army tm 5-683
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ARMY TM 5-683NAVY NAVFAC MO-116
AIR FORCE AFJ MAN 3 2-10 83
FACILITIES ENGINEERINGELECTRICAL INTERIOR FACILITIES
APPROVED FOR PUBLIC RELEASE: Distributionis unlimited
DEPARTMENTS OF THE ARMY, THE NAVY, AND THE AIR FORCENOVEMBER 1995
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REP RODUCTION AUTHORIZATION/RES TRICTIONS
T h i s m a n u a l h a s b e e n p r e p a r e d b y o r f o r t h e G ov e r n m e n t a n d i s
p u b l i c p r o p e r t y a n d n o t s u b j e c t t o c o p y r i g h t .
R e p r i n t s o r r e p u b l i c a t i o n o f t h i s m a n u a l s h o u l d in c l u d e a c r e d i t s u b -
s t an t i a l ly a s fo l low s : J o i n t D e p a r t m e n t s o f t h e A r m y , t h e N a v y a n d
t h e Ai r F o r c e , U S A, T e c h n i c a l M a n u a l T M 5 -6 8 3 /N AV F AC
MO-116/AFJ MAN 32-1083, Elect r ica l I n ter ior Fa ci l i t ies , 30 Novemb er
1995.
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TM 5-68NAVFACMQ-11
AFJMAN 32-108
TECH NICAL MANUAL NO. 5-683 H E A D Q U A R T E R S
NAVY MANUAL NAVFAC MO-116 DEPARTMENT OF THE ARMY,
THE NAVY, AND THE AIR FORC
AIR
FORCE
MANUAL
AFJ MAN 32-1083W A S H I N G T O N, DC, 30 November 199
ELECTRICAL INTERIOR FACILITIES
cHAPTER 1.
2.
3.
4.
5.
6.
7.
8.
INTRODUCTIONPurpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Codes and specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main ten an ce requ irem ent s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pr iorit y an d sch edu ling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hazards . . . . . . . . . .. .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SWITCHGEAR ASSEMBLIES 600V OR LESSPeriodic maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Metal enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bus bar an d t erm ina l connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Under floor ducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Busways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power circuit brea ker s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network protectors.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Auxiliar y swit ch gea r eq uipm ent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switchgear t rouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TRANSFORMERS
Sm all p ower t ra ns former s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dr y-type t ra ns former s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRIC MOTORS
Main ten an ce of electr ic motor s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alter na tin g curr ent (AC) motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dir ect cur ren t (DC) m otors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor opera tin g consider at ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Motor ins ula tion tes tin g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MOTOR CONTROLS
Functions o motor controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Types of motor controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Componen ts an d m ain ten an ce of mot or contr ols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pr event ive ma int ena nce an d t rouble-sh ootin g guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
POWER CABLES
Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Visual inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable insulation testing ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Over poten tia l tes tin g. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SOLID-STATE ELECTRONIC EQUIPMENT
Solid-sta te ma int ena nce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Solid-state components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical disturbances (power quality) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dist ur ban ce mea sur emen t a nd m onitor ing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage s ur ge su ppr ession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GROUNDING
Grou nd ma int ena nce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Types of grou ndin g syst ems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Grou nd fault int err upt ing m eth ods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Paragraph
1 1
1-21-3
1-41-5
1-61-7
2-1
2-22-32-42-52-6
2-72-82-9
3-13-2
4-14-24-3
4-44-54-6
5-15-25-35-4
6-16-26-36-4
6-5
717-27-37-47-5
8 -l8-18-3
P a g e
11
1-1111-11-11-21-2
2-1
2-12-22-2
2-22-32-102-122-16
3-13-1
4-14-14-13
4-204-244-24
5-15-1
5-66-15
6-l
6 -l6-16-2
6-5
7 17-17-77-77-8
8-18-1
8-9
*This manual supersedesTM 5-683/NAVFAC MO-116/AFM 91-17, dated 2 March 1972
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TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
CHAPTER 9.
10 .
11 .
12.
13.
14 .
15 .
APPENDIX A.
Figure 21.
2-2.
23.
2-4.
25.
2-8.
2-7.
28.
29.
2-10.
i i
ILLUMINATION
Light ing m ain ten an ce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluorescent lighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Incandescent lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High int ens ity d ischa rge ligh tin g (HID ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Relamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamp trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BACK-UP, SECURITY, AND PROTECTION SYSTEMS
Other systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Em ergen cy and st an d-by syst ems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Signa l syst ems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Detection systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HAZARDOUS SUBSTANCES
Environmental protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Polychlorinat ed biphenyls (PCBs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Lighting ballast. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flammable liquids and gasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Toxic mat erials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRICAL SAFETYHuman factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment isolation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switchgear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . .
Rotating equ ipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tra nsformer s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring and testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mecha nical . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dan ger w ar nin gs a nd fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pers onal protective equipmen t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TEST EQUIPMENT
Equ ipm ent ma int ena nce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Volt-ohm-m illiam met er (VOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clamp-on volt-ammeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Megohmmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
Ha rm onic mea su rem ent s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenan ce equipment guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TEST METHODS
Test evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ins ula tion tes tin g. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Protective relay testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment ground resistance testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Syst em gr ound res ist an ce tes tin g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery specific gravity test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Infrared inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE SCHEDULES
Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .
Respon sibilit ies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequencies and procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LIST OF FIGURES
Paragraph
9 -1
9 -2
9 -3
9 -4
9 -5
9 -6
9- 7
10-1
l 0 - 2
10-3
10-4
10-5
11-1
11-2
11-3
11-4
11-5
12-1
12-2
12-3
12-4
12-5
12-8
12-7
12-8
12-9
12-10
13-1
13-2
13-3
13-4
13-513-8
14-1
14-2
14-3
14-4
14-5
14-6
14-7
15-1
15-2
15-3
. . . . . . . .
Typical buswa y insta llation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dr awout circuit brea ker position s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power circuit brea ker ma in a nd ar cing conta cts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arcing contact gap and wipe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In ter med iat e conta ct gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main contact wipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electr omecha nical t rip device tim e-curr ent curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical dr awou t n etw ork p rot ector a nd enclosur e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Net work pr otector rem ovable u nit .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical cont act constr uction for a net work p rote ctor..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
9-1
9 1
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9- 4
9- 4
9 -5
10-1
10-1
10-1
10-1
l 0 - 5
11-1
11-1
11-3
11-3
11-3
12-1
12-1
12-3
12-4
12-4
12-5
12-5
12-5
12-5
12-5
13-1
13-1
13-4
13-6
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14-7
15-1
15-1
15-1.
A1
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2-5
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2-7
2 -8
2 -9
2-11
2-13
2-13
2-14
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LIST OF FIGURES (cont'd)
Figure 211. La rge cell for a st at ionar y bat ter y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1. Dry-type transformer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1. Cut awa y view of squir rel-cage in duct ion m otor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2. Cut awa y view of wound-r otor in duct ion m otor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-3. Cut awa y view of synchr onous m otor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-4. Pr ima ry pa rt s of an AC indu ction m otor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-5. Clean ing a nd dr ying m otors in p lace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-6. Bear ing in st alla tion pr ecaut ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-7. Const ru ction of ball a nd roller bear ings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-8. Greasing bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-9. Typical sleeve bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-10. Cut awa y view of a t ypical DC mot or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-11. Main types an d connect ions of DCm otors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-12. Arma tu re of a la rge DC mot or on st an ds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-13. Insp ecting a nd inst allin g bru sh es on a lar ge DC m otor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-14. Cut awa y section of a commu ta tor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-15. Brush "chatteraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-16. Poor commutator conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-17. Good commutator films.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-18. Exa mp le of eccent ric comm ut at or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-19. Dial ga uge t o mea su re comm ut at or concentr icity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-20. Comm on u nder cutt ing m ist ak es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-21. Connect ions for t est ing m otor in sula tion res ist an ce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-1. Man ua l st ar ter s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2. Typical m agn etic st ar ter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3. Combina tion s ta rt ers in N EM A enclosur es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4. Coordination of motor overload relay and curr ent limit ing fus e. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-5. Autot ra ns former st ar ter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-6. Resis ta nce st ar ter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-7. Pa rt -Windin g st ar ter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-8. Solid St at e st ar ter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-9. Typical motor control center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-10. Cut awa y view of typical molded ca se circu it br eak er . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-11. Molded case circuit brea ker tim e-curr ent curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-12. Fu se m ain ten an ce pra ctices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-13. Un der writ ers Labor at ories C ar tr idge fus e class ification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-14.Typica l thermal overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-15. Typical heater selection table for thermal overload device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-16. A NEMA size 6 m agn etic conta ctor (court esy of Sieme ns-Allis) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-1. Connections for tes tin g low volta ge cable in su lat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71. Typical capacitor types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-2. Diodes and SCRs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
73. Cha ra cter istics of diodes a nd Zener s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-4. Testing Zener voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75. Tr an sist or t est ing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1. Typical equipment ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-2. Typical grounding system for a building and its apparatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-3. Meth ods of syst em groun ding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-4. Methods o fsolidly grounding the neutral of three-phase systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-5. Methods of resista nce groundin g the neut ra l of th ree-pha se syst ems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-8. Groun ding for electr onic an d ADP syst ems .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-7. Groun d fau lt cir cuit in ter ru pt er oper at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1. Pre hea t fluore scent lam p a nd fixtur e componen ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-2. Mercury lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-3. Trouble-s hootin g fluores cent light ing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-1. Sam ple compu ter -based fire det ection s yste m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-2. Clas s A a nd B fire det ection circu its . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
121. Pa dlock an d m ult iple lock ada pt er . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
122. Typical safety tag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
123. Ground cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12-4. Grounding clamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
125. E ye an d face pr otection s election gu ide.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13-1. Set -up for m eas ur ing AC volt age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13-2. Set-up for measuring resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
2-15
3-2
4 -8
4 -9
4-14-1
4-1
4-1
4-14
4-1
4-1
4-1
4-1
4-1
4-1
4-1
4-2
4-2
4-2
4-24-2
4-2
4-2
5 -2
5-2
5-3
5-4
5-5
5 -6
5-7
5 -8
5-9
5-1
5-1
5-15-1
5-1
5-1
5-1
6 -2
7 -3
75
7 -6
7- 6
7-8
8 -3
8- 4
8-5
8 -6
8 -6
8-1
8-1
9-2
9-3
9-4
10-2
10-3
122
122
123
12-4
12-6
13-4
13-5
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LIST OF FIGURES (contd)
Figure 13-3.
13-4.
13-5.
14-1.14-2.
14-3.
14-4.
14-5.
14-6.
14-7.
14--6.
14-9.
14-10.
14-11.
Table 2-1.2-2.
4-1.
4-2.
4-3.
4-4.
4-5.
5-1.
5-2.
6-1.
6-2.
71.
9-1.
10-1.
111.
13-1.14-1.
14-2.
15-1.
15-2.
15-3.
1.54.
Set -up for t est ing ph as e sequ ence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Megohmmeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........
Diagram of megohmmeter connections...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......
Comparison of water f low wi th elect r ic current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Curves sh owing components of measured current during insulation testing . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical curves showing dielectric absorption effect in a time-resistence or double-reading test . . . . . . . . . . .
Resistive components of a made electrode . . . . . . . . . . . . ..... . . . . . . . . . . . . . . ........
So i l r es i s t i v i t y v s mo i s t u r e con t e n t o f r ed c l a y so i l . . . . . . . . . . . .. . . . . . . . . . . . -
Soil resistance vs temperature of clay soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .
Soil resistance vs depth of electrode..... . . . . . . . . . . . . . . . . . . . . . . . . .. ............
Ea rt h electr ode with hem isph eres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fall-of-potential method graph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sampling the cell electrolyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading the hydrometer float . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LIST OF TABLES
U.S. standa rd bolt torgues for bus connections hea t t reat ed steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Trou ble-shootin g procedu re s for swit chgea r e quipm ent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor application guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nam eplate voltage r at ings of sta nda rd indu ction motors . . . . . . . . . . . . . . . . . . . . . . . . . ....
AC synchronous motor trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........
DC motor generator trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor control preventative maintenance guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor contr ol trouble-shooting char t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -
Condu ctor sizes, in su lat ion th icknes s, te st voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable maintenance overheating problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
Power qua lity pr oblems s um ma ry .. ...--. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamp trouble-shooting guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
Comparison of fire detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comm on tr ade na mes for PCB by m an ufact ur ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tools and equipment for effective electrical maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........Int erp ret ing in sula tion r esist an ce test res ult s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condition of insulation indicated by dielectric absorption ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Per cent age of failur e cau se s ince m ain ta ined .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment failure rate multipliers vereus maintenance quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In ter ior wir ing a nd light ing s yst em . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric motors a nd contr ols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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TM5-683/NAVFAC MO-116/AFJMAN 32-1083
CHAPTER 1
INTRODUCTION
1-1 . Pu rpos e and s c op e .
This ma nu al provides guidan ce to facilities maint e-
na nce personnel in the ma inten an ce of inter ior elec-
trical systems of 600 volts and less. These systems
include such components as illumin at ion, low volt-
age systems, rota ting equipmen t, motor cont rol cen-
ters, solid-state equipment, t ransformers, and
switchgear. It also applies to low voltage controlled
devices on high-voltage systems. The procedures
presented in this manual are basic and can be ap-
plied to the equipment of any manufacturer. De-
tailed information and instructions should be ob-
tained from the instruction book for the particulartype of equipment being serviced.
1-2 . Re fe renc es .
Appendix A cont ains a list of references used in th is
manual .
1-3 . Codes and spec i f i c a t ions .
Maintenance on electrical systems and equipment
must adhere to the codes and specifications as they
apply to the work to be performed. Also, manufac-
tu rers maint enan ce instr uctions which accompanyselect electr ical component s mu st be applied in con-
junction with th e codes a nd specifications listed be-
low and the departmental specifications listed in
appendix A.
a. The National Electrical Code [National Fire
Pr otection Associat ion #70 (NFP A 70)]. This code is
th e most widely adopted set of electr ical sa fegua rd-
ing practices. It defines approved types of conduc-
tors and equipment, acceptable wiring methods,
mandatory and advisory rules, operating voltages,
limitations on loading of conductors, requir ed work-
ing spaces, methods of guarding energized parts,
interrupting capacity requirements of system pro-tective and control devices, requirements for con-
nections and splices, insulation resistance require-
ments, an d grounding requirements.
b. Recommended Practice for Electrical Equip-
ment Maintenance (NFPA 70 B).
C. A m er ican N a t iona l S t andards Ins t i t u t e /
Institute of Electrical and Electronics Engineers
Standard (ANSI/IEEE Std.) chapter 15, 242-1986,
IEEE Recommended Practice for Protection and Co-
ordination of Industrial and Commercial Power Sys-
tems. This code provides preventive maintenance
pra ctices for electr ical systems a nd equipmen t u sedin indust rial-type applicat ions.
1-4 . Ma in tenance requ i rements .
Preventive maintenance should not be confused
with repairs after a breakdown. The definition of
maintena nce implies tha t t he equipment or system
is inspected to discover its weaknesses and then
repair or replace the necessary elements before a
break down occur s. A mainten an ce progra m for pr o-
tective devices a nd th e electr ic system could be di-
vided into the following steps: inspecting, cleaning,
tightening, lubricating, testing, and recording.
a. The effectiveness of the distribution system is
measu red in t erms of volta ge regulation, power fac-
tor, load ba lan ce, reliability, efficiency of opera tion,
an d cost s. To ensu re t he syst ems efficiency, lessen
failures, and maximize safety, an effective mainte-
nance program must be employed. This program
should include and/or consider the following:
(1) Scope of work.
(2) Intervals of performance.
(3) Methods of application.(4) Safety requirements, practices and proce-
dures.
(5) Adherence to codes, specifications and di-rectives.
(6) Maintenance management procedures re-
garding tools, records, and follow-up procedures.
(7) Hazard s associat ed with work a nd t he facil-
ity.
(8) Emergency operating instructions.
(9) Requirements for periodic review to deter-
mine a dditiona l loading in circuits such a s in family
housing, bachelor quarters, and maintenance and
administrative buildings.
b. A well executed maintenance program will
provide benefits in ter ms of:
(1) Economic operation.
(2) Improved safety.
(3) Longer equipment life.
(4) Reduced repair and overhaul time.
(5) Fewer unplanned outages.
(6) Early detection of undesirable changes in
th e power system.
(7) Improved operation of the facility.
1-5. Records.
A good record keeping system is essential for safe,
efficient an d economical oper at ion of electrical facil-
ities and for planning and executing an effective
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TM5-683/NAVFAC M O-116/AFJMAN 32-1083
prevent ive maintenance program. I t is recom-
mended to use the Work Information Management
System (WIMS) or other data-automated systems to
keep records rather than paperwork files. Suitable
forms and reports requirements should be devel-
oped to suit local needs. When facilities are built,
instruction documents and spare parts lists for allequipment installed should be obtained prior to
beneficial occupancy acceptance.
a. In addition to charts, work orders, and real
property records, the following records have been
found useful in analysis and correction of recurring
trouble ar eas.
(1) Diagrams. Accurate single-line and sche-matic diagrams of the distribution system should be
readily accessible in the electrical shop. These are
essential references when switching circuits and re-
routing electric power in emergencies. Such dia-
grams also provide a simple means of locating facil-
ities and determining the characteristics of electricsupply to buildings requiring maintenance. Electri-
cal personnel must have access to latest "as-built"
building drawings for use in tracing out circuitry
within buildings.
(2) Equipment lists/ logs. These lists should be
maintained on all items of equipment such as mo-
tors, motor contr ollers, met ers, pa nelboards , electri-
cal controls, and switchgear. Lists should reflect
detailed information such as the density of all like
i t em s , i t e m r a t i n g s a n d p h y s i ca l l oc a t i on s .
Lists/logs will facilitate scheduling of inspections
and maintenance services.
(3) Equipment maintenance records. T h e s erecords should be maintained on every individual
item of electrical equipment that requires mainte-
nance services. Records should include detailed in-
formation such as scheduled maintenance and in-
spec t ion requ i rements , p rev ious tes t r esu l t s ,
maintenance repairs performed and any other re-
lated information that would facilitate analyzing
the equipment performance. Maintenance records
should be retained on file for as long as needed to
allow collection of sufficient data to perform the
equipment performance analyses. By observing the
equipment performance, downward trends can be
identified a nd problem ar eas corr ected before majorbreakdowns occur.
(4) Emergency operating instructions. E m e r -
gency operation of electrical facilities is safer and
quicker when instructions are prepared and posted
in advance. There should be instructions for each
general type of anticipated emergency, stating what
each employee in the electrical section should do,
setting up alternatives for key personnel, and estab-
lishing follow-up procedures for use after an emer-
gency has passed. Instructions should be posted in
the electrical shop, security guard office, all em
gency generating or operating areas, and other lo
tions as t he responsible supervisor deems n ecessa
Employees should be listed by name, title, offi
telephone number, home address and home t
phone number (where permissible). These instr
tions should emphasize safety under conditionsstress, power interruptions and similar emerg
cies.
1-6. Pr ior i ty and schedul ing.
In regard to the support of the installed phys
facilities, it is the policy of the Military Dep
ments that, in order of priority, maintenance sho
be second only to operations. It must be system
and timely. Subsequent sections in this docum
provide generaI suggestions on service frequenc
and procedures. Although these proposed acti
and frequencies may appear to be excessive, th
suggestions are based upon experience and equment man ufacturers recommen dations. They
not intended to supersede instructions that elec
cal manufacturers normally provide. Every reali
effort should be made to adher e to th ese suggesti
considering existing manpower levels and availa
test equipment. It is generally good practice to
spect equipment three to six months after it is f
put into service and then to inspect and maintai
every one to three years, depending on its serv
and operating conditions. Conditions that make
quent maintenance and inspection necessary
a. High humidity and high ambient temperatu
b. Corrosive atmosphere.c. Excessive dust and dirt.
d. High repetitive duty.
e. Frequent fault interruption.
f. Older equipment.
1-7. Hazards.
Material specifications, construction criteria, ins
lat ion s tandards, and safe working procedu
should be applied to minimize hazards. All w
should be performed by qualified electricians
conform to the latest accepted procedures and st
dards.
a. Building electrical systems. Fire and safhazards in building electrical systems often re
from tampering by unqualified personnel. Proba
the greatest example of tampering is the unaut
rized changing or replacing of fuses. Careful ob
vation by maintenance personnel is needed to c
trol excessive use of items such as extension co
heaters, air conditioners, and improper ground
which cause overloading of the wiring syste
Whenever possible, installation of additional rec
tacles is preferable to the use of extension co
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Each building should be inspected for loose wires,
poor connections, bare conductors, unauthorized or
nonsta nda rd a tt achment cords, use of wiring or fix-
tures as support for extraneous items, any condi-
tions likely to cause fires and lamps larger than the
sta nda rd size prescribed for outlets.
b. Hazardous locations. Special occupancy areasinclude gar ages, aircraft ha ngar s, gasoline dispens-
ing and service stations, bulk storage plants, and
TM5-683/NAVFAC MO-116/AFJMAN 32-1083
health care facilities. Such areas designed as "Haz-
ards Locations," as specified in Article 500 of the
Nat iona l Electr ical Code, require s pecial an d equip-
ment considerations. These considerations include
the use of special fitt ings, rigid conduit, and
explosion-proof apparatus. Maintenance personnel
must ensure that al l work performed in a hazardousarea complies with the code requirements for the
ar eas pa rticular ha zard classification.
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CHAPTER 2
SWITCHGEAR ASSEMBLIES 600V OR LESS
2-1 . Pe r i od i c Ma in t e nanc e .
A periodic maintenance schedule must be estab-
l i s h e d t o o b t a i n t h e b e s t s e r v i c e f r o m t h e
switchgear. Annual check should be made on all
major switchgear devices after installation. After
trends have been established regarding the equip-
ment condition and reliability, the maintenance in-
terval may be extended (1836 months) in keeping
with the operating conditions. A permanent record
of all ma intena nce work should be kept. The r ecord
should include a list of periodic checks and tests
made (including date of test), condition of the equip-
ment, repairs or adjustments performed, and test
data tha t would facilitat e performing a trend ana ly-
sis. Maintenance personnel must follow all recog-
nized safety practices, both the nationally published
standards and military regulations. Some specific
suggestions in dealing with switchgear mainte-
na nce are given below:
a. Tools designed for slowly closing switchgear
circuit breakers or other devices during mainte-
nance are not suitable for use on an energized sys-
tem. The speed necessary for device closing is as
important as its speed in opening; therefore, a
wrench or other manual tool is not fast enough.
b. Before working on a switchgear enclosure,verify that the enclosure is de-energized by check-
ing for voltage using a voltage detector.
c. Disconnect all drawout or tilt-out devices such
as circuit breakers, instrumentation transformers,
an d control power tra nsformer s.
d. Do not la y tools on th e equipment while work-
ing. It is all too common to forget a wrench when
closing up an enclosur e. Dont t ak e the cha nce.
e. Never rely upon the insulation surrounding an
energized condu ctor to pr ovide protection to pers on-
nel. Use suitable safety clothing and equipment.
f. Always use the correct maintenance forms and
equipment. When performing maintenance the fol-lowing should be available:
(1) Forms for recording the conditions as found
an d work done.
(2) Control power connections, test couplers,and spar e parts recommended by the man ufactur er
to facilitate repair and maintenance of each type of
circuit breaker.
(3) Special tools, such as lifting mechanismsfor removing and transporting power circuit break-
ers, relay test plugs for testing and calibrating pro-
tective relays, a low resistance ohmmeter for mea-
s u r i n g t h e r e s i s t a n c e o f c o n t a c t s , a m m e t e r s ,
voltmeters, megohmmeters, low voltage/high cur-
rent test set s for testing power circuit break ers, and
other special test equipment.
(4) Manu factu rers inst ru ction books regard ing
the maintenance of switchgear devices such as cir-
cuit breakers, relays, bus bars, meters, etc. The
fundamentals that are presented in the upcoming
sections are designed to supplement these instruc-
tions, giving the elements of the overall mainte-
nance program rather than the details.
2-2 . Me t a l enc los u res .
Mainten an ce is r ecommended below:a. With power off and t he bu s properly grounded,
open the enclosure and remove any accumulated
dust and dirt. Vacuum cleaning is recommended;
blowing with compr essed air is not.
b. Check structure and anchor bolts for tight-
ness . For bus and breaker connect ions ensure
ma nu factu rers specified torques ar e used.
c. Clean and lubricate circuit breaker racking
mechanisms with a non-hardening, non-conductive
grease.
d. Inspect operation and adjustment of safety
shutters, mechanical and key interlocks, auxiliary
and limit switches.e. Clean and inspect strip heaters.
f. Clean any air filters that are installed in the
ventilation openings.
g. Inspect all relays, contractors, switches, fuses,
and other auxiliary devices for correct operation
an d cleanliness.
h. Tighten control wiring connections.
i. Inspect alignment and contacting of primary
disconnecting devices, checking for signs of abnor-
ma l wear or oth er da ma ge. Discoloration of th ese or
other silvered surfaces is not usually harmful un-
less caused by sulphide deposits, which can be re-
moved by a solvent, su ch as a lcohol, or silver p olish.j. A f t e r c l e a n i n g , m e a s u r e t h e r e s i s t a n c e t o
ground and between phases of the bus with a
megohmmeter (para 14-2). It is not possible to give
definite limits for satisfactory insulation resistance
values, so that a change in the reading from one
inspection per iod to an other is t he best indicat ion of
any weakening tendency. The readings should be
taken under similar conditions each time, and the
record should include temperature and humidity.
k. Before replacing th e breaker , wipe the pr imar y
disconnecting device contacts. Apply a thin coat of
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TM 5-683/NAWAC MO-116/AFJMAN 32-1083
contact lubricant to the stationary studs and to the
primar y disconnects on t he break er.
l. Ensure that all metal shields are securely in
place. These shields must be installed to confine any
blast in t he event of circuit br eaker failure.
(1) A n ote on lubricants. One of the most useful
lubricants for motors is an extreme pressure (EP)
lithium-base petroleum grease. As the usage of
Class F winding temperature ratings has increased,
however, others have adopted synthetic greases to
withstan d h igher bearing temperatur es.
(2) Synthetic oils and greases. Synthetic oils
and greases compounded from various silicones,
alkyl benzene, diesters, and fluorinated ethers, are
available for extremely high-temperature service
tha t would cau se prema tur e oxidation of petroleum
lubricants. Some synthetics also suit extremely low
temperature, down to 40 or 50 degrees below zero.
The main uses for synthetic lubricants in motorbear ings are reduced f r ic t ion and res is tance to
moisture and chemical contamination. Such appli-
cations must be carefully worked out with bearing
and lubricant suppliers, becau se no universal lubri-
cant formulation will apply to all environments.
However, it is not unusual for lubricant to vary
little more than brand name. Thus substitutions are
often possible. Consu lt with t he ma nufacturer of the
switchgear to determine the important characteris-
tics of the lubricant prior to specifying a substitute
lubricant. Carefully selected substitutes will reduce
the cost of procurement, stocking and dispensing.
2 -3 . Bus ba r an d t e rm ina l c onnec t i ons .
Many failures are at tribut able to improper term ina-
tions, poor workm ansh ip, and different characteris-
tics of dissimilar metals. Loose bus bar or terminal
connections will cause overheating which can be
easily spotted by a discoloration of the bus bar. A
thermographic survey can be conducted to detect
overheating before discoloration occurs (para 14-7).
An overheating condition will lead to deterioration
of the bus system as well as to equipment connected
to the bus; i.e. protective devices, bus stabs, etc.
Therefore, bus ba r a nd t erminal connections should
be regularly checked to ensure that they are prop-
erly tightened without damaging the conductors.
Special attention should be given where excessive
vibration may cause loosening of bolted bus and
terminal connections. Tightening torque values for
electrical connections are provided in table 21.
This information should be used for guidance only
wher e no tighten ing inform at ion on t he specific con-
nector is available. It should not be used to replace
ma nu factu rer s instr uctions which should always be
followed. Do not assume that once a connection has
been torqued to its proper value that it remains
2-2
tight indefinitely. If signs of arcing are evident , then
the connections should be broken and the connect-
ing surfaces cleaned. Because of the different char-
acteristics of copper and aluminum, they should not
be intermixed in a terminal or splicing connector
where physical contact occurs between them, unless
the device is suitable for the purpose and conditions
of use. Materials such as solder and compounds
shall be suitable for the use and shall be of a type
which will not adversely affect the conductors.
a. Aluminum connectors. Special considerations
must be given to aluminum connections. Aluminum
connectors are plated and should not be cleaned
with abrasive. If these connectors are damaged,
they should be replaced. It should be noted that
when making connections with aluminum conduc-
tors, be sure to use a joint compound made for the
purpose. To assist in the proper and safe use of solid
aluminum wire in making connections to wiringdevices, refer to the National Electrical Code. Make
aluminum connections with solderless circumferen-
tial compression-type, aluminum-bodied connectors
UL listed for AL/CU. Remove surface oxides from
aluminum conductors by wire brushing and imme-
diately apply oxide-inhibiting joint compound and
insert in connector. After joint is made, wipe away
excess joint compound and insulate splice.
b. Bus insulators and barriers. Bus bar support
insulators and/or barriers should be wiped with a
clean cloth. Do not use steel wool or oxide papers to
remove dirt; use a cleaning solvent that will not
leave trace deposits. While cleaning, check insula-tors for cracks and signs of arc tracking. Defective
units should be replaced. Loose mounting h ardwar e
should be tightened.
2-4. Under f loo r duct s .
All undefloor duct systems require checks for evi-
dence of oil and water. Entrances and fi t t ings
should be checked and corrected as necessary to
prevent entrance of liquids, insects, and rodents.
Cockroaches, ants, beetles and rodents have been
known to at tack cable insulat ion, especial ly if
greases or oils are present. External heat and heat
caused by overloaded circuits can cause cracking of
cable insulation and drying of taped splices. Mois-
ture can then penetrate the cable and could cause a
fault. Therefore, underfloor conduits and duct sys-
tems should be kept sufficiently clear of electrical
and hot water floor-heating systems to prevent un-
due h eating of the en closures.
2-5. Busways.
Feeder busway, trolley busway and plug-in busway
(fig 21) require annual cleaning and removal of oil
substa nces and dirt . Ventilated-type busway should
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NOTE : REDUCE TORQUE BY 20% WHEN CADMIUM P LATED BOLTS ARE U S ED.
have the bus bars cleaned annually with clean, dry
compressed air a t a maximum pressure of 50
pounds per square inch. Plug-in devices should be
s e r v i c e d u s i n g t h e s a m e p r o c e d u r e s a s o t h e r
switches or breakers. The plug-in bus or prongs
should be checked annually for annealing or corro-
sion on all connections which are rated in excess to
75 percent of the r at ing of th e bus d uct. Conn ections
should not be retorqued as part of a routine main-
tenance procedure unless visibly loose or shown to
be loose by an infrared scan. All busway connections
should be torqued according to manufactures rec-
ommendations. If this information is not available,
use the torque specifications in table 2-1. Inspect to
ensure that :
a. Ventilation continues to be adequate.
b. Clearances are maintained and encroachment
from other equipment facilities has not occurred.
2-6. Pow er c i rc u i t b reakers .
Power circuit breakers encompass all breakers ex-
cept molded case breakers and breakers used for
control applications. It is recommended that power
circuit breakers be inspected once a year after in-
stallation. More frequent inspections are recom-
mended where severe load conditions, dust, mois-
ture or other unfavorable conditions exist, or if the
vital nature of the load warrants it. Any breaker
that has interrupted a fault at or near its short
circuit rating should be inspected immediately after
the interrupt ion and serviced i f necessary. Re-
energize equipment completely before working on
any devices, connections, bus work, breaker orfeeder cab le compar tments . Th is inc ludes de-
energizing any connections to outside primary or
secondary sources such as transformers, tie lines,
etc. Manufacturer s inst ru ction docum ents should
also be obta ined an d rea d carefully before disas sem-
bly or adjustments are performed.
a. Drawout circuit breakers. A drawout - type
breaker should be tested and inspected for proper
operation as follows:
(1) Withdraw the breaker to the test position.This position disconnects the primary power circuit
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TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
FEEDERBUSWAY
PLUG-IN
N>
BUSWAY
Figure 2 -1 . Typ ica l busw ay ins ta l la t ion .
but leaves the control circuits energized (fig 2-2). If
a test position is not provided, then complete-
ly withdraw the circuit breaker from its compart-
ment and use a test coupler to provide control
power.
(2) Test for voltage to ma ke sur e th at all path sof potent ial ba ckfeed from cont rol power circuits , as
well as outside sources, are disconnected. This is
especially important if an external source of control
power is being used for testing.
(3) Operate the breaker and check all func-tions. Use both the electrical means (when pro-
vided) and the mechanical means to charge, close
and trip the breaker. This is particularly important
for breakers that normally remain in either the
opened or closed position for long periods of time.
(4) Remove the breaker from its compartment
to a clean maintenance area. Close the compart-
ment door and cover the breaker cutout to prevent
access to live parts.
(5) Check and lubricate all safety rollers and
auxiliary contacts. Check all mechanical clearances
to ensure they are within manufacturer specified
toleran ces. Also inspect an d lubricate bus stabs and2-4
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\
~DISCONNECTEDALL POWER DISCON-NECTED
WITHDRAWNBREAKER WITHDRAWNREADY FOR REMOVAL
Figure 2-2. Drawou t c i r cui t break er pos i t i ons .
ac/dc control block contacts. Verify correct operation
of trip free and anti-pump mechanisms.
b. Fixed circuit breakers. Maintenance on fixed-
or bolter-type circuit breakers is normally per-
formed with the breaker in place inside its cubicle.
Special precautions must be exercised to assure
equipment is de-energized and the circuit in which
it is connected is properly secured from a safety
s tandpoint . Al l cont rol c i rcui t s should be de-
energized. Stored energy c los ing mechanismsshould be discharged.
c. Power circuit breaker components. M a i n t e -
nance on all power circuit breakers will encompass
maintenance on the following components.
(1) Insulation. The general rule for insulationis keep it clean and dry. Remove interpha se barr iers
and clean them and all other insulating surfaces
with dry compressed air and a vacuum cleaner.
Wipe insulation with clean lint-free rags and sol-
vents as r ecommended by the ma nufacturer if hard-
ened or encrusted contamination must be removed.
Repair moderate damage to bushing insulation by
sanding smooth and refinishing with a clear insu
lating varnish. Check insulating parts for evidence
of overh eat ing an d for cracks t ha t indicate excessive
thermal aging.
(2) Contacts. The major function of the power
circuit breaker depends among other things upon
correct operation of its contacts. These circui
breakers normally have at least two distinct sets o
contacts on each pole, main and arcing (fig 2-3)Some have an intermediate pair of contacts which
open after the main contacts and before the arcing
contacts.
(a) Main contacts. W hen the b reake r i s
closed, practically the entire load current passe
through the main contacts. Also, short circuit cur
rent must pass through them during opening o
closing faulted lines. If the resistance on these con
tacts becomes high, they will overheat. Increased
contact resistance can be caused by pitted contac
surfaces, foreign material embedded on contact sur
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TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
FIXED ARCING CONTACT
MOVABLECONTACT
MOVABLE MAIN
CONTACT
ARCI
Figure 2-3 . Power c i rcu i t break er m a in an d a rc ing con ta c t s .
faces, or weakened contact spring pressure. This (c) Contact maintenance. The general rules
will cause excessive current to be diverted through
the arcing contacts, with consequent overheatingand burning.
(b) Arcing contacts. Arcing contacts are the
last to open; any arcing normally originates on
them. In circuit interruption, they carry current
only momenta rily, but tha t current may be equal to
the interrupting rating of the breaker. In closing
against a short circuit, they may momentarily carr y
considerably more than the short circuit interrupt-
ing rating. Therefore, they must make positive con-
tact when they are touching. If not, the main con-
tacts can be badly burned or may r esult in a failure
to interrupt a fault.
for maintaining contacts on all types of breakers
are: keep th em clean, a ligned an d well adjusted. Toinspect t he circuit brea ker conta cts, th e ar c chut es
must be removed. When doing this, check the arc
chutes for evidence of damage, and replace dam-
aged parts. If not damaged, then blow off dust or
loose part icles. Once the m ain conta cts ar e exposed,
inspect their condition. Slight impressions on the
stat ionar y conta cts caused by the pr essure an d wip-
ing action of the m ovable cont acts is tolerable. Con-
tacts which have been roughened in service should
not be filed but large pr ojections, caused by un usu al
arcing, should be removed by filing. When filing,
take care to keep the contacts in their original de-
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sign. That is, if the contact is a line type, keep the
area of contact linear, and if ball type, keep the ball
shaped out. Discoloration of silver-plated surfaces is
not usually harmful unless caused by insulating
deposits. These deposits should be removed with
alcohol or a silver cleaner. Whether cleaned or not,lubricate the main contacts by applying a thin film
of slow aging, heat resistant grease. All excess lubri-
cant should be removed with a clean cloth to avoid
accumulation of dirt and dust. Under no circum-
stances should the arcing contacts be lubricated.
Where ser ious overhea ting is indicated by discolora -
tion of metal and surrounding insulation, the con-
tact and spring assemblies should be replaced in
accordan ce with m an ufactur ers instr uctions. While
carefully closing the circuit breaker, check for
proper gap, wipe and contact alignment. Contact
gap is the distan ce between t he sta tionar y and mov-
able contacts with the circuit breaker in the fully
open position. If th e ar cing cont act gap is too small,
a circuit breaker may not be able to interrupt a
fault. If the main contact gap is too small, the mainconta cts will interr upt the fault a long with th e arc-
ing contacts and possibly burn the main contacts.
Contact wipe is the amount of over travel between
the stationary and movable contacts from the time
when the contacts are just touching to the time
when the circuit breaker is fully closed (figs 24,
25, and 26). Check that all contacts make and
break at approximately the same time. Make ad-
justments in a ccordance with the man ufactur ers
recommenda tions. Lam inated copper or brush style
b
F i g u r e 2-4. A r c i n g c on t a c t g a p a n d w i p e .
CONTACT WIPE
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ACRING CONTACTS
TOUCHING
CON
Figure 2-5 In term ed ia te con ta c t gap .
contacts found on older circuit breakers should be
replaced when badly burn ed. Repairs ar e not pra c-
tical because the laminat ions t end t o weld together
when burning occurs, and contact pressure and
wipe are greatly reduced. These contacts may be
filed to remove large projections or to restore their
original shape. They should be replaced when theyare burned sufficiently to prevent adequate circuit
breaker operation or when half of the contact sur-
face is burn ed awa y. Car bon conta cts, used on older
circuit breakers, require very little maintenance.
However, inadequate contact pressure caused by
erosion or repea ted filing ma y cau se overh eat ing or
interfere with their function as arcing contacts.
(3) Operating mechanism. The purpose of the
operating mechanism is to open and close the
breaker contacts. This usually is done by linkages
conn ected, for most power brea kers , to a power op-
erating device such as a solenoid or closing spring
2-8
for closing, and contains one or more small sole-
noids or oth er t ypes of electro-ma gnets for t ripping.
Tripping is accomplished mechanically, independent
from t he closing device, so th at th e break er cont acts
will open even though the closing device still may be
in the closed position. This combination is called a
mechanically trip-free mechanism. After closing,the primary function of the operating m echan ism is
to open the breaker when it is desired, which is
whenever the tripping coil is energized at above its
rat ed minimum operat ing voltage. The breaker op-
erating mechanism should be inspected for loose or
broken part s; missing cotter pins or reta ining keep-
ers; and missing nuts and bolts. It should also be
examined for damage or excessive wear on cam,
latch, and roller surfaces. Excessive wear usually
results in loss of travel of the breaker contacts. It
can affect operation of latches; they may stick or
slip off and prematurely trip the breaker. Adjust-
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TM 5 + 5 8 3 / N A V F A C MO-1 1 6 /AFJMA N 32-1083
11L 1 3nCONTACT WIPE16 32
Figur e 2-6. Main contact wipe.
menta for excessive wear are possible for certain lubricate pins and bearings not disassembled. Useparts. For others, replacement is necessary. The non-hardening and non-conductive grease to lubclosing and tripping action of a breaker should be cate the ground or polished surfaces of cam
quick and positive. While documenting, operate the rollovers, latches and props, pins and bearings th
breaker several times, checking for obstructions or are removed for cleaning. Check the breaker ope
excessive friction. Any binding, s low a ction, d elay in ating mechanism adjustments and readjust as d
speration, or failure to trip or latch must be con- scribed in the manufacture% instruction book.
rected prior to returning to service. Clean and these adjustments cannot be made within specifie
relubricate the operating mechanism. Use a tolerances, it will usually indicate excessive we
nondetergent light machine oil (SAE-20 or 30) to and the need for a complete overhaul.
2-
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(4) T rip devices. The tr ip devices on low voltage
circuit breakers provide the electrical decisions
needed to detect th e difference between normal a nd
abnormal conditions of current flow. The mainte-
nance and adjustment of these devices is just as
importa nt as t he work per formed on t he ma in con-
tacts and operating mechanism. The trip devices
are either electro-mechanical or solid-state. Both
types are responsible for providing various degrees
of fixed, short, or inverse time delays based on the
am ount o f cu r ren t t hey sense . The e l ec t ro -
mechanical type, with an air or fluid dashpot for
time delay, should be tested as part of the mainte-
nance work performed. A dashpot is a pneumatic or
hydraulic device used for cushioning or damping of
movement t o avoid mechanical shock an d consist ing
essent ially of a cylinder cont ainin g air or liquid an d
a piston moving in i t . Testing of the electro-
mechan ical devices requ ires th e use of a low voltage
(abou t 0 -20V ) bu t h igh cu r ren t (usua l ly O -
50,000A) prima ry injection t est s et des igned specifi-cally for this purpose. Calibration tests should be
ma de to verify tha t t he per form an ce of the device is
within the values shown on the m anu factur ers pub-
lished curves; taking into account that the time-
current curves are plotted as a band of values
rather than a single line (fig 27). Pay careful atten-
tion to how the manufacturer has presented the
curve data. There is a wide variety of formats.
Check to see tha t th e curr ent is in amperes or mul-
tiples of a pickup value and whether temperature
ranges or previous conditions will affect results.
Usually, the trip devices are tested one unit at a
time. There are some devices which m ay use a ther-mal element for time delay. These may have to be
tested all at once to get results similar to those
published by the m anu factur er. Check th e test con-
ditions carefully. If the trip devices do not operate
properly, the calibration and timing components
should be adjusted or replaced per the ma nufactur-
ers recomm enda tions. If repair or r eplacement of
the electro-mechanical devices is being considered,
then thought should be given toward retrofitting
the existing breaker with solid-state trip devices.
This newer technology is generally more reliable
because t he par ts used to make t he tr ip unit do not
drift out of adjus tm ent or suffer t he effects of aging
or contaminat ion to the same degree as thei r
electro-mechanical forerunners. If the breakers are
already equipped with solid-state trip devices, they
should also be checked for proper operation and
time delay in accordan ce with th e man ufactur ers
published curves. The test procedure recommended
by the manufacturer should be followed.
(5) Auxiliary devices. Inspect the closing motoror solenoid, shunt trip coil and mechanism, alarm
2-10
mechanisms, and the control wiring for correct op-
erations, insulation condition and tightness of con-
nections. Check on-off indicators, sprin g-char ge in-
dicators, mechanical and electrical interlocks, key
interlocks, and lock-out fixtures for proper opera-
tion and lubricate where required. In particular,
test the positive interlock feature which prevents
th e insert ion or removal of th e break er while it is in
the closed position. Check control devices for free-
dom of operation. Replace contacts when badly worn
or burned. After the breaker has been serviced,
manually operate it slowly with a closing device to
check for tightness or friction and to see that the
contacts move to their fully open and fully closed
positions. Electrically operate the breaker several
times to check the performance of the electrical ac-
cessories using the TEST position, an external
test /contr ol cabinet, or a t est coupler.
2-7 . Netw ork pro tec tors .
The current-carrying parts, main contacts, and op-erat ing mechan ism of a n etwork pr otector a re very
similar t o th ose of th e air circuit br eaker . This simi-
larity usually ends with the principal mechanical
devices. Unlike the usual feeder circuit breaker, the
network protector is more like a tie circuit breaker;
that is, it is almost always energized on both sides.
This condition r equires tha t extreme care be taken
during inst allation or removal of the un it from ser-
vice. The net work protector is equipped with special
relays tha t sense t he net work circuit conditions a nd
command the mechanism to either open or close
automatically in response to those conditions. Net-
work protectors are used where large amounts ofpower must be distributed to high density load ar-
eas such as commercial buildings and office com-
plexes. To form a network, several incoming power
sources may be connected. As a result, a short cir-
cuit a t any point in the system usu ally involves very
high fault currents.
a. Safety precautions. Due to the construction
and purpose of the network protector, ta king it out
of service or p lacing it back in service is a procedure
that must be done while the circuit is energized.
During th is work, always use t he special insulat ed
tools provided with the particular model to be ser-
viced. Alternate or make-shift tools are not recom-
mended unless they have been laboratory tested
and are known to have good safety performance.
Electrical grade, safety gloves should still be worn
by the person servicing the unit regardless of the
type or condition of th e tools u sed.
b. Main tenance. A routine maintenance schedulefor network protectors should be observed. The fre-
quen cy of inspection will var y based on th e locat ion
and environment in which t he un it is installed, and
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TM 5 -683/NAVFAC MO-116/AFJMAN 32-1083
the number of operations the unit has made. In all
cases, open the circuit first. This is done by moving
t h e c o n t r o l h a n d l e f r o m A U T O M A T I C t o
MANUAL and then manually opening the circuit.
The control handle and/or operating mechanism
should t hen be locked in t he OPEN position beforefurther work is done. Maintenance should include
cleaning any accumulation of dust, dirt or corrosion
deposits, a thorough visual inspection, and overall
performa nce tests. Should the opera tion of any par t
be suspect, refer t o the m anu factur ers instr uctions
describing operation, adjustment, and replacement
of these part s. If th e network sensing relays are out
of calibration, they should be recalibrated by com-
petent shop personnel. The network protector is
housed in a cell or enclosure similar to those used
for air circuit breakers (fig 2-8). The circuit breaker
mechanism and the network relay panel assembly
of a net work protector ar e usu ally constructed aa anintegral, drawout unit which must be withdrawn
fmm the housing for proper maintenance. Removal
is done by unbolting the fuses at the top (usually)
and the disconnecting links at the bottom (some
models have bolt-actuated disconnecting fingers at
the bottom). After removing any additional lock-
down bolts or latches, the drawout unit may be
carefully withdrawn using the rails provided for
support . Although this provides a comparative
measure of safety, work should be done cautiously
since there is voltage present within the enclosure.
It is better to move the unit completely away fromth e en closure (fig 29). The following insp ection an d
maint enan ce operat ions can be done on t he dra wout
unit :
(1) Clean the breaker assembly. Use of avacuum cleaner is preferred. Use cloth rags free of
oil or grease for removing clinging dirt.
(2) Remove arc quenchers. Replace if damaged.
(3) Inspect main contacts (fig 2-10). Smooth
any heavily frosted area with a very fine file or a
burnishing stone which does not shed abrasive par-
ticles. Protect hinged joints from falling particles
during filing.
(4) File smooth any especially high projections
of metal on arcing contacts.
(5) See that all electrical connections are tight.
(6) Look for any abrasion of wire insulation
and repair .(7) Check for signs of overheating of control
wire and current carrying parts.
(8) See that all springs are in good condition
and are properly seated in place.
(9) See tha t a ll nuts, pins, snap r ings or r etain-
ers, and screws are in place and tight.
(10) Replace any broken or missing barriers.(11) With the rollout unit still set aside, per-
form the following maintenance operations inside
the enclosure:
**WARNING**B o t h s o u r c e a n d l o a d t e r m i n a l s a r e p r o b a b l y s t i l l e n e r g i z e d . U s e i n s u l a t e d t o o l s a n d s a f e t y
p r o t e c t i v e e q u i p m e n t f o r t h i s w o r k . D o n o t r e m o v e a n y b a r r i e r s f r o m t h e e n c l o s u r e .
(a) Look for loose hardware on the enclosurebottom or beneath the frame. If any is found, trace
to source and correct problem or replace.
(b) Clean sta nd-off bus insulators.
(c) Remove oxide film from ter mina l cont actsif necessary.
(12) M anua l ly c lose and t r i p t he b reake r
mechanism according to instructions furnished for
the particular model.(13) Perform an operational test using a net-
work protector test kit.
(14) Conduct insulation resistance tests, di-
electric test and electrical operating test in accord-
ance with the man ufactur ers r ecommenda tions.
(15) Carefully replace the drawout unit in theenclosure. Make a final inspection to be sure no
control wiring has become snagged, and that no
plugs or connecting surfaces have been bent or dam-
aged.
2-8 . Aux i l ia ry sw i t chgear equ ipment .
Auxiliary equipment includes devices such as fuses,
capacitors, meters, relays, etc. This equipment
should be serviced along with the major switchgear
components, unless there is some indication that a
device is being heavily or improperly used, in which
case it should be inspected more often. Protective
relays and meters should be inspected and cali-brated on a scheduled basis. Critical service equip-
ment should have the protective relays checked at
every maintenance turn (annually or according to
ma nu facturer s recommen dat ions). Relays applied
to other general distribution circuits may be done
less frequently (see para 2-8h).
a. Fuses. Fuse maintenance is covered as a sepa-
rate category of electrical equipment (para 5-4d).
b. Capacitors.
power capacitor
The maintenance requirement on
installations is so small that its
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TM 5-683/NAVFAC MO-116/AFJMA N 32-1083
) INGs
BREAKER UNIT J COUPLING
Figure 2-8 . Typ ica l dr awou t ne twork pro tec tor and enc losure .
H o l e s Fo r
M o u n t i n g
Sc rew s
( Two OnEach Side
Figu re 29. Net work protect or rem ovable un it .
importance is often overlooked. The voltage of the
system at the capacitor location should be checked
at light load periods to determine if an overvoltage
condition exists . Any cha nges in circuit conn ections,
which may increase voltage levels, warrant a re-
check of operating conditions. The conductor sizes
should provide for not less than 135 percent of ca-
pacitor current at rated voltage and WA. As a gen-
eral rule, if the side of the capacitor unit casing is
operat ing at a tempera tur e above 55 degrees C (131
degrees F a temperature almost too hot for bare-
hand contact), then a more complete investigationof operating conditions should be made. The case
temperatures should never exceed 65 degrees C
(149 degrees F) under any conditions. Adequate
ventilation is therefore necessary to remove the
heat generated by continuous full-load duty. Re-
move any obstructions at ventilation openings in
capacitor h ousings to ensur e th at this ventilation is
maintained. A disconnected capacitor retains its
electrical charge for some time and may even retain
the full-line voltage across its terminals. Therefore
always discharge a capacitor before handling or
making connections. An insulat ion short circuitjumper may be used for this purpose; however, it
should only be applied with full knowledge of the
circuit, and with the use of appropriate protective
equipment. Power capacitors are generally provided
with individual fuses to protect the system in case
of a short circuit within the capacitor. In addition to
a faulty capacitor, a fuse may be blown by an abnor-
mal voltage surge. Check for blown fuses and re-
place them with a type recommended by the manu-
facturer. Do not remove fuses by hand until the
capacitor has been completely discharged. Clean the
case of a capacitor, the insu lating bush ings, and a ny
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TM 5-683/NAVFAC MO-1 16/AFJ MAN 32-1083
ARCQUENCHER
BLOWOUT
COIL
ARC
QUENCHERSUPPORTINGSCREWS
SCREWS FORMOVABLE
ARCING
CONTACT
LOCKING
PLATE
FLEXIBLECONNECTION
STOP PINFOR MOVABLE
ARCINGCONTACT
CONTACT
SUPPORT
CROSS BAR