4.00.00 6.6 kv switchgear scope of supply … · explosion vents for different relief flaps which...

TENUGHAT VIDYUT NIGAM LIMITED 2x210 MW Tenughat Thermal Power Station

Jharkhand Dry Fly Ash Collection & Disposal System

SECTION-A / Electrics “© 2014 MECON Limited. All rights reserved”’

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4.00.00 6.6 KV SWITCHGEAR

4.01.00 SCOPE OF SUPPLY Following set of accessories for 6.6 KV Switchgear:- a) Earthing truck for feeders b) Earthing truck for bus c) The base channel frame of the switchgears with

hardware

4.02.00 CODES AND STANDARDS All equipment and materials shall be designed, manufactured and tested in accordance with the latest applicable Indian Standards (IS) and IEC except where modified and/or supplemented by this specification. Equipment and material conforming to any other standards, which ensure equal or better quality, may be accepted. In such case, copies of the English version of the standard adopted shall be submitted along with the bid. The electrical installation shall meet the requirements of Indian Electricity Rules as amended upto date and relevant IS Code of Practice. In addition, other rules and regulations applicable to the work shall be followed.

4.03.00 DESIGN CRITERIA The switchgear shall be used to supply power to HV Compressor motors, transformers and other loads for Compressor House. Duty involves direct-on-line starting of large induction motors and also under certain emergency conditions transfer of loads from normal to stand-by source of supply. The motor starting current varies from 6 to 8 times the full-load current, with a maximum of 3 starts per hour. The switchgear shall be located in a clean but hot, humid and tropical atmosphere. For continuous operation at specified ratings, temperature rise of the various switchgear components shall be limited to the permissible values stipulated in the relevant standards and/or this specification. The Switchgear and components thereof shall be capable of withstanding the mechanical forces and thermal stresses of the maximum system short circuit current without any damage or deterioration of material.




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Circuit breaker shall not produce any harmful over-voltage during switching off induction motors, unloaded lines and unloaded transformers. If required, surge protective device shall be provided in the scope of supply to limit over-voltage. The switchgear busbar rating shall be equal to the rating of incomer. Each incomer of HV switchgear shall be rated to carry continuously minimum 120 percent of rated secondary current of the transformer feeding the switchgear. Ratings of Bus-coupler and Tie Breaker shall be equal to the rating of the incomer breaker of the respective board. Incomer and bus-coupler of Switchgears not fed by any transformer shall be rated to carry at least the maximum simultaneous load of the entire switchgear with 10% positive margin. Each switchgear shall have 10% spare outgoing feeder of each type with a minimum of one (1) for each. All gadgets as required for sequential and protective interlocking with devices within or external to the switchgear, which are required for satisfactory and trouble-free operation of the system, are deemed included within the scope of work. For indicative power distribution scheme, the enclosed Single Line diagram for Auxiliary Power Distribution System shall be referred. All the rating shown in the above drawing represents the minimum requirement only. Exact rating, number and type of feeders etc. shall be decided by the bidder.

4.04.00 SPECIFIC REQUIREMENTS

4.04.01 Construction: The switchgear shall be indoor, metal-clad, floor mounted, draw out type. Design and construction shall be such as to allow extension at either end. The switchgear enclosure shall conform to the degree of protection IP-4X. The minimum thickness of CRCA sheet steel used shall be 2 mm and 1.6 mm for non load bearing member. The switchgear assembly shall comprise a continuous, dead-front, line-up of free standing, vertical cubicles. Each cubicle shall have a front hinged door with latches and a removable back cover. All covers and doors shall be provided with neoprene gaskets. Switchgear cubicle shall be so sized as to permit closing of the front access door when the breaker is pulled out to TEST position. The working zone shall be restricted within 750 mm to 1950 mm from floor level. Circuit breakers, instrument transformers, bus-bars, cable compartment etc., shall be housed in separate compartments within the cubicle.




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The design shall be such that failure of one equipment shall not affect the adjacent units. All relays, meters, breaker control switches, selector switches and indicating lamps shall be flush mounted on the respective cubicle door or on control cabinet built on the front of the cubicle. AC/DC auxiliary supply switches isolation switches for cubicle space heater, cubicle lamp, spring charging motor circuit shall be located inside metering compartment. Each transport unit not more than 3.2 m. Removable lifting arrangement for each transport unit. Screwed wire mesh for busbar and C.T chambers to prevent accidental contact with live parts. Explosion vents for different relief flaps which can not be opened from outside to release pressure that builds up in the event of arcing fault inside the cubicle. Dummy panel shall be provided in the switchgear line up, if required, for easy termination access of power and control cables. Dummy panel / bus trunking panel shall be of full cubicle with closed roof and rear door similar to enclosures for active cubicles.

4.04.02 Bus and Bus Taps The main buses and connections shall be of high conductivity aluminum/ aluminum alloy, sized for specified current ratings with maximum temperature limited to : a. For bolted joints (Plain or tinned) : 90oC b. For bolted joints (Silver plated) : 105oC Bus bars shall be of same size for the entire length of the switchgear. Continuous current rating of bus connections / dropper shall be same as that of continuous in panel current rating of associated breaker. All bus connections shall be silver plated. Adequate contact pressure shall be ensured by means of two bolts connection with plain and spring washers and locknuts. Bimetallic connectors shall be furnished for connections between dissimilar metals. Bus bars and connection shall be fully insulated for working voltage with adequate phase/ground clearances. Insulating sleeves for bus bars and cast-resin shrouds for joints shall be provided, suitable for maximum temperature rise of bus bars. Bus insulator shall be flame-retardant, track resistant type with creepage distance suitable for heavily polluted atmosphere. All buses and connections shall be supported and braced to withstand stresses due to maximum short circuit current and also to take care of any thermal expansion.




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Bus bars shall be color coded for easy identification and so located that the sequence R-Y-B shall be from left to right, top to bottom or front to rear, when viewed from front of the switch-gear assembly.

4.04.03 Circuit Breaker Circuit breaker shall be triple pole, single throw Vacuum breaker. Circuit breakers shall be horizontal isolation and horizontal draw out type, having SERVICE, TEST and DISCONNECTED positions with positive indication for each position. Circuit breakers shall be capable of racking in and racking out indoor closed condition. Circuit breakers of identical rating shall be physically and electrically interchangeable. Circuit breaker shall have motor wound spring charged trip free mechanism with anti pumping-feature and shunt trip. In addition facility for manual charging of spring shall be provided. For motor wound mechanism, spring charging shall take place automatically after each breaker closing operation. One open-close-open operation of the circuit breaker shall be possible after failure of power supply to the motor. Power supply to the spring charging motor shall be cut off when closing spring is charged manually. Mechanical safety interlock shall be provided to prevent:

a. The circuit breaker from being racked in or out of the service position when the breaker is closed.

b. Racking in the circuit breaker unless the control plug is fully engaged.

Automatic safety shutters shall be provided to fully cover the female primary disconnects when the breaker is withdrawn. Each breaker shall be provided with an emergency manual trip, mechanical ON-OFF, indication, an operation counter and mechanism charge/discharge indicator. Each breaker shall be provided with following: a. Auxiliary switch, with 6 NO + 6 NC contacts, mounted on the draw

out portion of the switchgear. b. Position/cell switch with 3 NO + 1 NC contacts, one each for

TEST and SERVICE position. c. Auxiliary switch, with 4 NO + 4 NC contacts, mounted on

the stationary portion of the switchgear and operated mechanically by a sliding lever from the breaker in SERVICE position. Alternatively electrically reset type latching relay may be used for the purpose.




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Switch contact shall be rated 10 A AC. and 2A DC at their respective operating voltage.

4.04.04 Control & Indication The circuit breaker shall be wired up for local & remote operation. Each breaker cubicle shall be equipped with following:- One (1) TEST-NORMAL-TRIAL selector switch stay put type with pistol grip handle and key interlock. Four (4) indicating lights on front of compartments:-

GREEN : Breaker Open WHITE : Spring Charged RED : Breaker Closed BLUE : Trip circuit healthy

Lamps shall be clustered type LED module pilot lights in thermoplastic enclosure with polycarbonate lens and diffuser. LED shall be protected by in- built fuse with surge suppressor and leakage voltage glow protection. Lamp and lens shall be replaceable from front. The general scheme of connection for control, interlock and protection is shown in the enclosed drawings. Detail scheme drawings shall be developed and submitted for approval by the successful bidder.

4.04.05 Current Transformer Current transformers shall be cast resin type. All secondary connections shall be brought out to terminal blocks where wye or delta connection shall be made. Accuracy class of the Current Transformers shall be :-

a. Class PS for differential relaying (or as required depending on the type of relay selected).

b. Class 5P20 for other relaying. c. Class 1.0 and ISF <=10 for metering. d. Class 0.5 or better and ISF <=2 for performance /

precision metering. e. Class of insulation shall be E or better.

Current transformer secondary shall be rated for 1 A. Feeders requiring remote metering and/or current monitoring shall be provided with current transducers with calibration for full-scale reading.

4.04.06 Voltage Transformer Voltage Transformer (VT) shall be cast-resin, draw out type and shall have an accuracy class of 1.0. Voltage transformer shall be mounted




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in a separate vertical panel. Class of Insulation shall be ‘F’ and minimum VA burden shall be 100. High voltage windings of voltage transformer shall be protected by current limiting fuses. The voltage transformer and fuses shall be completely disconnected and visibly grounded in fully draw-out position. Low voltage winding of voltage transformer shall have Fuse, installed in all ungrounded secondary leads. Fuse shall be suitably located to permit easy replacement while the switchgear is energized.

4.04.07 Relays Relays shall be of draw out design with built-in testing facilities and flush mounted at the front of panel. Small auxiliary relays may be in non-draw out execution and mounted within the cubicle. Relays shall be rated for operation on 110V secondary voltage and 1 secondary current. Number and rating of relay contacts shall suit the job requirements. Unless mentioned otherwise in the specification, protective relays shall be multifunction type numerical relays. All relays shall be able to communicate with PLC based control system through communication protocol. Numerical relay module in a switchboard shall be serially interface to PLC. Each breaker shall be monitored from PLC this serial communication link. Serial communication link shall have 100% redundancy. Numerical relay and PLC shall have common protocol for proper communication. Control of the breaker shall be from PLC through interposing/coupling relays which shall be located in the switchgear. Multifunction numerical relays shall be selected to provide an integrated protection, continuous measurement and monitoring functions. Features such as self-diagnosis and external testing, disturbance recording, sequence of event recording, time stampings and energy management shall be available with the relay. Relevant data shall be possible to be stored in non-volatile memory backed up by battery. The relay shall have multiple setting groups, optically isolated input / output, front LCD display and menus, fixed function and programmable LEDs, keypad and password protection. All functions including protection, automation, communication, LEDs, input / output shall be programmable and can be modified, if required, using the front panel user interface. Communication port for local and remote (with suitable protocol) communication shall be located in the front and rear part of the relay. A laptop loaded with support software (complete version) shall be supplied for local off line programming, measurements, extracting and viewing




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of events, disturbance etc. The relay shall be housed in dust tight enclosure, suitable for IP 52 degree of protection. Numerical relays of all modules in a switch board shall be serially interfaced to plant PLC through serial communication link. Serial communication link shall have 100% redundancy. Numerical relays and PLC shall have common protocol for proper communication. Control of breakers shall be from PLC through interposing/ coupling relays which shall be located in the respective panels. The Bidder shall furnish, install & co-ordinate all relays to suit the requirements of protection, interlock .

4.04.08 Meters Indicating instruments (96 x 96 mm) shall be switchboard type, with 240- degree scale, anti-glare glass and accuracy class of ± 2% full scale. Each meter shall have zero adjuster on the front. Motor ammeter shall have extended suppressed end-scale range to indicate starting current (6-8 times full load). Energy meter shall be three phase multifunction, digital type with communication port for PLC interface Transducer Transducers shall be provided for conversion of AC electrical quantities such as voltage, current and power. Transducers shall be of low burden type having 4 - 20 mA DC linear galvanically isolated output compatible with secondary indicating instrument. Transducer shall be dual channel type.

4.04.09 Switch Switches shall be dust protected, heavy duty, and switchboard type complete with escutcheon plate. Contacts shall be silver surfaced, rated 10A at operating voltage. Lockable stay-put type switchgear / field / remote selector switch shall be provided as per requirement and mounted on switchgear cubicle. Meter selector switches shall be maintained contact, stay put type with knob handle. Ammeter& voltmeter selector switches shall be four position types. Ammeter selector switches shall have make before break feature to prevent open circuiting of CT secondary. Breaker control switch shall be multistage, spring return to normal, with lost motion device and pistol grip handle.

4.04.10 Fuse & MCB




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Fuses shall be HRC, link type, with minimum interrupting capacity equal to the listed short circuit current. Fuses shall be furnished complete with fuse bases and fittings. Visible indication shall be provided on blowing of the fuse. MCBs, if used, shall be three/four pole, trip free, with manual close / open mechanism. Automatic tripping provision for over load and short circuit shall also be provided. MCBs shall be rated for full fault level of the system. MCB shall be provided with required number of auxiliary contacts as per circuit requirement.

4.04.11 Push Button Push button shall be heavy duty, shrouded, push to actuate type with colored button and inscription plate. Each push button shall have 2 NO + 2 NC contacts, rated 10A and 0.5A at their respective AC and DC operating voltage.

4.04.12 Secondary Wiring The switchgear shall be fully wired at the factory to ensure proper functioning of control, protection and interlocking schemes. Fuses and links shall be provided to permit individual circuit isolation from bus wires without disturbing other circuits. All spare contacts of relays, switches and other devices shall be wired up to terminal blocks. Wiring shall be done with flexible, 1100 V grade, PVC insulated switchboard wires with stranded copper conductors of 2.5 Sq. mm. Flexible wire of 4 mm2 will be used from CT to relay chamber. Each wire shall be ferruled by plastic tube with indelible ink print at both end having terminal block no., terminal numbers, destination no. as per approved

4.04.13 Wiring Diagram. Wire termination shall be made with crimping type connectors with insulating sleeves. Wires shall not be spliced between terminals. All spare contacts of relays, timers, auxiliary switches shall be wired up to the terminal block.

4.04.14 Terminal Blocks 650V grade, multi way terminal block complete with mounting channel, binding screws and washers for wire connections and marking strip for circuit identification shall be provided for terminating the panel wiring. Terminals shall be stud type, suitable for terminating 2 nos. 2.5 mm2 stranded copper conductor and provided with acrylic insulating cover. Terminals for C.T. secondary leads shall have provision for shorting and grounding.




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Not more than two wires shall be connected to any terminal. Spare terminals equal in number to 20% active terminals shall be furnished. Separate terminal blocks shall be used for AC/ DC wiring termination. 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. Terminal blocks used for interface with PLC via termination cabinet shall be suitably sized to facilitate proper termination of interconnecting cables.

4.04.15 Cable Termination Switchgear shall be designed for cable entry from bottom. Sufficient space shall be provided for ease of termination and connection All provisions and accessories shall be furnished for termination and connection of cables, including removable gland plates, cables supports, crimp type tinned copper/ aluminium lugs, brass compression glands with tapered washer (Power cables only) and terminal blocks. Gland plates shall be minimum 3 mm thick. The gland plate and supporting arrangement for 1/C power cables shall be of aluminum. Sufficient space shall be provided between the power cable termination and gland plate. Core balance CTs wherever specified, shall be accommodated within this space, inside the cubicle. Sufficient space shall be provided between the power cable termination and gland plate. Core balance CTs wherever specified , shall be accommodated within this space, inside the cubicle, sufficient space and support arrangement shall be available inside each panel to accommodate HT cable termination kits and sealing kits suitable for the size and number of XLPE, Aluminum cables to be terminated. Dummy panels to be provided adjacent to switch panel wherever the required number of cable termination can not be accommodate in the cabling chamber of the main panel. Rear extension is not acceptable.

4.04.16 Bus Duct Connection Bus duct connections, wherever provided shall be furnished along with transition panel if required. Bus duct connections shall be generally from the top. All connecting bus work shall have the same continuous rating as associated switchgear bus and shall be fully braced for the listed short circuit current. All provisions such as matching flange and other accessories required for proper connection to bus duct shall also be supplied.




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4.04.17 Ground Bus A ground bus, rated to carry maximum fault current, shall extend for the full length of the switchgear. The ground bus shall be provided with two-bolt drilling with G.I. bolts and nuts at each end to receive 75 x 10 mm G.I. flat. Each stationary unit shall be connected directly to the ground bus. The frame of each circuit breaker and draw out VT unit shall be grounded through heavy multiple contacts at all times except when the primary disconnecting devices are separated by a safe distance. Wherever, the schematic diagrams indicate a definite ground at the switchgear, a single wire for each circuit thus grounded shall be run independently to the ground bus and connected thereto. CT and VT secondary neutrals shall be earthed through removable links so that earth of one circuit may be removed without disturbing other.

4.04.18 Earthing Truck Earthing trucks shall be provided for earthing the switchgear bus bars or outgoing cables. The trucks shall have a voltage transformer and an interlock to prevent earthing of any live connection. The trucks shall have audio-visual annunciation to warn the operator against earthing of live connections. It shall not be possible to use bus-earthing truck for cable earthing & vice versa. Earthing truck shall be non- fault making type. Circuit breakers provided with integral earth switch, as an alternative, is not acceptable.

4.04.19 Name plates Nameplates of approved design shall be furnished at each cubicle (one no. each at front as well as at backside of cubicle) and at each instruments & device mounted on or inside the cubicle. The material shall be lamicoid or approved equal, 3 mm thick with white letter on black back ground. The nameplate shall be held by self-tapping screws. Nameplate size shall be minimum 20 x 75mm for instrument/device and 40 x 150mm for panels. Caution notice on suitable metal plate shall be affixed at the back of each vertical panel.

4.04.20 Space Heaters and Plug Sockets




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Each cubicle shall be provided with thermostat controlled space heaters and 5A, 3 pin plug socket. In addition, motor feeder cubicle shall be wired-up for feeding the motor space heater through suitable rated breaker auxiliary NC contact and/or contactor. Cubicle heater, Motor heater, Plug/socket circuits shall have individual switch fuse units.

4.04.21 A.C/D.C Power Supply Necessary 415V AC and 220V DC power supplies as required for control and service, shall be arranged by the bidder. Duplicate feeders shall be arranged for AC and DC supply. Isolating switch fuse units / MCCB (AC ckt Only) shall be provided at each switchgear for the incoming supplies, 4-pole, for AC and 2-pole, double throw and off for DC. Bus-wires of adequate capacity shall be provided to distribute the incoming supplies to different cubicles. MCCB/Isolating switchfuse units shall be provided at each cubicle for AC/DC supplies. AC load shall be so distributed as to present a balance loading on three-phase supply system. Sub circuits(control, spring charging motor, indication etc.) of each panel shall be protected by HRC fuses.

4.04.22 Tropical Protection All equipment, accessories and wiring shall have fungus protection, involving special treatment of insulation and metal against fungus, insects & corrosion. Screens of corrosion resistant material shall be furnished on all ventilating louvers to prevent the entrance of insects

4.04.23 Painting All surfaces shall be sand blasted, pickled and grounded as required to produce a smooth, clean surface free of scale, grease and rust. After cleaning, the surfaces shall be given a phosphate coating followed by 2 coats of high quality primer and stoved after each coat. The switchgear shall be finished in light gray color with two coats of powder paint. The coating shall be done electro statically followed by stoving. Sufficient quantity of touch-up paint shall be furnished for application at site. Paint shade shall be Siemens grey RAL 7032.




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4.04.24 Accessories Following accessories shall be furnished along with the Switchgear : a. Earthing equipment suitable for earthing the bus. b. Earthing equipment suitable for earthing the outgoing cable.

4.05.00 TESTS The switchgear shall be completely assembled, wired, adjusted and tested at the factory as per the relevant standards.

Routine Test The tests shall include but not necessarily limited to the following :

a. Operation under simulated service condition to ensure accuracy of wiring, correctness of control scheme & proper functioning of the equipment.

b. All wiring and current carrying part shall be given appropriate High Voltage test.

c. Primary current and voltage shall be applied to all instrument transformers.

d. Routine test shall be carried out on all equipment such as circuit breakers, instrument transformers, relays, meters etc. as per relevant standard.




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Type Test Following minimum tests shall be performed on a representative sample of 6.6 KV switchgear bus assembly, even if the offered equipment is already type tested.

a. Impulse Test b. Temperature rise Test c. Heat Run test

Test Witness All tests shall be performed in presence of Owner/ Purchaser's representatives, if so desired by the Owner / Purchaser. Test Certificate Certified reports of all the tests carried out at the works shall be furnished in requisite number of copies for approval of the Owner / Purchaser. The equipment shall be dispatched from works only after receipt of Owner / Purchaser's written approval of the test reports. Type test certificate on any equipment, if so desired by the Owner/Purchaser, shall be furnished. Otherwise the equipment shall have to be type tested, free of charge, to prove the design.

SPECIAL TOOLS & TACKLES A set of special tools & tackle which are necessary or convenient for erection, commissioning, maintenance and overhauling of the equipment shall be supplied. The tools shall be shipped in separate containers, clearly marked with the name of the equipment for which they are intended.

DRAWINGS, DATA, INFORMATION & MANUALS To be submitted with the Bid Typical general arrangement drawing of the equipment and foundation plan. Bill of material Proposal sheets duly filled in. Type test certificate of the offered model of the circuit breaker and switchboard for the specified type tests. Leaflets on equipment and other accessories explaining their constructional details, principle of operation, special features etc.




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To be submitted for Owner / Purchaser’s Approval and Distribution

(A) : ‘Approval Category’ (R) : ‘Reference Category’

Guaranteed Technical Particulars (A) and Quality assurance plan (R) Dimensional general arrangement drawing showing disposition of various fittings (A) Bill of material (R) Foundation plan and loading (R) Single Line Diagrams (A) Control schematic (A) and wiring diagrams (R) Back up calculation for selection of

i) Busbar size and rating (A) ii) CT, VT & Breaker ratings.(A)

Relay setting charts/drawings with back up calculations and co-ordination curves. (A) Instruction manuals on circuit breakers and its accessories (R) The manual shall clearly indicate method of installation, check ups and tests to be carried out before commissioning of the equipment. Any other relevant drawing or data necessary for satisfactory installation, operation and maintenance. The drawings and document marked with (A) above are of‘Approval’ category and are subject to review by Owner / Purchaser. Those marked (R) are for ‘reference’ category. The Owner / Purchaser may also review the documents marked (R) if found necessary. The bidder shall note that the approval of drawings & documents by the Owner / Purchaser does not relieve him of his contractual obligation. All drawings shall be prepared by using Auto CAD, approved version and documents shall be generated using MS Office. The paper copy of the drawings & document shall be submitted for approval & reference. All final drawings and documents shall be submitted in CD in Auto CAD (approved version) and MS office format as applicable for Owner / Purchaser’s future referance. The Bidder may note that the drawings, data and manuals listed herein are minimum requirements only. The Bidder shall ensure that all other necessary write-ups, curves and information required to fully describe the equipment are submitted with his bid.




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Annexure-A RATINGS AND REQUIREMENTS 1.0

SWITCHGEAR 6.6KV

1.1 General

Type ----------Metal-clad, drawout----------

Service ---------------Indoor-------------- Enclosure ----------------IP4X----------------- 1.2

System

Voltage 6600 ± 10% Phase 3 Frequency 50 Hz +/- 5% System ground Non-effectively earthed through

resistance. Earth fault current limited to 300A for 10 sec

1.3

Rated Current at50 Deg.C

Bus bar To be decided by bidder Circuit breaker To be decided by bidder 1.4

Short Circuit Rating

Short time for 3 Secs --------------------40 KA---------------- 1.5

Insulation level 40/10KV (peak/r.m.s)

1.6

AC/DC Power Supply

Control voltage 220 V DC (198 - 240 V) Service voltage 240 +/- 10%, 1 Ph, 50 Hz +/- 5%

2.0 CIRCUIT BREAKER 2.1 Duty Cycle -0 - 3' - CO - 3' -

CO-

2.2 Breaking Current A.C. Symmetrical ----------------40 KA ---------------------------

--- A.C. Asymmetrical -----------------As per IEC--------------------

-- 2.3 Making Current -----------------100 KA peak-----------------

------ 2.4 Operation Time




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Opening time (ms) Not more than 60 Closing time (ms) Not more than 100 2.5 Auxiliary Voltage 220 V DC (85% – 110%) Closing 220 V DC (70% – 110%) Tripping 220 V DC (85% – 110%) Spring Charging 3.0 Current transformer

details (i) Type (ii) Class of

Insulation

Cast resin bar primary Class E or better

4.0 Voltage transformer details

(i) Type (ii) Rated Voltage

–Primary Secondary

(iii) Rated Voltage Factor (iv) Class of insulation

Cast Resin 6600 / 3 V 110 / 3 V 1.2 Continuous Class F

6.0 Meters (If provided separately) Accuracy Class

0.5 for kWh, 1.0 for Others




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Microprocessor based Numerical Relay ( 6.6 KV SYSTEM) The Numerical Relay for 6.6KV Switchgears will comply with but not limited to the following technical requirements.

1 Purpose Protection, Metering and Monitoring of Incomer,

Tie/Board, Motor and Transformer feeders. 2 Auxiliary Supply 220V DC 3 CT Secondary

Current 1Amp.

4 PT Secondary Voltage

110V AC, 3 Phase

5 Ambient Temperature

50oC

6 Communication Compatible with DDCMIS system through suitable connectivity (OPC link)

7 Input & Output • Required number of analog and digital inputs as per scheme requirement with spare.

8 Metering Instantaneous and Integrated values as per annexure-B

9 Protection Complete protection for Incomer, Tie/Board, Motor and Transformer feeders as per Annexure-B

10 Monitoring Self-diagnostic facility. 11 Facility to be

made available in the Numerical relay.

• Programming keys for complete access with out computer (built in).

• Provision for external programming unit through suitable software and communication ports.

• Display unit. • Read/Write set points. • Current & Voltage actual values and any other

analog measurement. • ON/OFF/TRIP indication. • Event recording with Pre-trip data with starting

characteristics. • Statistical data. • Output relays. • Tamper proof security system.




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ANNEXURE-B

PROTECTIONS 1.0 Numerical relays will have following protection / metering for the switchgear panels. Minimum protections and metering required for various typical feeders shall be included but not limited to the following –

A Incomer a Incomer

b IDMTL over current (51N) for earth fault

c IDMTL over current (51SN) for stand by earth fault (for incomer from transformer only).

d Restricted E/F (64) (for incomer from transformer only)

e Under voltage with time delay (27)

f VT fuse failure

B Tie Feeder/Board feeder

a IDMTL over current (51) for phase fault

b IDMTL over current (51) for earth fault

c Under voltage with time delay(27)

d VT fuse failure

e Synchronizing check relay, if applicable, complete with guard relay and hard wires.

f D.C. Supply failure protection.

g Trip circuit supervision relay.

h Trip lockout relay

C Motor Feeder a Thermal overload(49)

b Phase fault(50)

c Unbalance(-ve seq.)(46)

d Locked rotor(ref. note 6)

e Definite time O/C (50G) for earth fault (through CBCT)

f Differential (87) protection for motor above 1000 KW rating.

g Winding temperature




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h Bearing temperature

i Bimetallic Thermal Overload relay (with single phase preventor), short circuit protection (through fuse/MCCB).

D Auxiliary Transformer

a IDMTL over current (50/51) with high set instantaneous units for phase faults

b Definite time O/C (50G) for earth fault (through CBCT).

c Differential protection (for transformers rated 10MVA and above).

d Gas pressure alarm and trip.

e Winding temperature alarm and trip

f Oil temperature alarm and trip

g Pressure relief device operated alarm

h Conservator oil level low alarm

i Short circuit

j Core balance protection

k Buchholz relay (for oil filled)

E Line Feeders a IDMTL over current (51) for phase fault

b IDMTL over current (51N) for earth fault

F Bus PT Feeders a Under voltage protection

b Fuse failure protection

c No Voltage protection

G Line VT Feeders

Protection Metering

Voltage supervision,U/V, No Voltage ,Fuse failureprotection

: Voltage – phase to phase(all the three phases), phase to neutral

The above list (for metering & protection) is only indicative. 2.0 In case any trip function is not available in a single relay,

separate numerical relays shall be provided to achieve the requirement.




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3.0 All protective relays shall be provided with self reset type of contacts.

4.0 Apart from protection relays, each breaker shall be provided with separatediscrete auxiliary relays for anti-pumping (94),trip annunciation (30), tripsupervision (74), electrically reset type breaker contact multiplication (52X) relay and lockout (86) functions. Lockout relay shall be hand reset type. For multifunction relays however, trip circuit supervision function as an integral feature of the relay is acceptable. Individual trip circuit supervision function shall be provided with respect to each trip coil of circuit breaker.

5.0 Numerical under voltage relays (27) with time delay relay including VT fuse failure relay shall be provided for Bus VTs.

6.0 IDMTL relay version shall be decided as per system requirement and the same shall be finalized during detail engineering.

7.0 Zero-sequence CT and associated relay combination shall be such as to ensure a pick-up sensitivity of 10A primary ground fault current.

8.0 Separate locked rotor protection relay (50 LR) with auxiliary relay (50 LRX) shall be furnished, if required.

9.0 Separate numerical difference relay to be provided for motor above 1000 KW with separate C.T. of P.S.class.

4.00.00 6.6 kv switchgear scope of supply … · explosion vents for different relief flaps which...

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