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1.0 SCOPE

1.1 This specification covers the design, material, construction features, manufacture,

inspection and testing at the Vendors / his SUB-Vendors Works, delivery to site and

performance testing of metal-enclosed Medium Voltage Switchgear of voltage notexceeding 1100 V AC.

2.0 CODES & STANDARDS

2.1 The design, construction, manufacture and performance of equipment shall conform to

latest applicable standards and comply with all currently applicable statutes, regulations

and safety codes in the locality where the equipment will be installed. Nothing in this

specification shall be construed to relieve the VENDOR of this responsibility.

2.2 Equipment shall conform to the latest applicable Standards as mentioned in Data Sheet

A2. In case of conflict between the Standards and this specification, the requirements of

this specification shall govern.

3.0 SHEET METAL WORK

3.1 The switchgear frame shall be fabricated using 1.6mm thick cold rolled mild steel plate

as per general industry standard.

3.2 Hinged doors shall be fabricated using sheet steel of thickness not less than 2 mm cold

rolled and fixed covers using sheet steel not less than 1.6 mm cold rolled, smoothly

finished levelled and free from flaws. Mounting plates shall be fabricated from 3.15mm

thick cold rolled DD sheet steel.

3.3 All panel edges and door edges shall be reinforced against distortion by rolling, bending

or by the addition of welded reinforcement members.

3.4 Cut outs shall be true in shape and devoid of sharp edges.

3.5 The complete structure shall be rigid, self-supporting, and free from vibration, twists and

bends.

4.0 PAINTING

4.1 All sheet steelwork shall be phosphated in accordance with the following procedure and

in accordance with applicable standards mentioned in Data Sheet-A2.

4.2 Oil, grease, dirt and swarf shall be thoroughly removed by emulsion cleaning.

4.3 Rust and scale shall be removed by pickling with dilute acid followed by washing with

running water, rinsing with slightly alkaline hot water and drying.

4.4 After phosphating, thorough rinsing shall be carried out with clean water, followed by

final rinsing with dilute dichromatic solution and oven drying.

4.5 The phosphate coating shall be sealed by the application of two coats of ready mixed,

stoving type zinc chromate primer. The first coat may be flash dried while the second

coat shall be stoved.

4.6 After application of the primer, two coats of finishing synthetic enamel paint shall be

applied, with each coat followed by stoving. The second finishing coat for the external of

panels shall be applied after completion of tests.

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4.7 Each coat of primer and finishing paint film on steel shall not be less than 100 microns,

and shall not be more than 150 microns thickness.

4.8 The final finished thickness of paint film on steel shall not be less than 100 microns, and

shall not be more than 150 microns.4.9 Finished painted appearance of equipment shall present an aesthetically pleasing

appearance, free from dents and uneven surfaces.

5.0 CONSTRUCTIONAL FEATURES

5.1 Switchgear shall be:

a) Of the metal clad, indoor, floor mounted modular typeb) Made up of the requisite vertical sectionsc) Of dust and vermin proof constructiond) Provided with a degree of enclosure protection grade of IP 52.e) Easily extendable on both sides by the addition of vertical sections after removing

the end covers

f) Provided with a metal sill frame made of structural steel channel section properlydrilled for mounting the Switchgear along with necessary mounting hardware.

Hardware shall be zinc plated and passivated.

g) Provided with name plates on the front and rear indicating the switchgeardesignation

h) Provided with cable entry facilities at top with thick removable gland plates ofthickness as per general industry standard on POWER panels with necessary cableglands. These plates shall be non-magnetic.

i) Of uniform height of not more than 2450 mmj) Of single front execution as specified in Data Sheet-Ak) Provided with neoprene gaskets all round the perimeter of adjacent panels, panel

and base frame, removable covers and doors

l) Provided with busbars running at the top or bottom, as required, all along the lengthof the switchgear in a separate sheet steel enclosure.

5.2 Operating devices shall be provided only at the front of the switchgear. No equipment

requiring manual operation shall be located at less than 250mm above ground level.

5.3 The switchgear shall be divided into distinct vertical sections each comprising:

a) A completely metal enclosed busbar compartment running horizontally.b) Individual feeder modules arranged in multi-tier formation. It is essential that the

modules are integral multiplies of the basic unit size to provide for flexibility in

changes, if any, at site.

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c) Enclosed vertical busbars serving all modules in the vertical section. For safetyisolation of the vertical bus bars, insulating barrier with cut-outs shall be provided to

allow the power stab contacts to engage with vertical busbars.

d) A vertical cable alley covering the entire height. The cable alley shall be 500 mmwide for circuit breaker controlled modules.e) Separation barrier between Main bus bar auxiliary Power & control buses as

required shall be located to enable easy identification, maintenance and segregation

from the main power buses. Tap-off connections from these buses shall be arranged

separately for each vertical section.

5.4 Each vertical section shall be equipped with space heaters, which may be located in the

cable alley.

5.5 One metal sheet shall be provided between two adjacent vertical sections running to the

full height of the switchgear except for the horizontal busbar compartment. However,

each shipping section shall have metal sheets at both ends.

5.6 All equipment associated with a single circuit shall be housed in a separate module

compartment of the vertical section. The compartment shall be sheet steel enclosed on all

sides and the rear, with rubber grommets provided on the cable alley side for power and

control cable entry. The front of the compartment shall be provided with a hinged door.

Components mounting details and panel fabrication details shall be submitted by

VENDOR for PURCHASERs approval.

5.7 For draw-out type modules, only the handles of control and selector switches, push

buttons, knobs & cut-outs for lamps and meters shall be arranged on the front doors of

the respective compartments to permit operation without opening the door. On circuit

breaker controlled circuits, protective relays shall be mounted on the front door of the

compartment. All other equipment pertaining to a circuit shall be mounted on the

withdrawable chassis. All cut-outs shall be provided with gaskets for dust proofing.

5.8 Current transformers shall not be directly mounted on the buses. Current transformers on

circuit breaker controlled circuits shall be mounted on the fixed portion of the

compartment.

5.9 In breaker compartments, external cable connections shall be carried out in separate

cable compartments for power and control cables.

5.10 After isolation of the power and control connections of a circuit, it shall be possible to

safely carry out maintenance in a compartment with the busbars & adjacent circuits live.

5.11 The withdrawable chassis shall move on suitable guides and on suitable plated steel or

stainless steel rollers or balls to facilitate easy and smooth withdrawal.

5.12 Cable alleys shall be provided with suitable hinged doors. It shall be possible to safely

carry out maintenance work on cable connections to any one circuit with the busbars and

adjacent circuits live. Adequate number of slotted cable support arms shall be provided

for clearing the cables.

5.13 Rear of single front switchgear shall be provided with removable covers. It shall be

possible for one person to remove and fix the removable panel.

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5.14 All doors shall be provided with concealed type hinges and captive screws.

5.15 The withdrawable chassis housing circuit breakers shall be of the fully draw out type.

5.16 The withdrawable chassis housing feeder control equipment not incorporating circuit

breakers/common control transformers of big size shall be of fixed type

5.16.1 Fixed Type Withdrawable ChassisIn this type of construction, all power connections to the equipment mounted on the

withdrawable chassis shall be of the bolted type. All control circuit connections to

equipment mounted on the withdrawable chassis shall be carried out through

conventional terminal blocks mounted in the respective chassis. It shall be possible to

draw out the chassis after unbolting/unscrewing all the power and control circuit

connections to the equipment mounted on the withdrawable chassis.

5.17 Interchangeability

5.17.1 All identical equipment and corresponding parts including chassis of draw out modulesof the same size and rating shall be interchangeable, without having to carryout

modifications. For trouble free interchangeability, the draw out arrangements shall be

designed such that normal dimensional variations are taken care of by self-aligning

feature of the modules.

5.17.2 Components and equipment of identical rating which are not fully interchangeable are

liable for rejection. VENDOR shall replace all such equipment by interchangeable

equipment at his cost.

5.18 The draw-out contacts shall be only between copper/copper alloy/aluminium faces,

which are silver or tinplated. The contact design shall be such that there should be no

arcing/deformation under the associated peak short-circuit current to be carried.

5.19 Switchgear shall be designed in such a way that all component equipment and bus-bars

operate satisfactorily without exceeding their respective maximum permissible rise in

temperature under ambient temperature conditions prevailing within the switchgear

cubicle, with reference ambient temperature outside the switchgear cubicles as specified

in Data Sheet-A1.

5.20 Provision of ventilating louvers is considered undesirable. If ventilating louvers are

considered essential by the VENDOR, these may be provided. However, all ventilating

louvers shall be provided with fine-screened brass or GI meshes to prevent entry of

vermin and dust.

6.0 MODULE TYPES

6.1 The various types of modules indicating the control requirements of each type are

detailed in the enclosed Single line diagram.

6.2 Physical size of compartment for each type of control and current rating shall be so

chosen that all the basic and additional equipment can be housed in the compartment. No

equipment/devices associated with any particular circuit shall be permitted to be

mounted in any other circuit module.

7.0 MAIN & AUXILIARY BUSES

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Main Buses & Taps

7.1 Switchgear shall be provided with three phases or three phase and neutral busbars as

specified in Data Sheets.

7.2 Busbars shall be of uniform cross section throughout the length of the switchgear, and upto the terminals of the incoming feeder circuit breaker/ switch.

7.3 The busbars shall be made of high conductivity copper or aluminium alloy of E91E

grade as specified in Data Sheets.

7.4 Busbars shall be provided with at least the minimum clearances in air as per applicable

standards for a 500V, 3 phase system.

7.5 All bus-bars, bus-taps shall be insulated with close fitting sleeve of hard, smooth, dustand dirt free plastic insulation of high dielectric strength (450 V/mil) to provide a

permanent high dielectric non-ageing and non-tracking protection; impervious to water,

tropical conditions and fungi. The insulation shall be non-inflammable and self-extinguishing and in fast colours to indicate phases. The joints shall be insulated in such

a way as to provide for accessibility of contact bolts for maintenance. Joints shall be

covered with removable moulded shrouds made out of fiber glass reinforced polyester.

The dielectric strength and properties shall hold good for the temperature range of 0oC to

90oC. If the insulating sleeve is not coloured but black, busbars shall be colour-coded

with coloured bands at suitable intervals.

7.6 Busbars shall be adequately supported and braced to withstand the stresses due to the

specified short circuit currents for the associated switchgear. Busbar supports shall be

made of Hylam sheets, glass reinforced moulded plastic material, Permali wood or cast

resin.

7.7 Separate supports shall be provided for each phase of the busbars. If a common support

is provided for all three phases, anti-tracking barriers shall be incorporated.

7.8 Busbar joints shall be complete with high tensile steel bolts and Belleville washers and

nuts. Busbars shall be thoroughly cleaned at the joint locations and suitable contact

grease shall be applied just before making a joint.

7.9 Auxiliary BusesAuxiliary buses for control power supply, space heater power supply or any other

specified service shall be provided. These buses shall be insulated, adequately supported

and sized to suit specific requirements. The material of control power supply buses shall

be electrolytic copper. The material for space heater power supply buses shall be same

as that for the main power buses. Auxiliary busbars and necessary connections to the

associated circuits shall be in the VENDORS scope.

8.0 CIRCUIT BREAKERS

8.1 Circuit breakers shall be provided with:

8.1.1 The air break draw out type, mounted along with its operating mechanism on a wheeled

carriage moving on guides, designed to align correctly and allow easy movements.

8.1.2 The shunt and/or series trip type as specified in Data Sheet-A1

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8.1.3 An operating mechanism of the type specified in Data Sheet-A1

8.1.4 Mechanically operated targets to show Open, Closed, Service and Test positions

of the circuit breaker

8.1.5 Mechanically operated, red trip push button, shrouded to prevent accidental operation

8.1.6 Locking facilities in the Service, Test, and Isolated, positions. In test position, the

breaker will be tested without energising the power circuits. The breaker shall remain

fully housed inside the compartment in the test position.

8.1.7 6 N/O and 6 N/C potential free auxiliary switch contacts, rated for 6A at 240V AC and

1A (inductive breaking at 220V DC).

8.1.8 Red, Green and Amber indicating lamps to show Closed, Open, and Auto-tripconditions of the circuit breaker when breaker operation is controlled by a control

switch.

8.1.9 Circuit breakers shall be provided with in-built microprocessor based over load, shortcircuit and earth fault releases with adjustable time delay settings.

8.2 Circuit breakers shall be provided with the following interlocks:

8.2.1 It shall not be possible to plug-in a closed circuit breaker, or to draw out a circuit breaker

in the closed position.

8.2.2 It shall not be possible to operate a circuit breaker unless it is in the fully plugged-in, test,

or fully isolated position.

8.3 Circuit breaker closing and trip coils shall be rated for satisfactory operation on a control

supply system indicated in Data Sheet-A1.

8.4 Whenever specified in Data Sheet-A1, breakers shall be provided with castle key

interlocking device to prevent paralleling of two breakers.

8.5 Closing and trip coil shall operate satisfactorily under the following conditions of supply

voltage variation:

8.5.1 Closing coils - 85% to 110% of rated voltage

8.5.2 Trip coils - 50% to 110% of rated voltage

8.6 In addition to the adjustable current setting range specified in the Data Sheet, short

circuit releases shall be provided with at least four adjustable time delay settings. If it is

not possible to provide the specified adjustable current setting range for the short circuitreleases, shunt trip circuit breakers shall be offered as indicated in Data Sheet - B by the

VENDOR.

8.6.1 Each of the foregoing releases shall be provided with a single pole, double throw, and

potential free alarm contact rated for 0.5A, 220V DC.

8.7 Operating Mechanism

8.7.1 Circuit breaker shall be provided with a manual operating mechanism or power operated

mechanism as specified in Data Sheet-A1.

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8.7.2 Manually operated mechanism shall be of the spring charging stored energy type, unless

otherwise specified in Data Sheet-A1.

8.7.3 Power operated mechanism shall be of the motor wound spring charging stored energy

type.8.7.4 The closing action of the circuit breaker shall charge the tripping spring ready for

tripping.

8.7.5 Speed of closing of contacts shall be independent of the speed with which the handle is

operated.

8.7.6 All stored energy mechanisms shall be provided with mechanical indicators to show the

Charged and Discharged conditions of the spring.

8.7.7 Circuit breakers provided with stored energy operating mechanisms shall be provided

with the following interlocks:

a) The circuit breaker shall not close unless the spring is fully charged.b) Shocks, vibrations, or failure of springs shall not operate the breaker or prevent

intended tripping.

8.7.8 Power operated mechanisms shall be:

a) Provided with a universal motor suitable for operation on AC and DC controlsupplies specified in Data Sheet-A1 with voltage variation from 85% to 110% rated

voltage.

b) Designed to enable a continuous sequence of closing and opening operation as long

as power is available and at least one opening operation on power supply failure.

c) Provided with emergency manual charging facilitiesd) Provided with facilities for remote panel closing and opening operations whenever

specified in Data Sheets as per breaker module designation and respective enclosed

control scheme drawing.

8.7.9 Spring charging time for power operated mechanism shall not exceed 15 seconds.

8.7.10 Power operating mechanisms shall be provided with the following additional features:a) Closing of the circuit breaker shall automatically initiate recharging of the spring

ready for the next closing stroke

b) The motor shall be mechanically de-coupled as soon as the emergency manualcharging handle is coupled

c) The circuit breaker mechanism shall make one complete closing operation once thecontrol switch has been operated and the first device in the control scheme has

responded even though the control switch is released before the closing operation is

complete provided there is no counter trip impulse.

d) Closing controls shall be so arranged that only one closing operation of the circuitbreaker shall result from each close initiating impulse, even if the breaker trips while

the initiating device is held in the Close position. An electrical anti-pumping relay

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shall be provided on the circuit breaker chassis for this purpose, incorporated in the

circuit breaker.

8.8 Protection Co-ordination:

It shall be the responsibility of the VENDOR to fully co-ordinate the overload and shortcircuit tripping of the circuit breakers with the upstream and downstream circuit

breakers/motor starters, to provide satisfactory discrimination.

9.0 MOULDED CASE CIRCUIT BREAKERS

9.1 Moulded case circuit breakers (MCCBs) shall be provided when called for in Data Sheet-

A1, for use in lieu of switch fuse units. The MCCBs shall conform to the latest

applicable standards.

9.2 MCCBs in AC circuits shall be of triple pole construction arranged for simultaneous 3pole manual closing and opening and for automatic instantaneous tripping on short

circuit. If indicated in Data Sheet-A1, power closing device for remote operation may beprovided. Operating mechanism shall be quick-make, quick-break and trip-free type.

The ON, OFF & TRIP positions of the MCCB shall be clearly indicated and visible to

the operator when mounted as in service. Front of board operating handle shall be

provided.

9.3 MCCBs shall be capable of withstanding the thermal stresses caused by overloads and

the mechanical stress caused by the peak short circuit current of value associated with the

switchgear rating. The maximum tripping time under short circuit shall not exceed 20

milliseconds.

9.4 The instantaneous short circuit release shall be so chosen by the VENDOR as to operate

at a current in excess of the peak transformer inrush current and a range of settings shallbe provided for the PURCHASERs selection.

9.5 MCCB terminals shall be shrouded and designed to receive cable lugs for cable sizes

relevant to circuit ratings.

10.0 MINIATURE CIRCUIT BREAKERS

10.1 Miniature circuit breakers for use on cubicle space heater control circuits shall comply

with the requirements of applicable standards, unless otherwise mentioned in Data Sheet-

A1.

11.0 EARTH LEAKAGE CIRCUIT BREAKERS

11.1 Earth leakage breakers for use on cubicle space heater control circuits shall comply with

the requirements of applicable standards, unless otherwise mentioned in Data Sheet-A1.

12.0 RCBO (With Overload and Short Circuit protection)

12.1 RCBO breakers for use on VT secondary for overload and short circuit protection shall

comply with the requirements of applicable standards, unless otherwise mentioned in

Data Sheet-A1.

13.0 CURRENT TRANSFORMERS

13.1. Current transformers shall be of the cast resin dry type.

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13.2. Current transformer shall have a short time current withstand rating equal to the shorttime current withstand rating of the associated switchgear for one second for breaker

feeders. CTs on feeders with fuse shall have withstand capacity equal to let through

fault current of associated fuse.

13.3. The minimum performance requirements of current transformers shall be as per thesingle line diagram enclosed.

13.4. Notwithstanding the above clause 11.3, it shall be the Vendors responsibility to co-ordinate the current transformer burden with the requirements of relays, instruments and

leads associated with that particular current transformer.

13.5. Test links shall be provided in both secondary leads of the CTs to easily carry outcurrent and phase angle measurement tests.

13.6. All current transformers shall be earthed through a separate earth link on the terminalblock to permit easy measurement of the current transformer insulation resistance.

14.0 VOLTAGE TRANSFORMERS

14.1 Voltage transformers shall be of cast resin dry type.14.2 The minimum performance requirements of voltage transformers shall be as per the

single line diagram enclosed.

14.3 All secondary windings of voltage transformers including open delta windings shall berated for 110 V/ 3 per phase.

14.4 Voltage transformer shall have a continuous over voltage factor of 1.2 and short timeover voltage factor as follows :

1.5 for 30 seconds in case of effectively earthed system

1.9 for 8 hours in case of non-effectively earthed system

14.5 Voltage transformers shall be complete with suitable rated primary and secondaryMCBs. The rupturing capacity rating of the associated switchgear shall be brought down

to the capacity of MCB by use of fault limiting devices mounted close to the bus.

14.6 It shall be possible to replace voltage transformers without having to de-energise themain bus bars.

14.7 The terminals of V.T. secondary and tertiary windings, which are required to beconnected to earth, shall be earthed by an isolating link without fuse.

15.0 INDICATING INSTRUMENTS & METERS

15.1 Electrical indicating instruments shall be of minimum 96mm square size, 90 degree scaledeflection with a class of accuracy of 0.5/1.0 as applicable, suitable for flush mounting.

15.2 Indicating instruments shall have provision for zero adjustment from outside the cover.15.3 Instrument dials shall be parallex free with black numerals on a white background dial.15.4 Watt-hour metes shall be of the direct reading electrodynamometer type complete with

cyclometer type registering dials and reverse running stop.

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16.0 INDICATING LAMPS

16.1 Indicating lamp shall be:* Of the multiple LED type and of low watt consumption

* Provided with step-down transformer

* Provided with translucent lamp covers of colours Red, Green and Amber as

Indicated in the control wiring diagrams.

16.2 Bulbs and lenses shall be easily replaceable from the front17.0 CONTROL & SELECTOR SWITCHES

17.1 Control and selector switches shall be:Of the rotary type with shrouded contacts

Adequately rated for the purpose intended (min. acceptable rating is 10A continuous at240V AC and 1A (inductive break) 220V DC.

Provided with escutcheon plates clearly marked to show the positions

17.2 Control switches shall be:

Of the spring return to normal type

Provided with pistol grip type handles

17.3 Control switches for circuit breaker control shall be provided with:

Contact development as specified in bill of material of enclosed drawings.

17.3.1 Wherever specified in data sheets, control switches with built-in flashing typediscrepancy lamps shall be provided to control circuit breakers in lieu of the normal

control switch, red, green and amber indicating lamps. The discrepancy lamp shall be

replaceable from the front of the module door.

17.3.2 Selector switches shall be:Of the maintained contact stay put type. Switches in ammeter circuits shall have make-

before-break type contact

Provided with oval handles

18.0 PUSH BUTTONS

18.1 Push buttons shall be:Of the momentary contact, push to actuate type rated to carry 10A at 240V AC & 1A

(inductive breaking) at 220V DC

Fitted with self reset, 2 NO and 2 NC contacts

Provided with integral escutcheon plates marked with its function

18.2 Start, Open, Close push buttons shall be green in colour18.3 Stop push buttons shall be red in colour

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18.4 All other push buttons shall be black in colour19.0 SPACE HEATER

Space heaters for switchgear panels shall be:

Suitable for operation on a supply system specified.

Provided with single pole MCB with overload and short circuit release whenever space

heater transformer is provided.

Provided with humidistat to cut off the heaters at 45 degree centigrade.

20.0 POWER CABLE TERMINATIONS

20.1 Suitable compression type, heavy duty brass cable glands with check nuts, rubber sealingring and brass washers mounted on a removable gland plate shall be provided to support

all power and control cables entering the switchgear, if asked for in Data Sheet-A1.

Cable glands shall incorporate built-in facilities for earthing the wire armour of cables.Cable glands shall be plated to avoid correction.

20.2 Power cable glands and crimping type lugs shall be supplied to suit the cable sizesindicated. Approximate quantity of control cable glands for different types of modules

are indicated in the module drawing, bill of material. If during course of detailed

engineering of the switchgear it is found necessary to provide more glands or glands of

higher size than those envisaged, the VENDOR shall provide and accommodate the same

20.3 The VENDOR shall select the power cable glands and lugs based on the cable sizesprovided at Data Sheet conforming to:

Type of power cable: 650/1100 V grade stranded aluminium conductor, PVC insulated,

PVC sheathed, armoured and overall PVC sheathed cable conforming to IS.

20.4 For supporting and clamping power cable cores at regular intervals inside the cablealleys, suitable slotted angles, up to the respective terminal blocks, shall be provided.

20.5 Necessary crimping type of tinned-copper cable lugs for connecting the individual coresto the respective terminals shall be provided.

21.0 INTERNAL WIRING

21.1 Wiring inside the switchgear shall be carried out with 650/1100 V grade, FRLS PVCinsulated, stranded conductor wires. Min. size of conductor for power circuits is 4

sq.mm copper or equivalent size aluminium conductor. Control circuits shall be wired

with copper conductor of at least 2.5 sq.mm for CT circuits and 1.5 sq.mm for othercircuits, the number and size of strands shall be 7 of 0.67 mm and 0.5 mm diameter

respectively.

21.2 Engraved identification ferrules, marked to correspond with the wiring diagrams shall befitted to each wire. Ferrules shall be of yellow colour with black lettering.

21.3 Wires forming part of a tripping circuit of circuit breaker shall be provided with anadditional red ferrule marked T.

21.4 Spare auxiliary contacts of all equipment forming part of the switchgear shall be wiredup to the terminal blocks.

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21.5 Wiring for equipment if supplied by the PURCHASER for which the VENDOR has toprovide cut-outs (where indicated in the data sheets) shall be provided upto the terminal

blocks.

21.6 Spare and unassigned modules shall be complete with internal wiring.21.7 Wiring shall be terminated on preferably stud type terminal blocks such that the wires

are connected by cable lugs with nuts and washers/lock nuts.

21.8 Not more than two connections shall be made on any one terminal.22.0 TERMINAL BLOCKS

22.1 Terminal blocks (both for power and control circuits) shall be of reputed make speciallyfor CT and VT circuits. It shall comprise finely threaded pairs of brass studs of at least 6

mm diameter, links between each pair of studs, washers, nuts and lock nuts. The studs

shall be securely locked within the mounting base to prevent their turning. Insulated

barriers shall be provided between adjacent terminals.22.2 Terminals for circuits with voltage exceeding 125 V shall be shrouded. Terminal blocks

shall be grouped depending on circuit voltage. Different voltage groups of terminal

blocks shall be segregated.

22.3 Terminal blocks shall be adequately rated to carry the current of the associated circuit.Minimum rating of the terminal block is 10A.

22.4 Terminals shall be numbered for identification as per enclosed drawings. Engravedwhite-on-black labels shall be provided on the terminal blocks, describing the function of

the circuit.

22.5 Where duplication of a terminal block is necessary, it shall be achieved by solid bondinglinks.22.6 Terminal blocks for CT secondary lead wires shall be provided with shorting and

disconnecting/earthing facilities.

22.7 Terminal blocks shall be arranged with at least 100 mm clearance between two sets ofterminal blocks.

23.0 LABELS

23.1 All labels shall comprise white letters on a black background23.2 Labels shall be made of non-rusting metal or 3-ply lamicoid, or engraved PVC23.3 Labels shall be properly fixed, with provision to prevent dis-rotation due to expansion23.4 .Size of lettering shall be 6 mm, unless otherwise specified.24.0 EARTHING

24.1 Each POWER circuit shall be provided with a earth busbar running along with entirelength of the board. Materials and size of the earth busbar shall be as specified in data

sheets. At either end of the earth bus, one (1) clamp type terminal with nuts, bolts and

washers shall be provided for connecting the PURCHASERS earthing conductor of size

and material indicated in data sheets. In case the earth bus is provided near top of the

8/13/2019 PCPL-0532-4-407-04-08

13/13

DOCUMENT No

PCPL-0532-4-407-04-08

MV SWITCHGEAR SECTION - 4

PAGE: 13 of 13

DATE:22-06-2006

ISSUE No: P0

switchgear, one down comer at either end shall be provided for connection to the

PURCHASERs earthing conductor.

24.2 Earth busbar shall be supported at regular intervals.24.3 Positive connection between all the frames of equipment mounted in the switchboard and

earth busbar shall be provided by using insulated copper wire/bare busbars of cross

section equal to that of the busbar, or equal to half the size of circuit load current

carrying conductor, whichever is smaller.

25.0 TESTS

25.1 Switchgear shall be subjected to following tests as per relevant standards along withfollowing tests:

25.1.1 Temperature rise test on power circuits.25.1.2 Short time current tests on power circuits.25.1.3 Mechanical operation test.25.1.4 Insulation resistance at 500V D.C before/after 1 minute H.V. Test.25.1.5 Electrical control, interlock and sequential operation tests.25.1.6 Verification of wiring as per approved schematic25.1.7 BIDDER shall submit available type test reports of temperature rise and short circuit

tests of similar switchgear. In addition, calculations of temperature rise shall be

submitted for approval.

25.1.8 Routine tests shall be carried out on all associated equipment supplied with switchgear,as per relevant standards. Type test certificates of all associated equipment shall befurnished.

25.1.9 Certified copies of all type and routine test certificates shall be submitted for thePURCHASERs approval before dispatch of the switchgear.

26.0 DRAWINGS & DATA

26.1 As part of proposal BIDDER shall furnish the following drawings and data:a) For each switchgear, overall dimension drawing showing front view, plan, elevation

and Cross-section in advance soon after the receipt of order.

b) Data Sheet-B shall be completely filled in.

26.2 All drawings and data sheets shall be annotated in English.