT

2.4.1 S h e l t e r s

2.4.1.1 Most electrical e q u i p m e n t € o r a i r p o r t l i g h t i n g a n d o t h e r f a c i l i t i e s i s loca ted i n vau l t s o r spec ia l she l t e r s fo r p ro t ec t ion f rom the wea the r and fo r be t t e r s ecu r i ty . Subs t a t ions fo r h igh vo l t age are usual ly outdoors , and medium v o l t a g e d i s t r ibu t ion t r ans fo rmers are o f t e n p o l e mounted or placed on fenced transformer pads. Most e l e c t r i c a l v a u l t s are above ground and made of f i reproof materials. Reinforced



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5-1 2 - Aerodrome Design Manual

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Part 5.- Electrical Systems 5-1 3

conc re t e fo r t he f l oo r s and concrete , concrete or c inder block, and/or br ick for the walls are materials commonly used i n t h e s e v a u l t s . The use of such materials reduce the hazard of electric shock, shorting of e l e c t r i c a l c i r c u i t s , a n d f i r e h a z a r d s Prefabri- cated metal s t ructures are occasional ly used as she l t e r s fo r t r ans fo rmers and engine- generator sets. These vau l t s are used t o house t h e power d i s t r i b u t i o n and control equipment, secondary power equipment, and the various devices used to provide power and con t ro l fo r t he a i rpo r t l i gh t ing sys t ems . These vaults should be of adequa te s i ze t o contain the necessary equipment without crowding. These vau l t s may be divided into moms f o r b e t t e r s e g r e g a t i o n of equipment and a c t i v i t i e s .

2.4.2 Loestion

2.4.2.1 Elec t r i ca l vau l t s shou ld no t be located where they would in f r inge on obstacle l imi ta t ion sur faces . The dis tances f rom the control tower to the vaul ts should be sho r t enough to avoid excess ive vo l tage d rop in the cont ro l cab les . The permissible length of these cables varies w i t h t h e s i z e of the cab le , the cont ro l vo l tage , and the types of control relays used, but some of the longer control systems limit the l ength of cont ro l cab les to about 2 250 metres. Vehicular access to the vaul t s in a l l types of weather conditions i s necessary and minimum c o n f l i c t w i t h a i r c r a f t t r a f f i c is desirable . The location should be convenient for connect ing to the appropriate l ight ing c i rcui ts and f a c i l i t i e s t o keep feeder cable lengths as shor t as i s p rac t i ca l . The vaul ts should be i so la ted f rom o ther bu i ld ings and faci l i t ies to prevent the spread of f i r e s o r explosions, except the shel ters for secondary engine-generator sets may be near the e l e c t r i c a l v a u l t t o r e d u c e c a b l e l e n g t h and s i z e and t o s impl i fy the power t r ans fe r system. Aerodsoaes with approach lighting systems may need separate approach l ighting vaul t s for each approach l igh t ing system. For major aerodromes, some au thor i t i e s u se a vault near each end of t h e runway or approach l ight ing system to more eas i ly a r r ange fo r i n t e r l eav ing o f t he l i gh t ing c i r cu i t s and t o improve i n t e g r i t y of the systems.

2.4.3 Special provisions

2.4.3.1 As spec ia l pu rpose bu i ld ings , e l ec t r i ca l vau l t s may r equ i r e spec ia l f ea tu re s t o provide safety and re l iable performance of t he equipment. Some of these features are as follows:

a) Vent i la t ion. Provide adequate vent i la t ion to prevent t ransformer temperatures exceeding the values prescribed by the manufacture. Most of the electrical hea t losses must be removed by vent i la t ion ; on ly a minor par t can be d i s s ipa t ed by the vaul t walls. Some electrical codes recommend 20 square centimetres of clear g ra t ing area p e r k i lovol t - ampere of transformer capacity. In l o c a l i t i e s w i t h above-average temperatures, such as t rop ica l o r sub t rop ica l a r eas , t he g ra t ing area should be increased or supplemented by forced vent i la t ion .

Access. Adequate access should be provided for repairs , maintenance, i n s t a l l a t i o n , and removal of equipment.

Drainage. All vauxts should be provided with drainage. When normal drainage is not possible, provide a sump p i t t o p e r m i t t h e u s e of a por tab le pump.

Security. Each e lec t r ica l vaul t should be equipped to de te r inadver ten t o r premeditated access by unauthorized persons. This secur i ty i s necessary to prevent interference with equipment operation and to protect those persons from possible electric shock. Some methods used



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- 5-1 4 Aerodrome Design Manual

are barred and screened windows, heavy-duty metal doors with padlocks, and securi ty fencing.

Vaul t l ight ing. Electrical vaul t s should be well i l l u m i n a t e d f o r u s e e i t h e r day o r n i g h t . T h i s l i g h t i n g i s usual ly provided by i n t e r i o r l i g h t s of a s i ze , t ype , and l oca t ion t o p rov ide good v i s i b i l i t y i n a l l areas. Poor v i s i b i l i t y c a n i n c r e a s e t h e p o t e n t i a l f o r a c c i d e n t s r e s u l t i n g i n electrical shock or improper control and adjustments-

Local communications. Most e lectr ical vaul ts should be provided with convenient and re l iable comrmnicat ions to the control tower , o ther vau l t s , and pe rhaps o the r f ac i l i t i e s o r o f f i ces . Spec ia l t e l ephone o r i n t e r c o m n i c a t i o n s y s t e m s may avo id ou t s ide i n t e r f e rence w i th t hese c i rcu i t s , bu t o ther dependable a r rangements can be used .

Electrical conduits. Electrical vaul t s should be provided with a s u f f i c i e n t number of conduits and cable entrance accesses t o a v o i d later m o d i f i c a t i o n o f t h e s t r u c t u r e t o p e r m i t t h e i n s t a l l a t i o n o f a d d i t i o n a l i n p u t o r o u t p u t c i r c u i t s . These cables en t rances are usual ly through underground conduits which may be connected t o e x i s t i n g c a b l e d u c t s , d i rec t -bur ia l cab les , o r unused condui t s ava i lab le for fu ture expans ion . Unused conduits should be plugged, and conduits with cables should be sealed.

I n s t a l l a t i o n s of equipment . Arrange the equipment , especial ly the l a r g e r items such as r e g u l a t o r s , d i s t r i b u t i o n t r a n s f o r m e r s , c o n t r o l panels, and c i r cu i t s e l e c t o r o r c o n t r o l d e v i c e s , t o p r o v i d e a s imple , unc lu t t e red , uncrowded plan. This arrangement should consider safety, e spec ia l ly p ro t ec t ion f rom h igh vo l t age electrical connections, as w e l l as access t o t h e equipment and controls. The electrical c i r c u i t s s h o u l d a l s o be arranged i n a s imple pat tern wherever possible . Fol low the app l i cab le electric s a f e t y c o d e s f o r i n s t a l l i n g a l l electrical c i r c u i t s and controls.

2.5 DISTRIBUTION OF POWER

2.5.1 General

2.5.1.1 The equipment discussed i n t h i s s e c t i o n relates o n l y t o t h a t u s e d i n t r ansmi t t i ng electrical power f o r t h e aerodrome l igh t ing and r ad io nav iga t ion a ids between t h e main aerodrome subs t a t ion ( s ) and t he l i gh t ing vau l t s o r t he l oca l s i t e dis t r ibut ion t ransformers . Descr ipt ions of equipment are i n g e n e r a l terms of character- ist ics and needs and usually are n o t r e l a t e d t o s p e c i f i c t y p e s o r items of equipments. Types of equipment and number of devices w i l l vary great ly with the s ize and complexi ty of the aerodrome. Economics i s an impor t an t pa r t o f i n s t a l l a t ions , and only equipment w h i c h c o n t r i b u t e s t o p e r f o r m a n c e , s a f e t y , r e l i a b i l i t y , a n d i n t e g r i t y s h o u l d b e u s e d . The circui ts and equipment used should provide for a reasonable expansion of f a c i l i t i e s . E f f i c i e n t u s e of electrical power i s always a des i r ab le goa l , bu t t he power c o s t f o r aerodrome l ighting and r ad io nav iga t ion a ids i s u s u a l l y a r a t h e r small p a r t of t h e t o t a l aerodrome energy cost and should not be emphasized to the point of overly increasing in s t a l l a t ion cos t s o r o f d imin i sh ing pe r fo rmance , s a fe ty , o r r e l i ab i l i t y . Fo l low the l o c a l electrical safety codes.

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ICAO 9357 PART*5 ** 4 8 4 3 4 3 6 0039943 3b5 W

P a r t 5.- Electrical Systems 5-1 5 -

2.5.2 Primary power f eede r c i r cu i t s

2.5.2.1 Primary power is usually reduced i n v o l t a g e a t the main aerodrome subs ta t ion f o r d i s t r i b u t i o n on t h e aerodrome. For major aerodromes, t h i s power a t t h e f i r s t s t a g e may be a t an intermediate voltage (usually 5 000 t o 20 000 vo l t s ) , bu t fo r smaller, less complex aerodromes, t h i s power may be d i s t r ibu ted at a medium voltage (usually 1 000 t o 5 000 vo l t s ) . The d is tance and t o t a l l o a d on t h e c i r c u i t are impor t an t f ac to r s i n determining the vol tage level of t ransmission. For an intermediatevol tage dis t r ibut ion system, power i s o f t en run t o subs t a t ions nea r l a rge power usage areas where i t is reduced t o medium v o l t a g e f o r l o c a l d i s t r i b u t i o n . A combination of these voltage dis t r ibut ion systems may be used. Primary power is t ransmit ted f rom the main subs ta t ion t o t h e l o c a l s u b s t a t i o n o r d i s t r i b u t i o n sites usual ly as mult i -phase c i rcui ts by above ground (overhead) circuits, underground circuits, or a combination of t hese c i r cu i t s . Above ground c i r c u i t s are less e x p e n s i v e t o i n s t a l l and are usually used i f f e a s i b l e , bu t these c i rcu i t s may be more exposed t o damage and i n some areas are a hazard t o a i r c r a f t and create electromagnet ic interference for other 'equipment . Underground feeder cables are usua l ly i n s t a l l ed i n duc t s , bu t sometimes d i r e c t b u r i a l i s used. Each type of c i r c u i t , whether overhead o r underground, involves specific types of equipment and design.

2.5.3 Above-ground (overhead) primary distribution systems

2.5.3.1 The following factors should be considered in the design of an overhead power d i s t r i b u t i o n system:

2.5.4

a) Application. Use overhead d i s t r i b u t i o n i n l i e u of underground d i s t r ibu - t i o n wherever feasible.

b) Capaci ty . Provide for spare capaci ty in each port ion of t h e c i r c u i t . Peak loads do not relate d i r ec t ly t o spa re capac i ty .

c) Wire s ize . Select the wire s i z e i n accordance with the current-carrying capaci ty required and, where appl icable , the vol tage-drop l imitat ion.

Linevol tage regula tors

2.5.4.1 Regulators are used for cor rec t ion of l i n e v o l t a g e v a r i a t i o n s r e s u l t i n g f r o m changing loads o r u t i l i ty company input vol tage changes. Do not use these regulators to correct for excessive voltage drops. Booster transformers .which co r rec t fo r vo l t age drop should be used only i n rare instances as, i n most cases, correct design e l iminates excessive voltage drop.

a) Rating. Choose t h e r a t i n g of the regulat ing devices in accordance with t h e amount of regulation required.

b) Selection. Choose the type of regulators f rom f ixed capaci tors , switched capacitors, multistep (motor-driven tap changing) regulators, and induction (stepless voltage change) regulators.

c) Multistep or induction regulators. Provide l ine-drop compensation for automatic operation when these regulators are used on more than one source or when more than one regulator is used on a s i n g l e c i r c u i t .



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I C A O 9157 PARTU5 t t m 4 8 4 3 4 3 6 0019942 2TL


2.5.5 Power lines

2.5.5.1 Select the type of power l i nes i n acco rdance w i th the type o f c i r cu i t involved and the conditions to which i t is subjected from the following:

a) Open wire (bare or weatherproof) on i n s u l a t o r s .

b) Aerial cable , se l f -supported or supported by a h i g h s t r e n g t h steel (messenger) cable, consisting of insulated, bundled, single-conductor cable or multiple-conductor cable.

2.5.5.2 Line support materials:

a) Poles. Wood, concre te ( re inforced wi th p res t ress ing or pos t tensioning) , or metal (steel o r aluminum) may be used. Concrete or metal poles should be used only where they are more economical o r special considerat ions warrant their use .

b) Footings. Provide footings, or reinforcements of the pole but t -end, as required by foundation conditions.

c) Configuration. Armless cons t ruc t ion fo r aerial l i n e s is usua l ly less costly than crossarm construction and i t s use is preferred, as i s multi- conductor secondary cable with a la rge neut ra l conductor as the support- i n g member over individual supported conductors. Use crossarms mainly f o r equipment support .

d ) Guys and anchors. Provide guys and anchors t o support poles o r l i n e towers against horizontal unbalanced loads caused by angles , corners , and terminations of l ines and where required because of extreme wind loadings. Consul t manufacturers ' catalogues for types of ear th anchors and design data. Select equ ipmen t su i t ab le fo r t he pa r t i cu la r so i l conditions and the cons t ruc t ion method t o be used.

2.5.6 Conductors

2.5.6.1 Size l imitat ions. Limit the use of pole-line conductors in accordance with Table 2-2 for an economical system from the installation, operational, and maintenance points of view. Special ins tances may requi re l a rger conductors . In a l l instances be s u r e t h a t t h e t y p e and s i z e of conductors used provides adequate s t rength for the span lengths and loading conditions.

Table 2-2

Size

Not la rger than Not smaller than Conductor type

Copper . . . . . . 13.0 mm2 170 m2 Aluminum . . . . . . .

8.3 m 2 110 mm2



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ICAO 9157 PARTb5 bt m 4 B 4 1 4 1 b 0019943 138 m

Part 5.- E l e c t r i c a l Systems 5-1 7 -

2.5.6.2 Composition. Base wire s i z e on the ranges shown i n Table 2-2. Primary wire sizes usually should not be less than 13.0 nun2 copper o r 33.0 mm2 aluminum. For primary conductors, select from the following:

a ) Bare copper conductor, stranded or solid copper.

b) Bare aluminum-alloy conductor, stranded or solid aluminum-alloy.

c ) Bare aluminum conductor, steel reinforced.

d ) Bare high-strength all-aluminum alloy conductor.

2.5.6.3 Special conductors. In special instances, use of the following conductors may be appropriate for primary conductors:

a) Insulated conductor, copper or aluminum, preassembled non-metallic- sheathed or metallic-sheathed, steel-cable-supported (messenger- supported) aerial cable is used where necessary to avoid exposure to open wire hazards, for example, h i g h r e l i a b i l i t y service i n heavy storm areas.

b) Compound conductor materials such as copper-clad steel, aluminum-clad steel, galvanized stee1, o r bronze are used to provide high s t rength and corrosion resistance.

2.5.6.4 Dissimilar conductors. Where i t i s necessary to connect aluminum conductors t o copper conductors, appropriate connectors specifically designed for such use should be i n s t a l l e d i n accordance with the instructions of the manufacturer.

2.5.7 Insu la tors

2.5.7.1 Types of insu la tors . Select from the following list the type of i n su la to r to support bare o r weatherproof insulated conductors.

Suspension type, single or multiple.

Spool type.

Une-post type (one-piece porcelain on a b o l t f o r mounting on crossarms o r on a saddle on t h e s i d e of a pole).

Strain type (suspension uni ts wi th s t rength equal or exceeding tensi le s t rength of the conductor usually having one to three extra disk sec t ions and arcing horns or r ings) .

Pin type (porcelain, usually two o r more sepa ra t e she l l s cemented together, with an internal thread for screwing onto a wood or metal pin).

Combinations. Various t y p e s of i n su la to r s may be combined; f o r example, s t ra in type for anchor po les o r t e rmina t ions wi th e i ther p in o r l ine- pos t types for l ine insu la t ion . Une-pos t t y p e s are considered to be both less expensive and superior to pin types.



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I C A O 9357 . . .. P A R T f 5 f f 484L4Lb OOL9944 074

5-1 a - Aerodrome Design Manual

2.5.7.2 If overhead lines are used in location sensitive to electromagnetic interference, the insulators should be of a static-free type.

2.5.8 Lo cknu t s

2.5.8.1 Hardware components should be provided with locknuts to avoid loose connections which could cause static. Locknuts mst be threaded and of a type which will prevent loosening of the connection when wood members shrink.

2.5.9 Transformers

2.5.9.1 Mounting of transformers. Mount transformers on poles or at ground level. When sheet metal enclosures are not tamperproof. ground mounted units should be provided with a fenced enclosure. A concrete or-brick structure should be used where adverse weather conditions make such an installation advisable.

a) Single-pole mounting. For single-pole mounting, limit the size of single-phase or three-phase units in accordance with approved practices.

b) Pole-platform mounting. Pole-platform mounting (two-pole structures) should not be used, except in instances where other methods are not satisfactory. For installations of 225 or 500 kilovolt-ampers, pad-mounted compartmental-type transformers become an attractive economic alternative to pole-mounted units.

c) Ground mounting. For ground mounting on a concrete base, there is no kilovoltampere limit. Usually tamperproof transformers (classified as pad-mounted compartmental-type units) should not be specified for ratings of over 500 kilovolt-amperes.

2.5.9.2 Ratings. Select transformers with standard kilovoltampere ratings and input and output voltage as single-phase or three-phase units. Transformers with input voltage taps for selecting the most suitable input voltage level may be desirable for some installations.

2.5.9.3 Indoor installations. Oil-immersed (flammable) transformers should not be installed indoors except in vaults conforming to the requirements of the applicable electric code. Such vaults should be provided only when other types of transformers are less economical or are prohibited by special considerations. Where such a vault is not provided, select transformers for indoor installation from the following:

a) high-fire-point , liquid-immersed; b) dry-type, ventilated;

c) dry-type, sealed tank; and

d) nonhazardous gas-insulated.

2.5.9.4 Toxic insulation fluids. The transformers should not use poly-chlorinated biphenyl (PCB) or other highly toxic insulation fluids. Leakage or mishandling of these chemicals during maintenance testing can be hazardous to personnel.



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I Part 5.- Electrical Systems 5.-19 -

I a 2.5.10 Capacitors

2.5.10.1 Types of capacitors. U s e shunt capac i tors to improve the power f a c t o r of the load carried by t h e c i r c u i t . In applying capacitors, consider the following:

a) Fixed capacitance. Fixed capacitance is t h e amount of capac i tance tha t can be applied continuously without excessive voltage rise a t reduced load.

b) Switched capacitance. Switched capacitance is an addi t iona l amount of capacitance that can be applied, i f p rov i s ion is made to swi t ch o f f t h i s addi t iona l amount a t reduced demand.

c) Capacitor switching. Select a type of capacitor switching that i s su i t ab le fo r t he cond i t ion a t hand. Possible choices include remote cont ro l of the capacitor-switching device, t ime-clock control, power- f ac to r r e l ay con t ro l o r vo l t age - sens i t i ve r e l ay con t ro l .

2*5.10.2 Location of capac i to r s . I n s t a l l c apac i to r s i n banks on poles, at ground l e v e l , o r i n a subs ta t ion as near ly as poss ib l e t o t he cen t ro id of the area where correct ion is required.

2.5.11 Ci rcu i t in te r rupt ion devices

2.5.11.1 Fuses. After consideration of the necessary current-carrying capaci t ies , in te r rupt ing du t ies , and time-current melting and c lear ing characteristics, select fuses from the following types: a

a) open f u s i b l e l i n k ;

b) expulsion type;

I c) boric-acid type; and

d) current-l imiting type

2.5.11.2 Ci rcu i t b reakers . Coard ina te the c i rcu i t b reaker ra t ing wi th the load '

in te r rupt ing du ty and wi th c i r cu i t b reake r s and fuses ahead of o r after t h e c i r c u i t breaker.

2.5.11.3 Automatic c i r c u i t r e c l o s e r s . U s e of au tomat ic rec losers for o ther than overhead l i n e l o a d s may cause problems from high-resistance ground faults. If an automatic c i r c u i t r e c l o s e r i s used , cons ide r t he r e l i ab i l i t y and continuity requirements of the service. Reclosers may cons i s t of a circuit-breaker or multiple switching devices. Reclosers operate s o t h a t a f a u l t e d c i r c u i t may be opened and then, e i ther instantane- ously or with del iberate time delay, reclosed. Up t o three reclosures with varying time in t e rva l s may be used. Co-ordinate automatic c i rcui t reclosers with fuses or c i rcui t breakers on t he same c i r c u i t .

2.5.11.4 Switches. Use swi tches to loca l ize defec t ive por t ions of aerial and underground c i r c u i t s and t o accomplish dead-circuit work. Select from one of the following pr incipal types:



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ICAO 9157 P A R T 8 5 X * 4 8 4 1 4 1 b 001994b 947


a) Nonload-break switches. Use nonload-b ' reak switches only for the inter- rup t ion o t c i r c u i t s tha t c a r r y no apprec iab le load . Select the t ype appl icable , depending on c i r cu i t impor t ance , l oad , vo l t age , and f au l t c i r c u i t d u t y . The types ava i lab le are porce l a in d i sconnec t fu se c u t o u t s , p l a i n o r f u s e d s i n g l e - p o l e a i r disconnect. switches, and disconnect fuse cutouts of var ious types. Msconmect ing and horn-gap switches may a l so be used as nonload-break switches.

b) Load-break switches. had-break switches are provided wi th an in te r - rupt ing device capable of disconnect ing c i rcui ts under load. Fuse cutouts, which are des igned to be load-break and load- in te r rupter switches, are ava i l ab le . Vacuum switches also provide load-break capab i l i t y .

2.5.12 , Lightn ing pro tec t ion

2.5.12.1 To determine the requirements for l i gh tn ing p ro t ec t ion , cons ide r .ove rhead ground wire, open or expuls ion gaps , and d i s t r ibu t ion- type surge ( l igh tn ing) arresters. The weather should a lso be considered. Protect ion for l ightning-induced surges may be unnecessary in areas where annual l ightning storms are few. Adminis t ra t ive po l icy or l o c a l electric power company prac t ice should usua l ly be fo l lowed. Select the p rope r a r r e s t e r in accordance wi th the chosen bas ic impulse insu la t ion leve l for which the c i r c u i t must be b u i l t .

2.5.13 Clearances

2.5.13.1 Provide the necessary hor izonta l and ver t ica l c learances f rom ad jacent phys i ca l ob jec t s , such as bu i ld ings , s t ruc tu res , and o the r electric l i n e s , as requ i r ed by t h e a p p l i c a b l e electrical safety code. Provide against cont ingency interferences, such as broken poles , broken crossarm, and.broken c i rcui t conductors . Provide for c learance condi t ions a r i s ing f rom mul t ipurpose jo in t use of poles. See t h e a p p l i c a b l e electrical sa fe ty code fo r c l imb ing space c l ea rances , j o in t u se , and supply conductor protect ion.

2.5.1.4 Grounding

2.5.14.1 For information on grounding of overhead dis t r ibut ion systems, use the app l i cab le electrical safe ty code or Adminis t ra t ive po l icy . For sa fe ty p rovide g round- i n g € o r a l l equipment and s t ructures associated with electrical systems to prevent shock from s ta t ic o r dynamic vol tages . Maximum ground resistance should not exceed values s p e c i f i e d i n t h e a p p l i c a b l e electrical safety code. Consider the source of electric power, capac i ty , magni tude o f fau l t cur ren t , and method of system grounding, as they affect t h i s r e s i s t a n c e .

2.5.14.2 Ground rods. Ground rods may b e u s e d e i t h e r s i n g l y o r i n c l u s t e r s . D r i v e the ground rods to ground water l e v e l f o r a n e f f e c t i v e a n d permanent i n s t a l l a t i o n . Provide €or corrosion prevention by a proper choice of metals o r by ca thod ic p ro t ec t ion . Where ground water cannot be reached, chemtcals such as magnesium su lpha te (MgS04,) o r copper sulphate (CuS04) may be used t o improve s o i l c o n d u c t i v i t y where necessary. Manu- facturers of ground rods can provide data on such treatment. Provide for easy maintenance and periodic testing. Although driving ground rods deeper (sectional type) may be more e f f ec t ive t han mu l t ip l e rods , in many cases, s o i l v a r i a t i o n s a n d p o s s i b l e b e d r o c k may make provis ion of add i t iona l rods less expensive.



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ICAO 9357 PART85 $8 = 484143b 0039947 883 W

Part 5.- Electrical Systems 5.-2 1 -

2.5.14.3 Grounding network. A buried network of ground conductors w i l l assure an e f f ec t ive s a fe ty ground i n poor s o i l and w i l l e l iminate large vol tage gradients a t s u b s t a t i o n s f o r u t i l i t y aerodrome interconnections. Mesh spacings of 3 t o 3.5 metres are commonly used and usually such spacings can control surface voltage gradients even though the ground resistance may be re la t ive ly h igh .

2.5.14.4 Water pipe connections. The electrical system may be grounded t o a water Supply system except where nonmetallic pipes, cathodically protected metallic pipes , or insulat ing coupl ings are inco rpora t ed i n t he water pipe system. The water pipe connec- t ion should be supplemented by other grounding electrodes where required by the appl icable electrical sa fe ty code.

2.5.14.5 Combination of grounding methods. Where t h e ground resistance i n a n existing system i s high, two or more of the aforementioned methods may be combined t o e f f e c t improvement.

2.5.14.6 Ground connections. Wires running from protective devices (for example, gaps, grading rings, expulsion or protection tubes, and surge arresters) t o ground should be kept as straight: and shor t as possible. Where bends are necessary they should be of l a r g e r a d i i t o keep the surge impedance as low as possible.

2.5.14.7 Overhead ground w i r e s . Where overhead ground wires are used for p ro tec t ion o f e l e c t r i c l i n e s , a ground connection should be provided a t the base of each pole from the overhead ground wire t o a wire loop or a ground p l a t e o r t o a driven rod, depending on the ex i s t ing so i l cond i t ions . Use of wire wraps o r po le bu t t p l a t e s i s allowed only i n areas of very low s o i l r e s i s t i v i t y .

2.5.14.8 Measurement of ground resis tance. Two methods of measuring ground res i s tance are:

a) Three-electrode method. In the th ree-e lec t rode method, two test elec- t rodes are used t o measure res i s tance of the th i rd e lec t rode , the ground point. A self-contained source of a l t e rna t ing cu r ren t and a ba t t e ry operated vibrator source equipment providing d i rec t read ings are available.

b) Fall-of-potential method. The f a l l a f - p o t e n t i a l method involves an ' ungrounded a l te rna t ing cur ren t source which c i r c u l a t e s a measured c u r r e n t t o ground. Voltage readings taken, of the connection to auxiliary grounds, al low use of Ohm's l a w to determine the ground resis tance.

2.5.15 Underground dis t r ibut ion systems

2.5.15.1 Primary power d i s t r i b u t i o n c i r c u i t s i n c e r t a i n a r e a s on and near aerodromes must be i n s t a l l e d underground. Although underground ins t a l l a t ions cos t more than overhead systems, radio interference problem6 o r t h e p r o x i m i t y o f t h e l i g h t i n g f a c i l i t i e s t o a reas of aircraft operat ions of ten ' requires the use of underground dis t r ibut ion systems. Underground c i r c u i t s may be i n s t a l l e d by d i r e c t b u r i a l o r by the pull-in method (pul l ing the cables through conduits) . Direct bu r i a l of d i s t r i b u t i o n c i r c u i t s i s usual ly less cos t ly than ins ta l la t ion in duc ts (pu l l - in method), but because of the poorer protec- t i on , d i r ec t bu r i a l is usually used only for small loads where re l iab i l i ty requi rements



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5-2 2 Aerodrome Design Manual -

are low. Medium-voltage direct burial cable should be provided with a metal armor covering or shield for protection against mechanical injury. Where corrosion resistance i s important, armored cables may require a plastic or syntheticrubber jacket over the armor. The underground distribution circuits used for aerodrome lighting and radio navigation facilities are pull-in circuits.

2.5.15.2 Details of the installation of underground distribution systems are given in Chapter 4 , and characteristics of cable suitable €or underground service are given in Chapter 5.



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3.1.1

ICAO 7157 PART*5 ** - 4B4L~Lb 0039949 656 -

CHAPTER3

EIzclRIcAL CIRCUITS FOB& liEwDMw LIGHTIHG'd#DRADI0rWIGATIoI!IAIDS

3.1 TYPES QF ELECTRICAL CIRCUITS

Electrical characteristics - --

3.1.1.1 Electrical power for aerodrome lighting aids is almost entirely alternating current (ac). (Some control circuits are direct current (dc) and energy for starting secondary power engines or for some uninterruptible power systems is stored in batteries.) This alternating current is usually 50 to 60 hertz. Both series and parallel circuits are used in these lighting installations. Most of the aerodrome lights are energized by series circuits, but the incoming power is distributed by parallel circuits, and some single units or shorter circuits of lights may'be energized by parallel circuits. Sequence-flashing lights of approach lighting systems, some floodlights, and some obstacle lights are the more important lighting systems using parallel circuits.

3.1.2 Series circuits

3.1.2,1 The circuit elements of serFes circuits are connected in a string with the same current flowing in each element. The circuit is one continuous loop starting and ending at the input power source. If a fixed input voltage were connected to the load, the current in the circuit would vary with the connected load; however, constant-current regulators will maintain a constant current independent of the load on the circuit. Thus the same current will flow in a long circuit as in a shorter circuit and will remain the same even if some of the lamps fail. This constant current means that a short-circuit across the output of a constant-current regulator is a no-load condition and an open-circuit is an overload. In a simple direct-connected series circuit, a lamp failure causes an open-ciruit; hence, it it necessary to provide a by-pass device, such as a fused film cutout or an isolating transformer , as part of each lighting fixture. Isolating transformers are preferred for aerodrome lighting circuits.

3.1.2.2 Advantages of series lighting circuits. Some of the advantages of series circuits for aerodrome lighting are:

a) all lamps are operating at the same current and thus at the same intensity. This uniform intensity and appearance of the lamps are helpful;

. . b) a single-conductor cable of one conductor size and insulation voltage

rating can be used throughout the circuit;

c) intensity control of the lights can be obtained over a wide range;

d) the circuit may have a single ground fault at any point along the circuit without affecting the operation of the lights; and

e) ground faults are easy to locate.

3.1.2.3 Disadvantages of series lighting circuits. The major disadvantages of series circuits when used for lighting are:

5-23



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I C A O 9357 P A R T M S ** m 484343b 0039950 378 m


a) i n s t a l l a t i o n c o s t s are h igh - the cons tan t -cur ren t regula tor and the i so l a t ing t r ans fo rmers o r by -pass dev ices add apprec i ab ly t o t h i s cos t ;

b ) poor e f f ic iency , p r imar i ly of the moving-coi l type constant-current r e g u l a t o r , i n u s e of electrical power;

c) a l l components - cable , i so la t ing t ransformers and lamp socke t s - must be i n s u l a t e d f o r f u l l v o l t a g e i f i s o l a t i n g t r a n s f o r m e r s are not used;

d) an open-c i rcu i t fau l t anywhere i n t h e c i r c u i t makes t h e e n t i r e c i r c u i t inoperat ive and possibly may damage the c a b l e i n s u l a t i o n o r t h e constant-current regulator ; and

e ) l o c a t i o n of f a u l t s , e s p e c i a l l y o p e n - c i r c u i t f a u l t s , may b e d i f f i c u l t

3.1.3 P a r a l l e l c i r c u i t s

3.1.3.1 The c i r c u i t e l e m e n t s o f p a r a l l e l ( m u l t i p l e ) c i r c u i t s are connected in para l l e l ac ross t he conduc to r s t o wh ich t he i npu t vo l t age is applied. In theo ry t he same vo l t age i s a p p l i e d t o e a c h l i g h t ; however, the cur ren t th rough the conductors causes a d e c r e a s e i n v o l t a g e ( l i n e d r o p ) w h i c h f o r l o n g e r c i r c u i t s may reduce appreci- ab ly t he vo l t age t o , and consequen t ly t he i n t ens i ty of, t h e l i g h t s a t t h e f a r end of the c i r c u i t . In d i s t r i b u t i o n c i r c u i t s where t h e v o l t a g e may be high and the current low, t h e v o l t a g e d r o p i n t h e l i n e s is less impor tan t , and para l le l circuits are o f t en u sed f o r s u c h c i r c u i t s . If i n t e n s i t y c o n t r o l o f t h e l i g h t s i s required, tapped transformers of i n d u c t i o n v o l t a g e r e g u l a t o r s may be u sed , bu t t hese i nc rease t he cos t o f t he i n s t a l l - a t i o n and reduce the e f f ic iency of t h e c i r c u i t .

3.1.3.2 Advantages of p a r a l l e l l i g h t i n g circuits. Some of the advantages of p a r a l l e l c i r c u i t s f o r aerodrome l i g h t i n g are:

a j lower c o s t of t h e i n s t a k l a t i o n , e s p e c i a l l y i f v o l t a g e r e g u l a t i o n a n d . i n t e n s i t y c o n t r o l are not requi red ;

b) more e f f i c i e n t u t i l i z a t i o n of electrical power;

c) e a s y t o a d d t o o r r e d u c e a n e x i s t i n g c i r c u i t ;

d ) t h e c i r c u i t s are more f a m i l i a r t o most people;

e) c a b l e f a u l t s , e s p e c i a l l y o p e n - c i r c u i t f a u l t s , may be easier t o l o c a t e ;

f) an open-circui t may n o t d i s a b l e the e n t i r e c i r c u i t ; a n d

g) these c i rcu i t s do no t need by-pass devices and may n o t n e e d i s o l a t i n g transformers .

3.1 .3 .3 Disadvantages of p a r a l l e l l i g h t i n g c i r c u i t s . Some of the major disadvant- a g e s o f p a r a l l e l c i r c u i t s f o r a e r o d r o m e l i g h t i n g are:

a) t h e i n t e n s i t y of t h e l i g h t s d e c r e a s e s w i t h l i n e d r o p a l o n g t h e c i r c u i t . This may be mis in t e rp re t ed i f i t is no t i ceab le in a p a t t e r n of l i g h t s ;



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I C A O 9357 P A R T * 5 ** 48434Lb 0019953 204

P a r t 5.- Electrical Systems 5-25 -

b) two conductors are requi red a long the comple te c i rcu i t , and la rger conductors may be needed to reduce the l ine vo l tage d rop;

c) lamp f i laments are usual ly longer which may r equ i r e l a rge r op t i c s and l a r g e r l i g h t f i x t u r e s ;

d ) i n t e n s i t y c o n t r o l , e s p e c i a l l y a t t h e l o w e r i n t e n s i t i e s , i s more d i f f i - c u l t t o furnish accurately, or the equipment cost adds appreciably to t h e i n s t a l l a t i o n c o s t ;

e) a s ingle g round fau l t on the h igh-vol tage feeder w i l l d i s a b l e t h e c i r c u i t s ; and

f ) ground f a u l t s are d i f f i c u l t t o l o c a t e .

3.1.4 Comparison of series and p a r a l l e l l i g h t i n g c i r c u i t s

3.1.4.1 Often acceptable l ight ing can be provided by either series o r p a r a l l e l c i r c u i t s . Series c i r c u i t s are usually used for aerodrome l ighting systems where t h e pat tern provides guidance information because of the more un i fo rm in t ens i ty of the l i g h t s and b e t t e r i n t e n s i t y c o n t r o l . Such systems include most runway and taxiway l i g h t s and most steady-burning l ights of approach l ight ing systems. Parallel c i r c u i t s are used fo r most area i l l umina t ion , i nd iv idua l o r small numbers of v i s u a l a i d s , and power d i s t r i b u t i o n . Aerodrome l i g h t i n g s y s t e m s u s u a l l y u s i n g p a r a l l e l c i r c u i t s are apron f loodl ight ing , o ther apron l igh ts , sequence- f lash ing l igh ts , spec ia l purpose v i sua l a id s such as beacons and wind d i r e c t i o n i n d i c a t o r s , some o b s t a c l e l i g h t s a n d e l e c t r i c a l d i s t r i b u t i o n c i r c u i t s .

3.2 SERIES CIRCUITRY FOR AERODROME LIGHTING

3.2.1 Factors to be considered

3.2.1.1 I f a series c i r c u i t is t o be used , cer ta in op t ions on t h e equipment t o b e used should be evaluated. Often when one choice i s made it reduces the opt ions of o ther equipment. F i r s t , the comple te c i rcu i t should be ana lysed for c r i t i ca l performance, r e l i a b i l i t y , econouy of i n s t a l l a t ions and ope ra t ions , ease of maintenance, and how t h e several types o f equipment are i n t e r r e l a t e d . Some o p t i o n a l f a c t o r s are the fo l lowing item . 3.2.1.2 Choice of current. Equipment development has l imited the available options of c u r r e n t t o b e u s e d i n a p a r t i c u l a r series c i r c u i t . Most aerodrome l ighting series c i r c u i t s are e i t h e r 6.6 o r 20 amperes a t r a t e d f u l l i n t e n s i t y , a l t h o u g h o t h e r c u r r e n t s are sometimes used. The l ine power l o s s f o r a fixed cable conductor and l e n g t h f o r 6.6 ampere c i r c u i t s i s abou t one -n in th t ha t fo r 20 ampere c i r c u i t s . Either value of cur ren t can be c a r r i e d i n 5 000 v o l t i n s u l a t i o n c a b l e by conductors of 4 rnm diameter without excessive temperature rise. The load on the regulator of series c i r cu i t s , shou ld be a t least one-half of i t s r a t ed capac i ty . 6.6 ampere c i r c u i t s are commonly used for long c i r c u i t s w i t h smaller electrical loads, and 20 ampere c i r c u i t s are used fo r l a rge r l oads and shor te r cab le l engths ( see paragraph 3.2.1.4 fo r r egu la to r capac i t i e s . ) Runway edge l i g h t s and taxiway edge l ights are usua l ly 6 .6 ampere c i rcu i t s , and approach l igh ts and touchdown zone l i g h t s are o f t e n 20 ampere c i r c u i t s . Runway c e n t r e l i n e and taxiway c e n t r e l i n e l i g h t s may b e e i t h e r 6.6 ampere o r 20 ampere c i r c u i t s . Note t h a t t h e cir-



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5-2 6 Aerodrome Design Manual - -

c u i t c u r r e n t i s not necessar i ly de te rmined by t h e c u r r e n t of t h e lamps i n t h e f i x t u r e s . For example by s e l e c t i n g t h e i s o l a t i n g t r a n s f o r m e r s p r o p e r l y , 6.6 ampere lamps can be used on 20 ampere c i r c u i t s and 20 ampere lamps on 4.6 ampere c i r c u i t s o r c o m b i n a t i o n s o f lamp currents can be used on e i t h e r c i r c u i t .

3.2.1.3 Aerodrome l i g h t i n g c i r c u i t s . The prefer red a r rangement for aerodrome l igh t - i n g circuits i s a number of h igh voltage series c i r c u i t l o o p s w i t h a series i s o l a t i n g t r a n s f o r m e r f o r each f i t t i n g , a n d each circuit f e d f r o m a n electrical supp ly subs t a t ion a d j a c e n t t o t h e runway end. One s u b s t a t i o n p e r runway end i s p r e f e r r e d f o r a l l aerodromes *

a ) 8.2 of Annex 14 s p e c i f i e s that f o r a precis ion approach runway the electrical c i r c u i t s b e d e s i g n e d so t h a t t h e f a i l u r e of one c i rcu i t w i l l n o t l e a v e t h e p i l o t w i t h o u t v i s u a l g u i d a n c e a n d w i l l n o t r e s u l t in a mis leading pa t te rn .

b) Approach and runway lighting systems. Every approach and runway l i g h t - ing system should be inter leaved over a t least two c i r c u i t s . Examples of c i r c u i t i n t e r l e a v i n g t o i m p r o v e i n t e g r i t y are shown i n F i g u r e s 3-1 t o 3-7. Each c i r c u i t i n an in te r leaved se rv ice should ex tend th roughout the whole of t h a t s e r v i c e a n d b e so a r r a n g e d t h a t a balanced symmetrical l i g h t i n g p a t t e r n r e m a i n s i n t h e e v e n t of f a i l u r e o f o n e o r more of t h e C i rcu i t s . Thresho ld l i gh t s are u s u a l l y on s e p a r a t e c i r c u i t s . Runway c e n t r e l i n e l i g h t s mus t be i n t e r l eaved i n a way t h a t w i l l no t des t roy t h e c o l o u r c o d i n g o f t h e s e l i g h t s . S e c t i o n s o f t h e c e n t r e l i n e s y s t e m c o n s i s t i n g of w h i t e l i g h t s o n l y a n d o f r e d l i g h t s o n l y may be i n t e r - leaved as shown on Figure 3-5a. Annex 1 4 r e q u i r e s t h e c e n t r e l i n e l i g h t s i n t h e s e c t i o n of t h e runway f rom the po in t 900 m from the runway end (or from the midpoint of t h e runway f o r runways less than 1 800 m i n l eng th ) t o t he po in t 300 m f rom the runway e n d b e a l t e r n a t e l y v a r i a b l e w h i t e a n d r e d l i g h t s e x c e p t t h a t f o r runway c e n t r e l i n e l i g h t s s p a c e d a t 7.5 m a l t e r n a t e p a i r o f va r i ab le wh i t e and r ed l i gh t s are requi red . Examples of c i r c u i t i n t e r l e a v i n g w h i c h w i l l ma in ta in t he r equ i r ed co lou r coding are shown i n F i g u r e s 3-5b and 3-5c. When o n e c i r c u i t f a i l s w h e r e t h e p a t t e r n o f l i g h t s a n d i n t e r l e a v i n g are as shown i n F i g u r e 3-5c, a p a t t e r n of a l t e rna t ing r ed and wh i t e l i gh t s un i fo rmly spaced a t twice the no rma l i n t e rva l w i l l show. This spacing is t h e same as tha t of t h e a l l white and a l l r e d s e c t i o n s when o n e c i r c u i t f a i l s . Wi th t he pa t t e rn of l i g h t s a n d i n t e r l e a v i n g shown i n F i g u r e 3-5b, t he spac ing would be a l t e r n a t e l y t h r e e times the normal interval and then the normal i n t e r v a l .

C) Visual approach s lope indicator systems. Visual approach s lope indica- to r sys tems should have two c i rcu i t s per runway end. When a v i s u a l approach s lope ind ica tor sys tem i s a VASIS, 3-BAR VASIS, o r T-VASIS, power t o a l l l i g h t u n i t s on one s ide o f t he runway should be supplied by t h e same c i r c u i t . T h i s a r r a n g e m e n t e n s u r e s t h a t s h o u l d o n e c i r c u i t f a i l a comple te pa t te rn w i l l be re ta ined on t h e o t h e r s i d e o f t h e runway. When approach s lope i nd ica to r s are i n s t a l l e d on on ly one s ide of t h e runway as w i t h t h e PAPI, t h e AVASIS, t h e 3-BAR AVASIS, and t h e AT-VASIS, p a r t of t h e lamps i n e a c h l i g h t u n i t s h o u l d b e c o n n e c t e d t o o n e c i r c u i t a n d t h e r e m a i n d e r t o t h e o t h e r c i r c u i t i n o r d e r t o m a i n t a i n t h e i n t e g r i t y of t he pa t t e rn , bu t w i th r educed i n t ens i ty . V i sua l app roach s l o p e i n d i c a t o r s y s t e m s h o u l d b e d e e n e r g i z e d when a mis leading s igna l r e s u l t s f r o m t h e f a i l u r e of a l i g h t u n i t .



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ICAO 9157 PART*S ** 48V343b 0039953 087

P a r t 5.- Electrical Systems 5 -2L

Taxiway l igh t ing . Taxiway l ight ing should be designed for series c i r c u i t s . Taxiway c e n t r e l i n e l i g h t i n g c i r c u i t s s h o u l d b e i n t e r l e a v e d as shown i n Figure 3-Sa on those p a r t s of the taxiway system that are used i n Category I11 condi t ions, but for economic reasons a s i n g l e c i r c u i t may be used for other taxiways. Taxiway l igh t ing should be c i r cu i t ed t o pe rmi t s e l ec t ive l i gh t ing of segments of the sys tem to provide rou te gu idance to p i lo t s . This c a p a b i l i t y may be obtained by using an individual constant-current regulator for each segment o r by connecting several segments to a s ing le r egu la to r and us ing se lec tor r e l a y s , e i t h e r i n t h e f i e l d o r a t t he r egu la to r , t o sho r t - c i r cu i t t hose segments which are no t pa r t of the rou te . Note t h a t t h e v o l t a g e r a t i n g of t h e s e l e c t o r r e l a y s must be higher than the open-circuit voltage of the regulator . Select ive switching may be obtained i n s e v e r a l ways. Among these are:

1) t h e u s e of a control switch for each segment. The prefer red loca t ion of such switches i s on a facsimile diagram on the control p a n e l i n t h e c o n t r o l tower with each switch loca ted on t he segment which it controls ;

2 ) interconnect ing the controls which energize the regulators or s e l e c t o r r e l a y so tha t ac tua t ing a s ingle swi tch w i l l cause a l l segments on a designated-route to be l ighted; and

3) using a minicomputer programmed t o l i g h t t h e optimum r o u t e a f t e r t h e operator designates the runway e x i t t o be used and the des t ina t ion of t h e a i r c r a f t .

Stop bars. Stop bars rmst be controlled independently of each other and of the taxiway l ights . The electrical c i r cu i t s shou ld be designed so t h a t a l l of t h e l i g h t s of a s top bar will n o t f a i l a t t h e same time. The l i g h t s of a s top bar should be inter leaved. They may be supplied by two separate c i r c u i t s or from two common c i r c u i t s w i t h c o n t r o l r e l a y s loca ted ad jacent to the s top bar . S top bars may be connected into in te r leaved runway or taxiway l ighting systems with each stop bar cont ro l led by r e l ays which shor t - c i r cu i t t he l i gh t s of t he s top ba r when it is des i red to deenerg ize the bar . In o rder to reduce the vo l tage requirements of t hese r e l ays , l i gh t s of the stop bar should be connected i n t o a runway o r tax iway l igh t ing c i rcu i t th rough an i so la t ing transformer of su i tab le capac i ty wi th the shor t -c i rcu i t ing re lay connected across the secondary of t he i so l a t ing t r ans fo rmer . The appl icable runway o r t ax iway l i gh t ing c i r cu i t must be energized whenever the use of a s top ba r i s required. The re lays cont ro l l ing a s top bar must be s o connected that the appl icat ion of control power i s required t o t u r n t h e s t o p b a r o f f . Thus the s top ba r w i l l be l ighted if t h e c o n t r o l c i r c u i t s h o u l d f a i l .

Grounding. All t h e equipment in the cont ro l !d is t r ibu t ion cen t re should be bonded t o ea r th . A ground w i r e (counterpoise) should also ‘ne run from the d i s t r ibu t ion cen t r e s w i th t he series c i r c u i t c a b l e s . The secondary s ide of a l l isolat ing t ransformers and the supports of a l l e leva ted l igh ts should be connec ted to th i s wire. The ground wire should be pos i t i oned above t he c i r cu i t c ab le s i n a conduit nearer the s u r f a c e o r i n t h e same trench not less than 10 c m above the top cable . Usually uninsulated conductors are used as ground wires.



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ICAO 9357 P A R T * 5 ** 4843YLb 0039954 T13 = - 5-2 8 Aerodrome Design Manual

. -. I R I

f) I 1 9

I

R R I R R

I o 0

L R Q 5) R R R

0 CIRCUIT 1 0 CIRCUIT 2 P R F I I R R R x 2

Figure 3-1. Precision approach lighting system type A (system with distance coded centre l ine)



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I C A O 9357 PART*5 ** = 484343b 0039955 95T

Part 5.- Electrical Systems 5-2 9 -

0 CIRCUIT 3 Ct RCUlT 4

Figure 3-2. Supplementary l ighting t o expand a precision approach l ighting

approach category I1 and I11 l ighting system system type A (system with distance coded centre line) t o a precision



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I C A O 9157 PART*5 M t W 484141b 003995b 896

I RUNWAY THRESHOLD I

qx2

.x 1 x 2

OPTION A. INTERLEAVING BY ALTERNATING BARRETTES

Figure 3-3. Precision approach lighting system type B (system with barrette centre l ine)



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ICAO 9357 PART*5 ** 484543b ClO3995’7 ’722

P a r t 5,- E l e c t r i c a l S y s t e m s 5-3 1 -

RUNWAY THRESHOLD

0 CIRCUIT 1 CIRCUIT 2

x 2 x 1

OPTION B. INTERLEAVING BY ALTERNATING LIGHTS I N EACH BARRETTE TO PROVIDE SIMILAR APPEARANCE IN ELTH SINGLE-CIRCUIT OPERATION

i

ER

F i g u r e 3-3. P r e c i s i o n a p p r o a c h l ight ing s y s t e m t y p e B ( s y s t e m w i t h barrette centre l ine )



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I C A O 91157 PART*5 ** m YBY34Lb 0039958 669 m

5-32 ~ - Aerodrome Design Manual

RUNWAY THRESHOLD D

0 CIRCUIT 1 CIRCUIT 2

OPTION C. INTERLEAVING BY ALTERNATING LIGHTS IN EACH BARRETTE WITH ALL STATION ALIKE IN ANY OPERATING CIRCUIT MODE

Figure 3-3. Precision approach lighting system type B (system with barrette centre line)



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RUNWAY THRESHOLD

2 I

PART OF CENTRE LINE LIGHTS OF PRECISION APPROACH

0 CIRCUIT 1 LIGHTING SYSTEM TYPE B

0 CIRCUIT 2

OPTION A. INTERLEAVING BY ALTERNATING BARRETTES

I RUNWAY THRESHOLD

0000.

0.000

00.0.

0.0.0

.0.0.

0.000

00.0.

PART OF CENTRE LINE LIGHTS OF PRECISION APPROACH

0 CIRCUIT 1 LIGHTING SYSTEM TYPE B

CIRCUIT 2

OPTION B. INTERLEAVING BY ALTERNATING LIGHTS IN EACH BARRETTE TO PROVIDE SIMILAR APPEARANCE FOR EITHER SINGLE-CIRCUIT OPERATION

Figure 3-4. Supplementary lighting to expand a precision approach lighting system type B (system with barrette centre line) to a precision approach

category I1 and I11 lighting system (Supplementary lighting for a system with distance coded centre line

is shown in Figure 3-2.)



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I C A O 9357 PART*5 *ct 484L4Lb 00L99b0 217


2 x- 2 x

x 1

Y

x 1 1

0 CIRCUIT 1

CIRCUIT 2

T x x 1 1

1- 0 WHITE LIGHT CIRCUIT 1

0 WHITE LIGHT CIRCUIT 2

CIRCUIT 1 RED LIGHT

RED LIGHT CIRCUIT 2

7- : X 1 2

B . INTERLEAVING I N SECTIONS CONSISTING OF ALTERNATING RED AND WHITE LIGHTS FOR LIGHT SPACINGS OF 15 AND 30 METERS

0 WHITE LIGHT CIRCUIT 1

WHITE LIGHT CIRCUIT 2

CIRCUIT 1 RED LIGHT

RED LIGHT CIRCUIT 2

A. INTERLEAVING IN SECTIONS IN WHICH ALL LIGHTS ARE OF THE SAME COLOUR

x x x x 1 1 2 2

C . INTERJLEAVING I N SECTIONS CONSISTING OF ALTERNATE TWO RED AND TWO WHITE LIGHTS FOR LIGHT SPACINGS OF 7 . 5 METERS

Figure 3-5. Runway or taxiway centre line lighting on two interleaved circuits



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. . . ~

Part 5. - Electrical Sys terns - .

5-3 5 -

1

0 CIRCUIT 1 0 CIRCUIT 2

Figure 3-6. Runway edge l ights on two interleaved series circuits



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ICAO 9357 P A R T * 5 ** = 484343b 0039962 09T


c + RUN WAY

O C I R C U I T 1 @ C I R C U I T 2

2 x L X

x 2 x 1

NOTE: When used i n con junc t ion w i th Type A prec i s ion app roach l i gh t i ng systems each barrette should have f o u r 1 i g h ts .

-

Figure 3-7. Touchdown zone l i g h t s on two interleaved series c ircui ts e



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P a r t 5.- E l e c t r i c a l Systems 5.-3 7 -

3.2.1.4 Constant-current regulators. The electrical power f o r most aerodrome ground

regula tors are designed to produce a constant-current output independent of va r i a t ions i n t h e c i r c u i t l o a d and i n t h e v o l t a g e of t he power source. They are also designed to provide two o r more output currents when dimming of t h e l i g h t s i s required. Some types of constant-current regulators used for aerodrome l i g h t i n g are as follows.

8 l i g h t i n g c i r c u i t s i s suppl ied by constant-current (ser ies c i rcui t ) regulators . These

a) Moving co i l r egu la to r s . Moving co i l r egu la to r s have been used f o r many years to supply power t o series l igh t ing c i r cu i t s . Th i s t ype r egu la to r has separate primary and secondary coils which are f r e e t o move with respect to each other, thus varying the magnetic leakage reactance of the input and output c i rcui ts . This reactance automatical ly adjusts i t s e l f t o a value which, when added t o t h e l o a d impedance, permits a constant current to f low. The des i red ou tput cur ren t sets up a fo rce of repuls ion which f loa ts the moving c o i l i n t h e p o s i t i o n which produces t h i s c u r r e n t . A state of mechanical equilibrium i s a t t a ined such t ha t t h e f o r c e of repulsion exactly balances the weight of t he moving co i l . Any change i n l o a d o r i n p u t v o l t a g e i s immediately counteracted by a movement of t he f l oa t ing co i l t o r e s to re t he mechan ica l electrical ba lance . In tens i ty cont ro l i s obtained through the use of a tapped transformer across the output of the regulator. The main disadvantages of moving c o i l r e g u l a t o r s are the mechanical movement of the coi ls and t h e low power f ac to r s fo r l oads less than rated load. For a load of 50 p e r cent of t he r a t ed l oad , t he power f a c t o r may be 75 p e r c e n t o r less. In addi t ion some moving c o i l r e g u l a t o r s must be p rec i se ly l eve l l ed and isolated f rom vibrat ion.

b) Monocyclic square regulators . One static type (no moving p a r t s ) cons tan t -cur ren t regula tor for series c i r c u i t s i s the monocvclic sauare regulator . The current regulat ing network usual ly consis ts-of two * inductive and two condensive reactors, each of. equal reactance (resonance) a t t h e power frequency, arranged i n a b r idge t ype c i r cu i t . With such a network, the secondary current is independent of the impedance of the load. Intensi ty control can be provided by a tapped input or ou tput t ransformer o r by continuously variable input transformer. The advantages of this type of regula tor are no moving p a r t s and high Power f ac to r . The disadvantages are lack of compensation f o r v a r i a t i o n s i n i n p u t v o l t a g e and adverse effects on the regulation caused by loads which cause high harmonic frequencies i n t h e r e s o n a n t c i r c u i t , s u c h as open-circuited secondaries of series i so l a t ing t r ans fo rmers and gaseous- vapour lamps.

c) Compensation s ta t ic- type regulators . By sensing the secondary current from the regulator, adjustment may be made i n the monocyclic square or i n t he cu r ren t - r egu la t ing network t o compensate f o r primary voltage va r i a t ions and f o r harmonic frequencies caused by open-circuited secondaries of isolating transformers. This compensation provides improved current regulat ion and prevents shortening of lamp l i f e from above ra ted secondary current.

d ) Sol id state control constant-current regulators . These regula tors use ac s o l i d s ta te c i r cu i t s fo r con t ro l l i ng t he t r ans fo rmer l eakage reactance. This technique permi ts the use of low con t ro l l eve l s t o ob ta in constant current from regulators with the electrical c h a r a c t e r i s t i c s of



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I C A O 9 3 5 7 PARTS5 ** m 484343b 00399bY 962 m

5-3 8 Aerodrome Design Manual - c o n s t a n t v o l t a g e , s e r i e s r e s o n a n t c i r c u i t s . T h e s e s o l i d s ta te c o n t r o l s p r o v i d e f a s t r e s p o n s e , h i g h power f a c t o r , compact r e g u l a t o r s w i t h e a s y maintenance of t h e r e g u l a t o r c o n t r o l s .

3.2.1.5 O p e r a t i n g c h a r a c t e r i s t i c s of cons tan t -cur ren t regula tors . Cons tan t -cur ren t regulators supply ing power t o aerodrome l igh t ing c i rcu i t s should have the fo l lowlng c a p a b i l i t i e s :

a) main ta in a cons t an t - cu r ren t ou tpu t w i th in k 2 per cen t fo r any l oad f rom one-half t o f u l l l o a d w i t h up t o 30 p e r c e n t of i s o l a t i n g t r a n s f o r m e r s having open-c i rcu i t secondar ies ;

b ) i n d i c a t e a g r o u n d i n g f a u l t o n t h e c i r c u i t w h i l e p e r m i t t i n g t h e c i r c u i t t o ope ra t e no rma l ly -when a s i n g l e g r o u n d f a u l t p r e v a i l s ;

c) have a high degree of r e l i a b i l i t y a n d t h e r e f o r e h a v e n o moving p a r t s ;

d ) i nco rpora t e an open-c i r cu i t dev ice wh ich l ocks ou t t he p r imary vo l t age w i t h i n two seconds and requi res rese t t ing o f the regula tor ;

e) respond t o c i rcui t changes within 15 cyc le s ;

f ) i n c o r p o r a t e a s e c u r i t y d e v i c e t h a t sets t h e r e g u l a t o r o u t of s e r v i c e o r a s s u r e s a r e d u c t i o n o f t h e c u r r e n t i n case of an over cur ren t ;

g ) p rov ide the requ i r ed number of i n t e n s i t y s e t t i n g s o r a cont inuous ly v a r i a b l e c o n t r o l as requi red . The regulator should be designed s o t h a t t he i n t ens i ty s e t t i ng can be changed w i thou t deene rg iz ing t he r egu la to r ;

h ) e l e c t r i c a l l y i s o l a t e t h e p r i m a r y power c i r c u i t f r o m t h e s e c o n d a r y l i g h t - i n g c i r c u i t ; and

i) opera te cont inuous ly a t fu l l l oad i n ambien t t empera tu res be tween -40% and +55OC and relative humidity between 10 and 100 per cen t and a t a l t i t u d e s u p t o 2 000 m.

3.2.1.6 Ra t inp cha rac t e r i s t i c s o f cons t an t - cu r ren t r egu la to r s . The fo l lowing are examples of r a t ing cha rac t e r i s t i c s o f cons t an t - cu r ren t r egu la to r s wh ich are a v a i l a b l e :

a) Power. Output (secondary) loads between 4 and 70 k i l o w a t t s . Many s i z e s i n t h i s r a n g e are a v a i l a b l e .

b) Secondary (output) current . 6.6 and 20 amperes are most common. Un i t s supplying 6.6 amperes f o r l o a d s up t o 30 ki lowat t s and 20 amperes f o r loads of 10 ki lowatts and more are of ten used .

Frequency. As required by the f requency 50 o r 60 he r t z .

of the primary power, u s u a l l y

d) Primary voltage. Rated primary voltages between 120 and 1 2 000 v o l t s have been used. Primary voltages of 240 v o l t s f o r s i z e s u p t o 30 ki lowat t s and 2 400 v o l t s f o r s i z e s of 10 t o 70 k i l o w a t t s are used by one State . Other pr imary vol tages may also be used.



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Part 5.- E l e c t r i c a l Systems 5-3 9 - 3.2.1.7 Isolat ing t ransformers . Most aerodrome l i g h t i n g c i r c u i t s u s e i s o l a t i n g transformers to provide continuity of t he series c i r c u i t so t h a t f a i l u r e of a lamp does not make an open-c i rcu i t fau l t . The second funct ion of i so la t ing t ransformers i s t o p r o v i d e e l e c t r i c a l i s o l a t i o n of t he lamp from the h igh vo l t age c i r cu i t fo r s a fe ty purposes. Circuit continuity can also be attained by using by-pass devices, such as f i lm cu touts , which shor t across the lamp when the lamp f a i l s , bu t i n t h i s a r r angemen t the lamp may be a t a h igh po ten t i a l when t h e c i r c u i t i s energized. Isolating transformers are used to p rovide the p roper cur ren t to the lamp i f t h e lamp c u r r e n t d i f f e r s from t h a t of t he series c i r c u i t .

a ) Transformer design. An i so la t ing t ransformer cons is t s of a primary and a secondary coi l wound on a magnetic core i n a waterproof case with primary and secondary leads for connecting the series c i r c u i t t o t h e lamp. The primary and secondary coils are i s o l a t e d e l e c t r i c a l l y b u t l inked by the magnet ic c i rcui t . The secondary c i rcu i t i s s u b j e c t e d t o a lesser e l e c t r i c a l p o t e n t i a l and one s i d e of the secondary should be brought out t o a grounding connection. The core of an i so la t ing t rans- f o r m r is magnetically unsaturated i n o p e r a t i o n b u t becomes s a t u r a t e d i f the lamp f a i l s o r t h e s e c o n d a r y c i r c u i t is open-circuited, thus main- t a i n i n g t h e i n t e g r i t y of t he primary c i r c u i t . If t h e lamp c i r c u i t should be short-circui ted, the isolat ing t ransformer would be i n a no- load condition and have minimum e f f e c t on the series c i r c u i t . These transformers should be capable of continuous operation a t ra ted load , open-circui t , or short-circui t wi thout damage. The t u r n s r a t i o of t he pr imary co i l to the secondary co i l of a series/series transformer is 1:l i f t h e lamp current i s the same a s t h e series c i rcu i t cur ren t bu t is inverse ly p ropor t iona l to the cur ren t ra t io o therwise .

b) Enclosure. The waterproof case for enclosing the core, windings, and leads may be of metal , rubber , or p last ic and should be s u i t a b l e f o r i n s t a l l i n g by direct burial , underwater, in bases, or exposured t o t h e weather. The case should protect the unit from damage i f the t ransformer is dropped o r i s car r ied by a s ing le l ead . The case should prevent water from entering through the case or where jo ined t o t he l eads , main ta in res i l ience to avoid sha t te r ing or damage a t very low tempera- tu res , and pro tec t the un i t dur ing handl ing , s torage , ins ta l l ing , and service. The primary leads should be not less than 8.4 mm2 i n s i z e and should be insulated for not less than 5 000 vo l t s . These leads should be not less than 50 c m long. Usually these leads will be provided with a plug type connector on one lead and a receptac le on the o ther su i tab le fo r connec t ing t o t he s e r i e s -c i r cu i t c ab le . The secondarq leads should be two-conductor with conductor size not less than 3.3 mm and insulated f o r n o t less than 600 v o l t s and have a length of no t less than 100 cm. Usually these leads are provided with a s u i t a b l e two-conductor connector f o r connec t ing to the l igh t .

c) Ambient temperature. These transformers should be capable of operat ing in t empera tures between -55OC and +65 OC.

d ) Series/series isolating transformer ratings. Ratings of i s o l a t i n g transformers are by output power, primary and secondary current, the frequency, and the insulation voltage of- primary and secondary circuits . These transformers may be eas i ly manufactured for a lmost any desired ra t ing . Some commonly ava i lab le ra t ings are as follows:



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- 5-40 Aerodrome Design Manual

1) Power. Ratings of 3 0 / 4 5 , 65, 100, 200, 300 and 500 watts are frequently used and sometimes 1 000 and 1 500 watt u n i t s are used.

2) Current . Current ra t ings are usua l ly g iven as a r a t i o of primary t o secondary current . Common c u r r e n t r a t i n g s are 6.6/6.6, 20/20, 6 . 6 / - 20 and 20/6.6 amperes.

3) F'requency. The common f requencies are 50 and 60 h e r t z . P r e f e r a b l y the transformer should be used on the f requency for which it was designed.

4 ) Insu la t ion . Most i s o l a t i n g t r a n s f o r m e r s are i n s u l a t e d f o r 5 000 v o l t s on the p r imary c i r cu i t and 600 v o l t s on the- secondary. Larger power s i z e s of t ransformers may r e q u i r e a h igher secondary insu la- t ion because of t he i r h ighe r open-c i r cu i t vo l t age .

e) Several lamps from a s ing le t r ans fo rmer . P re fe rab ly each l i gh t i s supp l i ed by i t s own i so la t ing t ransformer . Sometimes to reduce the i n s t a l l a t i o n c o s t s , s u c h as f o r i n s t a l l i n g c e n t r e l i n e l i g h t s on e x i s t - ing runways, or to reduce the mass and s t rength of cables , as f o r t a l l f rangib le approach l igh t suppor ts , severa l l amps may be connected i n a series across a s ing le i so l a t ing t r ans fo rmer . Of course the t ransformer must h a v e t h e c a p a c i t y t o s u p p l y t h e t o t a l l amp load p lus l ine losses . Two problems of this arrangement are: f i r s t , i f one lamp f a i l s c a u s i n g an open-c i rcu i t , the o ther l amps are inope ra t ive un le s s su i t ab le by -pass devices are used; and secondly, at t h e i n s t a n t of the open-circui t f a i lu re t he i n s t an taneous s econda ry vo l t age may become very g rea t e s p e c i a l l y f o r t h e l a r g e r s i z e s of i so l a t ing t r ans fo rmers . These problems are d iscussed below.

f ) E f fec t s o f open-c i r cu i t ed s econda r i e s of i s o l a t i n g t r a n s f o r m e r s . The des ign of most i so l a t ing t r ans fo rmers limits the root-mean-square (ms) vo l t age of open-circui ted secondariers t o 300 v o l t s o r less. However, t he i n s t an taneous vo l t age of some i s o l a t i n g t r a n s f o r m e r s a t t h e time t h e open-circuit occurs may exceed 1 000 v o l t s . I s o l a t i n g t r a n s f o r m e r s w i t h magnet ic cores des igned to sa tura te at a v o l t a g e o n l y s l i g h t l y greater than t he i r ope ra t ing vo l t age u sua l ly have l ower rms and ins tan taneous peak open-circuit secondary voltages than do less sa tura ted t ransformers. High rms open-c i r cu i t vo l t ages r equ i r e h ighe r s econda ry i n su la t ion and present a g r e a t e r electrical shock hazard, but they a lso make f i l m cu tou t ope ra t ions more r e l i a b l e . The reactance of series/series i s o l a t - ing t ransformers wi th open-c i rcu i t secondar ies d i s tor t s the p r imary c u r r e n t waveform, and the resu l t ing harmonic f requencies may a f f e c t t h e r egu la t ion of some types of constant-current regulators .

g ) Lamp by-pass devices. Whether lamps are connec ted d i r ec t ly i n to t he series c i r c u i t o r as a group i n series ac ross a s i n g l e i s o l a t i n g t r a n s - former, when the f i l amen t of one lamp burns out, a l l t h e lamps of t h e group are out unless a s u i t a b l e by-pass deviGe is connected across the t e rmina l s of t h e f a i l e d lamp. From t h e e a r l y d a y s of series l i g h t i n g c i r cu i t s w i thou t i so l a t ing t r ans fo rmers , fu sed f i lm cu tou t s have been used t o by-pass fa i led l amps . For th i s device , spr ing- loaded contac ts are connected across the t e rmina ls of each lamp. The spring-loaded con tac t s are sepa ra t ed by a f i lm cu tout which is a small d i sk of a t h i n

s _ _ _ _ s /- -.



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I C A O 9157 P A R T * 5 ** 484L4Lb 0019967 671

Part 5.- Electrical- Systems 5-41 -

non-conducting f i lm between conducting outer surfaces. When the lamp i s operat ing, the f i lm disk keeps the lamp terminals insulated from each o the r and the lamp filament completes the series c i r c u i t . I f a lamp f i lament fa i l s , the vo l tage across the lamp terminals rapidly rises t o a value (perhaps 1 000 v o l t s ) which p e r f o r a t e s t h e f i l m and shorts out the lamp terminals and r e s to re s t he series c i rcu i t before the cons tan t - cur ren t regula tor ' s open-c i rcu i t p ro tec t ion opera tes . When the lamp i s replaced a new fused f i lm cu tout must be in s t a l l ed . The outage of the o ther lamps of a small c i r cu i t connec ted i n series with the secondary of an i so la t ing t ransformer when one lamp fails may not be acceptable, and by-pass devices for these lamps are needed. The open-circuit secondary voltage peak o f some i so la t ing t ransformers may be 100 to 200 vo l t s o r l e s s . Fused f i lm cu tou t s which operate a t these vo l t ages a r e ava i l ab le but may be unre l iab le as the open-c i rcu i t vo l tage may f a i l t o p e r f o r a t e the f i lm cu tou t and shor t ou t t he f a i l ed lamp. A recent development of a by-pass dev ice fo r lamps i n t h e s e c i r c u i t s is a shor t ing re lay . These r e l a y s a r e more expensive than fused f i lm cutouts but provide more r e l i ab le ope ra t ion .

3.2.1.8 Connections for series c i r c u i t s . The connect ions in series c i r cu i t s shou ld be careful ly made t o a s s u r e c i r c u i t c o n t i n u i t y and to p reven t development of ground f a u l t s . An open-c i r cu i t f au l t i n the primary w i l l cause an outage of a l l l i g h t s i n that c i rcui t . Unless the constant-current regulator is equipped with open-circuit protect ion, the regulator may be damaged. Most ground-type f a u l t s on series c i r c u i t s occur a t connections. A s i n g l e ground faul t does not cause an outage of t h e l i g h t s , b u t two o r more ground f a u l t s w i l l s h o r t - c i r c u i t a l l l i g h t s between t h e f a u l t s .

3-.3 PARALLEL (MULTIPLE) CIRCUITRY

3.3.1 Use of p a r a l l e l ( m u l t i p l e ) c i r c u i t r y i n aerodrome l i g h t i n g

3.3 .1 .1 The use o f pa ra l l e l (mu l t ip l e ) c i r cu i t s fo r av i a t ion ground l i g h t i n g is n o t recommended f o r l a r g e aerodromes and/or complicated lighting systems for the following reasons :

a ) p a r a l l e l c i r c u i t s u s u a l l y e n t a i l a much more expens ive cab l ing ins ta l l - a t ion than does a h i g h v o l t a g e s e r i e s c i r c u i t ;

b) accurate br i l l iancy balance of a l l l i g h t s i n the pa t te rn cannot be obtained easily; and

c ) t h e mass burn out of lamps i n a c i r c u i t i s much more l i k e l y due t o t h e i n a b i l i t y of average vol tage regulators to control very rapid f luctua- t i o n s i n incoming supply volts.

3.3.1.2 In view of these cons idera t ions , para l le l c i rcu i t s should on ly be used when there a re on ly a few f i t t i n g s e x i s t i n g i n t h e c i r c u i t and accura te in tens i ty ba lance is not c r i t i ca l ; f o r example, a sho r t taxiway. Smaller aerodromes with short runways and taxiways can employ pa ra l l e l vo l t age fo r t he l i gh t ing .

3.3 .1 .3 Effects Of f a u l t s . If t h e l i g h t f i x t u r e s are connec ted across the l igh t ing

0 Circui t , a burned-out lamp o r an open-c i r cu i t f au l t i n a f ix tu re does no t s e r ious ly



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ICAO 9357 P A R T t 5 t t 484393b 0039968 508


a f f e c t the l i g h t i n g c i r c u i t , b u t a s h o r t - c i r c u i t f a u l t w i l l be an overload condi t ion and, depending on which protect ive device ( fuse or c i rcui t breaker) operates , may make t h e c i rcu i t o f l i gh t s i nope ra t ive . To p r o t e c t t h e l i g h t i n g c i r c u i t , o f t e n e a c h lamp i s c o n n e c t e d t o t h e l i n e v o l t a g e s i d e of t h e c i r c u i t by a fuse .

3.3.1.4 Vo l t age cha rac t e r i s t i c s . Most p a r a l l e l - t y p e l i g h t f i x t u r e s are d e s i g n e d f o r low appl ied vo l tages (less than 300 v o l t s ) , a n d t h e c i r c u i t v o l t a g e is t h a t r e q u i r e d by the lamps o r step-down transformers are used. The l i g h t s may be supplied from a s i n g l e c i rcu i t connected between the l i n e a n d n e u t r a l o r by a l t e r n a t i n g between neutral and l i n e v o l t a g e on each s ide of t h e n e u t r a l . Examples o f t h e s e c i r c u i t s are 120 v o l t s l ine- to-neut ra l and 240/120 vol t (240 vo l t s l ine- to- l ine and 120 v o l t s l i n e - t o - n e u t r a l ) c i r cu i t s . O the r vo l t ages are o f t e n u s e d . U s u a l l y t h e c a b l e i n s u l a t i o n o f p a r a l l e l l i g h t i n g c i r c u i t s i s r a t e d a t 600 v o l t s , which l i m i t s t h e v o l t a g e f o r p a r a l l e l l i g h t i n g c i r c u i t s t o n o t more than 500 v o l t s .

3.3.1.5 Step-down transformers. The use o f h igher vo l tages for t ransmiss ion of power reduces the l ine vol tage drop and then step-down d i s t r ibu t ion t r ans fo rmers r educe t h e v o l t a g e t o t h a t more s u i t a b l e f o r l o c a l d i s t r i b u t i o n . S i m i l a r l y , t h e power t o a e r o - drome l i g h t i n g c i r c u i t s may be a t a higher vo l tage on the f eede r c i r cu i t s and r educed by a s tepdown t ransformer a t the beginning of t h e l i g h t i n g c i r c u i t t o match t h e d e s i r e d c i r c u i t v o l t a g e . O f course, these feeder cab les must be adequa te ly i n su la t ed fo r t he feeder vol tage. Sometimes i t is d e s i r a b l e t o u s e l o n g l o w v o l t a g e c a b l e s f o r f e e d e r s , such as when these cab les are a l r eady i n s t a l l ed and ava i l ab le . Assuming t h e s e f e e d e r s have 600-vol t insulat ion, the l ine drop can be reduced by us ing a h ighe r vo l t age w i th in t h e insu la t ion limit of t he cab le on the feeders and reducing the vol tage with step-down transformers a t t h e i n p u t t o t h e c i r c u i t o r t o t h e i n d i v i d u a l l i g h t f i x t u r e s . An example i s t o u s e 4 8 0 v o l t s on the feeders and step-down t o 120 v o l t s a t t h e l i g h t i n g c i r c u i t . Use of lamps i n t h e v o l t a g e r a n g e of 6 t o 30 v o l t s i n aerodrome l i g h t f i x t u r e s i s usua l ly more e f f ec t ive t han t he u se o f 120 o r o f 240 v o l t lamps. Thus, when s tepdown transformers are t o b e u s e d f o r i n d i v i d u a l l i g h t s , o r f o r a small group of l i g h t s i n a bar re t te , cons idera t ion should be g iven to choos ing l igh ts which use lowvol tage lamps. Unless individual ly fused, s tep-down t ransformers used as indicated above should b e of the high-reactance type s o that a s h o r t - c i r c u i t i n t h a t p a r t of t h e l i g h t i n g system fed by one transformer w i l l no t cause fa i lure o f the en t i re sys tem.

3.3.1.6 Constant voltage transformers. The u s e of a cons tan t vo l tage t ransformer a t t h e l o c a t i o n of a l i gh t supp l i ed by a long feeder cab le to compensa te for l ine-vol tage drop changes may be advantageous. For example, an aerodrome beacon supplied by a long feeder cab le which a l s o s u p p l i e s a number of intermit tent loads which causes the l ine - vol tage drop t o f luc tua te wide ly .

3.4 CONTROL OF AERODROME LIGHTING SYSTEMS

3 . 4 . 1 Cont ro l c i r cu i t ry

3.4.1.1 The c o n t r o l c i r c u i t r y f o r aerodrome l igh t ing p rov ides t he means of swi t ch ing on or off and of changing the intensi ty of the var ious l igh t ing sys tems. These cont ro ls may be manual or au tomat ic .

3 . 4 . 1 . 2 Local manual con t ro l . The s imples t con t ro l sys t em i s a switch a t t h e power supply un i t of t h e c i r c u i t which is operated by a person to energ ize o r deenerg ize the



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i I

ICAO 9357 PART*5 ** 4843436 0039969 444 W


circuit. This control method is used at some small aerodromes or some miscellaneous associated lightig circuits. Some aerodromes may use local manual controls as an alternate control point for emergency operations.

3.4.1.3 Remote control. The lighting systems for larger aerodromes are complex and proper control is related to atmospheric conditions, time of day, perhaps the pilot's preference, the positions and manoeuvring of several aircraft, and other activities on the field. The person or persons most knowledgeable of these conditions are the air traffic controllers; therefore, most of the aerodrome lighting controls are on a remote lighting control panel in the aerodrome control tower and operated by the traffic controllers. Some aerodromes may have special control stations other than in the control tower with the operator in direct comnication with the air traffic controllers. The remote lighting control panel is connected to the appropriate lighting vault by a system of control cables to provide capability of controlling the various lighting circuits . 3.4.1.4 Types of remote control systems. Several types of control systems are used for aerodrome lighting. Alternating current (ac) power is often used to energize the controls. This ac power may be at the low distribution voltage or at a special voltage more suitable for the length of the control cable runs and the size of the conductor. These controls may be connected diretly to the power control device from the remote control panel or by auxiliary relays to operate the control devices. Some control circuits use direct current for the control voltage, especially to reduce inductive coupling between circuits. Some major aerodromes with very complex control circuits use multiplex control systems t o provide greater flexibility for extensions and variations to lighting patterns and to facilitate changes in the control requirements. Some aerodromes use radio signals for control, either air-to-ground for pilots or ground-to ground for equipment located in areas not easily accessible to control circuits. These control systems should be capable of a high degree of operational reliability and should be designed to provide, as far as possible, the integrity of the lighting patterns selected regardless of control cable faults or equipment failures. Solid state equipment may be used where practicable, although relays may be more satisfactory at the interface between the control circuits and the lighting circuit power equipment.

3.4.2 Control panels

3.4.2.1 Primary control panel. The primary control panel is usually located in the control tower at a lighting control desk or panel. This panel should be designed to provide the operator with control switches, operating circuit indicator lights and intensity controls, and their associated indicating features which are easily indentifi- able under all conditions of illumination in the control room. For this purpose it may be necessary to provide self-illuminated legends for control selectors and a desk brilliancy level selector for the indicator lamps. There are advantages to be derived from a standardized form of layout for control and indicating facilities and the current trend is towards standard modular panel layouts. Each service should be provided with its own control selector and group of indicator lamps. Where a separate control desk is provided for each runway, a diagram can be combined with the control desk but where one control desk serves the whole airport a separate facsimile diagram may need to be provided. Complex taxiing guidance systems using selective switching of centre line lights and stop bars can best be controlled from an operational diagram fitted with combined indication lamp/push buttons for stop bars and indicator lamps for taxiway routes.



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ICAO 9 3 5 7 P A R T t 5 t t 484343b 0039970 Lbb W

5 - 4 4 Aerodrome Design Manual - 3 . 4 . 2 . 2 Fascimile diagrams. Facsimile diagrams are required for aerodromes having complex p a t t e r n s . They are s p e c i a l l y made t o s u i t i n d i v i d u a l l a y o u t s and s o involve cons iderable cos t . Panels wi th runways and taxiways delineated i n a con t r a s t ing co lou r are accommodated t o p r o v i d e a d iagrammat ic d i sp lay o f l igh t ing se rv ices . F ibre op t ics may a l so be u sed fo r t h i s pu rpose .

3 . 4 . 2 . 3 Controls. The switches and controls should be types which are e a s y t o i d e n t i f y , p r o v i d e p o s i t i v e i n d i c a t i o n of t h e o p e r a t i n g s t a t u s , and be grouped t o a s s o c i a t e r e l a t e d f u n c t i o n s a n d c i r c u i t s . These controls should be a type which are n o t eas i ly swi tched inadver ten t ly .

3 .4 .2 .4 Alternate c o n t r o l panel. Provision should be made f o r l o c a l c o n t r o l o f a e r o d r o m e l i g h t i n g i n t h e l i g h t i n g v a u l t s o r c o n t r o l c e n t r e s t o e n a b l e o p e r a t i o n of t h e l igh t ing sys tems a t times when the remote control system i s inope ra t ive . A l l l i gh t ing sys tems essent ia l to the aerodrome opera t ion should have an a l te rna te cont ro l pane l . The a l t e rna te con t ro l pane l shou ld be l oca t ed s o that i t i s a c c e s s i b l e t o a n o p e r a t o r w i thou t h i s hav ing t o en t e r an area housing high voltage equipment or switch gear. Often the alternate con t ro l pane l i s loca ted i n a s e c t i o n of t h e l i g h t i n g v a u l t near t h e entrance, which is separa ted f rom the area conta in ing the power equipment. Usually only one a l t e r n a t e c o n t r o l p a n e l i s provided, and i t i s l o c a t e d i n t h e v a u l t c o n t a i n i n g t h e equipment for supplying power t o t h e p a r t i c u l a r l i g h t i n g c i r c u i t s i n v o l v e d . Thus t h e r e may be several alternate control panels, each of w h i c h c o n t r o l s d i f f e r e n t circuits. Some aerodromes may use a c e n t r a l a l t e r n a t e c o n t r o l p a n e l , similar to the pr imary remote c o n t r o l p a n e l l o c a t e d i n a c o n t r o l c e n t r e , f o r emergency operations. Constant-current r egu la to r s u sua l ly p rov ide con t ro l s on each r egu la to r fo r ope ra t ion o f t ha t r egu la to r for maintenance or during an emergency. Authorized persons are usua l ly the on ly ones pe rmi t t ed t o ope ra t e t hese con t ro l s .

3 . 4 . 2 . 5 Transfer re lay panel . For safety of maintenance personnel and to avoid conf l i c t ing ope ra t ion o f t he con t ro l s , on ly one con t ro l s t a t ion ' shou ld be ab le t o ope r - a te a g i v e n c i r c u i t a t any time. Transfer re lay pane ls are used t o s w i t c h t h e o p e r a t i n g capab i l i t y f rom the p r imary con t ro l pane l t o t he a l t e rna te con t ro l pane l . To accommo- d a t e a l l t h e c o n t r o l c i r c u i t s i n v o l v e d i n t h e t r a n s f e r , s e v e r a l t r a n s f e r c o n t r o l p a n e l s may be used but usually a s i n g l e t r a n s f e r s w i t c h a c t u a t e s a l l of t he con t ro l pane l s . The t r a n s f e r c o n t r o l p a n e l s a n d t h e t r a n s f e r s w i t c h are u s u a l l y l o c a t e d a t t h e s i te o f t he a l t e rna te con t ro l pane l .

3 . 4 . 3 Use of re lays

3 . 4 . 3 . 1 Relay pane l s fo r l ong con t ro l c i r cu i t s . Where c o n t r o l c i r c u i t s are l o n g , t h e v o l t a g e d r o p i n t h e l i n e s may be such tha t power control devices cannot be operated d i rec t ly f rom the p r imary remote cont ro l pane l . Even c i r c u i t s which earlier operated s a t i s f a c t o r i l y may become i n o p e r a t i v e a f t e r a d d i t i o n a l c o n t r o l c i r c u i t s are added. To permi t cont ro l a t the l onge r d i s t ance , r e l ays w i th l ow-cur ren t co i l s may be u s e d t o energ ize the cont ro ls of t h e power equipment. These relays are o f t en a s sembled i n pane ls conta in ing severa l (16 o r more) relays. (These relay panels are sometimes c a l l e d p i l o t r e l a y p a n e l s . ) A r e l a y may be provided for each control l ine f rom the pr imary remote control panel. The con tac t s of t h e s e r e l a y s c o n t r o l t h e power t o t h e s w i t c h e s o r c o n t r o l s of t h e power equipment functions.

3 .4 .3 .2 Relays i n t h e f i e l d . Some i n d i v i d u a l v i s u a l a i d s o r s h o r t l i g h t i n g c i r c u i t s (aerodrome beacons, wind d i r e c t i o n i n d i c a t o r s , s e c t i o n s of o b s t a c l e l i g h t s , s i m p l e approach l ight ing systems, etc.) may o b t a i n power from a l igh t ing vau l t o r f rom a l o c a l source of power. If t h e power i s from a l o c a l s o u r c e , t h e r e l a y f o r c o n t r o l l i n g t h e s e l i g h t s i s u s u a l l y l o c a t e d a t o r nea r t he l i gh t o r sou rce of power. If t h e c o n t r o l



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I ICAO 9357 PART*5 ** 484343b 0039973 O T 2 = Part 5,- Electrical Systems 5-4 5 -

cables are long, the conductors of the control cable may need t o be large to reduce the

able when the r e l ay is actuated. Also i f t h e r e l a y is t o be located outdoors, i t w i l l need to be provided with protection from the most severe weather to which i t w i l l be subjected. It should have a provision to lock i t for secur i ty .

* voltage drop. The relay should be selected to operate from the control voltage avail-

3.4*4 Interconnection of controls

3.4.4.1 Often the operations at the aerodrome are such that certain combinations of l i g h t s a r e always used together or other combinations are prohibited. Examples are:

a) runway edge l i gh t s , t h re sho ld l i gh t s , and runway end l i g h t s may be operated a t the same time although the power may be provided from d i f f e r e n t c i r c u i t s ;

b) runway edge l i g h t s may be operated without the runway c e n t r e l i n e l i g h t s b u t i f t h e runway cen t r e l i ne l i gh t s are used the runway edge l i g h t s are always energized;

c) the sequenced-flashing l ights of the approach lighting system can be used only when the incandescent l ights of the system are 'at the higher i n t e n s i t y steps;

d ) s e t t i n g of t he i n t ens i ty con t ro l fo r a given atmospheric condition may operate the approach lighting system at one in t ens i ty s t ep , t he runway l i g h t s a t another intensi ty s tep, and the taxiway l ights a t yet another i n t e n s i t y s t e p ; and

e ) i n t e r s e c t i n g runways should not be lighted simultaneously. Only by properly interconnecting the controls and c o n t r o l c i r c u i t s , can the desired combinations be obtained or undesired combinations prohibited with simpler operations by the cont ro l le r and lesser chance of error . Each aerodrome should consfder possible control interconnection Combinations i n r e l a t i o n t o t h e i r i n s t a l l a t i o n s and operating procedures.

3.4.5 Automatic cont ro ls

3.4.5.1 Some t y p e s of aerodrome l igh t ing a ids may be con t ro l l ed s a t i s f ac to r i ly by automatic controls. More often these automatic controls are used a t smaller a i r p o r t s , but they may be used f o r less critical v i sua l a id s a t l a rge aerodromes espec ia l ly a t locat ions not easily connected to t he con t ro l c i r cu i t s . Pho toe lec t r f c con t ro l s may be used to energ ize and deenergize aerodrome beacons, wind d i rec t ion ind ica tors , and obs tac le l igh ts i n less c r i t i c a l a r e a s . The controls are usual ly actuated by sky i l luminance levels. Most of these controls energize the c i rcui t when the i l luminance f romthe no r th sky decreases to about 400 lux and deenerg izes the c i rcu i t when the illuminance increases to about 600 lux. Time-clock controls may be used to automatical- l y c o n t r o l t h e aerodrome l i g h t i n g a t aerodromes with non-instrument capability only. Time-clock controls are often used a t aerodromes where the v i sua l a id s are turned off a f t e r a ce r t a in hour a t night to conserve energy. Thermal cont ro ls may be used t o actuate heaters of some visual a ids to prevent the formation or accumulat ion of ice, snow or condensation. These thermal controls may be obtained with fixed or adjustable cont ro l for many different temperatures. Some i n s t a l l a t i o n may need manual cont ro l t o overr ide the automatic control of cer ta in l ight ing c i rcui ts . I e



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I C A O 9357 PART*5 t t 484l14Lb 0039972 T39

5-46 Aerodrome Design Manual 7

3.4.6 Radio remote controls

3.4.6.1 Radio s igna l s f rom a i r c ra f t t o con t ro l ae rod rome l i gh t ing sys t ems have been used, t o a l imi ted degree , a t smaller aerodromes for severa l years . This cont ro l method has s eve ra l advan tages i n t ha t i t p e r m i t s t h e p i l o t t o select t h e l i g h t i n t e n s i t y o f h i s choice , e l imina tes the need for cos t ly cont ro l cab les , and conserves power by hav ing t he l ight ing system deenergized when not needed. Radio controls for air-to-ground, ground- to-ground, and a combination of air-tcrground and ground-to-ground systems are ava i l ab le . Radio c o n t r o l can p r o v i d e i n t e n s i t y c o n t r o l as well as energizing the l i g h t i n g c i r c u i t s . Most r a d i o c o n t r o l s a u t o m a t i c a l l y d e e n e r g i z e t h e l i g h t i n g c i r c u i t s 15 t o 60 minu tes a f t e r t he las t contact . Radio controls have been used to control runway edge l igh ts , t ax iway edge l igh ts , s imple approach l igh t ing sys tems, v i sua l approach s lope indicator systems, as indvidual systems or in predetermined combinat ions. Radio control of aerodrome l ight ing systems f rom aircraf t should be used only a t uncontrolled aerodromes or a t other aerodromes during periods when t r a f f i c c o n t r o l i s not in opera t ion . L ight ing sys tem which should no t be rad io cont ro l led inc lude obs t ac l e l i gh t s , a e rod rome beacons , p rec i s ion approach l i gh t ing sys t ems , runway c e n t r e l i n e l i g h t s , and touchdown zone l i g h t s .

3.4.6.2 For air-to-ground operation only a receiver and decoder are i n s t a l l e d on t h e a i r p o r t . The a c t u a t i n g s i g n a l may be provided by a s p e c i f i e d s h o r t series of c l i c k s accomplished by keying the microphone of an a i rcraf t communicat ions t ransmit ter . Ground-to-ground c o n t r o l i s used mostly when c a b l e c o n t r o l c i r c u i t s are n o t a v a i l a b l e and are n o t p r a c t i c a l t o i n s t a l l . Ground-to-ground control may be used only temporar i ly u n t i l c a b l e s c a n be i n s t a l l e d or permanent ly especial ly to remote locat ions.

3.5 LAMPS

3.5.1 C h a r a c t e r i s t i c s of incandescent lamps

3.5.1.1 Incandescent lamps are used in most f i t t i n g s i n s t a l l e d i n aerodrome l igh t ing systems. The fol lowing character is t ics of incandescent lamps are p e r t i n e n t t o t h e design of t h e aerodrome l i g h t i n g c i r c u i t s .

3.5e1.2 The l i g h t o u t p u t , l i f e , power consumed, and e f f i cacy ( e f f i c i ency) of incandescent lamps is a complex func t ion o f t he app l i ed vo l t age o r cu r ren t , as i n d i c a t e d by Figure 3-8 and Table 3-1. For example, i f t h e v o l t a g e a p p l i e d t o a lamp is f i v e p e r cen t g rea t e r t han r a t ed vo l t age , t he l i gh t ou tpu t w i l l be about 120 per cen t o f ra ted l i gh t ou tpu t , and t he lamp l i f e w i l l be about one-ha l f the des ign l i fe . The e f f e c t s of changes i n lamp c u r r e n t are g rea t e r . If the cur ren t th rough a lamp is f i v e p e r c e n t above r a t ed cu r ren t , t he l i gh t ou tpu t will be about 135 per cen t o f the ra ted l igh t ou t - put , and the lamp l i f e w i l l be about - three- ten ths the des ign l i fe . These va lues i l l u s t r a t e t h e n e e d f o r c l o s e c o n t r o l of t h e a p p l i e d v o l t a g e o r c u r r e n t .



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I C A O 9157 P A R T t S t t m 484141b 0039973 975 m

Part 5.- E l e c t r i c a l Systems 5-4 7 - Table 3-1, Table of Lamp Exponents

output

OUTPUT = =

l i f e

LIFE

watts

WATTS

amperes

AMPERES

- =

=

=

- - amperes 2.85

[AMPEREJ

Note: Capi ta l letters represent rated values.

3.5.1.3 The designer of an aerodrome l ight ing system may have some l a t i t u d e i n h i s choice of lamps f o r c e r t a i n aerodrome l i g h t f i x t u r e s , s e l e c t i n g a ser ies ' lamp, a lowvol tage mult iple lamp, o r a h ighe rvo l t age m u l t i p l e lamp. The fol lowing factors are per t inent in the choice :

a ) the vo l tage d rop across series lamps u s u a l l y f a l l s i n t h e " l o w v o l t a g e " category; the voltage drop across a 6.6 ampere, 200 watt runway edge l i g h t i s 30 v o l t s , and the vol tage drop acorss a 20 ampere, 500 w a t t approach l ight lamp i s 25 vol t s ;

b) because of their d i f ferences in design tolerances, series lamps should n o t b e u s e d i n p a r a l l e l c i r c u i t s , and mult iple lamps should not be used i n series c i r c u i t s ; and

c ) t h e l i f e of a " lowvoltage" lamp will be g rea t e r t han t ha t of a "high- voltage"* lamp, f o r a given rated power consumption and l i gh t ou tpu t .

* "High-voltage" i s used i n t h i s s e c t i o n as being the voltage normally.used for household lights.



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I C A O 9157 P A R T t S t t 4 8 4 1 4 L b 0019974 801


Figure 3-8. Effects of current and voltage variations on operating characteristics of incandescent lamps

3.5.1.4 Tungsten-halogen lamps. Many lamps now being used for aerodrome lighting are tungsten-halogen lamps. The filaments of these lamps are enclosed in small quartz tubes which contain small amounts of a halogen, such as iodine, in addition to the usual inert fill gas. When the filament is heated, tungsten evaporates from the filament and condenses on the inside walls of the lamp envelope. The vapourized halogen combines with this condensed tungsten forming a vapour. This vapour travels to the hot filament where it disassociates and redeposits the tungsten on the filament. This process reduces blackening of the lamp bulb, increases the life of the lamp, maintains better light intensity, and improves the efficiency of the lamp. The cost of the lamps is however increased.

3.5.2 Characteristics of gaseous-discharge lamps

3.5.2.1 Lamps for sequence-flashing approach lights ("strobes"). The lamps used in the sequence-flashing approach lights are gaseous, capacitor-discharge lights and not incandescent lamps. The lamp is a tube which may be formed into various shapes containing an inert gas such as argon or krypton which emits light when an arc is created in the gas. The power supply charges electrical capacitors t o provide power for the arc and provides a triggering voltage to initiate the arc upon application of the triggering signal. The arc in the gas emits a high-intensity flash of light of short duration (microseconds) which rapidly expends the charge of the capacitors and extinguishes the arc. Very high voltages are involved for the power supply and lamp. This hazard should be considered in the design of the lighting system. The peak intensity of these lights



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ICAO 9357 P A R T * S ** m 484143b 0039975 748 m


@ may be very great but of short durat ion. The f l a s h must be integrated to determine the e f f e c t i v e i n t e n s i t y of the emi t ted l igh t and i ts effect iveness as a visual a id . The frequency of f lash ing of t hese l i gh t s is l imited by the time required to recharge the capacitors and usual ly i s only a few times per second. The output of t h e . l i g h t i s pro- por t iona l to the square of t he vo l t age app l i ed t o t he l i gh t f i t t i ng , un le s s i t has a regulated power supply.

3.5.2.2 Other gaseous-discharge lamps. The higher eff ic iency of gaseousdischarge lamps encourages t h e i r use. Types of these lamps include fluorescent, mercury-vapour, metal-halide, and low- or high-pressure sodiumvapour l ights. The use of l i g h t s of these types i s usual ly l imi ted to i l lumina t ion of areas such as apron areas, except for the use of f luorescent lamps i n some taxiway edge l i g h t s and for i l lumina t ing s igns . When consider ing using l ights of these types the following are factors that should be investigated.

a) Restarting. Some of these lamps cannot be restar ted for several seconds t o minutes a f t e r t h e a r c i s extinguished. Power in te r rupt ions or switching can cause loss of l i g h t s a t c r i t i c a l times. Emergency l i gh t - ing by other types of lamps may be desirable .

Cold s t a r t i ng . Some of these lamps cannot be s tar ted or are d i f f i c u l t t o start i n low ambient temperatures.

In tens i ty cont ro l . These lamps of ten are not capable of i n t ens i ty con- t r o l o r have a limited range of control as compared to incandescent lamps . Stroboscopic effects. The stroboscopic effects of t he lamps may be disturbing. Where such l igh ts are used, including for i l lumination of areas, the use of three-phase electrical supply systems with a balance i n connec t ing the l igh ts may be desirable.

Colour shift ing. Typically the l ight emitted from these lamps covers a l i m i t e d p a r t of the v i sua l spectrum. This makes recognition of colour coding d i f f i c u l t as colours may not have their ordinary appearance when i l luminated by gaseous-discharge lamps. The colour "red" is par- t i cu l a r ly a f f ec t ed .

3.6 METHODS OF OBTAINING INTEGRITY AND RELIABILITY F O R AERODKOME LIGHTING

3.6.1 Definit ions of terms

3.6.1*1 The terms i n t e g r i t y and r e l i a b i l i t y as app l i ed t o aerodrome l igh t ing are not Precise , easi ly def ined or measured terms. Previous e f f o r t s t o def ine these terms have concluded t h a t r e l i a b i l i t y i s a question of mean time between f a i l u r e of components whi le in tegr i ty i s a question comprising such matters as f a i l u r e s u r v i v a l of the overa l l system. It i s considered that visual aids should have a comparable i n t e g r i t y and relia- b i l i t y t o t h a t a f f o r d e d by non-visual aids. Thus r e l i a b i l i t y i s af fec ted by the selec- t i o n of components and operat ional use , and i n t e g r i t y i s af fec ted by the design and i n s t a l l a t i o n of the systems and maintenance of the equipment. It i s d i f f i c u l t t o state what t h e r e l i a b i l i t y of present visual a ids i s . In general i t is considered that well



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designed and maintained visual a ids have a ve ry h igh i n t eg r i ty and t ha t t he p robab i l i t y of a f a i l u r e o c c u r r i n g a t a c r i t i ca l moment i s extremely low. Nevertheless a l l reason- a b l e e f f o r t s s h o u l d be made t o improve upon i n t e g r i t y and r e l i a b i l i t y . Electrical fac- t o r s w h i c h a f f e c t i n t e g r i t y and r e l i a b i l i t y may b e c l a s s i f i e d as follows:

a ) f a i l u r e of t h e c i r cu i t ;

b ) f a i l u r e of t h e power supply; and

c) f a i l u r e of t h e control circuit .

3.6.2 Summary of means of improving electrical i n t e g r i t y and r e l i a b i l i t y

3.6.2.1 Reducing f a i l u r e of t h e c i r c u i t . A s t anda rd p rac t i ce is t o u s e several circuits t o p r e v e n t a f a i l u r e of one c i r c u i t b l a c k i n g o u t a n e n t i r e l i g h t i n g s y s t e m . Four c i r c u i t s are sometimes employed f o r l i g h t i n g the approach and threshold. One c i r c u i t is used for the threshold l ights and three for the approach l ight ing system. The l a t te r t h r e e c i r c u i t s are so d e s i g n e d t h a t i f o n e s h o u l d f a i l o n l y e v e r y t h i r d b a r r e t t e would be out of operation. Where a l i g h t i n g p a t t e r n i s fed by s e v e r a l c i r cu i t s , t he p rac t i ce o f each c i r cu i t f eed ing one pa r t i cu la r geograph ica l s ec t ion o f t h e p a t t e r n i s not recommended because loss of one c i rcui t can then change the pa t te rn in to someth ing en t i re ly d i f fe ren t . For example , an approach l igh t ing pattern comprising a c e n t r e l i n e and f i v e c r o s s b a r s i f f e d i n two d i s t i n c t h a l v e s by two c i r c u i t s c o u l d change from a c e n t r e l i n e a n d f i v e b a r s y s t e m t o a cen t r e l i ne and t h ree ba r sys t em wi th t h e loss of one c i rcu i t .

3.6.2.2 Reducing f a i l u r e of the power supply. Steps can be taken t o ensure a con- t inuous supply of power t o t h e l i g h t i n g system. One of the most simple and most relia- b l e i s t o have a l t e rna t ive sou rces of power from two d i f fe ren t genera tors which are capable of a u t o m a t i c a l l y s t a r t i n g i n case of a power f a i l u r e . Equipment has been developed which w i l l r educe t o a v e r y s h o r t i n t e r v a l the time between power f a i l u r e and d e l i - very of current f rom the a l ternat ive system. Switching rates as low as 0.3 t o 0.5 seconds are be ing ob ta ined fo r equ ipmen t i n s t a l l ed i n con junc t ion w i th p rec i s ion approach runways. Switching rates for o ther sys tems vary be tween 10 to 20 seconds. Another procedure which i s used i s to opera te f rom the secondary genera tors cont inuous ly during cr i t ical times such as dur ing l ow v i s ib i l i t y cond i t ions o r when a s torm i s f o r e c a s t . In case of a f a i lu re o f t he gene ra to r , t he swi t ch -ove r is then made t o t h e Primary power supply. These systems and arrangements are d i scussed i n Chap te r 2.

3.6.2.3 Reducing f a i l u r e of t h e c o n t r o l c i r c u i t . Sometimes a l t e r n a t e c o n t r o l c i r - c u i t s are neglec ted . Carefu l a t ten t ion i s g i v e n t o t h e l i g h t i n g c i r c u i t s and secondary power supp l i e s are provided for them, bu t p rov i s ion o f a l t e rna te c i rcui ts f o r c o n t r o l s of t he l i gh t s f rom the con t ro l t ower i s overlooked. The p r o b a b i l i t y of a c o n t r o l cir- c u i t f a i l i n g may be equa l t o t ha t o f a l i g h t i n g c i r c u i t f a i l i n g , and dua l cont ro l c i rcui ts should be provided.

3.6.2.4 Des ign ing fo r i n t eg r i ty and r e l i a b i l i t y . The d e s i g n a n d i n s t a l l a t i o n of aerodrome l i g h t i n g systems can a f f e c t i n t e g r i t y and r e l i a b i l i t y i n ways o t h e r t h a n s e l e c t i o n of components and i n t e r l e a v i n g of c i r c u i t s . These f e a t u r e s are o f t e n t h e same as those used t o reduce and simplify maintenance. Some o f t he f ea tu re s de t e rmined i n the des ign dec is ions are i n s t a l l i n g c a b l e s i n c o n d u i t ( d u c t s ) i n s t e a d of d i r e c t b u r i a l , u s i n g i n s e t l i g h t s i n s t e a d o f e l e v a t e d l i g h t s i n areas where su r f ace t r a f f i c o f t en co l - l i des w i th t he l i gh t f i x tu re s , p rov id ing g round-wi re circuits throughout the system t o r e d u c e t h e e f f e c t s of l i g h t n i n g and h igh vo l t age su rges , equ ipp ing l i gh t f i x tu re s w i th



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d)

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heating elements to eliminate moisture condensation and i c ing problems, etc. Relia- b i l i t y and i n t e g r i t y are fac tors which should be considered i n the design and in s t a l l a t ion .

3.7 MONITORING OF AERODROME LIGHTING CIRCUITS

3.7.1 Methods of monitoring

3.7a1.1 8.3 of Annex 14 states tha t a system of monitoring visual aids should be employed to ensure l ighting system reliabil i ty. Monitoring may be accomplished by visual observations or by an automatic sensor. Visual monitoring, except €or what A i r Traffic Control sees and p i lo t s repor t , is seldom used. Some of the monitoring of l ight ing systems in use consis t of ind ica tor l igh ts which ind ica te on ly tha t the switches which cont ro l the c i rcu i t s are turned to ON o r t h a t one or more l i gh t s i n a c i r c u i t have failed. Reliable monitoring is very desirable, but partial or incomplete monitoring can create a secure feel ing which hinders instead of a i d s i n r e l i a b i l i t y . Examples a re : ind ica tor l igh ts which respond only to switch posi t ion or control re lay operation m y not detect a malfunctioning constant-current regulator or a grounded out l ight ing c i rcui t ; or monitors of power waveform d i s to r t ion t o de t ec t lamp f a i lu re s may not respond t o f a u l t s of t he l i gh t ing c i r cu i t s or f a i l u r e of power or control equipment.

3.7.2 Design of monitoring devices

3.7.2.1 The ideal monitoring device for aerodrome l i g h t s measures the intensi ty of each l i gh t i n t he d i r ec t ions from which it will be observed and ind ica tes any deficien- cies by loca t ion and amount. Such monitoring may not be pract ical or possible . The design of monitoring devices should consider related information that would be he lpfu l as w e l l as the f a i lu re s which they can detect. Some devices may sense important information which is not presented by the indicator . Instruct ions for use of the monitoring system should explain the limitations as well as the capab i l i t i e s of the system. The quant i t ies usual ly measured are current , vol tage, power, waveform, time, and photoelectric emission. Recorders of these values are a form of monitor, but t h i s type information is seldom used f o r immediate response or t o produce act ions automatically.

3.7.3 Classes of monitors

3.7.3.1 Monitors may be classed as active or passive. Active monitors take a predetermined action when a specif ic condi t ion is sensed or at a selected time af te r the condition occurs. Examples of monitors i n t h i s class a re t he primary source voltage sensors which automatically start the secondary engine-generator set and t ransfer the load when the primary power source fails , or the high intensity time limit control which automatically resets to a lower in t ens i ty s t ep and sounds a buzzer and/or energizes an i n d i c a t o r lamp a f t e r t h e l i g h t s have been a t f u l l i n t e n s i t y f o r 15 minutes.* Passive monitors provide a signal such as an indicator lamp or buzzer when a predetermined

* Autolnatic r e se t t i ng of t he i n t ens i ty is not des i rab le s ince the change could be made when a p i l o t is i n a c r i t i c a l p a r t of h i s approach.



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condi t ion occurs and does not change any of the systems operat ions. A human ope ra to r must eva lua te t he meaning of t h e s i g n a l and take the appropr ia te ac t ion . Examples of passive monitor ing are the sequence-f lashing l ights monitor which alerts when a p rese l ec t ed number of l i g h t s is inope ra t ive , o r t he i nd ica to r lamp which shows t h a t s p e c i f i c c i r c u i t s are energized and operat ing.

3 .7 .4 Monitor overr ide controls

3.7 .4 .1 Often controls or procedures which can be used to overr ide or c i rcumvent the ac t ion of the monitor are provided. By a c t i v a t i n g a special c i r c u i t o r r e s e t t i n g a cont ro l , the opera tor can main ta in the sys tems opera t ion wi thout change for new o r i n d e f i n i t e time period. The s igna l ind ica t ing the moni tor ' s response may be provided dur ing the over r ide opera t ion to keep the operator informed that the system is i n an undes i rab le opera t ing s ta tus . An example i s t o reset t h e timer t o f u l l i n t e n s i t y operat ions a t the beginning of each approach i n low v i s i b i l i t y c o n d i t i o n s t o e n s u r e t h a t t h e l i g h t s w i l l not automatical ly be changed t o a lower in tens i ty dur ing the approach.

3.8 ELECTRICAL CIRCUITS FOR R A D I O NAVIGATION AIDS

3 .8 .1 Types of r ad io nav iga t ion a ids

3.8.1.1 The types of rad io naviga t ion a ids which may be l o c a t e d on o r n e a r t h e aerodrome and require electrical power e i the r f rom the aerodrome power sys tem or as a separa te sys tem var ies with t h e aerodrome. These rad io naviga t iona l a ids o f ten inc lude instrument landing systems ( ILS) , very high f requency omnidirect ional radio range (VOR), non-direct ional beacon (NDB), d i r e c t i o n f i n d i n g (DF) f a c i l i t i e s , p r e c i s i o n a p p r o a c h radar systems, distance measuring equipment (DME), a i r s u r v e i l l a n c e r a d a r (ASR), and similar equipment. Most aerodromes are equipped with some of these devices and the electrical power requirements may r equ i r e spec ia l cons ide ra t ion . Note t h a t t h e ILS f o r category I1 and 111 operat ions i s more p rec i s ion equ ipmen t t han t ha t r equ i r ed fo r category I operations.

3.8.2 Electrical c h a r a c t e r i s t i c s

3.8.2.1 Electrical power f o r r a d i o n a v i g a t i o n a i d s i s u s u a l l y a l t e r n a t i n g c u r r e n t (ac) . Batteries may be used t o p r o v i d e power f o r s t a r t i n g s e c o n d a r y power sources and t o supply energy for some u n i n t e r r u p t i b l e power systems. This ac power i s u s u a l l y e i t h e r 50 o r 60 he r t z .

3.8.2.2 Primary power. Fo r r ad io nav iga t ion a ids l oca t ed on o r a d j a c e n t t o t h e aerodrome, the primary power source i s u s u a l l y t h e same as the aerodrome primary source. These sources are discussed i n paragraph 2.1.2. S i n c e t h e t o t a l k i l o w a t t s r e q u i r e d by r ad io nav iga t ion a ids u sua l ly is n o t l a r g e , t h e i n p u t power t o t h e s e i n s t a l l a t i o n s is o f t en t r ansmi t t ed a t t h e i n t e r m e d i a t e v o l t a g e l e v e l a n d f e d t o l o c a l d i s t r i b u t i o n t ransformers for step-down to t he vo l t age su i t ab le fo r t he equ ipmen t .

3.8.2.3 Secondary power. S ince t hese r ad io nav iga t ion a ids p rov ide s igna l s fo r i n s t rumen t gu idance o f t he a i r c ra f t and are e s s e n t i a l f o r o p e r a t i o n s i n a t least some condi t ions, Annex 10, Volume I, P a r t 1, Chapter 2 requires secondary power s o u r c e s f o r most of t h e s e r a d i o a i d s . The switch-over time f o r some of t h e s e r a d i o n a v i g a t i o n a i d s are shown i n Table 2-1 and d iscussed in paragraphs 2.2 and 2.3 of t h i s manual. The r ad io nav iga t ion a ids are o f t e n l o c a t e d i n i s o l a t e d areas o r a r e a s well separated f rom



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other buildings requiring electrical power. Secondary power i s usually provided by engine-generator power u n i t s because, fo r t he amount of power needed, secondary power may be more economical t o i n s t a l l t h a n a second f e e d e r t o t h e s i te . If an independent power source is used, the feeder from this source should be i n a separate duct or even a separate route from the primary power feeder. Some of the radio navigat ion a ids are more l ike ly to requi re un in te r rupt ib le power supplies than are aerodrome l igh t ing systems. The redundant configuration of Figure 2-3 is of ten advisable for some radio navigat ion a ids and r e l a t ed computers. ~-

3.8.2.4 Grounding. Radio navigat ion a ids may require lower resistance and more s t ab le grounding than do aerodrome l igh t ing systems. The grounding, as d iscussed in paragraph 2 .5 .14 , applies but grounding networks are more often required. The grounding requirements of both the e lectr ical system a t the rad io a ids bu i ld ing and a t the antenna should be considered carefully. Some of the antennas may requi re special grounding p lanes in some locat ions, Protect ion of the grounding systems from corrosion may be necessary for some radio navigation aids.

3.8.2.5 Lightning arresters. Lightning and surge protect ion for radio navigat ion a i d s i s more important than for most electrical systems because the r ad io s igna l s are more eas i ly a f fec ted , and antennas are of ten the t a rge t of l ightning strikes. Paragraph 2 .5 .12 discusses l ightning protect ion. Also these rad io a ids o f ten use so l id-s ta te devices which are vulnerable to vol tage and power surges. Often batteries or converters are used to provide dc power for the sol id-s ta te devices to e l iminate or reduce the l ightning and power surge problems.

3 .8 .2 .6 Feeds t o antenna arrays. The cabling between the r ad io equipment and t h e antenna often requires special handling. Usually coaxial cables are used t o conduct these s ignals . The cable may be required to provide a proper impedance match between the output of the s igna l genera tor and the input to the antenna but may a l s o need t o be of an accurate length for frequency phasing. The radio equipment o f t en exp l i c i t l y states these cabling requirements but some radio a ids may not furn ish these de ta i l s . The feeds to the antenna arrays should be carefully coordinated with the suppl ier of t he equipment and t h e i n s t a l l e r s of the antenna and radio equipment.

3 . 8 . 3 Contro l c i rcu i t s for rad io naviga t ion a ids

3 .8 .3 .1 Uses of con t ro l c i r cu i t s . The con t ro l c i r cu i t s fo r r ad io nav iga t ion a ids '

are pr imari ly used to energize and deenergize the systems, t o t r a n s f e r from primary t o stand-by o r a l t e rna te t r ansmi t t e r , and t o t r a n s f e r from primary to.secondary. power s ource

3 .8 .3 .2 Types of con t ro l c i r cu i t s . The radio navigat ion a ids may be located on t h e aerodrome o r s eve ra l miles away. Most radio navigation aids provide local control a t the t ransmit ter s i te and remote c o n t r o l a t one o r more a i r t r a f f i c o r equipment cont ro l sites. If the rad io a ids a re loca ted on or near the aerodrome and the cont ro ls are r e l a t ive ly s i m p l e , a c o r dc power con t ro l c i r cu i t s similar to t hose used f o r aerodrome l igh t ing may be used. These control c i rcui ts are discussed in paragraphs 3 . 4 . 1 . 4 , 3 . 4 . 2 . 3 , 3 . 4 . 3 . 1 , and 3 .4 .3 .2 as guides. If the dis tances are grea t o r the cont ro l c i r c u i t s a r e complex, te lephone c i rcui ts are often used for remote control. By d ia l ing a par t icu lar code of one, two, o r t h ree numbers, the desired switching can be obtained. The te lephone dial ing control system i s a form of multiplex control which can be expanded for control l ing very complex systems.

i I



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3 .8 .4 R e l i a b i l i t y and i n t e g r i t y o f r a d i o n a v i g a t i o n a i d s

3.8.4.1 As discussed in paragraph 3.6 .1 , t h e r e l i a b i l i t y and i n t e g r i t y of non-visual a ids ( rad io naviga t ion a ids) should be comparable t o t h a t of v i s u a l a i d s . I n a d d i t i o n t o the e lectr ical f ac to r s a f f ec t ing ae rodrome l i gh t ing of f a i l u r e of t h e c i r c u i t , f a i l u r e of t h e power supply, and f a i l u r e of t he con t ro l c i r cu i t , t he r ad io nav iga t ion a i d s must t ransmit a s igna l hav ing s eve ra l qua l i t i e s w i th in accep tab le t o l e rances . These s i g n a l q u a l i t i e s and t o l e r a n c e s f o r t h e s e a i d s are d i scussed i n Annex 10, Volume I, P a r t 1 , Chapter 3. Not only must the equipment be ope ra t ing and t r ansmi t t i ng a s igna l , bu t it should be monitored to assure an acceptable s ignal . Usual ly no s i g n a l is p r e f e r a b l e t o a bad s igna l . To improve r e l i a b i l i t y many radio navigat ion a ids have a l t e r n a t e t r a n s m i t t e r s e n e r g i z e d and ready for switching to t ransmission upon f a i l u r e of the p r imary t ransmi t te r o r of a d e f i c i e n t s i g n a l . The rad io naviga t ion a ids o f ten have individual secondary power sources to automatical ly assume power i f the pr imary power s o u r c e f a i l s . The control system should be designed so t h a t i f t h e c o n t r o l s h o u l d f a i l when t h e a i d is being operated by remote manual con t ro l , t he r ad io a id w i l l remain ope ra t ing and switch to automatic control. Attachment F t o P a r t I of Annex 10 con ta ins addi t ional guidance material r e g a r d i n g r e l i a b i l i t y and a v a i l a b i l i t y of rad io naviga t ion a i d s .

3.8.5 Monitor ing of radio navigat ion a ids

3.8.5.1 Signal monitoring. The moni tor ing of rad io naviga t ion a ids , except for l i gh t s t o i nd ica t e t ha t t he equ ipmen t is energized, requires automatic sensors of t h e s i g n a l t o d e t e r m i n e i f i t is acceptab le . Severa l qua l i t i es of t h e s i g n a l and funct ioning of sec t ions of t he equipment may require monitoring. The monitoring of t h e s i g n a l q u a l i t y f o r these rad io a ids are d i s c u s s e d i n Annex 10, Volume I, P a r t 1 , Chapter 3. The monitor may be r equ i r ed t o au tomat i ca l ly switch t o t h e a l t e r n a t e t r a n s m i t t e r o r deact ivate the equipment and a l so s igna l t he des igna ted con t ro l po in t s of t r ansmi t t ed s igna l de f i c i enc ie s . O the r less es sen t i a l r ad io nav iga t ion a ids may have monitors which i n d i c a t e a t t h e c o n t r o l p o i n t s i f o p e r a t i o n is s a t i s f a c t o r y . I f i t is n o t s a t i s f a c t o r y , the opera tor can make the requi red t ransfers . For the rad io a ids wi th cr i t ical s i g n a l requirements, the monitor may automatical ly deact ivate the equipment to prevent t ransmission of a d e f i c i e n t s i g n a l i f a s a t i s f a c t o r y signal f rom an a l t e rna te t r ansmi t t e r is not obtained.

3.8.5.2 Monitor ing auxi l iary funct ions. Several o the r func t ions may be monitored t o a s su re s a t i s f ac to ry ope ra t ion of radio navigat ion a ids . These may inc lude ba t t e ry v o l t a g e s f o r t h e s t a r t i n g of the secondary power set o r f o r o p e r a t i n g u n i n t e r r u p t i b l e power supplies, ambient or room temperature to maintain sui table environments for the equipment, and fuel supply for the secondary power source. These monitors may provide alarms or ind ica t ions t ha t t he func t ions exceed e s t ab l i shed cri teria.

3.9 ACCEPTANCE TESTING OF AERODROME ELECTRICAL CIRCUITS

3.9 .1 Application

3.9.1.2 The test procedures descr ibed in th i s sec t ion apply to the acceptance tes ts of new i n s t a l l a t i o n s and should be performed before making the system operat ional .



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3.9.2 Guarantee period

3.9.2.1 Each installation contract should include a guarantee clause specifying a period of at least one year during which the installing contractor can be held responsi- ble for repairing and replacing all cable and equipment failures resulting from poor work or defective materials and equipment. (Damp or dirty cable connectors and cable damage due to faulty installation practices often fail several months after installation. )

3.9.3 Inspection procedures

3.9.3.1 Visual examination. The most important of all inspection and test procedures are thorough visual inspections. Visual inspections should be made frequently during installation, at completion of installation, and before energizing the circuits. A careful visual inspection will reveal defects that can be corrected prior to acceptance tests and energization. Serious damage may occur if defects are subjected to electrical tests or energization. Visual inspections should include inspection appraisal of:

a) correctness of external connections;

b) good work performance;

c) cleanliness;

d) safety hazards; and

e) specific requirements for individual items.

All equipment manufactured under specifications should pass strict factory tests prior to shipment, but it should be visually inspected for shipping damage immediately upon receipt . 3.9.3.2 Cable, connectors and isolating transformer inspection. The primary and secondary cable leads of the transformers should be supplied with factory installed molded connectorse Visual inspection of these items diiing installation is especially important, as minor cuts, bruises, or mishandling may result in a progressive deterioration which will eventually cause complete failure, but not until some time after acceptance tests. During installation, these items should be inspected to determine the following:

a) that the mating surfaces of molded connectors are clean and dry when plugged together. If clean and dry inside, these high voltage connectors with taping form a connection equal to, or superior to, a conventional high voltage splice. Conversely, if they are wet or dirty inside, no amount of taping can produce a satisfactory connection. Two or three turns of tape are recommended to hold the connector together and keep the parting lines clean. Cleanliness of mating surfaces can best be insured by keeping the factory installed caps in place until the final connection is made. The mating surfaces of uncapped connectors should not be laid down, touched, or breathed upon. If it is necessary to break a connection, the connectors should be immediately capped;



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ICAO 9157 P A R T * 5 ** M 484341b 0039982 988 H


t ha t t he connec to r s are comple te ly p lugged toge ther . Af te r in i t ia l plugging, trapped air p res su re may par t ia l ly d i sengage the p lug and r ecep tac l e . If th is happens , wait a few seconds and push them t o g e t h e r again. Apply two o r t h r e e t u r n s of t a p e t o h o l d them i n place;

tha t the cab les have no t been cut by shovels, kinked, crushed by vehicle wheels , bruised by rocks , o r damaged i n any way during handl ing a n d i n s t a l l a t i o n ;

t h a t the cab le s are bur i ed t o t he spec i f i ed dep th below f i n i s h e d g r a d e and a l l o ther de ta i led requi rements of t h e i n s t a l l a t i o n s p e c i f i c a t i o n are accomplished;

t h a t t h e c a b l e s do no t d i r ec t ly c ros s each o the r and are separa ted by t h e r e q u i r e d d i s t a n c e s ;

tha t sc reened material has been placed under and over the cables , and that rocks or pebbles do not contact the cables; and

that the cables have not been bent sharply where they enter (or leave) a condui t and are supported properly by tamped ground, so f u t u r e s e t t l i n g cannot cause sharp bends.

3.9.3.3 Constant-current regulator inspect ion. Each cons tan t -cur ren t regula tor should be inspec ted to ensure tha t porce la in bushings have no t been c racked , no sh ipp ing damage has occurred, connections are co r rec t , swi t ches and r e l ays ope ra t e f r ee ly and are n o t t i e d o r b locked , fuses ( i f requi red) are c o r r e c t , a n d t h a t t h e o i l l e v e l of o i l - f i l l e d r e g u l a t o r s i s c o r r e c t . Only re lay pane l covers should be removed f o r t h i s inspect ion. It is not necessary to open the main t ank o f o i l - f i l l ed r egu la to r s . In fomra t ion on t he r egu la to r i n spec t ion p l a t e must be followed. All covers should be c leaned and t igh t ly rep laced a f te r inspec t ion and tests are completed.

3.9 .3 .4 Ligh t f i x tu re and beacon inspect ion. An inspect ion should be made t o de te rmine tha t the co lour , quant i ty , and loca t ions of l i g h t s are i n accordance with the in s t a l l a t ion d rawings . Each l i g h t s h o u l d be i n s p e c t e d t o d e t e r m i n e t h a t it is operable , t h a t g l a s s is not b roken or c racked , tha t cor rec t lamps are i n s t a l l e d , and t h a t i t has been properly leveled and aimed.

3.9 .3 .5 Inspect ion of miscellaneous components. Components such as c o n t r o l p a n e l s , re lay cab ine ts , pane lboards , etc., shou ld be v i sua l ly i n spec ted fo r damage, c o r r e c t connect ions, proper fuse and c i rcui t -breakder ra t ings, and compliance with the in s t a l l a t ion d rawings .

3.9 .3 .6 System operat ion test. Af t e r components and c i rcu i t s have been inspec ted , as ind ica t ed i n the p receeding paragraphs , the en t i re sys tem should be res ted as fol lows :

a) each switch of the l i gh t ing pane l s i n t he con t ro l t ower shou ld be operated SO t h a t e a c h s w i t c h p o s i t i o n i s reached a t least twice. During t h i s p r o c e s s , a l l l i g h t s and v a u l t equipment should be observed t o de te rmine tha t each switch p rope r ly con t ro l s t he co r re spond ing c i r cu i t ;



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ICAO 9157 P A R T * 5 ** m 48414Lb 0019983 814 m

P a r t 5.- E l e c t r i c a l Systems 5-57 -

b) t he above test should be repea ted us ing the pane ls in the a l te rna te c o n t r o l s t a t i o n ( v a u l t ) and then repeated again using the local control switches on the regulators ; and

c ) each l i gh t ing c i r cu i t shou ld be t e s t ed by opera t ing i t continuously a t maximum i n t e n s i t y f o r a t least 6 hours. Visual inspection should be made a t the beginning and a t the end of t h i s test to de te rmine tha t the correct number of l i g h t s are operat ing a t f u l l i n t e n s i t y . Hmming of some o r a l l of t h e l i g h t s i n a c i r c u i t is an ind ica t ion of ground f a u l t s . In addition, the lamp-terminal voltage should be measured on a t least one l i g h t i n each mu l t ip l e c i r cu i t , t o de t e rmine t ha t it is with in k 5 p e r cen t o f the ra ted lamp vol tage as marked on t h e lamp.

3.9.4 Electrical tests of s e r i e s -c i r cu i t equipment

3.9.4.1 Electrical tests are h e l p f u l i n d e t e r m i n i n g t h a t t h e q u a l i t y of t h e i n s t a l - l a t i o n i s acceptable and that the performance w i l l meet the operational requirements. Some of t h e tests involve the use and measurements of h i g h v o l t a g e c i r c u i t s . These tests should be performed only by qual i f ied persons who are f ami l i a r w i th h ighvo l t age electrical equipment and the sa fe ty p recaut ions which mst be observed.

3.9 .4 .2 Electrical tests on cable. Cables buried i n e a r t h ( t h a t i s , n o t i n d u c t ) should be tested before and after backf i l l ing the cab le t rench .

3 . 9 . 4 . 3 Each series c i r cu i t shou ld be t e s t ed fo r con t inu i ty by ohmmeter o r equ i - va len t method. The r e s i s t a n c e of t h e c i r c u i t t o ground should then be checked with a s u i t a b l e test set t o make s u r e i t i s f r e e o f grounds. Any f a u l t s i n d i c a t e d by these tests should be located and repaired before proceeding with highvol tage tests.

3.9.4.4 Each series c i r cu i t shou ld be sub jec t ed t o h ighvo l t age i n su la t ion resistance tests to determine complet freedom from grounds. Whenever possible , these tests should be performed when t h e ground i s thoroughly w e t . Experience has shown t h a t cir- c u i t s which pass i n su la t ion r e s i s t ance tests during dry weather may f a i l a f t e r a heavy ra in . Each circui t , including t ransformers , should be tes ted as follows:

a ) Disconnect both leads from the regulator output terminals. Support both leads so t h a t a i r gaps of several inches exist between bare conductors and ground. Make s u r e t h a t t h e c a b l e s h e a t h is c lean and dry for a distance of a t least 3 0 cm from the end of the cable. Also make sure t h a t exposed insulat ion a t each end of the cab le i s clean and dry.

b) Each c i r cu i t shou ld be t e s t ed immedia t e ly a f t e r i n s t a l l a t ion , i n acco rd - ance with " F i r s t T e s t For New Circui ts" descr ibed in sub-paragraph e). Any c i r c u i t which h a s been i n s t a l l e d f o r 60 days o r more, e v e n i f i t has no t been operated, should be tested i n accordance with "Succeeding T e s t and Old Circui ts" . (See sub-paragraph e). )

c ) The maximum acceptable l eakage cu r ren t , i n microamperes, should not exceed the values indicated in paragraph 3 . 9 . 4 . 7 .

d ) When addi t ions are made t o o l d c i r c u i t s , o n l y t h e new sections should be tes ted in accordance wi th " F i r s t T e s t On New Circui ts" . !I'he complete circuit should be checked a t the reduced vo l tages to ensure re l iab le operation.



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I C A O 9357 P A R T * 5 ** 4843416 0039984 750


e) Connect both conductors, and apply the test v o l t a g e i n d i c a t e d below f o r a period of 5 minutes between conductors and ground.

- Complete approach l ighting system ( t ransformers with 5 OOOYolt primary leads)

Touchdown zone and centre l i n e l i g h t c i r c u i t s ( t ransformers wi th 5 000- vol t p r imary leads)

High i n t e n s i t y runway edge l i g h t c i r c u i t s ( t r a n s f o r m e r s wi th 5 OOO-volt primary l e a d s )

Medium i n t e n s i t y runway and t a x i w a y l i g h t s c i r c u i t s ( t ransformers with 5 000- vo l t p r imary l eads )

6 0 0 ~ o l t s c i r c u i t s

F i r s t Test on New C i r c u i t s

9 000 V, dc

9 000 V, d c

.9 000 V, d c

6 000 V, d c

1 800 V, dc

Succeeding Tests and Old C i r c u i t s

5 000 V, d c

5 000 V, dc

5 000 V, d c

3 000 V, d c

600 V, dc

3 . 9 . 4 . 5 The tests outlined above should be performed with a su i t ab le h igh -vo l t age tester which has a s t e a d y , f i l t e r e d d c o u t p u t v o l t a g e , The high-vol tage tester should con ta in an accu ra t e vo l tme te r and mic roamete r fo r r ead ing t he vo l t age app l i ed t o the c i r cu i t and t he i n su la t ion l eakage cu r ren t .

3 . 9 . 4 . 6 These tests should be superv ised carefu l ly by q u a l i f i e d p e r s o n n e l t o ascer- t a i n t h a t e x c e s s i v e v o l t a g e s are not applied.

3.9.4.7 During the last minute of t h e tests the i n su la t ion l eakage cu r ren t i n mic ro - amperes for each complete c i rcui t should be measured and should not exceed the value c a l c u l a t e d f o r e a c h c i r c u i t as follows:

a ) a l l ow 2 micorampere f o r e a c h series transformer;

b ) a l low 1 microampere fo r each 100 meters of cable (This va lue inc ludes al lowances for the normal number of connectors and splices.); and

c) add the va lues ob ta ined to de te rmine the total a l lowable microampere leakage for each complete c i rcui t .

3.9 .4 .8 If the l eakage cur ren t exceeds the va lue ca lcu la ted as out l ined above , the c i r cu i t shou ld .be sectXonalized and the tests repea ted for each sec t ion . Defec t ive components must b e - l o c a t e d a n d r e p a i r e d , o r r e p l a c e d u n t i l t h e e n t i r e c i r c u i t p a s s e s t h e test.



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I C A O 9157 P A R T * 5 ** W 48434Lb 0039985 697

P a r t 5.- Electrical Systems 5-5 9 -

3.9.4.9 Make s u r e t h a t t h e test vol tage spec i f ied in paragraph 3.9.4.4 e) i s a c t u a l l y a p p l i e d t o t h e c i r c u i t a t t h e time the leakage current i s measured. The vol t - age should be adjusted so the vol tmeter reads the desired value before the leakage current is read. If any d i f f i c u l t y is encountered in ob ta in ing the des i red vo l tage , e i the r t he c i r cu i t be ing t e s t ed o r t he test set i s defective, and should be corrected before the tes t i s continued.

3.9.4.10 On new c i r c u i t s , a r e s i s t ance measurement should be made immediately a f t e r the c i rcu i t has passed the h ighvol tage tests with the test set used by aerodrome maintenance. This measurement reading then can be used during maintenance as a comparison with future readings to determine c i rcui t condi t ions. Ambient temperature and weather conditions should be recorded a t t h e time of test.

3.9.5 E l e c t r i c a l tests of other cables

3.9.5.1 Power cables ra ted 5 000 v o l t s and more. Power cables should be tested as out l ined using the methods i n paragraph 3.9.4.4 except that , cables ra ted a t 5 000 v o l t s should be tested a t 10 000 v o l t s and power cables ra ted above 5 000 volts should be t e s t e d at twice the cab le vo l t age r a t ing p lus 1 000 vol ts . The test should be made between conductors and from conductors to ground with the cable's shield and armor grounded and f o r a period of not less than one minute af ter inst rument readings have s t ab i l i zed . The minimum acceptable res is tance value i s 50 megohms. Or ig ina l insu la t ion values of the cable have been substantially reduced to the specified 50 megohms i n o r d e r t o compensate for cab le l ength , ag ing of conductor insulation, and other factors which may a f f e c t test resul ts both before and during instal la t ion. Unless cable length should appreciably exceed 3 000 metres, no r educ t ion i n t he spec i f i ed i n su la t ion r e s i s t ance should be considered. (Note. Insulat ion readings w i l l be erroneous unt i l the cable has been completely charged by the measuring instrument.) A test should be made f o r cont inui ty of the cable 's shield or armor. An ohmmeter type instrument may be used.

3.9.5.2 Power cable ra ted 600 v o l t s and below. Secondary power c a b l e s r a t e d a t 600 v o l t s and below and used for l ight ing and power wiring should have a res i s tance of not less than 50 megohms between conductors and between conductors and ground when measurements are made a t not less than 500 v o l t s dc.

3.9.5.3 Control and telephone cable. After ins ta l la t ion these cab les should comply with the following requirements:

Size cable Minimum no. of acceptable conductors

12 pa i r o r less All

Over 12 p a i r t o 25 p a i r , inc lus ive

All, except one pair

Over 25 pair Al l , except 2 p a i r

Acceptable conductors include satisfactory test as to cont inui ty , f reedom from short- c i r c u i t s , and a minimum of 50 megohms re s i s t ance betwen conductors and from each conduc tor to grounded sh ie ld when t e s t ed a t not less than 500 v o l t s dc.



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5-6 0 Aerodrome Design Manual - 3 .9 .5 .4 Coaxia l cab les . Radio f requency cab les should be t es ted for insu la t ion and l o o p r e s i s t a n c e p r i o r t o i n s t a l l a t i o n a n d t h e r e s u l t s r e c o r d e d . The i n s u l a t i o n test should be made be tween the cen t re conductor and sh ie ld wi th a 500 v o l t d c i n s t r u m e n t . The loop r e s i s t ance test shou ld be a l so made as above, but with the centre conductors s h o r t e d t o t h e s h i e l d a t t h e f a r end of the cab le . This test may be made wi th a b r i d g e , ohmmeter, o r o the r su i t ab le i n s t rumen t . Af t e r i n s t a l l a t ion , t he conduc to r - to - sh ie ld and conductor- to-grond res is tance should exceed 50 megohms when measured a t 500 vo l t s dc . h o p r e s i s t a n c e s h o u l d b e w i t h i n p l u s o r minus 10 per cen t o f the measured va lues p r ior t o i n s t a l l a t i o n , e.g. measured res is tance per 1 000 metres of cab le on reel, m u l t i p l i e d by each 1 000 metres and f rac t ion thereof o f ins ta l led cab le . Shie ld- to g round resistance should a l so be measured and the resu l t s recorded .

3.9.5.5 Coaxial cable , pressurized. Upon c o m p l e t i o n o f t h e c a b l e i n s t a l l a t i o n , t h e fo l lowing test should be made:

a) Electrical test. A h i g h - v o l t a g e i n s u l a t i o n tester with microammeter current-leakage meter should be used and 3 000 vo l t s dc app l i ed be tween t h e i n n e r a n d - o u t e r c o n d u c t o r s f o r a minimum per iod of th ree minutes While t h i s v o l t a g e i s app l i ed no not icable cur ren t should f low be tween t h e c o n d u c t o r s a f t e r c h a r g i n g c u r r e n t h a s s t a b i l i z e d .

b) Nitrogen gas test. Nitrogen gas a t t h e s p e c i f i e d p r e s s u r e s h o u l d b e app l i ed t o t he cab le , t he gas va lve c losed , and ambien t t empera tu re recorded. Six successive, hourly measurement of pressure should be taken and recorded. After the s ixth measurement i s taken and af ter a time in t e rva l o f abou t 24 hours , a seventh measurement should be made- If v a r i a t i o n s i n g a s p r e s s u r e are due only t o changes i n ambient temper- a t u r e , t h e l e n g t h o f c a b l e is acceptab le . A tempera ture cor rec t ion f a c t o r of 0.017 per degree C should be used.

3.9.6 Electrical tests of r e g u l a t o r s

3 .9 .6 .1 The supp ly vo l t age and t he i npu t t ap of t h e r e g u l a t o r s h o u l d b e c h e c k e d t o see that they correspond.

3 .9 .4 .2 With load d i sconnec ted , energ ize the regula tor once , and watch the open- c i r c u i t p r o t e c t o r t o see t h a t i t deene rg izes t he r egu la to r w i th in 2 o r 3 seconds.

a) Connect t h e l o a d c i r c u i t a f t e r i t has been checked for opens and ground as r e q u i r e d i n p a r a g r a p h s 3 .9 .4 .3 and 3 .9 .4 .4 and i n spec ted t o see t h a t a l l t ransformers are proper ly larnped.

b) Obtain a vol tmeter and an ammeter with an e r r o r of n o t more than J- 1 p e r c e n t of f u l l scale, and s imul taneous ly measure input vo l tage and ou tput cur ren t (connec t the ammeter t o t h e t e r m i n a l s of a n i s o l a t i n g t r a n s f o r m - er i n s e r t e d i n t o t h e o u t p u t c i r c u i t of t h e r e g u l a t o r ) f o r e a c h i n t e n s i t y s e t t i n g t a p .

c) Use a reco rd ing vo l tme te r o r t ake r ead ings du r ing bo th day and n igh t a t s u f f i c i e n t i n t e r v a l s t o o b t a i n a n a v e r a g e s u p p l y v o l t a g e .

d ) If regu la to r has i npu t vo l t age t aps , select the t ap which mos t near ly corresponds to average supply vol tage. The o u t p u t c u r r e n t f o r e a c h i n t e n s i t y s e t t i n g t a p s h o u l d b e w i t h i n k 2 p e r c e n t of the nameplate va lues a f te r any necessary supply vo l tage cor rec t ion is made.



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3.9.6.3 In a l l current regulators which have input vo l tage t aps , the ou tput cur ren t w i l l vary i n p r o p o r t i o n t o i n p u t v o l t a g e changes. I f a supply voltage of 2 350 is app l i ed t o t he 2 400 vol t t ap , the ou tput cur ren t va lues should be 2 p e r cent below t h e nameplate values.

3.9.6.4 Regulators which have automatic supply vol tage correct ion in l ieu of i npu t taps do not change the ou tput cur ren t as the supply vol tage var ies .

a ) If the ou tput cur ren t on f u l l i n t e n s i t y d e v i a t e s f r o m t h e n a m e p l a t e value by more than 2 per cen t (and i f t h e r e g u l a t o r is not overloaded), the internal adjustment should be checked, as descr ibed on the regulator instruct ion plate . Since the adjustment may be de l i ca t e , i t is recommended t h a t a deviat ion of k 5 per cen t be allowed on lower set- t ings before a t tempt ing to read jus t the regula tor .

b) Furthermore, a check should be made t o see whether the adjustment had been changed purposely fo r an unusua l l oca l f l i gh t ope ra t iona l requirement .

3.9.7 Troubleshooting tests

3.9.7.1 The following tes t shou ld he lp l oca t e t he f au l t i n t he even t t ha t t he tests indicate improper operation.

3.9.7.2 Disconnect the load, short-circui t regulator output terminals through an ammeter, and measure output current . If measured values are e q u a l t o o r s l i g h t l y h i g h e r than nameplate values , the regulator is opera t ing s a t i s f ac to r i ly and the l o a d c i r c u i t should be checked for faults.

3.9.7.3 Connect t he l oad cab le s ( a f t e r l oad c i r cu i t has been checked for opens and grounds, as spec i f i ed i n pa rag raphs 3 . 9 . 4 . 3 and 3.9.4.4 and inspected to see t h a t a l l transformers are properly lamped), and measure output current and output voltage s iml t aneous ly w i th t he r egu la to r ope ra t ing on the h ighes t i n t ens i ty s e t t i ng . The s igni f icance of the readings i s as follows:

a ) Sa t i s fac tory opera t ion is indica ted by cor rec t ou tput cur ren t and an output voltage which is s l igh t ly h ighe r t han that e s t ima ted fo r t he '

load, but which does not exceed the rated output voltage. The vol tage r equ i r ed fo r t he l oad may be estimated by mul t ip ly ing t he i so l a t ing transformer primary voltage a t rated load (wat ts divided by primary cur ren t ) by t h e number of transformers connected i n series i n t h e l o a d cir cuFt

b) A correc t ou tput cur ren t wi th an output vol tage appreciably less than the es t imated load vo l tage ind ica tes comple te o r par t ia l shor t ing of the load.

c ) A correct output current with an output vol tage exceeding the ra ted load output vol tage indicates an overload.

d) A reduced output current with an output vol tage indicat ing an overload is possibly caused by a poor connection i n t h e l o a d c i r u i t . The regulator should be deenergized immediately to p reven t damage.



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e ) A reduced output current with an output voltage not exceeding the rated output vo l tage ind ica tes a f a u l t y r e g u l a t o r o r reduced supply voltage.

f ) A zero ou tput cur ren t wi th excess ive ou tput vo l tage ind ica tes an open in t h e l o a d c i r c u i t and f a i l u r e of the open-c i rcu i t p ro tec tor in the regula tor . In th i s case, the r egu la to r must be deenergized immediately to p reven t s e r ious damage.

g) CAUTION: The open-circui t protector of t he r egu la to r mst not be deactivated or by-passed during these tests.

3.9.8 Electrical t e s t s of other equipment

3.9.8a1 Measure the input and output vol tages and currents and determine the loads of the connected c i rcui ts . Check to de te rmine i f these vo l tages and loads are wi th in the manufacturer ' s ra t ing of t h e equipment. Record these measurements f o r f u t u r e reference during maintenance or for modif icat ion of the c i rcui t .

3.9.9 Tests of monitors

3a9.9.1 After t h e t e s t s l i s t e d above have been completed and the system is func t ion- i n g as designed, monitors should be t e s t e d by s i m l a t i n g s u c h f a i l u r e s as open-circui ts , shor t -c i rcu i t s , g rounds , fa i lure of l i g h t s , l o s s of power i n b o t h t h e l i g h t i n g c i r c u i t s and t h e c o n t r o l c i r c u i t s , and observing the performance of the monitor. Monitors which f a i l t o perform as intended should be repaired before the system is accepted.



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ICAO 9357 PART*5 st - 48414Lb 0039989 232 -

UND- ELgcTBIcAL SYSTEMS

4.1 GENERAL REQUIREMENTS

4.1.1 Initial considerations

4.1.1.1 Installation of electrical cables underground is expensive and techniques to assure long and effective service with a minirrmm of maintenance should be used. All work should be done by experienced personnel regularly engaged in their type of work. Most underground cables will be located on, or very close to, the manoeuvring area of the aerodrome. Hence, at active aerodromes great care must be exercised to ensure that the installation does not present a hazard to aircraft or to the installers.

4.1.2 Preconstruction arrangements

4.1.2.1 Obtain prior approval of the engineer in charge for the materials, workmen, time of day or night for the work, method and procedures for the installation, and procedure for any temporary or permanent repairs to be made. Arrange for co-ordinating the effort with Air Traffic Control if it may be involved. Carefully determine and mark the route for the cables. Take all reasonable precautions to protect existing underground utilities such as fuel tanks, water lines, buried control and power cables, etc. All known utilities and power and control cables leading to and from any operating facility should be marked in the field before any work in the general vicinity is started. Thereafter and throughout the entire time of construction they should be protected from any possible damage. Any underground cables which are damaged during installation should be immediately repaired with equal quality material.

4.1.3 Methods of installation

4.1.3.1 There are two methods of installing underground electrical cables, by direct burial or in duct (conduit). These methods are discussed below.

4.2 DIRECT BURIAL OF CABLE

4.2.1 Steps of installing

4.2.1.1 The major steps of installing electrical cables by direct burial are trenching, placement of the cable, and backfilling.

4,2,2 Trenching

4.2.2.1 Basic requirements. Unless required otherwise, all cables in the same location and running in the same general direction should be installed in the same trench. Walls of trenches should be essentially vertical so that a minimum of shoulder surface is disturbed. The bottom surface of trenches should be essentially smooth and free from coarse aggregate. If possible, trenches should be opened only to the extent that cables can be installed and the trench closed in the same working day. Where turf is well established and the sod can be removed, it should be carefully stripped and properly stored.

5-63



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I C A O 9357 P A R T * 5 ** = 4B414Lb 0019990 T 5 4

5-5 4 Aerodrome Design Manual - 4.2.2.2 Trench depth. The t rench depth should be no t less than 5 cm below t h e l e v e l of the lowes t cable. Gables should be a minimum of 50 cm be low the f i n i shed g rade when on the aerodrome property and 75 cm below t h e f i n i s h e d g r a d e when off the aerodrome proper ty . I f cab les are t o be placed a t more than one l eve l , t he ver t ical s e p a r a t i o n should be the same as t h e h o r i z o n t a l s e p a r a t i o n i n d i c a t e d i n paragraph 4.2.3, except v e r t i c a l s e p a r a t i o n o f c o n t r o l a n d t e l e p h o n e c a b l e s a n d of low vo l t ages power c a b l e s shou ld be no t less than 6 cm. The ground wire or counterpoise should be a minimum of 15 cm above the uppermost layer of cables . Trench depths should a l low for these v e r t i c a l s e p a r a t i o n s r

4.2.2.3 Heavy t r a f f i c areas. Cables should not be direct bur ied under paved areas, roadways, r a i l r o a d t r a c k s , o r d i t c h e s , In t h e s e areas t h e c a b l e s h o u l d b e i n s t a l l e d i n c o n c r e t e - e n c a s e d d u c t s o r i n r i g i d s teel conduit .

4.2.2.4 Areas of rocks. Where rock excavat ion is encountered the rock should be removed t o a depth of a t least 8 cm below the requi red cab le depth and it should be replaced with bedding material of e a r t h o r s a n d c o n t a i n i n g n o m i n e r a l a g g r e g a t e p a r t i c l e s l a r g e r t h a n 6 mm i n diameter. When s o l i d r o c k i s encoun te red , a l t e rna t ives such as r e r o u t i n g t h e t r e n c h or i n s t a l l a t i o n i n r i g i d s teel condui t should be considered.

4.2.2.5 Trench width. Trench width for a s i n g l e c a b l e s h o u l d b e n o t less t h a n 15 cm. Where more than one cab le i s l o c a t e d in a t r ench , t he t r ench w id th shou ld be ad jus t ed so tha t the separa t ions g iven be low can be main ta ined .

4.2.3 Separation between cables

Power cab le s , of t h e same c i r c u i t , may be l a i d s i d e by s i d e i n t h e t r ench w i thou t s epa ra t ion , excep t as noted below. Ser ies l ight ing cab le s may be considered as of t h e same c i r c u i t .

Power cab le s o f t he same o r d i f f e r e n t c i r c u i t s o f less than 6Q0 v o l t s , may b e l a i d t o g e t h e r i n the same t r e n c h w i t h o u t h o r i z o n t a l s e p a r a t i o n .

Power cab le s of d i f f e ren t c i r cu i t s w i th vo l t ages be tween 600 and 5 000 vol t s should be separa ted a minimum of 10 cm.

All power cab le s , 5 000 vol t s and be low, should be separa ted f rom a l l control , te lephone, and coaxial type cables by a minimum of 15 cm.

Power cab le s , of more than 5 000 v o l t s , should be separated f rom a l l o t h e r c a b l e s by a minirmm of 30 cm.

Control , te lephone, and coaxial cables may b e l a i d i n t h e . t r e n c h w i t h o u t ho r i zon ta l s epa ra t ion f rom each o the r .

Vertical separa t ions should be similar t o t h o s e g i v e n in a) through f ) excep t t ha t cab le s wh ich do no t r equ i r e ho r i zon ta l s epa ra t ion shou ld be sepa ra t ed a minimum of 6 c m v e r t i c a l l y . No cab le shou ld d i r ec t ly ove r - lap another cab le because compact ing may damage the cab le .

Ground wires and counterpoises should be approximately 15 cm above t h e uppermost l eve l o f the cab les .



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I C A O 9357 P A R T S 5 t% 48434Lb 0039991 990

Part 5.- E l e c t r i c a l Systems 5-6 5 -

4.2.4 I n s t a l l a t i o n of d i rec t -bur ia l cab les

4.2.4.1 In i t i a l back f i l l i ng . Be fo re p l ac ing any cables , backfi l l and compact a 5 c m l aye r of e i ther ear th or sand containing no mater ia l aggregate par t ic les larger than 6 mm i n diameter.

4.2.4.2 Placing of cables. Wherever possible, cable should be run i n one p iece , without splices, from connection to connection. Use the longes t p rac t icable l engths of c a b l e i n o r d e r t o minimize splicing requirements. When cable cu t t ing i s required, cable ends should be effectively sealed against moisture immediately after cutt ing. Bends of a radius less than e ight times the diameter for rubber- or plast ic-covered cable and twelve times the diameter for metall ic-armored cable should not be made. Cable t h a t has been kinked should not be installed. A man should be stationed a t the reel to observe and report any i r r e g u l a r i t i e s i n t h e c a b l e when the cab le is being unreeled. Cable for direct ear th bur ia l should be unree led in p lace in the open t rench or unreeled near the trench and ca re fu l ly p l aced i n t he t r ench bottom. Pul l ing the cab le in to the t rench by dragging over the ground sHould not be permitted.

4.2.4.3 Cable slack loops. A cable slack loop of approximately one metre should be l e f t on each end of cable runs, and a t a l l poin ts where cable connections are brought above ground. The slack loop should be installed a t the same minimum depth as the cable run. Loops should have bends with an inner radius not less than twelve times the outs ide diameter of the cable. Where cable i s brought above ground, additional slack should be l e f t above ground. A t a l l c a b l e splices, provide s lack loops f ree of bends a t t he sp l i ce o r w i th in 30 c m of the ends of t he sp l i ce .

4.2.4.4 Final backfi l l ing. After the cable has been instal led, the t rench should be a backfi l led as follows:

a) Backfil l separating cables should be f i rmly tamped i n place. The cable separa t ions g iven in 4.2.3 should be maintained. These separat ions may be e i t h e r h o r i z o n t a l , v e r t i c a l , o r a combination of t he two.

b) The f i r s t l a y e r of backfi l l ing should be not less than 7 - 5 c m deep * loose measurement, and should be e i t h e r earth or sand containing no material aggregate par t ic les larger than 6 mm diameter. This l aye r should not be compacted, except for tamping to main ta in separa t ion of cables .

c) The second layer should be not less than 12 c m deep, loose measurement, and should contain no pa r t i c l e s l a rge r t han 25 nrm diameter.

d ) The remainder of t he back f i l l i ng may be excavated or imported material and should not contain stones or aggregate larger than 100 mm i n diameter. The t h i r d and subsequent layers of the backf i l l ing should no t exceed 20 c m i n maximum depth, loose measurement. The second and subsequent layers should be thoroughly tamped and compacted t o a t least the dens i ty of the ' ad jacent undis turbed so i l . I f necessary to ob ta in the desired compact ion, the backfi l l mater ia l may be moistened o r aera ted as required. Trenches should not be excessively w e t and should not contain pools of water during the backfi l l ing operat ions. The trench should be completely backfil led and tamped l eve l w i th t he adjacent surface.



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e) When sod i s t o be p l aced ove r t he t r ench , t he back f i l l i ng shou ld be stopped a t a dep th equa l t o t he t h i ckness o f t he sod t o be u sed . Any excess excavated material should be removed.

f ) Where sod has been removed i t should be rep laced as soon as p o s s i b l e a f t e r t h e b a c k f i l l i n g i s completed. All areas d i s tu rbed by t he t r e n c h i n g , s t o r i n g o f d i r t , c a b l e l a y i n g , p a d c o n s t r u c t i o n , a n d o t h e r work shou ld be r e s to red t o i t s o r i g i n a l c o n d i t i o n . The r e s t o r a t i o n s h o u l d i n c l u d e a n y n e c e s s a r y t o p s o i l i n g , f e r t i l i z i n g , l i m i n g , s e e d i n g , sodding, sprigging, or mulching. If t r e n c h i n g c u t s are made through paved areas, t h e c u t s , a f t e r p r o p e r b a c k f i l l i n g , s h o u l d b e r e s u r f a c e d with paving similar to t he o r ig ina l pav ing . Resu r faced cu t s shou ld be l e v e l w i t h t h e o r i g i n a l p a v i n g , f r e e f r o m c r a c k s , a n d c a p a b l e of w i ths t and ing t r a f f i c l oads imposed w i thou t s e t t l i ng o r c r ack ing .

4 . 3 INSTALLATION OF DUCTS (CONDUIT)

4.3.1 Ins ta l la t ion t echniques and procedures

4.3.1.1 Se lec t ion of rou te s . Duc t - l i ne rou te s shou ld be s e l ec t ed t o ba l ance maximum f l e x i b i l i t y w i t h m i n i m m c o s t a n d t o a v o i d f o u n d a t i o n s f o r f u t u r e b u i l d i n g s a n d o t h e r s t r u c t u r e s . Where i t may be necessary to run communica t ion l ines a long wi th electric power d i s t r i b u t i o n l i n e s , two i s o l a t e d s y s t e m s i n s e p a r a t e manhole compartments should be provided. Where p o s s i b l e , d u c t s s h o u l d b e i n s t a l l e d i n t h e same concrete envelope. Electric and commnication ducts should be kept clear of a l l other underground u t i l i t i e s , e s p e c i a l l y h i g h - t e m p e r a t u r e water o r steam pipes .

4.3 .1 .2 Duct materials. Acceptable s tandard materials f o r d u c t s i n c l u d e f i b e r , asbestos-cement, t i l e , and p las t ic . Rig id steel condui t may a l s o b e i n s t a l l e d below g rade and shou ld be p rov ided w i th f i e ld o r f ac to ry app l i ed coa t ings where r equ i r ed .

4.3.1.3 Size of ducts . S ize of condu i t s in a duct bank should be not less t h a n 10 cm ins ide d i ame te r excep t t ha t duc t s fo r comnun ica t ion l i nes w i th a minimum diameter of 7.5 cm are acceptab le .

4.3.1.4 I n s t a l l a t i o n of duc t s w i thou t conc re t e encasemen t . T renches fo r s ing leduc t l i nes shou ld be no t less than 15 c m nor more than 30 c m wide , and the t rench for two o r more d u c t s i n s t a l l e d a t t h e same level should be proport ionately wider . Trench bot toms for ducts without concrete encasement shold be made t o conform accura te ly to g rade so as t o p r o v i d e u n i f o r m s u p p o r t f o r t h e d u c t a l o n g i t s e n t i r e l e n g t h . A l a y e r of f i n e e a r t h material a t least 10 cm thick ( loose measurement) should be placed i n t h e bottom of the t r e n c h as bedding f o r t h e d u c t . The bedding material s h o u l d c o n s i s t of s o f t d i r t , s a n d , o r o t h e r f i n e f i l l , and i t should conta in no p a r t i c l e s l a r g e r t h a n 6 mm diameter. The bedding material should be tamped u n t i l f i r m . When two o r more d u c t s are i n s t a l l e d i n t h e same t rench without concrete encasement , they should he spaced not less than 5 cm apart (measured f rom outs ide wall t o o u t s i d e w a l l ) i n a h o r i z o n t a l d i r e c t i o n o r n o t less t h a n 15 cm a p a r t i n a v e r t i c a l d i r e c t i o n . R i g i d steel and heavy-wall conduit may be d i r e c t e a r t h b u r i e d . All other condui t s should be encased .

4.3.1.5 I n s t a l l a t i o n of d u c t s e n c a s e d i n c o n c r e t e . A l l d u c t s i n s t a l l e d i n c o n c r e t e encasement should be placed on a layer o f concre te no t less than 7.5 c m t h i c k . Where two o r more duc t s are encased i n concre te they should be spaced no t less than 5 CIU



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-8

Part 5.- Electrical Systems 5-6L

(measured from ou t s ide wa l l t o ou t s ide wa l l ) . As the duct laying progresses , concrete not less than 7.5 c m thick should be placed around the sides and top of the duct bank. Flared ends of ducts or coupl ings should be instal led f lush with the concrete encasement o r i n s ide wa l l s of manholes or handholes. Interlock spacers should be used a t not more than 1.5 metre spacing to insure uniform spacing between duc t s . Jo in t s i n ad j acen t ducts should be staggered a minimm of 60 cm apar t and should be made waterproof prior to concret ing. No duct having a defective joint should be installed. Concrete-encased duc t o r r ig id steel condui t should be instal led s o t h a t t h e t o p of the concrete envelope or conduit i s not less than 40 c m below the bottom of the paving where it is i n s t a l l e d under roadways, ra i l roads , runways, taxiways, other paved areas , and d i tches and not less than 40 cm below the f inished grade elsewhere.

4.3.1.6 Grounding bushings. Where r i g i d s teel condui t enters or leaves a manhole o r , handhole a grounding bushing should be provided for a l l conduits.

4.3.1.7 Arrangement of duct banks. An arrangement of two ducts wide or high should be used for best heat d iss ipat ion. Correspondingly, the duct banks may be several ducts high or wide. (This may be impossible where a l a r g e number of ducts are involved.) The v e r t i c a l two conduit-wide arrangement enables the cables to be more easi ly racked on manhole walls but may not be as economical as the horizontal two conduit-high arrangement. For dimensions and arrangement of duct banks, see Figure 4-1.

4.3.1.8 Drainage. All duct l ines should be la id s o as t o s l o p e toward handholes, manholes and duct ends for drainage. Grades should be a t least 2.5 millimetres per metre. Where it i s no t p rac t i cab le t o ma in ta in t he s lope a l l one way, t he duc t l i nes may be s loped f rom the cen ter in bo th d i rec t ions toward manholes, handholes, or duct ends. Pockets o r t r a p s where moisture may accumulate should be avoided.

4.3.1.9 Pu l l wire. Each spare duct installed should be provided with a copper-clad steel p u l l w i r e of not less than 5 mm2 i n a r e a . The open ends of the spare ducts should be plugged with removable tapered plugs. The plug should secure the pul l wire firmly.

4.3.1.10 Spare capaci ty . Suff ic ient ducts for planned instal la t ions, future expansion, plus a minimum of 25 per cent of spare ducts, should be included for a l l new underground systems.

4 - 4 MANHOLES AND HANDHOLE S

4.4.1 Select ion

4.4.1.1 Factors bearing on the choice of manholes and handholes are number, d i rec t ion , and loca t ion of duct runs; cable rack arrangements; method of drainage; adequacy of work space ( e s p e c i a l l y i f equipment i s t o be i n s t a l l e d i n t h e manhole); and the s i z e of the opening required to instal l and remove equipment.



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ICAO 9357 PART*5 ** 4B4L4Lb 0019994 bTT


. ... L

7.5 cm -. 5 cm 7.5 cm

SINGLE DUCT

7.5 c m l 5 cm 7.5 cm 5 cm r 7.5 cm

7.5 cm

5 cm

7.5 cm

ELECTRIC OR COMMUNICATION

7.5 cm

5 cm

7.5 crn

COMBINED ELECTRIC (E) AND COMMUNICATION (C)

REINFORCED DUCT BANKS

1.5 cm TYPICAL

1.25 cm BARS AT 15 cm TO 20 cm ON CENTRES'

(2.5cm WIRE HOOP) APPROXIMATELY 20 crn

ON CENTRES1

1. WHERE REINFORCEMENT IS PROVIDED UNDER RAILROAD TRACKS IT SHOULD EXTEND AT LEAST 3.5 rn BEYOND THE OUTER RAtLS.

Figure 4-1, Duct line sections

e



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ICAO 9157 P A R T * 5 ** 484L43b 0039995 536

Part 5.- Elec t r ica l Systems 5-62

- 4.4.2 Location

4.4.2.1 Manholes o r handholes should be placed where required for conrrectione o r sp l i ces and where c o n f l i c t w i t h o t h e r u t i l i t i e s w i l l be avoided. Manhole separation should not exceed 200 wtres on s t r a i g h t rune and 100 metres on curved duct runs. Spacing should be decreased where necessary t o prevent ins ta l la t ion damage during pul l ing of cables. Strain should be l imi t ed du r ing i n s t a l l a t ion t o a point that will not davlge cable insulation or deform the cable (see Table 4-1).

4.4.3 S t u b

4.4.3.1 It is good prac t ice t o provide a ret of two or =re spare s tubs (short

- lengths of ducto leading out from the manhole) so t ha t t he manhole wall need not be disturbed when a future extension i s -de. The stubs should be plugged on both ends.

4.4.4 Hardware

4.4.4.1 tbirdware appl icable to t h e i n s t a l l a t i o n should be chosen. Where f lared ends of ducts are provided, cable-duct ohields are neccooary only for protection of retallic- sheathed cabler.

4.4.5 Two-mection u n h o l e r

4.4.5.1 Twoaect ion unholer should be used t o u in ta ia separat ion of t h e circuits where electric parer and coraralcat ion line. are i n s t a l l e d i n t h rare duct bank or w e the same -hole.

4.5 INSTALLATION OF UNDERGROUND CABLES

405.1 Preparation of ductr

4.5.1.1 After the duc t ins ta l la t ion i o completed, the cable6 are i n s t a l l e d by drawing or pul l tng in to the duc ts . The duct should be open, continuous, and clear of debris before the cable is ine ta l led . The cable should be i n s t a l l e d i n a manner t o prevent harmful stretching of the conductor, injury to the insulation, or dapage t o the outer protective covering. The ends of a l l cables should be sealed with wisture-seal tape before instal l ing, and they should be kept sealed until connections are made. Where more than one cable is t o be i n s t a l l e d i n a duct or conduit , a l l cable should be i n s t a l l e d at t he sa= time. In no case should a sp l i ce or connection be placed i n a duct or conduit.

4.5.2 ..

Cable pul l ing in ducts

4.5.2.1 Method of pull ing. The cable to be i n s t a l l e d i n t h e d u c t may be pulled by a power winch or by hand. An adequate amount of cable pul l ing compound should be used on a l l p u l l s . Petroleum grease should not be used. The surface of any cable sheath or jacket should not be damaged t o a depth greater than 1/1Oth i t s original thickness. The cable should not be f la t tened out of round more than l/lOth i ts outside diameter. Maxinum pul l ing tensions for commonly i n s t a l l e d c a b l e s a r e l i s t e d i n Table 4-1. The l i m i t a t i o n s i n Table 4-1 are not intended to preclude the use of steel or wire rope as a means of pulling. However, unless a dynamometer is used to indicate the proper tension 0 for the cable being pulled, a harness of the proper size rope that w i l l limit the



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I C A O 9357 PARTWS t t m 4d4343b 0037796 472 m


Table 4-1

MAXIMUM ALLOWABLE NON-ARMORED CABLE PULL USING DYNAMOMETER OR ROPE

CABLE TENSION ROPE DIAMETER - 2 - IC 8.4 mm2 Sol 125 kg 4.8 mm C 3 - IC 8.4 mm2 So l 165 kg 6.4 mm C 4.8 mm M 4 - IC 8.4 mm2 S o l 250 kg 6.4 mm M

2 - IC 13.3 mm2 S t r 190 kg 6.4 mm C 4 . 8 mm M 3 - IC 13.3 nnn2 S t r 285 kg 8.0 mm C 6.4 mm M 4 - IC 13.3 m2 S t r 380 kg 9.6 UUII c 4.8 mm D

1 - 2c 8.4 mm2 S t r 140 kg 6 . 4 mm C 1 - 3c 8.4 mm2 S t r 180 kg 6.4 mm C 1 - 4c 8.4 -2 S t r 265 kg 6.4 mm M

1 - 2c 13.3 mm2 S t r 220 kg 6.4 mm C 4.8 mm M 1 - 3c 13.3 mm2 S t r 310 kg 8.0 mm C 1 - 4c 13.3 m a 2 S t r 400 kg 9.6 mm C 8.0 mm M 4.8 mm D

1 - 6c 3.3 mm2 S t r 140 kg 6.4 mm C 1 - 12c 3.3 mm2 S t r 285 kg 8.0 mm C 6.4 mm M

1 - 12PR 0.6 mm2 105 kg 4.8 mm C 1 - 25PR 0.6 mm2 245 kg 6.4 mm M 1 - 50PR 0.6 mm2 480 kg ll..5 mm C 4.8 mm N 1 - lOOPR 0.6 mm2 12.0 mm M 8.0 mm D

RG - 11/U RG - 213/U RG - 214/U

55 kg 4.8 mm C 65 kg 4.8 mm C

(formerly RG-8/U) (formerly RG-~/u)

RG - 216/U 60 kg 4.8 mm C (formerly RG-l3/U) RG - 217/U 115 kg 6.4 mm M (formerly RG-l4/U) RG - 218/U 360 kg 11.5 uun C (formerly RG-l7/U)

c - Conductor Sol - Solid S t r - Stranded PR - P a i r C - Cotton M - Manila D - Dacron N - Nylon

Maximum pu l l ing t ens ions fo r cab le s no t l i s t ed shou ld be ob ta ined f rom the manufac tu re r of the cable .



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Part 5.- E l e c t r i c a l Systems 5.-7 1 - tension of t h e p u l l t o f o r c e s i n d i c a t e d i n T a b l e 4-1 should be used. Any combination of a group of cables t o be p u l l e d i n t o a duct should not exceed the sum of ind iv idua l allowable tension of each cable plus 15 p e r cent.

4.5.2.2 Length of pul l . To min imize sp l i c ing , t he l onges t p rac t i cab le l eng ths of cable should be pul led into the ducts a t one time. Unless otherwise required, manholes and handholes should be as f a r a p a r t as prac t icable for the type o f cab le be ing ins ta l led , bu t under no condition should the distance between handholes or manholes exceed 200 metres. ~.

4.5.2.3 Severa l cab les ins ta l led in one duc t . The following are a p p l i c a b l e t o t h e i n s t a l l a t i o n of two o r more c a b l e s i n t h e same duct.

Power cables of the same vol tage may b e i n s t a l l e d i n t h e same duct.

Power cables of less than 600 v o l t s may b e i n s t a l l e d i n t h e same duct.

Power cables of less than 600 volts s h o u l d n o t b e i n s t a l l e d i n t h e same duct with control , te lephone, or coaxial type cables .

Power cables of more than 600 v o l t s s h o u l d = b e i n s t a l l e d in t h e same duct with control. telephone, coaxial or power cables of less than 600 v o l t s .

Control, telephone, and coaxial cables may b e i n s t a l l e d i n t h e same duct c

Power, control , and te lephone cables may b e i n s t a l l e d i n t h e same duct sys tem, subjec t to p rovis ions of sub-paragraphs g ) and h).

Cable i n s t a l l a t i o n i n manholes or handholes. Power and c o n t r o l c a b l e s shou ld be i n s t a l l ed i n s epa ra t e manholes and handholes unless required otherwise. If space i s ava i l ab le , cab le s l ack su f f i c i en t fo r one sp l i ce f o r e a c h c a b l e s h o u l d b e l e f t i n e a c h manhole.

Separa t ion of cab les in manholes and handholes. When i t i s n o t p o s s i b l e t o i n s t a l l power and o the r t ype cab le s i n s epa ra t e manholes o r handholes , they should be ins ta l led in separa te compar tments o r on opposi te s i d e s of t h e manhole o r handhole.

4.5.3 I n s t a l l a t i o n of cables i n manholes and handholes

4.5.3.1 Cable racks. Cables shal l be careful ly formed around the inter ior of manholes or handholes avoid ing sharp bends o r k inks . Al l~spl ices and cab les should be t i ed t o cable racks using 3.2 mm diameter nylon line. Handhole and manhole racks should be t h e p las t ic type o r p rovided wi th porce la in insu la tors . Spl ices o r connec tors should be a minimum of 0 .6 metre from the mouth of the duc t opening in to the manhole or handhole. Where f eas ib l e , sp l i ces i n d i f f e ren t cab le s shou ld be staggered.

4.5.3.2 Cable terminations. Termination of a l l control , te lephone, and coaxial cables should be as required. Termination of a l l power cables ra ted above 5 000 v o l t s should be made w i t h a stress re l i e f dev ice . Where potheads are-used, strict conformance t o manufacturer’s recommendations should be followed. Where terminat ions are made a t transformer bushings, exposed conducting surfaces on both high- and low-voltage sides should be taped €or fu l l vo l tage and pa in ted wi th a h igh insu la t ion water - res i s tan t coating.



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4.5.3.3 Cable grounding. The fol lowing condi t ions apply to the grounding of cables .

a) All sh ie lded power cables should have the shield grounded a t each end. The grounding conductor should be connected t o a ground rod by means of a grounding connec tor spec i f ica l ly des igned for th i s purpose . The shields or armor on direct ear th-buried power cables should be grounded on each end, but not at t h e splices.

b) All shielded control cables should have the shield grounded a t each end. The s h i e l d a t each splice should have insulat ion res is tance f rom ground e q u a l t o t h a t of t h e o r i g i n a l c a b l e .

c) Telephone cables should have the shields grounded a t =end only. The s h i e l d a t each sp l ice should have insulation resistance from ground e q u a l t o t h a t of t h e o r i g i n a l c a b l e .

d ) Coaxia l cab le sh ie lds should be insulated f rom ground throughout the length of the cable run. The sh ie lds shou ld be grounded only a t t h e coaxial connector terminat ing. in to the equipment on each end of t h e cable run.

4.5.4 Pressur ized type coaxia l cab les

4.5.4.1 Precaut ions. Special precaut ions should be observed during the instal la t ion of gas - f i l l ed coax ia l cables. These cables shou ld be fu rn i shed and i n s t a l l ed i n one piece under n i t rogen gas p ressure wi th cab le and seals k e p t s e c u r e l y i n p l a c e a t a l l times dur ing cab le handl ing , sh ipping , and ins ta l la t ion . Do n o t c u t o r s p l i c e t h i s cab le a t any time. As t h e c a b l e is unwound f rom the reel, a supplementary device for s t r a i g h t e n i n g t h i s c a b l e i s des i r ab le . Utmost care should be exercised a t a l l times t o prevent k inking any par t o f the cab le dur ing ins ta l la t ion ,

4.5.4.2 Pre-instal la t ion check. In order to determine whether the cable has been damaged or punctured, determine i f t h e n i t r o g e n g a s s h i p p i n g p r e s s u r e is s t i l l r e t a i n e d i n the cab le . I f th i s gas p ressure reading has decreased and the loss is not due t o temperature change, a n i t rogen gas test should be conducted.

4.5.4.3 Styroflex and hel iax cables . Styrof lex coaxial cable of 45 mm diameter should not be subjected to a bending radius of less than one metre d u r i n g i n s t a l l a t i o n o r less than 0.6 metre rad ius when secured i n place. The maximum a l lowable pu l l ing t e n s i o n f o r t h i s s i z e o f c a b l e i s 800 kg. J3eliax coaxial cable should not be sub jec t ed t o a bending radius of less than 0.75 metre d u r i n g i n s t a l l a t i o n n o r less than a 0.5 metre rad ius when s e c u r e d i n place. The maximm a l l o w a b l e p u l l i n g t e n s i o n f o r t h i s s i z e of cab le i s 380 kg.

4.5.4.4 Slack co i l c ab le l oops shou ld no t be u sed fo r p re s su r i zed coax ia l cab le s . The cable end should be fed through the opening provided a t the bu i ld ing f rom the reel loca ted ou t s ide t he bu i ld ing . The cable be tween the s t ruc ture en t rance and the r e spec t ive cab le end shou ld con t inue i n to t he bu i ld ing on r e l a t ive ly t he same h o r i z o n t a l plane. Bends should not be less than the minimum prescribed above. Temporarily support the cab le end so t h a t t h e c a b l e w i l l not "droop" or "hang", pending f i n a l c o n n e c t i o n t o the e l ec t ron ic appa ra tus .



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4.5.5 C a b l e i n s t a l l a t i o n i n saw c u t s

4.5.5.1 Use of saw cuts . When new l i g h t s a r e i n s t a l l e d i n e x i s t i n g p a v e m e n t s , f o r example, runway c e n t r e l i n e a n d touchdown zone l i gh t s and taxiway centre l i n e l i g h t s , c a b l e i n s t a l l a t i o n i n saw c u t s o r k e r f s may be required. Only secondary c i r cu i t s of i s o l a t i n g t r a n s f o r m e r s s h o u l d b e i n s t a l l e d i n saw cuts. This technique should not. be used i n new pavement as it weakens t h e pavement.

4.5.5.2 Cut t ing the pavement. Saw c u t s are made wi th diamond blade saws. The saw cut or kerf should be not less than 1 cm wide and not less than 2 cm deep. The width and depth should be increased i f several cables are t o be i n s t a l l e d i n t h e same saw c u t and a t en t r ances t o l i gh t f i x tu re s , t r ans fo rmer enc losu res , and sp l i ce chambers. The depth o f the ker f should be increased suf f ic ien t ly to a l low s lack wire under the pavement j o i n t where a saw cu t c ros ses a c o n s t r u c t i o n j o i n t i n t h e pavement. All saw c u t s should be i n s t r a i g h t l i n e s w i t h v e r t i c a l s i d e s . The in te rsec t ing edges should be chamfered where saw c u t s intersect to r educe damage t o t h e c a b l e i n s u l a t i o n . It may be d e s i r a b l e t o c o l l e c t t h e d e b r i s f r o m saw cut t ing and process it t o r e c o v e r t h e diamond g r i t .

4.5.5.3 Cleaning the saw cut. The saw cut should be sandblasted to remove a l l f o r e i g n and l o o s e material. Sand f o r b l a s t i n g s h o u l d be of t h e p r o p e r s i z e a n d q u a l i t y f o r t h i s work and appl ied wi th p roper s ize nozz les and a i r p ressure , Immedia te ly p r ior t o i n s t a l l i n g t h e c a b l e s o r wires, t h e saw cut should be f lushed with a high-speed j e t of water o r steam and dr ied wi th a high speed j e t of air. Keep t h i s area c l e a n u n t i l completion of the work.

4.5.5.4 I n s t a l l a t i o n of c a b l e s i n saw cuts . Since these cables are f o r t h e secondary current of i so l a t ing t r ans fo rmers , 600-vo l t i n su la t ion su i t ab le fo r w e t o r damp locat ions should be used. Polyvinyl-chlor ide, polyethylene, rubber , and e thylene- probylene-rubber are s u i t a b l e t y p e s of insu la t ion . A j a c k e t o v e r t h e i n s u l a t i o n is not required. The conductor should be stranded copper not less than 3.3 m2 i n cross- s e c t i o n a l area. If the t o t a l l eng th o f t he conduc to r w i l l exceed 350 metres, t h e conductor s ize should be not less than 5.2 m2. Usually single-conductor wire i s used, but two-conductor cable i s acceptable. Do n o t s p l i c e t h e c a b l e i n t h e saw cuts ; use on ly fu l l l eng th runs o f cab le . The cables should be placed a t the bot tom of the saw cuts and anchored with rubber or plast ic wedges or with non-corrosive metal c l i p s . There is no need f o r s e p a r a t i o n o f c a b l e s when more than one cable is placed i n t h e same cut . The wedges or c l ips should be spaced approximate ly one metre a p a r t e x c e p t t h a t c loser spac ing may be des i red a t pavement j o i n t s , saw cut in t e r sec t ions , and en t r ances t o s p l i c e chambers o r l i g h t s . C a b l e s s h o u l d b e e n c a s e d i n f l e x i b l e t u b i n g o f p o l y e t h l e n e o r o t h e r s u i t a b l e material of n o t less than 0.3 metre i n l e n g t h a t j o i n t s i n t h e pavements. The s i z e o f t he t ub ing shou ld be su f f i c i en t t o a l l ow movement of the cables . The tubing should be centered on the jo in t and the ends o f the tub ing wrapped wi th t ape t o p reven t t he en t r ance of s e a l i n g materials.

4.5.5.5 Seal ing the saw cu t . The saw cu t shou ld be s ea l ed w i th su i t ab le adhes ive compounds a l o n g t h e e n t i r e l e n g t h a f t e r t h e c a b l e s are i n s t a l l e d . The compounds are usua l ly two-component l i q u i d t y p e s s u i t a b l e f o r t h e c a b l e i n s u l a t i o n a n d t h e t y p e of concrete. Test samples of the sea lan t should have a minimum e longat ion of 45 per cent . The adhesive components should not be older than recommended by the manufacturer and should not be s tored where the temperature exceeds 30°C or the manufacturer ' s recommendations. The manufac turer ' s ins t ruc t ions should be fo l lowed in mix ing and

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ICAO 9357 PART*5 ** m 4843436 0020000 397 W


i n s t a l l i n g . U s u a l l y i f t h e a d h e s i v e components are pre-warmed t o 25OC before and during mixing, the compound may be s a t i s f ac to r i ly i n s t a l l ed and cu red w i thou t t he app l i ca t ion of ex te rna l hea t i f t he ambien t t empera tu re i s 7°C o r g r e a t e r . The j o i n t s of pavement i n t h e areas of saw cuts should be packed with roving mater ia l such as hemp, j u t e , c o t t o n , o r f l a x t o p r e v e n t t h e s e a l i n g material f rom f lowing into the open j o i n t . All surp lus and s p i l l e d material should be removed.

4.5.5.6 Cable terminations. Cables should be properly terminated i n f i x t u r e s , t ransformer enclosures , and s p l i c e chambers. The e n t r a n c e s t o t h e s e t e r m i n a t i o n u n i t s should be sealed. The te rmina t ion ends o f the cab les should be su i tab ly connec ted and the cable protected f rom moisture enter ing the cable between the conductor and the end of t h e i n s u l a t i o n .

4.5.6 Cable marking

4.5.6.1 All cables and cab le rou tes should be marked f o r e a s y i d e n t i f i c a t i o n i n t h e f u t u r e . 4.5.6.2 Cable tagging. All cables should be tagged i n e a c h manhole or handhole with n o t less than two tags per cable , one near each duct entrance hole . Tags should be a t t ached t o t he cab le immedia t e ly a f t e r i n s t a l l a t ion . Cab le t e rmina t ions and po theads should be tagged as t o f u n c t i o n , f a c i l i t y w h i c h it se rves , and o the r pe r t inen t da t a . Tags should be of sui table s ize and thickness , preferably of copper. They should be securely attached to the cable using nylon cord. Marking of tags should consis t of an abbrev ia t ion of t h e name of f a c i l i t y o r f a c i l i t i e s s e r v e d by the cab le , t he l e t t e r ind ica t ing t he t ype of service (power, te lephone, control and radio f requency (coax)) provided by the cable. Where telephone type cable i s used fo r con t ro l func t ions , i t should be marked as a con t ro l cab le , no t a telephone cable. Where two o r more i d e n t i c a l cab le s are used t o serve t h e same f a c i l i t y , t h e y may be bundled under one tag.

4.5.6.3 Cable route markers. Direct earth-burial cable routes should be marked every 6 0 metres along the cable run, a t each change of direction of the cable, and a t each cab le sp l i ce w i th a concrete s lab marker of su i t ab le s i ze and t h i ckness . These m a r k e r s s h o u l d b e i n s t a l l e d s h o r t l y a f t e r t h e f i n a l b a c k f i l l of the cab le t rench . The markers should be instal led f la t in the ground with the top approximately 2.5 cm above the f i n i shed g rade . After the concrete marker has set a minimum of 24 hours , the top sur face should be pa in ted b r ight o range wi th pa in t su i tab le for uncured ex ter ior concrete. Each cable marker should have the following information impressed upon i t s top surface:

a) t h e word "CABLE" o r "SPLICE". The l e t te r des igna t ing t he t ype of c a b l e sp l iced should p recede the word "SPLICE";

b) t h e name of t h e f a c i l i t y s e r v e d ;

c ) t he t ype of cab le i n s t a l l ed shou ld be marked wi th "POWE;R", "CONTROL", "TELEPKONE", o r "COAXIAL", o r w i t h s u i t a b l e a b b r e v i a t i o n s f o r these terms. The designat ion of a l l t ype cab le s i n s t a l l ed shou ld be shown on the marker;

d ) a r rows t o i nd ica t e t he d i r ec t ion o r change of d i r ec t ion o f t he cab le run;



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Par t 5.- Electrical Systems 5-75 -

e) t h e le t ters should not be less than 10 cm high, 7 c m wide and 1 c m deep;

f ) c a b l e s i n s t a l l e d i n d u c t o r c o n d u i t s h o u l d h a v e z a b l e m a r k e r s i n s t a l l e d eve ry 60 metres and a t every change i n d i r ec t ion o f cab le , excep t marke r s shou ld no t be i n s t a l l ed i n conc re t e o r a spha l t su r f aces ; and

g) manholes and handholes sha l l b e i d e n t i f i e d by purpose.

4.5.7 Enclosures for connec t ions

4.5.7.1 Ins t a l l a t ion o f enc losu res . Most cable connect ions t o t h e i s o l a t i n g t ransformers are i n t ransformer enc losures , i n b a s e s f o r l i g h t i n g f i x t u r e s w h i c h are below t h e s u r f a c e a t the edge of paved runways o r t ax iways , o r i n the pavement. P r e f e r a b l y , t h e s e e n c l o s u r e s are i n s t a l l e d a t the des igna ted l oca t ions i n a poured concrete foundat ion which encases the enc losure conta iner by n o t less than 10 t o 15 c m of concrete around the bot tom and s ides . Metal condui t s connec ted to en t rances of t h e c o n t a i n e r f o r a d m i t t i n g the cables o f the c i rcu i t should ex tend th rough the concre te walls. These conduits should be provided with clamps for connecting the ground wires or counterpoises . The top o f t he con ta ine r must be l e v e l and a t the proper depth below the top su r f ace o f t he conc re t e fo r moun t ing the l i g h t f i x t u r e o r c o v e r p l a t e . A holding device o r j i g s h o u l d b e u s e d t o maintain level , a l ignment , and proper depth of the t o p of the enc losu re con ta ine r du r ing i n s t a l l a t ion and cu r ing of the concrete . The ends of cab le s are pu l l ed i n to t he enc losu re con ta ine r and t he end of the c o n d u i t o u t s i d e t h e concre te foundat ion i s sealed around the c a b l e w i t h a s u i t a b l e compound t o k e e p t h e enc losu re f r ee of water. The e l e v a t e d l i g h t s , s e m i - f l u s h l i g h t s , o r b l a n k c o v e r s mounted on these conta iners should inc lude a g a s k e t o r o t h e r means o f s ea l ing t o p reven t water f rom en te r ing t he con ta ine r .

4.5.7.2 I n s t a l l a t i o n i n e x i s t i n g pavement. I f l i g h t s are t o b e i n s t a l l e d i n ex i s t ing pavemen t s , i n s t a l l i ng t he t r ans fo rmer enc losu res i n concre te foundat ions may not be practical. Usual ly the t ransformer enc losure i s l o c a t e d a t the edge of t h e pavement and t h e s e c o n d a r y c a b l e s t o t h e l i g h t are i n s t a l l e d i n saw cu t s . A transformer enc losure , junc t ion box, o r t h e l i g h t f i x t u r e may b e i n s t a l l e d a t t h e l o c a t i o n f o r the l i g h t f o r making t h e c o n n e c t i o n s t o t h e l i g h t by boring a h o l e of t he p rope r s i ze and d e p t h i n t h e pavement. The l i g h t f i x u t r e may be mounted on an e n c l o s u r e o r be of a type s u i t a b l e f o r i n s t a l l i n g d i r e c t l y i n t h e h o l e . H o l e s of p r o p e r d i a m e t e r f o r t h e f i x t u r e s or enc losures should be bored in the pavement wi th diamond-edged bi ts . The bottom of t he ho le fo r j unc t ion boxes and l i gh t : f i x tu re s shou ld be f l a t o r s l i gh t ly concave excep t t h a t an area 2.5 c m wide around the per imeter should be f la t . I f the holes are d r i l l e d too deep , t hey shou ld be f i l l ed with s e a l a n t compound t o the des i r ed dep th and t he compound permit ted t o cure before p roceeding with t h e i n s t a l l a t i o n .

4.5.7.3 I n s t a l l i n g t h e e n c l o s u r e . The s ides and bot tom of the t ransformer enc losure , junc t ion box, o r f i x tu re shou ld be s andb las t ed immedia t e ly p r io r t o i n s t a l l a t i o n . Also sandb las t t he i n s ide f aces o f t he bo red ho le . The bot tom and s ides of the enc losure o r f ix ture and the faces and bottom of the bored hole should be covered with a coa t ing of a s u i t a b l e sealant wi th a minimum amount t h a t w i l l completely f i l l t h e space be tween the concre te and the ' f ix ture o r enc losure . The s e a l a n t compound i s usua l ly a two-par t pas te compound which i s mixed and i n s t a l l e d i n accordance with the manufac turer ' s ins t ruc t ions . A hold ing device o r j i g s h o u l d be u s e d f o r i n s t a l l i n g e a c h l i g h t o r e n c l o s u r e t o a s s u r e i t s proper e levat ion and a l ignment . The hold ing device s h o u l d b e l e f t i n p l a c e u n t i l t h e s e a l a n t h a s set. The c a b l e s s h o u l d b e p u l l e d i n a n d b r o u g h t i n t o p o s i t i o n f o r c o n n e c t i n g o r s p l i c i n g as requi red and the entrance should be sealed. All s u r p l u s s e a l a n t o r embedding compound should be removed.



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I ICAO 7357 P A R T * 5 ** 4 8 4 3 4 1 6 0020002 LbT =

5-7 6 Aerodrome Design Hanual

transformers. Direct-burial isolating ed a t the same depth as the cables connected to

the transformers . T r a n s f o k r s and cables should be arianged so that there w i l l be no bends o r stresses on the connectors, and the cables and leads should be provided with s lack t o accoumdate ear th se t t l ing and frost heaves, IIse proper connectors and tape the outside joint wi th 2 or 3 turns of e lectr ical tape. I b not make sp l ices for connecting the cables to the transformers.

4.5.7.5 Install ing isolating transformers in transformer enclosures. When i s o l a t i n g transformers are ins t a l l ed i n traaeforner enclosures, the tranaforners should be positioned with a f l a t s i d e on the bo t tom of the encloeurea, if possible. Connect t h e cables t o the leade o f the t ranefor~ers us ing su i tab le connec tors , no t sp l ices , and tape the jo in ts . Connectors should l i e f l a t on the bo t tom of the enclosures without bending or tension i f possible . Ground connections on isolat ing t ransformers should be connected t o ths ground wire i f such connections are provided. If the in t e rna l tempera- t u r e r i n the enclorurcs will be more than 120°C, a sec t ion of aluminum f o i l between the l i g h t f i x t u r e s and the t raneforrers will reduce the effects of the heat on the t r a m f o r m r .



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ICAO 9157 P A R T f S f t 4 8 4 1 4 L b 0020003 OTb =

5.1 FEATURES OF THE CABLES

5.1.1 Characteristics of cables for underground service

5.1.1.1 Insulation. The following insulation materials are commonly specified because they provide the maximum rated conductor temperatures for operating, overload, and short-circuit conditions for cables rated up to a maximum of 35 kilovolts:

a) Cross-linked polyethylene (XLP). This thermo-setting compound has excellent electrical properties, good chemical resistance, good physical strength characteristics, and remains flexible at low temperatures.

b) Ethylene-propylene rubber (EPR). This compound has electrical properties which are considered equal to cross-linked polyethylene; therefore, the contractor should be given the option to provide either type.

5.1.1.2 The following insulation materials may be used where special-circumstances warrant their lower rated conductor temperatures or their lower rated maximrm voltage class

a) Rubber. Rubber insulated conductors provide ease of splicing, good moisture resistance, and low dielectric losses.

b) Varnished cambric. Varnished cambric insulation is used for resistance to ozone and oil and for ease of splicing. Use varnished cambric prin- cipally in conjunction with paperdnsulated cable where oil migration is a problem. Where installed in wet or highly humid locations or underground, varnished-cambric insulation must be provided with a suitable sheath.

c) Paper insulated. Use paper insulated cable for low ionization, long life, high dielectric strength, low dielectric losses, and good stable characteristics under temperature variations. As with varnished-cambrh insulation, paper.insulation requires a suitable protective metallic sheath. It may be specified as an option when existing cables are paper insulated, or as a requirement when the extra cost is justified because neither cross-linked polyethylene or ethylene-propylene rubber Provide the required qualities.

d) Butyl rubber. This thermosetting insulation has high dielectric strength and is highly resistant to moisture, heat, and ozone. It can be used up to 35 kilovolts, but has lower rated conductor temperatures than either cross-linked polyethylene or ethylene-propylene rubber.

5-7 7

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I C A O 9357 PART*5 ** 4 8 4 L 4 3 b 0020004 T32


e) Si l icone rubber . This thermoset t ing insulat ion i s h i g h l y r e s i s t a n t t o heat, ozone, and corona. It can be used i n w e t o r d r y l o c a t i o n s , exposed, o r i n c o n d u i t . It has the h ighes t ra ted conductor t empera tures but can be u sed on ly fo r app l i ca t ions up t o f i ve k i lovo l t s .

5.1.1.3 Cable sheaths

a ) Nonmetallic. Nonmetal l ic sheaths should be f lexible , moisture repel- l a n t , and long l a s t ing . Neoprene, which is of ten used as nonmetal l ic cab le shea ths , i s u n s u i t a b l e i n many loca t ions . This material f r e - quent ly absorbs excessive amounts of water which may penet ra te th rough t o t h e i n s u l a t i o n . Some n o n m e t a l l i c s h e a t h materials, e s p e c i a l l y i n some t r o p i c a l areas, are repor t ed t o be damaged by micro-organisms, i n s e c t s , a n d p l a n t l i f e . Some shea th materials, which perform well where in s t a l l ed unde rg round o r i n c o n d u i t s , d e t e r i o r a t e r a p i d l y i f i n s t a l l e d where i t i s exposed t o s u n l i g h t . Materials which become b r i t - t l e a t low temperatures should not be used i n c o l d r e g i o n s . In some loca t ions , roden t s f r equen t ly damage nonmeta l l icshea thed cab le . In t h e s e areas the cab le should be i n s t a l l e d i n d u c t s o r metall ic-sheathed cable should be used.

b) Metallic. Cables exposed t o mechanical damage o r h i g h i n t e r n a l p r e s s u r e r equ i r e a metallic shea th , such as lead, aluminum, o r steel. Certain insu la t ions , such as paper and varnished cambric, require such p r o t e c t i o n i n a l l cases.

5.1.1.4 Cable coverings. A su i t ab le cove r ing o r j acke t may be r equ i r ed fo r co r ros ion p ro t ec t ion of me ta l l i c shea ths .

5.1.1.5 Shielded cables. Shielding of a med iumvol t age d i s t r ibu t ion cab le i s r e a u i r e d t o c o n f i n e t h e e l e c t r i c f i e l d t o t h e i n s u l a t i o n i t s e l f a n d t o p r e v e n t l e a k a g e cur ren ts f rom reaching the ou ts ide sur face of t he cab le . In su la t ion sh i e ld ing i s requ i r ed on a l l nonmeta l l ic -sh ie lded cab le ra ted two k i lovol t s and above , except for aerodrome- l igh t ing se r ies -c i rcu i t cab les , and a l l m e t a l l i c s h e a t h e d c a b l e r a t e d f i v e ki lovol ts and above. Shields should be grounded to reduce the hazards of shock. Grounding i s required a t each terminat ion, o therwise dangerous induced shield vol tages may occur.

-

5.1.1.6 Cable f i reproof ing . Cables in manholes , handholes , and t ransformer vaul t s ope ra t ing a t 2 400 v o l t s or over , o r exposed to the fa i lure of o the r cab le s ope ra t ing a t these vol tages , should be f i reproofed with a su i tab le spray coa t ing . Except ions may be made where phys ica l separa t ion , i so la t ion by ba r r i e r s , o r o the r cons ide ra t ions pe rmi t .

5.1.1.7 Pro tec t ion aga ins t corona damage. In su la t ion of h i g h v o l t a g e cables which may be damaged by ozone should be protected against th is damage by cont ro l l ing corona , which produces ozone, by placing a thin semi-conducting f i lm between the conductor and i t s insu la t ion . T h i s f i l m f i l l s t h e v o i d s between the conductor and the insulat ion thus prevent ing the genera t ion of corona and hence ozone. (See 5.1.3.6.)

5.1.1.8 Cable conductors. Annealed copper is used i n most forms of insu la ted conductors because of i t s h igh conduc t iv i ty , f l ex ib i l i t y , and ea se of handling. Medium- harddrawn copper has g rea te r t ens i le s t rength than annea led copper . Aluminum conduc to r s may be permitted as a conductor 's option except where corrosive conditions limit the i r us age



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ICAO 9357 PART*5 ** = 48434Lb 0020005 979


5.1.2 Classes of s e r v i c e

5.1.2.1 Low-voltage cables. Low-voltage cables -- i n s u l a t i o n r a t e d a t 600 v o l t s o r less -- are used t o connect the secondaries of series/series i s o l a t i n g t r a n s f o r m e r s t o t h e lamps i n t h e f i x t u r e s , f o r l o w - v o l t a g e d i s t r i b u t i o n c i r c u i t s , a n d as low-voltage f e e d e r c i r c u i t s t o s i n g l e u n i t s a n d t h e s h o r t e r c i r c u i t s . The conductors are usua l ly copper but may be aluminum, and e i the r s ing le - o r mu l t i - conduc to r cab le s are used. Both s o l i d and stranded conductors are used but stranded is p r e f e r r e d i f f r e q u e n t f l e x i n g Qf the cab le is expected. The c ross -sec t iona l area of the conductor may vary from 2 nun2 t o 8 mm2 o r l a r g e r i f n e c e s s a r y t o d e c r e a s e t h e v o l t a g e d r o p .

5.1.2.2 Highvo l t age cab le s . For ae rodrome l i gh t ing , h ighvo l t age cab le s are used most ly for source power d is t r ibu t ion and feeder cab les . The cr i ter ia and materials are t h e same as f o r power d i s t r i b u t i o n c a b l e s d i s c u s s e d i n p a r a g r a p h s 2.5.5 t o 2.5070 The vol tages used usual ly range f rom 1 000 t o 5 000 vol t s . Conductor s izes usua l ly are i n the range of 3.3 mm2 t o 21 mm2 i n c r o s s s e c t i o n b u t l a r g e r s i z e s a r e o c c a s i o n a l l y u s e d . These cables may be e i ther s ing le-conductor o r two- or three-conductor cables. Consider the so i l , envi ronment , method of i n s t a l l a t ion , sub jec t ion t o chemica l s , and any spec ia l p r o b l e m i n s e l e c t i n g t h e i n s u l a t i o n , j a c k e t s , s h e a t h i n g , a n d s h i e l d i n g f o r t h e s e cables . 5.1.2.3 Series aerodrome l ight ing cables . The requirements of the cables for t h i s purpose have been standardized more than have the cab le requi rements for most power c i r c u i t s . The series cur ren t used i n t h e s e c i r c u i t s i s between 6 and 20 amperes. The conductor s ize commonly used i s 8.4 mm2 in c ros s - sec t ion bu t some 3.3 m2 cable i s a l so used. These ca-bles are single-conductor. The conductor is usua l ly s t r anded bu t so l id conductor can also be used. The i n s u l a t i o n i s usua l ly 5 OOO-volt ra ted. A non-metal l ic j a c k e t o v e r t h e i n s u l a t i o n i s commonly used. Metal l ic- tape shielding between the insul- a t ion and jacke t o r be tween the j acke t and non-meta l l ic cover ing i s of ten used but may not be requi red for some i n s t a l l a t i o n . The p re fe r r ed s e r i e s - l i gh t ing cab le s are stranded, copper, 8.3 mm2 conductor; cross-linked polyethylene, ethylene-propylene-rubber , or buna-rubber insulat ion; chlorosulfonated polyethylene, polyvinyl chlor ide, polyethylene, or heavy duty neoprene jacketed; metal-tape shielded types.

5.1.2.4 Control cables . Control cables are l o w v o l t a g e c a b l e s u s u a l l y i n p a i r s o r multi-conductor. A group of single-conductor cables may be used f o r some s imple cont ro l c i r c u i t s . Some cont ro l cab les have one o r two l a r g e r c o n d u c t o r s f o r t h e l i n e v o l t a g e '

and /o r neu t r a l and s e v e r a l smaller conductors for the ind iv idua l cont ro ls . Other i n s t a l l a t i o n s may u s e a p a i r of l a r g e r wires f o r t h e l i n e a n d n e u t r a l and o the r cab le s wi th many smaller conductor wires for the ind iv idua l cont ro ls . Mul t i -conductor cont ro l cables have 7, 12, 16, o r many more conductors are used. Most con t ro l cab le s have stranded copper conductors. The s i z e of the conductor is s e l e c t e d t o k e e p t h e l i n e vol tage d rop wi th in an acceptab le range. The cross -sec t iona l s ize o f the conductors i s usually between 3.3 mm2 and 0.5 mm2. The i n s u l a t i o n r e s i s t a n c e r a t i n g must b e s u i t a b l e fo r t he con t ro l vo l t age wh ich i s usua l ly 250 v o l t s o r less. Rubber, polyethylene, polyvinyl chlor ide, varnished cambric , and paper are some of t h e t y p e s o f i n s u l a t i o n f o r cont ro l cab les . Thin insu la t ion i s d e s i r a b l e t o r e d u c e t h e d i a m e t e r o f t h e c a b l e . Twis t ed pa i r s o r sp i r a l ing of the conductors is des i r ab le fo r a l t e rna t ing -cu r ren t con- t ro l c i rcu i t s to reduce the induced vo l tage be tween c i rcu i t s . Mul t i -conductor cab les must have an outs ide jacket and may be sh ie lded wi th metal tape.

5.1.2.5 Communications cable . Special in tercommunicat ions or te lephone c i rcui ts should be instal led to provide comrmnicat ions between control tower , l ight ing vaul ts , a n d o f f i c e s o r s t a t i o n s . The c i r c u i t s a r e u s u a l l y o n e o r more twisted-pair te lephone



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I C A O 9357 PART*5 ** 484141b 002000b 805 =

5-80 Aerodrome Design Manual -

type cables. These cables should be su i tab le for underground ins ta l la t ion . Al though t h e c o n t r o l c a b l e s may be used for communications a t some i n s t a l l a t i o n s , s e p a r a t e c a b l e s i n s e p a r a t e c o n d u i t s o r well s e p a r a t e d i n t h e t r e n c h , i f d i r e c t b u r i a l , are p re fe r r ed .

5.1.2.6 Ground wires. A ground wire or counterpoise wire s h o u l d b e i n s t a l l e d t o protect underground power and cont ro l cab les f rom h igh ground cur ren t surges in a reas where damage f r o m l i g h t n i n g s t r i k e s may be expected. The ground wire should be ins ta l - l e d between the earth 's surface and the underground cables. It is usua l ly an uninsulated, stranded copper conductor. The s i z e of t h i s ground wire should be not less than the la rges t s ize conductors which i t protects . Cross-sect ion area of the conductor may range from 8.4 mm2 t o 21 mm2 o r l a r g e r . It should be a continuous conductor and connected t o each f ix ture , l igh t base , and ground rod o r connection along i ts route .

5.1.3 Causes of cab le damage

5.1.3.1 Cab le f au l t s are f r e q u e n t r e a s o n s f o r a e r o d r o m e l i g h t i n g c i r c u i t f a i l u r e s and o f t e n r e q u i r e c n s i d e r a b l e time a n d e f f o r t t o l o c a t e a n d repair. Effective methods of r educ ing cab le f au l t s improve r e l i ab i l i t y of the system. Better knowledge of t h e causes of damage t o c a b l e s h o u l d a i d i n choosing types of c a b l e a n d i n s t a l l a t i o n procedures. Some of these causes are discussed below.

5.1.3.2 Mechanical damage. Probably most c a b l e f a u l t s are caused by mechanical damage. Poor ins ta l la t ion t echniques and procedures are probably the most common cause of mechanical damage, b u t f r o s t h e a v e s , v i b r a t i o n f r o m a i r c r a f t o r v e h i c l e t r a f f i c , rodents , ground s h i f t i n g o r s e t t l i n g , and many o ther reasons may phys ica l ly damage t h e cable. Some types of mechanical damage are:

Nicks and scrapes of the i n s u l a t i o n .

Over s t r e s s i n g of t h e c a b l e when p u l l i n g i n t o d u c t s o r u n r o l l i n g t h e c a b l e f o r d i r e c t b u r i a l .

S t o n e s o r f o r e i g n o b j e c t s i n t h e b e d s o r b a c k f i l l s of t r enches .

Inadequate s lack a t en t r ances t o o r i n s ide o f handho les , manho les , l i gh t bases , condui t s , f ix tures , connec t ions to equipment , connec tors , sp l i ces , a long t r enches o r condu i t , or o t h e r l o c a t i o n s w h e r e s e t t l i n g , main tenance , ins ta l la t ions , o r weather may i n c r e a s e stresses.

Nicking of the conductor a t s p l i c e s o r c o n n e c t o r j o i n t s may la ter break the conductor.

Inadequate separat ion of cables i n t r e n c h e s , e i t h e r v e r t i c a l l y o r h o r i - zon ta l ly , a t slack loops of cable, or places where earth compaction or f r e e z i n g a c t i o n may f o r c e two s e c t i o n s o f c a b l e i n t o d i r e c t c o n t a c t .

Freez ing or f ros t heaves forc ing the cab le aga ins t ice, f r o z e n e a r t h , o r any o the r so l id ob jec t o r material. Proper cushioning and s lack to reduce stress at t h e s e p o i n t s i s necessary.

Improperly supported cables in manholes or other areas where sagging o r exposure may r e s u l t in o b j e c t s o r pe r sons pu t t i ng p re s su re on the cab le .



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i I

ICAO 9 3 5 7 P A R T * 5 ** W 48414Lb 0020007 741

Part 5 .- Electrical Systems 5-8 - 1

i) Vibration from traffic passing over the cable or from equipment opera- t ion a t tached to o r near the cable may cause fatigue of the conductor or of the jacket and insual t ion. Where such condi t iols may e x i s t or be developed, i n s t a l l t h e c a b l e s i n d u c t s which extend w e l l beyond the area of vibration.

j) Breaking o r separat ion of conduits o r ducts may break the cable. The i n s t a l l a t i o n of the duc ts and conduit must be properly joined and sui tably backfi l led and tamped.

5.1.3.3 Water penetration. A ground f a u l t is formed when water is ab le to pene t ra te through the cable sheath and in su la t ion t o t he conductor. Water penetration or leakage may occur a t splices, connections, cable terminations, physical damage areas, unsat is- factory insulation, pinholes from l ightning o r over voltage, or other defects.

a) Improperly made sp l i ces and improperly installed connector kits are a frequent source of water penetration. See Section 5.2 for ins t ruc t ions f o r making sp l i ces and instal l ing connectors .

b) In order to avoid water penetrat ion a t the ends of cable, these ends should be kept c lean and f r e e from moisture before as well as a f t e r connecting t o t he equipment. The ends of spare cables should be similarly protected. Some types of insulation, especially paper and mine ra l f i l l ed , may a t t rac t mois ture from the atmosphere during periods of high humidity. The ends of the cables of these types should be kept sealed a t a l l times even after connecting t o t h e equipment.

c ) Some insu la t ions , e i t he r from defects or composition, may permit exces- s i v e water penetration. Quality tests of insulat ion res is tance should detect such defects . There are reports that some neoprene-jacketed cable i s not adequately water resis tant , a l though other reports state tha t cab le of t h i s t y p e performs w e l l . Before cable i s purchased, the performance of the t y p e of cable a t o ther ins ta l la t ions , p referab ly from the same manufacturer, should be investigated.

d) Lightning s t r ikes may severly damage cab le s o r t he induced voltages may be enough t o damage the insu la t ion by creating pinholes. These pinholes are more l i k e l y t o occur a t points of crossing cables or where the cable i s near or in contact wi th metal conductors . Properly instal led ground wire or counterpoises should reduce the damage from l ightning s t r ikes .

e) Excessive voltage may be app l i ed t o a cable , e i ther accidental ly or f rom faul ty operat ion. Damage to t he cab le may not be not iceable immediately.

5.1.3.4 Chemical damage. Often aerodrome l igh t ing cab les are l o c a t e d i n areas where fuel , o i l , acids , or other chemicals may be present regularly or occasionally. These chemicals a f f ec t t he i n su la t ion r e s i s t ance of some types of cables. If i t i s known, o r suspected, that cables may be exposed to such chemicals, select a type of cable which i s r e s i s t a n t t o t h e s e chemicals.



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I C A O 9357 PARTb5 b t 4843436 0020008 688 W


5.1.3.5 Rodent damage. In some areas, d i r e c t b u r i a l c a b l e is damaged by roden t s , espec ia l ly gophers , gnawing the insulat ion. There i s some evidence tha t the rodents may b e a t t r a c t e d t o t h e c a b l e e i t h e r by t h e heat emitted from i t o r by i ts taste. Where rodent damage i s a s e r i o u s problem, i t may be d e s i r a b l e t o i n s t a l l t h e c a b l e i n d u c t s o r t o use me ta l shea thed cab le .

5.1.3.6 Micro-organism o r p l a n t damage. Micro-organisms and plants are r e p o r t e d t o have damaged some types o f cab le s i n t rop ica l o r sub t rop ica l areas. Other types of cab le are no t s e r ious ly a f f ec t ed . I f i t i s an t ic ipa ted tha t such problems may occur , select a type of cable which i s known t o be r e s i s t a n t t o s u c h micro-organisms and p l a n t s

5.1.3.7 Ozone and corona damage. Some c a b l e i n s u l a t i o n s are damaged by ozone and t h u s by the corona produced by t h e c i r c u i t o r by nearby c i rcu i t s . Cable insu la t ions are a v a i l a b l e w h i c h s a t i s f a c t o r i l y resist t h e s e e f f e c t s . Select c a b l e s w i t h t h e s e q u a l i t i e s i f t h e c a b l e is car ry ing h igh vo l tages o r may be exposed t o o t h e r s o u r c e s of ozone o r corona., In t h e past some States have used cables which were no t p ro t ec t ed aga ins t corona damage f o r runway and approach l ight series sys t em r eason ing t ha t t hese sys t ems are operated a t f u l l i n t e n s i t y f o r o n l y a r e l a t i v e l y small number of hours p e r year . Consequently, these cables are sub jec t ed t o h igh -vo l t age stress during only a small f r a c t i o n o f t h e time i n service. This pract ice has been found to be undesirable since t h e r e d u c t i o n i n c o s t i s small and because some of t h i s c a b l e i n v a r i a b l y is i n s e r t e d i n t o t h e power d i s t r i b u t i o n c i r c u i t s a n d are subjec ted to cont inuous h igh-vol tage stress . 5.1.3.8 U l t r a v i o l e t damage. Some c a b l e i n s u l a t i o n , w h i c h p e r f o r m s s a t i s f a c t o r i l y i n underground ins ta l la t ions , may become b r i t t l e and de te r io ra t e r ap id ly where exposed t o s u n l i g h t i f u s e d on elevated supports such as approach l ight towers . I f the cable w i l l r e c e i v e t h i s s o r t of exposure, select cab le w i th i n su la t ion wh ich resists u l t r a v i o l e t o r i n s t a l l t h e c a b l e i n metal conduit.

5.1.3.9 Cable de te r iora t ion . Most c a b l e i n s u l a t i o n d e t e r i o r a t e s slowly. The service l i f e of underground cables should be 10 t o 20 years .

5.2 CABLE CONNECTIONS

5.2.1 Cable sd ices

5.2.1.1 All cable spl ices should be performed by exper ienced and qua l i f ied cab le splicers using high s tandards of workmanship. Splicing methods and materials should be of types recommended by the manufacturer of t h e s p l i c i n g material f o r t h e p a r t i c u l a r t ype of cable being spliced. A l l c ab le sp l i ces shou ld meet the fol lowing requirements .

5.2.1.2 Power cab le s i n su la t ed f o r more than 5 000 v o l t s . S p l i c e k i t s d e s i g n e d f o r t h e t y p e of cable being spl iced should be used. When s u c h k i t s are not ava i lab le , t aped splices made i n accordance with paragraph 5.2.2 may be used. Epoxy o r r e s i n s p l i c e s should not be used.



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ICAO 9357 P A R T x 5 ** 4B4L4Lb 0020009 514

P a r t 5.- Electrical Systems 5-83 - 5.2.1.3 Power cables with 610- t o 5 OOO-volt insulation. Pressure epoxy-esin spl ices envelopes and cast sp l i ce k i t s des igned fo r t he cab le shou ld be u sed i n str ict conformance with the manufacturer ' s ins t ruct ions. Taped splice.: should be used only i f necessary

5.2.1.4 Power cab le s i n su la t ed fo r 600 v o l t s o r less. Cast s p l i c e k i t s o r p r e s s u r e epoxy-resin spl ice envelopes sui table for a l l d i r ec t ea r th -bur i a l cab le may be used. Taped sp l ices us ing pres t re tched or hea t - shr inkable tub ing as a covering may a l so be used.

5.2.1.5 Control and telephone cables. A type of r e -en te rab le f i l l ed sp l i ce enve lope i s ava i l ab le fo r u se on thermoplastic-insulated non-pressurized cables. Splices to ex is t ing p ressur ized , l ead-covered , o r paper insu la ted cab les should be in accordance with the requirements of the authori ty involved.

5.2.2 Taped s p l i c e s

5.2.2.1 Taped s p l i c e s are usually used only when sa t i s fac tory connec tors and sp l ice k i t s cannot be obtained. If taped sp l ices are t o be made, the correct technique mst be used i n o r d e r t o o b t a i n s a t i s f a c t o r y s e r v i c e . The technique described below is intended for single-conductor cable but applies with suitable adaption to multi-conductor cable sp l ice .

5.2.2.2 Keep the ends of the cables t o be joined clean and protected from moisture a t a l l times.

5.2.2.3 Carefully taper and remove the covering, jacket , metallic sh ie ld , shea th , and insulat ion f rom the ends of t he cab le s t o be joined. Remove a l l traces of insula- t i o n from the conductors for a length of approximately 2 c m be ing very carefu l no t to nick the conductor. Smoothly t a p e r t h e i n s u l a t i o n back from the conductor for 2 cm o r more. Remove the sheath, metal tape , j acke t , etc. back a long the ou ter sur face of t h e i n s u l a t i o n l a y e r f o r a n a d d i t i o n a l 2 c m (see Figure 5-la). This o f f s e t of t he t ape r ing should block paths of water penetrat ing a long the taper ing. Keep i n t a c t t h e metal t ape fo r sh i e ld ing , i f i nvo lved , ove r t he en t i r e l eng th o f t he sp l i ce . S imi l a r ly , t ape r t he non-meta l l ic shea th for 2 c m o r more. Remove any steel o r metal armor or outer metal covering but leave s tubs or ends for reconnect ing across the spl ice .

5.2.2.4 Use a crimp-type connector t o j o i n t h e e n d s of the conductor. Crimp t h e connector onto the ends of the conductors using a too l des igned to make a complete crimp before the tool can be removed (see Figure 5-lb). The conductor connector may a l s o be so ldered i f des i red .

5.2.2.5 Using rubber o r synthet ic rubber tape of good qua l i ty , ca re fu l ly wrap t h e j o i n t one l aye r at a time maintaining enough tension on the tape for approximately 25 per cent e longat ion and overlapping the tape approximately 50 per cen t of i t s width. Each l aye r w i l l ex tend fur ther up the t aper a long the insu la t ion . Cont inue th i s bu i ld- up of l aye r s of r u b b e r t a p e t o t h e f u l l s i z e of the insu la t ion layer . See Figure 5-IC.

5.2.2.6 If sh ie ld ing tape i s used over the insulat ion, connect the metal tape, which should have been kept intact , across the splice by so lde r ing o r u s ing su i t ab le connectors. Wrap wi th ex t r a metal tape of similar type if needed.



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( a ) . TAPERING INSULATION.

* A t t a c h with a tool designed to make a complete crimp before the tool can be r e m o v e d .

(b) CONDUCTOR CONNECTION.

T WEATmR-RESISTANT PLASTIC TAPE

RUBBER INSULATION TAPE - ( C ) CROSS SECTION

Indicate tape layers are wound i n both directions

OF SPLICE.

F igure 5-1. Taped s p l i c e of s ing le -conduc to r cab le



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ICAO 9357 PART*5 ** 484143b 002OOLL 372


5.2.2.7 Continue t o wrap the rubber tape as i n 5.2 .2 .5 t o n o t less than 1.5 times the diameter of the cable. Carefully apply tension on the t ape to p revent any voids and obtain good adhesion to t he cab le su r f aces and each inside laycr of tape.

5.2.2.8 Over the rubber t a p e , add severa l l ayers of high-insulation-resistance, flame-retardant, weather- and cold-resistant tape. Apply the p l a s t i c t ape w i th apprec i - able tension and overlapping each turn by approximately 50 per cent of i t s width. The p l a s t i c t a p e should extend for 3 cm or more along the surface of the insu la t ion of sheath on each s ide of t he sp l i ce .

5.2.2.9 I f the cable has a s t e e l a r m o r o r o t h e r metallic cover, connect a length of grounding braid across the splice and f a s t e n t o t h e armor on the cab le wi th su i tab le clamp connectors and/or solder on each s ide of the spl ices (see Figure 5-2a). If t h e cable i s lead encased, make a su i t ab le wiped-lead jo in t ove r t he sp l i ce t o p rov ide a waterproof seal to t he l ead cove r ing on the cable. If the metal covering i s protected from corrosion by a coating, apply a coating of similar material over the en t i re sur face of the cable and s p l i c e i n t h e area of t h i s work.

5.2.3 Connector k i t s f o r aerodrome l i g h t i n g

5.2.3.1 Use of connector ki ts . In recent years most series-circuit connections have been made using connector ki ts . Although the cos t of connec tor k i t s i s s ign i f i can t , t he time saved i n i n s t a l l a t i o n and the ease with wfch c i r cu i t s can be opened and reclosed when l o c a t i n g f a u l t s have made their use desirable . Since the leads of most i s o l a t i n g transformers are now manufactured with connectors, cable connectors are required and provide an easy means of connecting or disconnecting the transformer into the series circuit and to the light. Single-conductor connectors are shown in Figure 5-3.

5.2.3.2 I n s t a l l a t i o n of connectors. "he cable ends should be prepared carefully i n accordance with the instructions, keeping both the cable ends and the connector surfaces f r e e of d i r t and moisture. Make c e r t a i n t h a t any c a v i t i e s between the cable and i n t e r i o r of the connector are f i l l ed wi th the ge l p rovided to p revent vo ids . After joining the connectors ensure that air i s not trapped which may t end t o fo rce t he connect ion apart. Taping over the joint with vinyl electric t a p e t o keep the area clean and from separat ing i s suggested.

5.2.4 Coaxial cables

5.2 .4 .1 Non-pressurized coaxial cables. Coaxial cable should be joined using appropr ia te coaxial connectors . Each connector should be covered with a 15 c m minirmm length of heatshr inkable tubing having a 3:l or h ighe r sh r ink r a t io . A su i tab le spray cab le adhesive may be sprayed on the cable but not the connector pr ior to shr inking. A flame- less heat gun should be used for shr inking the heatshr inkable tubing. An a l t e r n a t e covering may be prestretched, mechanically shrinkable tubing applied as recommended by the manufacturer.

5 .2 .4 .2 Splices in pressurized coaxial cables. No f i e l d i n s t a l l e d s p l i c e i n pressurized coaxial cable should be' al lowed unless specifically authorized.



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ICAO 9357 PART*5 ** m 4B434Lb OQ200L2 009 m

5-8 6 -cI

Aerodrome Design Manual

.._____.___I__.-.-. ~

VINYL PLASTIC TAPE ANCHOR FOR BRAID

METAL ARMOR

ELECTRICAL GROUND BRAID

RUBBER INSULATION TAPE

(a) CONNECTING ARMOR ACROSS THE SPLICE

WEATHER-RESISTANT PLASTIC TAPE ( 4 LAyERs-1/2 LAPPED, WITH LIQUID . ELECTRICAL COATING APPLIED)

(b) OUTER COVEFUNG.OF THE SPLICE

Figure 5-2. Taped s p l i c e f o r metal-armored cable

----- -: , -.



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=- .- ICAO 9157 PART*5 ** W 48414Lb 0020013 T45 W

Part 5.- Electrical Systems 5-87

(a) FACTORY MOLDED PLUG

@- (b) FACTOR MOLDED RECEPTACLE

OPt lONU INTERNAL LOGnlHC DESIGH

PLUG.

I @-

SOCKET

RECEPTAC L F

(c) FIELD ATTACHED CONNECTORS

Figure 5-30 Connectors for single-conductor non-metallic-jacket cable



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5.2.5 Connection of conductors

502.5.1 Power conductors. Connections of cable conductors should be made us ing cr imp connectors ut i l iz ing a cr imping tool designed to make a complete crimp before the tool can be removed. Spl i t -bol t connectors may be used f o r l o w v o l t a g e c i r c u i t s of 600 v o l t s o r less.

5.2.5.2 Control and telephone cables. Joining of te lephone or control conductors should be done with a tw i s t ed and so lde red splice or an appropr i a t e s e l f - s t r ipp ing , prefnsula ted connec tor ins ta l led wi th the spec i f ic too l des igned to c r imp the connec tor . Color coding of the conductors should be fol lowed throughout the instal la t ion.

_ _ -

5.2.5.3 Cable armor and shields. Armor sh ie lds shou ld be e l e c t r i c a l l y bonded a c r o s s t h e splice by cleaning and soldering. Use sec t ions o f metal braid and conducting tape, i f needed. Armor and shielding should be completely insulated from each and from ground, except as noted in paragraph 4.5.3.3.

- END -



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ICAO TECHNICAL PUBLICATIONS

Tite following summmy gives the status, and also describes in general terms the contents of the vm'ms sm'cs of technical publications issued by the Inter- national Civil Aviation Organization. I t does not include specialized publications that do .not fall specifically within one of the series, such as the Aeronautical Chart Catalogue or the Meteorological Tables for International Air Navigation.

International Standards and Recommended Rae tices are adopted by the Council in accordance with Articles 54, 37 and 90 of the Convention on International Civil Aviation and are designated, for convenience, as Annexes to the Convention. The uniform application by Contracting States of the specifications contained in the International Stan- dards is recognized as necessary for the safety or regularity of international air navigation while the uniform application of the specifications in the Recommended Practices is regarded as desirable in

I the interest of safety, regularity or efficiency of i international air navigation. Knowledge of any differ-

I e n a s between the national regulations or practices of ! i a State and those established by an International

Standard is essential to the safety or regularity of international air navigation. In the event of non- con-,pliance with an International Standard, a State has, in fact, an obligation, under Article 38 of the Convention, to notify the Council of any differences. Knowledge of differences from Recommended hac- tices may also be important for the safety of air navigation and, although the Convention does not impose any obligation with regard thereto, the Council has invited Contracting States to notify such differences in addition to those relating to Interna- tional Standards.

I I

procedures for Air Navigation Senices (PANS) are approved by the Council for world-wide application. They contain, for the most part, operating procedures

regarded as not yet having attained a sufficient degree of maturity h r adoption as International Standards and Recommended Practices, as well as material of a more permanent character which is considered too detailed for incorporation in an Annex, or is suscep- tible to frequent amendment, for which the processes of the Convention would be too cumbersome.

Regional Supplementary Procedures (SUPPS) have a status similar to that of PANS in that they are approved by the Council, but only for application in the respective regions. They are prepared in consoli- dated form, since certain of the procedures apply to overlapping regions or are common to two or more regions.

The following publications are prepared by authority of the Secretary General in accordance with the principles and policies approved by the Council.

Technical Manuals provide guidance and information in amplification of the International Standards, Recommended Practices and PANS, the implementa- tion of which they are designed to facilitate.

Air Navigation Plans detail requirgments for facilities and services for international air navigation ir, the respective ICAO Air Navigation Regions. They are prepared on the authority of the Secretary General on the basis of recommendations of regional air navigation meetings and of the Council action there- on. The plans are amended perigdically to reflect changes in requirements and in the status of imple- mentation of the recommended facilifies and seMces.

ICAO Circulars make available specialized information of interest to Contracting States. This includes studies on technical subjects.



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I C A O 9357 PART*5 ** 48414Lb 002OOLb 754 W

PRICE: U.S.$5.00 (or equlvaient in other currencies)

@.ICAO 1983 5183, UP112500 9/84, UP2/2000

Doc 9157-AN/901, Part 5 Order No. 801511



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