SPECIFICATION FOR SUPPLY, ERECTION, TESTING AND COMMISSIONING OF 36 KV

OUTDOOR TYPE PORCELAIN CLAD VACUUM CIRCUIT BREAKER, 22 KV CURRENT

TRANSFORMER, 33 KV ISOLATOR, 33 KV LIGHTENING ARRESTOR, CONTROL & RELAY

PANEL AND CABLE TAKE OFF STRUCTURE

All the Works covered under this contract shall be executed as per this technical specification,

applicable drawings & standards and as per the instructions of Engineer – in- charge.

1.0 SCOPE:

1.1 This specification covers design, manufacture, Supply, erection, testing and commissioning of 1 no. of

36 KV outdoor type porcelain clad vacuum circuit breaker, 1 set of 22 KV current transformer along

with required isolators, lightening arrestors, control & relay panel and cable take off structure at

Marapalam 110/22-11 KV sub-station, Electricity Department, Puducherry

1.2 The objective of this specification is to form an OUTGOING 11 KV FEEDER with required vacuum

circuit breaker, Current Transformers, Isolators, Lightening arrestors, mounting structures in the

available bay and Control & Relay equipments in the available C & R panel at Marapalam 110/22-11

KV sub-station, Electricity Department, Puducherry. Though the equipments are going to serve for the

11 KV system voltage levels of them are so selected to have more creepage distance to avoid faults

due to creepers and to maintain uniformity with the existing feeders

1.3 SYSTEM DETAILS:

1.3.1 Power is fed from 400/230 KV Grid sub stations to the grid stations at 230/110 KV of Transmission,

which in turn feed 110/11 KV sub stations where it is stepped down to the primary distribution

voltage of 11 KV

1.4 SITE/ CLIMATE CONDITIONS:

1.4.1 The equipments and the work covered under this specification is of outdoor, very near to the sea shore

prone to saline effect and should be suitable for the prevailing climatic conditions enumerated below:-

Maximum ambient air temperature: : 50⁰C

Minimum Ambient air temperature : 18⁰ C

Maximum daily average ambient air temperature : 36⁰ C

Maximum humidity : 100 %

Maximum Wind pressure : 200 Kg/ sq. m

Average thunder storm days per annum : 50

Average annual rainfall : 1240 mm

Average no. of rainy days per annum : 60 days

Note: Climate may be moderately hot and humid tropical Conducive to rust and fungus growth. The climatic

conditions are also prone to wide variations in ambient conditions. Smoke Pollution is also present in the

atmosphere. Heavy lightning also occurs during September to December.

1.5 BILL OF MATERIALS

1.5.1 The equipment covered under this specification shall consist of:-

a) 36 KV, 1250 amps Porcelain clad Vacuum circuit breaker with CT

mounting structure

1 No.

b) 22 KV outdoor type oil cooled Current transformer 1 set

c) 33 KV 800 amps Isolator 2 sets

d) 33 KV post type insulator 9 Nos.

e) 2” IPS aluminum tubes, ACSR conductor & clamps required for inter

connecting LV bus, isolators, VCB, CT as required for completing the

work

1 set

f) Control cables for connecting VCB, CT & existing bus PT to Control &

Relay panel.

1 set

g) Earthing of the VCB, CT, Isolators, mounting structures with 2 nos. of

earth electrode using 50 mm MS rod and linking it with the existing earth

grid

1 set

h) Control, Protection and Metering scheme

Numerical combined over current and earth fault relay with CB failure

protection, solid state trip circuit supervision relay, high speed trip relay

Breaker control switch, indication bulbs, semaphore, control fuses, wiring

the C&R panel etc.

Tri vector meter, Ammeter, Power factor meter etc.

1 set

1.5 CODES AND STANDARDS:

1.5.1 Unless or otherwise specified elsewhere in this specification, products covered under this tender shall

conform to the latest revisions and amendments of standards issued by the Bureau of Indian Standards

(BIS) and International Electro-technical commission (IEC). Codes and standards to be followed are

listed at detailed specification of each of the equipment hereunder.

1.5.2 In case of imported equipments, standards of the country of origin shall be applicable if these

standards are equivalent or stringent than the applicable Indian standards.

1.5.3 The equipment shall also conform to the provisions of Indian electricity rules and other statutory

regulations currently in force in the country.

1.5.4 In case Indian standards are not available for any equipment, standards issued by IEC / BS/ IEEE or

equivalent agency shall be applicable.

1.5.5 In case of any contradiction between various referred standards / specifications / data sheet and

statutory regulations the following order of priority shall govern

a) Statutory regulations

b) Guaranteed technical particulars

c) Job specification

d) This specification

e) Codes and standards

1.6 The equipments offered shall conform in all respects to high standards of Engineering, design,

workmanship and latest revisions of relevant regulations/ standards/ rules at the time of offer except

where modified and/ or supplemented by this specification and shall be performing in continuous

operation for rated output under operating conditions of voltage & frequency variations as per statuary

limits governed by relevant Indian Standard and EA 2003 and its amendments in force. The offered

material shall be complete with all components necessary for their intended purpose. The design and

components shall be deemed to be within the scope of vendor's supply irrespective of whether those

are specifically brought out in this specification and/ or in the commercial order or not. Purchaser

shall have the right to reject any work or material which in his judgment is not in full accordance

therewith.

1.7 The contractor shall submit the Type test certificate of the offered equipments confirming to relevant

IS/ IEC of latest issue obtained from a Government Lab/ Recognized laboratory/ CPRI, Bangalore

along with the tender document. Detailed General arrangement drawings of the offered equipments

with dimension and statutory clearance required for its erection shall be furnished along with tender.

Routine test certificates in quadruplicate shall be furnished along with the supply of the equipments

1.8.1 TESTING & INSPECTION:

1.8.2 The inspection will be carried out by the PED at any stage of manufacture. The supplier shall grant

free access to PED’s representative at a reasonable time when the work is in progress. Inspection and

acceptance of any equipment under this specification by the PED shall not relieve the supplier of his

obligation of furnishing equipment in accordance with the specification and shall not prevent

subsequent rejection if the equipment is found to be defective.

1.8.3 The supplier shall keep PED informed in advance about the manufacturing programme so that

necessary arrangement can be made for inspection by the PED officials. The Department reserves the

right to insist for witnessing the acceptance/ routine testing of the bought out items. PED has rights to

inspect the supplier’s premises for each and every consignment for type & routine test.

1.8.4 Equipment either entirely or in part shall not be dispatched to site for erection until the Department

inspection officers have inspected, tested, satisfied about the compliance with the requirement of these

specifications/ unless the same is waived by the PED in writing.

1.8.5 Routine tests to be carried out on the equipment does not limited to the tests listed under the detailed

specification.

1.8.6 The scope of inspection, testing and commissioning shall include the conditions for statutory

inspection by the Electrical Inspector of C. E. A.

1.9 DOCUMENTATION & DRAWINGS.

1.9.1 The supplier shall submit following along with his tender for various items in the equipment and fully

assembled ring main unit in the required combination.

a) Schematic diagram.

b) General arrangement drawings

c) Illustrative literatures

d) Instruction manuals

e) Catalogues of spares recommended with drawing to indicate each items of spares

f) List of spares and special tools recommended by the supplier.

g) Copies of Type Test Certificates as per latest IS/IEC.

h) Drawings of equipments, relays, control wiring circuit, etc.

i) Drawings of foundation & mounting structures required the erection of the above equipments

along with dimensions.

1.9.2 All drawings shall conform to relevant International Standards Organization (ISO) specification. All

drawings shall be in ink and suitable for microfilming.

1.9.3 Five copies of printed and bound volumes of erection, operation and maintenance manuals in English

along with the copies of approved drawings and routine test reports etc. shall be supplied to the

consignee along with the supply of the equipments ordered. A soft copy of the all Technical details

and drawings shall be furnished in a CD.

1.10 Successful tenderer shall provide required earthing arrangement for each of the equipment along with

its detailed drawings for the above RMU to enable this Department for its provision. Required

connecting earth flats between equipments & earth electrodes and its terminal clamps are also under

the scope of this tender. Associated power cables (HT cable and their termination shall be provided

by the Department) and earth connectors shall be connected with the respective equipments/ positions.

1.11 ADDITIONAL TESTS: The Department reserves the right for carrying out any other tests of a

reasonable nature at the works of the supplier/ laboratory or at any other recognized laboratory/

research institute in addition to the tests listed at detailed specification at the cost of the PED to satisfy

that the equipment/ material complies with the intent of this specification.

1.12 PRE-COMMISSIONING TESTS: Before test commissioning of entire system, all erection work and

earthing work have to be completed in full. All the tightness of electrical connections from main bus

bar shall be thoroughly checked and all equipments shall be thoroughly cleaned.

a) The following pre- commissioning tests shall be conducted by the contractor.

i) All routine Megger test.

ii) Earth resistance test.

iii) Interlock function check.

b) The earth continuity conductor shall be tested for electrical continuity. The electrical

resistance of the same along with the Earthing lead but excluding any added resistance,

measured from the connection with earth electrode to any point in the earth continuity

conductor in the complete installation shall not exceed one ohm.

c) All the instruments required for carrying out the testing shall be arranged by the contractor.

d) All the test results shall be furnished to the Department.

e) The contractor shall carry out the erection of the required RMU at any other location if

Puducherry Electricity Department insists on.

1.13 TRAINING: The supplier shall give adequate training to at least 2 PED Engineers & staff at the site in

attending trouble shooting and maintenance works to the satisfaction of the Department.

1.14 WARRANTY PERIOD: The supplier shall be responsible to replace, free of cost, with no

transportation or insurance cost to the Purchaser, up to destination, the whole or any part of the

material which in normal and proper use proves to be defective in quality or workmanship, subject to

the condition that the defect is noticed within 18 months from the date of receipt of material in stores

or 12 months from the date of commissioning whichever is earlier. The consignee or any other officer

of Electricity Department, Puducherry actually using the material will give notice of each such defect

to the supplier. The replacement shall be effected by the supplier within a reasonable time, but not in

any case exceeding 30 days. The supplier shall also arrange to remove the defects within a reasonable

period but not exceeding 45 days from the date of issue of notice in respect thereof, failing which the

purchaser reserve the right to dispose of defective material in any manner considered fit by him

(Purchaser), at the sole risk and cost of the supplier. Any sale proceeds of the defective material after

meeting the expenses incurred on its custody, disposal handling etc., shall however be credited to the

supplier’s account and set off against any outstanding dues of the purchaser against the supplier. The

EMD and the security deposit shall be refunded only after the guarantee period is over.

1.15 DEVIATION: All deviations from this specification shall be separately listed under the requisite

schedules, in the absence of which, it will be presumed that all the provisions of the specification are

complied with by the bidder.

1.16 The VCB, CT, Isolator, control & relay equipments and other accessories offered shall comply with

the detailed specifications hereunder.

2.0 TECHNICAL SPECIFICATION FOR 36 KV OUTDOOR VACUUM CIRCUIT BREAKERS.

2.1 SCOPE:

2.1.1. This specification is intended to cover the supply, delivery, erection, testing & commissioning of 36

KV Outdoor Vacuum Circuit Breaker Complete with all materials and accessories for efficient and

trouble free operation.

2.1.2. The equipment shall conform in all respects to high standards of engineering, design & workmanship

and shall be capable of performing continuous commercial operation up to the Bidder's guarantee. The

offered equipment shall be complete with all components necessary for its effective and trouble free

operation along with associated equipments, interlocks, protection schemes etc. Such components

shall be deemed to be within the scope of works irrespective of whether those are specifically brought

out in this specification and/or in the work order or not.

2.2 STANDARDS:

2.2.1 The circuit breaker shall conform to the latest revisions with amendments available at the time of

testing of relevant standards, rules and codes. Some of which are listed herein for ready reference:-

2.2.2

Equipment meeting with the requirements of any other authoritative standards, which ensure equal or

better quality than the standard mentioned above shall also be acceptable. If the equipment offered by

the Bidder conforms to any other standard adopted and the specific Standards shall be clearly brought

out in relevant schedule.

2.3 DESIGN CRITERIA:

2.3.1. The 36 KV Outdoor VCBs shall be conforming to M-2 Class. The equipment will be used in high

voltage system having characteristics as listed in the specification. The equipment will be installed

outdoor in a hot, humid and tropical atmosphere. All equipment, accessories and wiring shall have

tropical protection, involving special treatment of metal and insulation against fungus, insects and

corrosion.

a. IS 13118/IEC 62271-100 Specification for HV Alternating current Circuit breakers

b. IS 3427/ IEC 62271-200 AC metal enclosed switchgear and control gear for rated

voltage above 1 KV and upto 52 KV

c. IS 10118-Part III Code of practice for selection, installation and maintenance

of switchgear and control gear.

d. IS 2165-1977 Phase to earth insulation co-ordination principles and rules

e. IS 3716-1976 Application guide for insulation co-ordination

2.3.2. The maximum temperature in any part of the equipment at specified rating shall not exceed the

permissible limits as stipulated in the relevant standards even at an ambient temperature of 50 ⁰C

2.3.3. The equipment shall be capable of withstanding the dynamic and thermal stresses of listed short

circuit current without any damage or deterioration.

2.3.4. The safety clearances of all live parts of the equipment shall be as per relevant standards.

2.4 CONSTRUCTIONAL FEATURE:

2.4.1. The circuit breaker shall be for outdoor installation, three pole vacuum type, having internal isolation

without any sequential interlock. The duty of the circuit breaker shall involve satisfactory interruption

of short circuit currents as listed in the specification.

2.4.2. The circuit breaker shall comprise three identical poles, complete with a gang operated mechanism for

specified duty. All these poles of circuit breaker shall be linked together electrically and mechanically

for specified duty.

2.4.3. The circuit breaker units shall be complete with operating mechanism and other accessories and

materials to ensure complete assembly and proper functioning. The following features should be

ensured.

a) Hinges of door shall be concealed type to avoid rusting and obstructive opening of the door.

b) The quality of welding shall be good and there should not be any lumps and splatters on the

panel.

c) All the connecting bus bar and current carrying parts shall be made of copper.

d) All the gaskets shall be of chemically treated neoprene.

e) Hole & Pin locking (Check nut) arrangement should also be provided while fixing the vacuum

interrupter at bottom side.

f) The vacuum interrupter should be housed in epoxy pole unit and make of Vacuum Interrupter

is required to be from BEL, CGL, SIEMENS, ABB or ALSTOM/AREVA.

2.5 BUS BAR, MAIN CONTACTS AND ARC QUENCHING CHAMBER:

2.5.1. The buses within the cubical shall be of high conductivity electrolyte grade copper. The Bus bar joints

shall be silver plated and bolted in such a manner that initial contact pressure around the square

headed high tensile bolt will remain substantially undiminished at all temperature up to rated full load

temperature. The Bus support and bushings shall be of epoxy resin cast type. All drop off from main

bus to VCB and VCB to bushing terminations shall be suitable for current rating of circuit breaker.

All the bus bar shall be sleeved with heat shrinkable sleeves of 33 KV voltage level (Insulated for a

service voltage of 33 KV) and bus bar shall be shrouded wherever possible. All the bus bar joints shall

be shrouded and where shrouding is not possible, it shall be taped with HV self-amalgamation tape.

The entire tap off bus bar connections inside panel and PT jumpers shall be sleeved with HT heat

shrinkable sleeves.

2.5.2. Special care shall be taken in the design of bus bar system to provide for thermal expansion and to

minimize the chances of bus fault. Bimetallic washers shall be provided at the joints of two different

metal surfaces.

2.5.3. The main contacts shall have adequate area and contact pressure for carrying rated continuous and

short time current without excessive heating liable to cause pitting and welding. The tips of the arcing

and main contacts shall be heavily silver plated (Min. 40 microns) or made of copper chromium alloy.

The contacts shall be adjustable to allow for wear, shall be easily replaceable and shall have minimum

movable parts and adjustments.

2.5.4. The arc quenching device shall be of robust construction and shall not require any critical, adjustment.

The devices shall be easily accessible and removable for access to the breaker contacts.

2.6 AUXILIARY CONTACTS:

2.6.1. Each breaker shall be provided with eight normally open & eight normally closed electrically separate

auxiliary contacts. These shall be in addition to those required for its own operation and indication.

2.6.2. The auxiliary contacts shall be convertible type so that normally open contacts can be converted into

normally close contact and vice versa at site.

2.6.3. The auxiliary contacts shall be rated 10A at 240V AC and 4A at 110 V DC.

2.7 INTERLOCK: All electrical and mechanical interlocks which are necessary for safe and satisfactory

operation of the circuit breaker shall be furnished.

2.8 INSULATOR:

2.8.1 Insulator shall be wet process porcelain, brown glazed and free from all blemishes. Metal parts and

hardware shall be hot dip galvanized.

2.8.2 Insulator shall have adequate mechanical strength and rigidity to withstand the duty involved.

2.8.3 When operated at rated voltage, there shall be no electrical discharge. Shielding rings, if necessary,

shall be provided.

2.8.4 Insulation shall be coordinated with basic impulse level of the system. The creepage distance shall

correspond to heavily polluted atmosphere.

2.8.5 The bushing shall not be subjected to direct point loading. They shall be provided with neck around

clamps for evenly distributed pressure.

2.8.6 The bushing shall be mounted using suitable clamps and gasket arrangement to provide required

degree of protection.

2.8.7 The bushing assembly shall be provided with lock nut and check nut which will be non-magnetic and

non-corrosive.

2.8.8 The provision shall be kept on roof bushing assembly to adopt arcing horn.

2.8.9 The lifting arrangement shall not cause any effective loss of creepage distance/ phase to earth

clearances as specified in the ISS/IEC.

2.9 OPERATING MECHANISM:

2.9.1 Operating mechanism shall be spring operated with anti pumping and trip free features, complete with

shunt trip coils. All three breaker poles shall operate simultaneously. Circuit breakers shall have

provision so as to be suitable for three phase auto reclosing. In case of spring closing mechanism, no

main spring of the mechanism shall be plated, powder coated or given any other treatment, so that

spring property is not lost. The motor shall be universal type suitable for 220/240V. Spring Charge

Indication Lamp shall be provided.

2.9.2 The mechanism shall be designed for electrical control from remote as well as local position. In

addition to this, local manual trip button shall be provided. Operation counter and mechanical ON-

OFF indicator shall be provided.

2.10 CONTROL CUBICLE:

2.10.1 A common control cubicle shall be furnished to house electrical, controls, monitoring devices and all

other accessories except those which must be located on individual poles. The cubicle shall be IP-55

of gasket weatherproof construction, fabricated from sheet steel minimum 3 mm thick.

2.10.2 The cubicle shall have front access door with lock and keys, and removable gland plate at the bottom

for owner's cable entry.

2.10.3 Thermostat controlled space heater, internal illumination lamp 3 pin 6 A socket with individual ON-

OFF switches shall be provided in the cubicle.

For local operation following shall be provided:

a) Local/ Remote selector switch.

b) Trip normal close control switches with pistol grip handle.

All electrical, mechanical connections between the control cubicles and individual poles shall be

furnished.

2.11 WIRING:

2.11.1 Wiring shall be complete in all respects to ensure proper functioning of the control, protection,

monitoring and interlocking schemes.

2.11.2 Wiring shall be done with flexible 650V grade, PVC insulated, switch board wires with 2.5 sq.mm

stranded copper conductor. Wiring between individual poles and control cubicle shall be routed

through G.I. conduits.

2.11.3 Each wire shall be identified at both ends with permanent markers bearing wire numbers as per wiring

diagram.

2.11.4 Wire termination shall be done with crimping type connectors with insulating sleeves. Wires shall not

be spliced between terminals.

2.11.5 All spare contacts of relays, push buttons, auxiliary switches etc. shall be wired up to terminal blocks

in the control cubicle.

2.12 TERMINAL BLOCKS: Terminal blocks shall be 650 V grade, box clamp type ELMEX 10 sq.mm or

approved equal. Not more than two wires shall be connected to any terminal. Spare terminals equal in

number to 20% of active terminals shall be furnished. Terminal blocks shall be located to allow easy

access. Wiring shall be so arranged that individual wires of an external cable can be connected to

consecutive terminals.

2.13 TYPE OF MOUNTING: The circuit breaker shall be suitable for mounting on fabricated galvanized

steel pedestal which shall be supplied along with the breakers. CT mounting bracket will also be

supplied along with the breaker and shall be galvanized.

2.14 TERMINAL CONNECTORS: 800 Amps Current rating terminal connectors of the circuit breakers

suitable for connecting to ACSR Panther and Dog Conductor shall be supplied along with the

breakers. Suitable earth connectors for earthing connections shall also be supplied with the circuit

breakers. The terminal connectors shall conform to relevant standard IS-5561.

2.15 FITTING AND ACCESSORIES:

Each circuit breaker shall be furnished complete with fittings and accessories as listed below:

a) Clamp type bimetallic/Aluminum Alloy terminal connectors suitable for ACSR Panther and

Dog Conductor suitable both for horizontal & vertical takeoff.

b) Two ground pads suitable for termination of 50 x 6 mm flats.

c) Complete mounting steel pedestal along with CT mounting bracket

d) Operating mechanism, double tripping coils and closing coil.

e) Auxiliary contacts and relays.

f) Local/ remote selector switch, trip normal close control pistol control switch.

g) Manual tripping devices with protective flap for VCB's only mechanical ON-OFF indicator.

h) Operation counters.

i) Weather proof outdoor type control cubicle and pole boxes. Set of switch fuse units for AC

and DC supply.

j) Space heater with thermostat and ON-OFF switch.

k) Cubicle illumination lamps with ON-OFF switch.

l) Pin 6A socket with ON-OFF switch.

m) Terminal blocks and internal wiring – lot, as required.

n) Set of prefabricated pipe, fittings, clamps, hardware, interconnecting wires/cables etc. for

connection between control cubicle and pole boxes as may be required to complete.

o) Interconnecting wires, GI conduits and accessories for connection between control cubicle and

pole boxes.

p) Other standard accessories which are not specifically mentioned but are required to be

supplied with breakers of similar type and rating for efficient and trouble free operation.

2.16 PAINTING & FINISHING: All interiors and exteriors of switchgear enclosure, breaker mechanism

etc shall be finished and painted to produce a neat, fire resistant and durable surface which would

prevent rusting and corrosion. Sheet metal component shall be pre-treated using 7 tank Phosphating

process consisting of de-greasing, acid pickling, de-rusting, Phosphating and passivation including

repeated rinsing in between. On completion of the passivation of the components, they shall be

preheated and then epoxy power coated or treated with one coat of primer & zinc chromate and

finished with two coats of light gray enamel paint of shade 631 of IS 5 and stoved to achieve excellent

anti-rusting and scratch resistant properties. The thickness of painting shall be around 60 microns.

2.17 TESTS:

2.17.1 TESTS BEFORE DESPATCH: The 36 KV circuit breakers and accessories shall be subjected to the

following tests as per relevant IS/IEC.

A) Routine tests on each unit as per relevant standards:

a) One minute power frequency voltage withstand dry test on main circuit.

b) Voltage withstand test on control & auxiliary circuits.

c) Measurement of the resistance of main circuit.

d) Mechanical operating test as per M-2 class.

e) Design and visual checks.

B) Type tests conducted on one unit of each rating as per relevant standards:

a) Dielectric tests.

i) Lightning Impulse Voltage Test.

ii) One Minute Power Frequency Test (Wet & Dry).

b) Short time withstands current and peak withstand current test.

c) Basic short circuit duties test.

d) Single phase short circuit test.

e) Mechanical Operation Test as per M-2 class.

f) Out of phase making & breaking test.

g) Capacitive current switching test.

i) Cable Charging Test.

ii) Single Capacitor Bank Current Switching Test.

h) Measurement of resistance of main circuit.

i) Temperature .rise test.

j) Environmental Tests.

k) IP-55 test (for cubical/control cabinet).

l) Any other type tests not specified above but covered as per amendment/latest edition of

relevant IS/IEC.

2.17.2 TYPE TESTS: The contractor must furnish type test reports before commencement of the works.

2.17.3 TEST ON BOUGHT OUT ITEMS: Tests are not required to be performed on bought out

equipments/items like motor, terminal connector, CTs, PTs, Relays, Meters etc. at the works of

manufacturer. Furnishing Test Certificate of these items from the original equipment manufacturers

shall be deemed to be satisfactory evidence. Inspection of the tests at Sub-contractors works will be

arranged by the contractor whenever required.

2.17.4 ROUTINE/ACCEPTANCE TESTS:

The following acceptance and routine tests shall be got conducted in presence of purchaser's

representative as per stipulation of the relevant standards on each unit.

a) One minute power frequency voltage withstand dry test on main circuit.

b) Voltage withstand test on control & auxiliary circuits.

c) Measurement of the resistance of main circuit.

d) Mechanical operating test as per M-2 class.

e) Design and visual checks

f) Any other test not specified above but covered as per amendment/latest edition of relevant

IS/IEC.

2.17.5 TOLERANCE ON TEST RESULTS:

As per relevant standards/ specification.

2.17.6 TESTS AT SITE:

The Department reserves the right to conduct all tests on 36 KV circuit breakers after arrival at site

and the contractor shall guarantee test certificate figures under actual service conditions.

2.17.7 PRE-COMMISSIONING TESTS: Following pre-commissioning tests shall be carried out:-

a) Visual inspection.

b) Cleaning

c) Testing of relays/ CTs/PTs.

d) Testing of current circuitry by primary injection

e) Testing of breaker by primary injection.

f) IR value.

g) Checking of various equipments viz. Ammeter, Voltmeter, Energy meter etc. and alarms/ flags/

trip circuit healthiness etc.

2.18 INSTALLATION & COMMISSIONING OF VACUUM CIRCUIT BREAKER.

2.18.1. Contractor should engage team of experienced Engineers & skilled staff for the purpose of Installation

& Commissioning of 33 KV Vacuum Circuit Breaker.

2.18.2. The following main activities are to be carried out by the supplier for installation & commissioning of

36 KV Vacuum Circuit Breaker:-

a) All civil works including foundation, foundation bolts, grouting related with erection of the

mounting structures and installation & commissioning of 36 KV Breaker.

b) Connection of Earthing of breaker from the earth mesh of the GSS) (The requisite MS Strip will

be provided by the contractor and end connection duly welded/ nut bolted with Mesh/Breaker

shall be provided).

c) Connection of control cables from breaker to Control & Relay panel.

d) Conductor & PG/ T-Clamps of required size to connect incoming & outgoing terminals of VCB to

main bus bar shall be arranged by the supplier.

2.19 PARAMETERS OF CIRCUIT BREAKERS:

1. Type Vacuum Circuit Breaker

2. Service Outdoor

3. Pole 3

4. Rated voltage 33/36 KV (Nominal/max.)

5. Rated frequency 50 Hz

6. System details

a) System voltage 11/12 KV (Nominal/ Max)

b) Phases 3

c) System neutral earthing Effectively grounded

d) Fault level 25 KA rms symmetrical

7. Insulation level

a) Impulse withstand voltage 170 KV (p)

b) Power frequency withstand voltage

for 1 min.

70 KV (rms)

8. Rated current

a) Continuous rated current 1250 A

b) Short time current for 3 sec. 25 KA

9. Rated breaking capacity

Symmetrical 25 KA

Asymmetrical

10. Rated making capacity 3 x 25 KA

11. Rated short time withstand current for 3 sec. 25 KA

12. Total break time 3 cycles

Total closing time 4 cycles

13. mounting Steel pedestal

14. Operating duty for gang operation O-0.3sec-CO-3min-CO

15. Operating mechanism Motor operated spring charged closing

mechanism or magnetic actuator.

16. a) Auxiliary voltage 110 V DC

b) Spring charging motor 230 V/ 415 V AC off

c) Heater/ Lamp/ socket 230 V DC

17. Terminal connector

a) Type Bimetallic/ Aluminum alloy type clamp

suitable for both horizontal/ vertical take

b) Suitable for ACSR conductor 10% Panther and 90 % Dog

3.0 TECHNICAL SPECIFICATION FOR 22 KV CURRENT TRANSFORMERS

3.1 GENERAL DESIGN FEATURES

3.1.1. The current transformers shall be of outdoor type single phase, 50Hz, oil immersed, self-cooled

suitable for operation in the climatic conditions specified. The current transformers shall be complete

in all respects. The 22KV C.T. shall be of Dead Tank design for all ratio CTs.

3.1.2. The core shall be high grade, non-ageing, silicon laminated steel of low hysteresis loss and high

permeability. The core material used in case of metering core shall be stated in the tender.

3.1.3. The current transformers shall be hermitically sealed to eliminate breathing and entering of air and

moisture in the tank. Each C.T. shall be provided with a pressure-relieving device to release abnormal

internal pressures.

3.1.4. Current transformer provided with nitrogen cushion for compensation of oil volume variation should

be provided with prismatic type oil sight window at suitable location so that the oil level is clearly

visible with naked eye to an observer standing at ground level. If metal bellow is used for the above

purpose, a ground glass window shall be provided to monitor the position of metal bellow.

3.1.5. For compensation of variation in volume of the oil due to temperature variation nitrogen cushion or

stainless steel bellows shall be used. Rubber diaphragms shall not be permitted for this purpose.

3.1.6. The core of current transformers to be used for metering and instrumentation shall have situation

factor low enough to avoid damage to the instruments in the event of maximum short circuit current.

3.1.7. The C.T. core to be used for protective relays shall be of accuracy class specified or appropriate class

suitable for back up, over current, earth fault, differential and bus bar protection.

3.1.8. As specified elsewhere in the tender specification, over and above the specified guarantee clause the

tenderer shall give assurance for trouble free and maintenance free performance for a period of 60

months from the date of commissioning during which period of 60 months from the date of

Commissioning the CTs shall be repaired / reconditioned / replaced free of cost, immediately in case

of any trouble. Therefore, the tender shall ensure that sealing of current transformer is properly

achieved. In this connection the arrangement provided by the tenderer at various locations including

the following ones shall be described supported by sectional drawings.

a) Between porcelain housing and metal tank.

b) Cover of the secondary terminal box.

3.1.9. Nuts and bolts (or screws used for fixation of interfacing porcelain bushings for taking out terminals)

shall be provided on flanges cemented to the bushing and not on the porcelain i.e. Flange type 22KV

bushing for CT. shall be provided.

3.1.10. For gasketed joints, wherever used, nitrite butyl rubber gaskets shall be used. The gaskets shall be

fitted in properly machined grove with adequate space for accommodating the gasket under

compression.

3.2. WINDING AND TERMINALS:

3.2.1 Ratio changing arrangement shall be provided on secondary winding for multi-ratio design, either a

number of identical secondary winding may be provided to achieve desired ratios by series, parallel

connection for the secondary winding or the secondary winding may be tapped. However, identical

secondaries for tapped secondary winding shall meet requirement as specified.

3.2.2 Primary and secondary windings shall be of electrolytic grade copper& shall have continuous thermal

rating as specified for all ratios. However, the tenderer may furnish the additional cost (if any)

adjustment for primary winding to be designed for extended primary current at 120%of rated.

3.2.3 The primary terminals shall be of standard size of 30mm dia x 80mmlength for all CTs rated up to

1200 Amps. For higher values of primary current, each primary terminal shall be made out of two

such rods of 30mm dia x 80mm length in parallel. The primary terminals shall be of heavily tinned

electrolytic grade copper. The maximum thickness of tinning shall be 15 microns.

3.2.4 The secondary terminals shall be brought out in a compartment for easy access. Secondary terminal

studs shall be provided with at least three nuts and adequate plain and spring washers for fixing the

leads. The studs, nuts and washers shall be of brass, duly nickel plated. The minimum outside

diameter of the studs shall be 6mm. The length of at least 15mm shall be available on the studs for

inserting the leads. The horizontal spacing between centers of the adjacent studs shall be atleast 1.5

times the outside circum dia of the units.

3.2.5 The current transformer shall be provided with suitable test tap for measurement of capacitance, tan

delta as well as partial discharges, in factory as well as at site. Provision shall be made of a screw on

cap for solid and secured earthing of the test tap connection when not in use. A suitable caution plate

shall be provided duly fixed on the cover of the secondary terminal box indicating the purpose of the

test tap and necessity of its solid earthing as per prescribed method, before energizing the C.T.

3.3 TERMINAL BOX OF CURRENT TRANSFORMER:

The exterior of the terminal box shall be hot dip galvanized. A cable box along with necessary glands

for receiving control cables suitable for mounting on bottom plate of the terminal box shall be

included in the scope of supply. A door with locking arrangement shall be provided on the front of the

terminal box. A duplicate set of secondary terminal connected through a suitable link shall be

provided in the terminal box to avoid undue pressure to internal leads and failure of studs.

3.4 TEMPERATURE RISE: The maximum temperature rise of the current transformer and its oil,

winding and external surface of the core and other parts shall be as specified in Table I of IS: 2705

(Part – I) 1992.

3.5 BUSHING AND INSULATORS:

3.5.1 The porcelain insulator used in manufacturing the bushings shall be homogenous free from

laminating, cavities and other flaws or imperfection that might affect the mechanical or dielectric

qualities. All bushings of identical ratings shall be interchangeable. The bushing shall confirm to the

latest edition of IS: 2099. The puncture strengths of the bushings shall be entirely free from external

and internal corona. The protected and total creepage distance of the bushings shall be suitable for

heavily polluted atmosphere i.e. the total creepage distance shall be 600mm (minimum).

3.5.2 C.T. the bushings shall be oil filled, free from oil leakage and shall be designed to prevent

accumulation of explosive gases and to provide adequate oil circulation to remove internal heat. Oil

used in the bushings shall be the same as that used in the C.T. Suitable means shall be provided to

accommodate conductor expansion and there should not be any undue stress on any part of the

equipment due to temperature changes. They shall be equipped with oil level indicator and means for

sampling and draining oil from the bushings.

3.5.3 Oil filled condenser type porcelain bushings conforming to the latest edition of IS: 2099 shall be used

for current transformers. The insulation of bushings shall be coordinated, with that of the instrument

transformer such that the flashover if any will occur only external to the current transformers. The

bushings should not cause radio interference when operating at rated voltage.

3.5.4 The quantity of insulating oil for the first filling of oil in each CT and the complete specifications of

the oil shall be stated in the tender. The oil shall confirm to the requirements of latest edition of IS:

335 subject to the requirements of the contractor's specification being fulfilled, the actual oil to be

used shall be at the desecration of the purchaser. The insulating oil required for first filling of current

transformer shall be included in offer. The manufacturer of CT shall measure the PPM value of oil

before filling inside the CT and shall keep record of the same.

3.6 TERMINAL CONNECTORS AND EARTHING TERMINALS: Bimetallic terminal connectors

suitable for ACSR 'PANTHER' conductor shall be supplied and they shall be suitable for both vertical

and horizontal connections of the transmission lines conductor or station bus-bar. Two grounding

terminals suitable for receiving grounding connectors shall be provided in the current transformers.

The terminal connectors shall be suitable for short time current of 25 kA for 3 sec.

3.7 GALVANIZING: All ferrous parts of current transformers including bolts, nuts etc., shall be hot dip

galvanized as per IS: 2629 – 1966 (latest edition)

3.8 TESTS AND TEST REPORTS: Reports of all type tests as stipulated in the latest edition of IS : 2705

for current transformer shall be submitted by the contractor.

3.9 PARAMETERS OF CIRCUIT BREAKERS:

1. CT ratio

600-300/1-1 amps

2. Core 1

2

3. Highest system voltage 24 KV

4. Purpose Core1 - Metering

Core2 - Protection

5. Rated burden (VA)

(lowest ratio)

(at minimum tap)

30 (core1)

30 (core2)

6. Class of accuracy

Core 1: 0.2

Core 2: 5P20

7. a) Rated accuracy/ limit factor 20 at minimum ratio for all

22 KV CTs

b) Instrument security factor 5 or less at minimum ratio

for all CTs

8. Minimum knee point voltage (at highest ratio) 600 V for core 1

600 V for core 2

9. Exciting current at knee point voltage.

As per IS 2705-1992

10. Resistance of secondary winding

As per IS 2705-1992

11. Basic insulation level KV (peak)

125

12. Power frequency voltage KV(rms)

50

13. Short time withstand current

25 KA for 3 secs

14. Minimum creepage distance

600 mm

4.0 TECHNICAL SPECIFICATION FOR 33 KV ISOLATORS WITH EARTH SWITCH:

4.1.1 33 KV isolators shall be three phase, out door type, with double break central pole rotating

arrangement with 800A continuous current rating. Earthing blades shall be capable to discharge the

trapped charge of the line. Isolator main switch shall be required to make or break the line charging

current when no significant change in voltage occurs across the isolating distance on account of make

or break. Other details shall be as per Guaranteed Technical parameters attached. Isolators shall

conform to IS-9921 amended up to date. All isolators shall have a short time rating of 25 KA for 3

second. The contacts and blades of the isolators shall be of electrolytic grade copper. The fasteners

(nut-bolts) used for current carrying parts shall be of nonmagnetic stainless steel. Spacing between

phases for all isolators shall be of 1000mm. Further the current density for copper current carrying

parts shall not be more than 1.6 Amp /mm. sq in solid conductor and 2 Amp/sq. mm. in hollow tubes.

4.1.2 Isolators shall have built-in mechanical inter lock between the main and earth blades so that the

closing of the main blade is not possible without opening the earth blade and closing of the earth blade

will not be possible without opening the main blade.

4.2 OPERATING MECHANISM: Manual operating mechanism gang operated through Hand operated

lever shall be provided for main switch and earth switch separately. The operating mechanism shall

provide quick, simple and effective operation. The design shall be such that one man shall be able to

operate the isolator without undue effort. The operating mechanism shall be suitable to hold the main

switch or earth switch in closed or opened position to prevent operation by gravity, wind, short circuit,

seismic acceleration, vibration, shock, accidental touching etc.

4.3 PADLOCKING DEVICE: The isolator and earthing switch shall be provided with padlocking device

to permit locking of the isolator and earthing switch in both fully open and fully closed positions.

4.4 EARTHING: Flexible branded copper connections shall be provided between rotating earth blades

and the frame which shall have a cross section of at least 50 Sq. mm and shall be tinned or suitably

treated against oxidation. The frame of each disconnect and earthing switch shall be provided with

two reliable earthing terminals for connection to the purchaser's earthing conductor/flat so also

clamping screw suitable for carrying specified short time current. Flexible ground connectors shall be

provided for connecting operating handle to the earthing flat. The diameter of clamping screw shall be

at least 12 mm. The connecting point shall be marked with earth symbol.

4.5 MOVING BLADES: Contact surface of moving blades and associated connectors/ contacts and

terminal pads shall be heavily silver plated to at least 15 microns thick. The surface shall be wiped

during closing and opening operations to remove any film, oxide coating etc. Wiping action shall not

cause scouring or abrasion of surfaces. Material of Earthing blades & contacts shall be the same as

those of the main moving blades and contacts respectively. Cross-sectional area of the Earthing blades

and contacts shall not be less than 50% of corresponding area of main moving blades and contacts.

4.6 BEARINGS: All the friction locations and rotating parts shall be provided with two nos. of bearings

of at least 75 mm ID. 50 mm clear spacing between the bearings shall be provided. The housing for

bearings shall be made of gravity dia cast metal with smooth surface and suitably machined for

seating the bearings. The bearings bushes, joints, springs etc. shall be so designed that no lubrication

shall be required during the service.

4.7 TANDEM PIPE: Tandem pipe shall be of at least 25 mm ID and class B Mild Steel galvanized. One

single tandem pipe shall be used for phase coupling of double break isolators. Base plate of rotating

insulators for connection of tandem pipe shall be made out of one piece of at least 6 mm thick MS

plate. Bolt and shackle device shall be used to connect tandem pipe to the base plate. Whenever

unavoidable sliding clamps are to be used, these clamps shall be made out of at least 6 mm thick MS

flat with four nos. of nuts and bolts. A grub screw shall be provided for securing connection on

tandem pipes.

4.8 DOWN PIPE: 50 mm ID, class B, Mild steel galvanized single piece pipe shall be provided for

operating disconnects. The pipe shall be terminated into a suitable swivel type joint between the

tandem pipe driving mechanism and the operating mechanism if required to take care of marginal

angular misalignment at site.

4.9 INSULATORS:

4.9.1 All outdoor type Porcelain insulators shall have a creepage distance of 25mm/kV (ie 900mm). The

insulators shall be of outdoor post type conforming to IS 2544. All insulators shall have a rated

voltage not less than 24 kV and rated current of 2000 Amps.

4.9.2 Post type insulators with 76 mm PCD shall only be provided. Pin type or polycone insulator shall not

be acceptable.

4.9.3 The insulators shall be provided with a completely galvanized steel base designed for mounting on the

support. The base and mounting arrangement shall be such that the insulator shall be rigid and self-

standing. Cap provided on top of the insulator shall be of high grade cast iron/malleable steel casting

or aluminum alloy. It shall be machine faced and hot dip galvanized in case of first two options. The

cap shall have four nos. of tapped holes with PCD same of that of insulator base. The holes shall be

suitable for bolts with threads having anticorrosive protection. The effective depth of threads shall be

adequate.

4.9.4 The insulator shall be made of homogeneous and vitreous porcelain of high mechanical and dielectric

strength. It shall have sufficient mechanical strength to sustain electrical and mechanical loading on

account of wind load, short circuit stresses etc. Glazing of the porcelain shall be of uniform brown or

dark brown colour with a smooth surface arranged to shed away rain water. The porcelain shall be free

from lamination and other flaws or imperfections that might affect the mechanical or dielectric

quality. It shall be thoroughly vitrified, tough and impervious to moisture.

4.9.5 The porcelain and metal parts shall be assembled in such a manner and with such material that any

thermal differential expansion between the metal and porcelain through the range of temperature

specified in this specification shall not loosen the parts or create undue internal stresses which may

affect the mechanical or electrical strength or rigidity. The assembly shall not have excessive

concentration of electrical stresses in any section or across leakage surfaces. The cement used shall

not give rise to chemical reaction with metal fittings. The insulator shall be suitable for water washing

by rain or artificial means in service condition.

4.9.6 The insulator unit shall be assembled in a suitable jig to ensure correct Positioning of the top and

bottom metal fittings relative to one another. The faces of the metal fittings shall be parallel and at

right angle to the axis of the insulator and corresponding holes in the top and bottom metal fittings

shall be in a vertical plane containing the axis of the insulator.

4.10 It shall be the sole responsibility of the supplier to carry out thorough inspection and quality checks on

the insulators at the insulator supplier's works, before offering the insulators for purchaser's

inspection. Other details shall be as per Guaranteed Technical Parameter listed below.

4.11 GUARANTEED PARAMETERS OF 33 KV ISOLATOR:

1. Type

: Outdoor double break

2. Rated current at 50 °C : 1250 amps

3. Rated short time withstand current of isolator & earth

switch

: 25 KA for 3 Sec.

4. Operating mechanism of isolator & earth switch : Manual operation

5.0 TECHNICAL SPECIFICATION FOR CONTROL, PROTECTION AND METERING SCHEME

5.1 Control & Protection scheme for the 11 KV feeder shall be through Numerical combined Over

current, Short circuit and Earth fault relay with instantaneous highest stage built in circuit breaker

failure protection.

5.2 The protection scheme shall be supported by:-

a. Solid state trip circuit supervision relay with post and pre-close supervision.

b. High speed trip relay with manual reset facility.

5.3 Following accessories required wiring, indication and operation of the control equipments shall be in

the scope of supply and erection of this tender.

a. CT/ PT Terminal blocks of the feeder.

b. Breaker control switch suitable for the logic

c. Semaphore

d. Required indication bulbs, control fuses, MCBs etc.,

e. Required wiring within the C&R panel using 2.5 sq. mm PVC copper wires as per IS code of

practice for panel wiring.

5.4 Required quantity of supply & laying of following sizes of armoured copper control cable including

termination at both ends.

a. 3c 2.5 sq. mm from AC distribution board to VCB.

b. 12c 2.5 sq. mm from C&R panel to VCB.

c. 12c 2.5 sq. mm from C&R panel to CT junction box.

d. 12c 2.5 sq. mm from C&R panel to VCB.

e. 3c 2.5 sq. mm from DC distribution board to C&R panel.

5.5 Above equipments accessories & control cables/ wires shall be erected/ fixed in the available reserve

C&R panel at the control room of the Marapalam 110/22-11 KV SS.

5.6 Required modification/ fabrication for fixing the equipments in the available C&R panel shall in the

scope of the tenderer. Special care shall be taken to avoid any disturbances to the existing feeders at

the time of modification of the panel, fixing of equipments and wiring the control panel. Special care

shall also be taken at the time of testing the VCB, CT also.

5.7 Control cables shall be routed from the VCB, CT to the control & relay panel through the existing

cable duct.

5.8 Metering shall be complete with following equipments and accessories:

Digital Tri-vector meter with complete wiring. - 1 No.

Digital Ammeter - 3 Nos.

Digital Power factor meter -1 No.

Provision for remote metering, controlling and indication in future and shall compatible with SCADA.

Sd/-

SUPERINTENDING ENGINEER-II