SPECIFICATION FOR 11000V SF6 INSULATED RING MAIN UNITS

SPECIFICATION FOR 11000V SF6 INSULATED RING MAIN UNITS

1.0 INTENT OF SPECIFICATION

1.1 This specification is intended to cover the manufacture, assembly, testing at manufacturer's works, supply & delivery, properly packed for transport F.O.R. site of Out door type 11000 Volt SF6 Insulated Ring Main Units with all accessories for efficient and trouble free operation.

1.2 The scope of work shall also include, at the option of the owner, the supervision of erection, testing & commissioning all equipment furnished under this specification.

2.0 SCOPE OF WORK

2.1 SCOPE OF SUPPLY

2.1.1 Out door type, 11 KV SF6 Ring Main Units having

4 Nos. Cable Switch Modules (Switch Disconnector + Earthing Switch)

2.1.2 Out door type, 11 KV SF6 Ring Main Units having

1 Nos. Cable Switch Module (Switch Disconnector + Earthing Switch) &

1 Nos. VCB Module for Transformer (VCB + Earthing Switch)

2.1.3 One set of special tools and tackles.

2.1.4 Spare parts for Three years operation

2.1.5 All relevant drawings, data and instruction manuals

2.2SCOPE OF SERVICES

The services of a Senior Engineer, experienced in the erection & commissioning of the equipment of similar type & rating on per Diem basis. The work includes but not limited to: -

2.2.1 Advice on procedure of erection to be followed.

2.2.2 Successful testing & commissioning of the equipment.

2.3 EXCLUSION FROM SCOPE OF WORK

2.3.1 All concrete foundation works.

2.3.2 Power and control cables for connection

3.0 GENERAL REQUIREMENTS

3.1 CODES AND STANDARDS

3.1.1 All equipment and materials shall be designed, manufactured and tested in accordance with the latest applicable Indian standards (IS).

3.1.2 The electrical installation shall meet the requirements of Indian Electricity Rules as amended upto date and relevant IS Codes of Practice.

3.2 COMPLETENESS OF SUPPLY

3.2.1 It is not the intent to specify completely herein all details of the equipment. Nevertheless, the equipment shall be complete & operative in all aspects and shall conform to highest standard of engineering, design and workmanship.

3.2.2 Any material or accessory which may not have been specifically mentioned but which is necessary or usual for satisfactory and troublefree operation and maintenance of the equipment shall be furnished without any extra charge.

3.3 GUARANTEED PERFORMANCE

The performance figures quoted by the vendor shall be guaranteed within the tolerance permitted by relevant standards. In case of failure of the equipment to meet the guarantee, the equipment may be liable for rejection.

3.4 DEVIATION

3.4.1 Should the bidder wish to deviate from the specification in any way, he shall draw specific attention to such deviation.

3.4.2 All such deviations shall be clearly mentioned on the Deviation sheet, with reference to the respective clause of the specification.

3.5 DRAWING APPROVAL

Before starting manufacture of any equipment, the contractor shall have to take approval of relevant drawings and data from purchaser in writing.

3.6 RECORD OF PAST EXPERIENCE

3.6.1 The Bidder shall submit along with his bid a list of major contracts of supply and erection of similar equipment already executed or under execution, giving detailed particulars such as equipment rating, contract value, name of the owner, year of commissioning etc.

3.7 QUALITY ASSURANCE

3.7.1 Contractor shall follow his standard procedures for quality assurance and control. The procedures shall be in such a form as to clearly delineate the manufacturing sequence & major inspection point.

3.7.2 Manufacturing and quality control procedures shall be available for audit to the Owner and/or its representative at the place of manufacture.

4.0 SITE CONDITIONS

4.2 The site is also connected to National Highway by an all weather metal road.

4.3 Equipment shall be packaged for transportation so as to meet the space and weight limitation of transport facilities, especially along the railroad right-of-way.

4.4 For the purpose of equipment design, the following data shall be taken into consideration:

a) Average Grade

:173 M above MSL

b) Ambient Air Temperature (mean)

:31.6oC(max.), 18.9oC(min.)

c) Relative Humidity

:69% Maximum

d) Wind Velocity

:162 Km/Hr

e) Isoceraunic Level

:29.4

f) Seismic Zone

:Zone-III

5.0 DESIGN CRITERIA

5.1 The outdoor type SF6 insulated Ring Main Units shall be used to replace 11 KV Overhead Isolators used for isolation of overhead line & transformers installed in the field.

5.2 For continuos operation at specified ratings, temperature rise of the various panel components shall be limited to the permissible values stipulated in the relevant standards and/or this specification.

5.3 The Ring Main Units and the components thereof shall be capable of withstanding the mechanical forces and the thermal stresses of the short circuit current without any damage or deterioration of material.

5.4 All the Cable Switches Modules shall be 630 Amp Fault making Load breaking spring assisted SF6 Ring switches, fitted with fixed type voltage indicator device as per IEC 61958.

5.5 Vacuum Circuit Breaker Module shall be 630 Amp tee off spring assisted type vacuum circuit breaker unit with self actuating electronic over current & earth fault relay, fitted with fixed type voltage indicator device as per IEC 61958 and ring core type protection current transformer.

5.6 The ring main units are to be installed at outdoor remote locations. Therefore, suitable protection to be provided against Lightening Surges.

5.7MECHANICAL DATA

Pressure of SF6 gas

:

1.4 bar at 20 0C

Temperature Class

:

(-) 25 0 C indoor

Degree of Protection

:

SF6 Tank

:

IP67

Fuse Canisters

:

IP67

Front Cover

:

IP2X

Cable Cover

:

IP3X

Busbars

:

240 mm2Cu

Earth Bar (external)

:

120mm2Cu

Thickness of Stainless Steel Tank

:

3.0 mm

5.8ELECTRICAL DATA

Rated Voltage

:

12 kV

Rated Current for busbars

:

630 A

Rated Current for Cable switch disconnector:

630 A

Short time with stand current (3 sec)

:

21 kA RMS

Rated Current for transformer T-off

:

630 A

Impulse withstand voltage

:

95 kV

(To earth and between phases)

Insulation Level

:

28kV

(Power frequency 1 min.)

6.0 SPECIFIC REQUIREMENTS

6.1 CONSTRUCTION

6.1.1 The SF6 Ring Main Units shall be 11kV, 3 Phase-3Wire, 50Hz, outdoor, free-standing, metal-clad, IP-54 Enclosure, Non-extendable type.

6.1.2 The RMUs shall be suitable for cable termination from the front having bolted arc proof cable doors. The overall design of the switchgear shall be such that front access only is required.

6.1.3 The SF6 insulated Ring Main Units shall accommodate all live parts and switching equipments in a robotically laser welded stainless steel tank having IP67 degree of protection.

6.1.4 The ring main unit shall be of the fully arc proof, flush fronted type, consisting of modules assembled into one or more units.

6.1.5 The cubicle shall have a pressure relief device. In the rare case of an internal arc, the high pressure caused by the arc will release it, and the hot gases is allowed to be exhausted out at the bottom of the cubicle. A controlled direction of flow of the hot gas should be achieved.

6.2APPLICABLE STANDARDS

Metal Enclosed Switchgear

:

IEC 60298

General Purpose Switches

:

IEC 60265

Disconnectors and Earthing Switches

:

IEC 60129

Circuit Breakers

:

IEC 60056

Common Clauses

:

IEC 60694

Cable Bushings

:

DIN 47636

6.3CABLE SWITCH MODULE

Each Cable Switch Module with a three position load break switch and earthing switch, busbars, interlocking and earthbar shall have a minimum of following:

(i)Cable switch 12Kv, 630 A, 21 kA for 3 sec.

(ii)Snap action mech. for manual operation

(iii) Cable bushings, 630 A suitable for 11KV, XLPE, Aluminium cable of size 3Cx300 Sq. mm.

(iv) Arc proof cable cover including Interlocking

(v) Capacitive voltage indication (fixed type)

6.4VACUUM CIRCUIT BREAKER MODULE

Vacuum circuit Breaker module with vacuum circuit breaker, three-position isolator/ earthing switch, busbars, interlocking, earthbar and stored spring energy mechanism shall have following:

(i) Vacuum circuit breaker 12kV, 630A, 21kA for 3 sec.

(ii) Stored energy mechanism for manual operation

(iii) Protection relay for Over Current & Earth Fault of Transformer

(iv) Ring Core current transformer suitable for 250KVA Distribution Transformer

(v) Cable bushings, 630 A suitable for 11KV, XLPE, Aluminium cable of size 3Cx300 Sq. mm.

(vi) Arc proof cable cover including Interlocking

(vii) Capacitive voltage indication (fixed type)

6.5 CABLE TERMINATION

6.5.1 The Ring Main Unit Modules shall be designed for cable entry from the bottom. Sufficient space shall be provided for ease of termination and connection.

6.5.2 Power Cable shall be XLPE insulated, 11kV grade, armoured, overall PVC sheathed with stranded Aluminum conductor of size not less than 3Cx300 Sq. mm.

6.5.3 All provision and accessories shall be furnished for termination and connection of cables, including removable gland plates, cable supports etc.

6.5.4 The gland plates shall be minimum 4 mm thick. The gland plate and supporting arrangement for I/C Power cables shall be such as to minimize flow of eddy current.

6.6 GROUND BUS

A ground bus rated to carry maximum fault current shall extend full length of the switchgear.

6.7 NAMEPLATES

6.7.1 Nameplates of approved design shall be furnished at each module and at each instruments and device mounted on or inside the RMU.

6.7.2 The material shall be lamicoid or approved equal, 3 mm thick with white letter on black background.

6.10TROPICAL PROTECTION & PAINTING

6.10.1 All equipments, accessories and wiring shall have fungus protection, involving special treatment of insulation and metal against fungus, insects & corrosion.

6.10.2 Screens of corrosion resistant material shall be furnished on all ventilating louvers to prevent the entrance of insects.

6.10.3 All surfaces shall be sand blasted, pickled and grounded as required to produce a smooth, clean surface free of scale, grease and rust.

7.0 TESTS

7.1The Ring Main Unit shall be completely assembled, wired, adjusted and tested at the factory as per the relevant standards.

7.2Routine 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 HI Voltage test.

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

d. Routine test shall be carried out on all equipment such as Circuit Breaker panel, instrument transformers, relays, meters etc.

7.3Test Witness

All tests shall be performed in presence of Owner's representatives. The contractor shall give at least thirty (30) days advance notice of the date when tests are to be carried out.

7.4 Test Certificate

7.4.1 Certified reports of all the tests carried out at the works shall be furnished in six (6) copies for approval of the Owner.

7.4.2 Type test certificate on any similar equipment shall be furnished to prove the design.

8.0 SPECIAL TOOLS & TACKLES

A set of special tools & tackles, which are necessary or convenient for erection, commissioning, maintenance and overhauling of the equipment shall be supplied.

9.0 SPARES

The Bidder shall submit a list of recommended spare parts for three (3) years satisfactorily and trouble free operation, indicating the itemized price of each item of the spares.

10.0 DRAWINGS, DATA & MANUALS

10.1 Drawings, Data & Manuals shall be submitted with the bid and in quantities and procedures as specified in General Conditions of contract and/or elsewhere in the specification for approval & subsequent distribution after the issue of Letter of Intent.

To be submitted with the Bid:

a. General arrangement drawing showing constructional features

b. Bill of Materials

c. Technical leaflets

To be furnished for Approval and Distribution:

a. Outline dimensional Drawing of the RMU Panel showing general arrangement, space requirements and cable entry points.

b. Foundation plan and loading

c. Single line diagram

d. Control Schematics & wiring diagrams

e. Instruction Manuals of RMU Modules

ANNEXURE-I

TECHNICAL SPECIFICATIONS OF SF6 INSULATED RING MAIN UNIT

1.0 CABLE SWITCH MODULE

1.1 It shall consist of an SF6 cubicle housing a switch disconnector and an earthing switch. The switch disconnector, earthing switch shall be interlocked to each other for safety of the operator.

1.2 Busbars and all electrical connections shall be located inside the tank. The operating shafts for switches shall have rotary seals where they enter the SF6 cubicle. The operating mechanism shall be located outside on the front of the SF6 tank.

1.3 Cable bushings shall be located on the front of the SF6 cubicle in a separate cable compartment. Front covers containing the mimic diagram and having a degree of protection IP2X close the fronts.

1.4 The switch disconnector and earthing switch shall have padlocking facility from maintenance point of view.

2.0 CIRCUIT BREAKER MODULE (630 A)

2.1The circuit breaker module shall consist of an SF6 cubicle housing a circuit breaker unit and a disconnector-earthing switch. For isolation of the circuit breaker and safety of the operator, a disconnector switch shall be provided in line with the breaker.

2.2The Vacuum breaker, disconnector switch, earthing switch and its cable covers shall be operated in the sequence and interlocked with each other. It shall not be possible to open the cable cover when earthing switch is not in earth position. Similarly the earthing switch shall not be closed when the disconnector switch is in ON position. The circuit breaker shall be closed only when the disconnector switch is in ON position.

2.4 Busbars and all electrical connections shall be located inside the tank. The operating shaft for the switches shall have rotary seals where they enter the SF6 cubicle. The operating mechanisms shall be located outside on the front of the SF6 tank. Cable bushings shall be located on the front of the SF6 cubicle in a separate cable compartment. Front covers containing the mimic diagram and having a degree of protection IP2XC seal off the fronts.

2.5 An integrated relay and related CTs are used for tripping of the circuit breaker.

2.6 The switch disconnector and earthing switch shall have padlocking facility from maintenance point of view.

2.7 Circuit Breakers shall use vacuum bottles as interrupters of the currents. The circuit breaker main circuit should be connected in series with a disconnector switch for isolation purpose.

5.0EARTHING SWITCH

Earthing switches shall be rated equal to the switchgear rating. Earthing switches shall be quick make type capable of making full Rated Fault Current. Earthing switch shall be operated from the front of the cubicle by means of a removable handle. The earthing Switch shall be interlocked with the isolator and cable cover for the safety of the operator.

6.0BUSBARS

Comprising the 3 single phases copper busbars and the connections to the switch or circuit breaker. The busbar shall be integrated in the cubicle. Busbars shall be rated to withstand all dynamic and thermal stresses for the full length of the switchgear. The busbars shall be inside the SF6 gas chamber made of 3-mm stainless steel sheet.

7.0CABLE COMPARTMENT

It shall be possible to terminate 11kV, armoured, aluminium conductor, 3Cx300 sq. mm. HV cables.

The access to the compartment shall be possible by removing the arc proof cable cover, bolted to the main frame.

Each module shall have a separate cable compartment that is segregated from each other by means of a partition wall. A partition wall shall be fitted to divide the cable compartment from the rear side of the switchgear. In case of an arc inside the tank, followed by the opening of the pressure relief, the partition wall prevents the hot gases flowing out from the pressure relief to enter the cable compartments.

The ground continuity shall be achieved when the covers are in place by means of bolted connections.

The cable covers shall be interlocked to the corresponding earthing switch of the module.

8.0 ACCESSORIES:

All the required accessories in the each module shall be provided. Some for the Accessories are list as below:

(i) Cable Support Bars

(ii) Short Circuit Indicator

(iii) Cable boots

(iv) Manometer for SF6 pressure/density monitoring

(v) Emergency trip push button

(vi) Lifting Lugs

(vii) Aux. Switch for circuit breaker Position

(viii) Aux. Switch for disconnector position

(ix) Aux. Switch for Earth switch position

ANNEXURE - II

RATINGS AND REQUIREMENTS

1.0

RING MAIN UNIT SWITCHGEAR 11KV

1.1 General

Type

:SF6 Insulated Ring Main Units

Service, Enclosure

:Out door, IP-52

1.2 System

Voltage

:11kv 10%

Phase, Frequency

:3, 50 Hz 5%

System ground:Non-effectively earthed through

resistance

1.3 Rated Current

Cable Switch Module

:630 Amp

Vacuum Circuit Breaker Module:630 Amp

1.4 Short Circuit Rating (for 3 Sec.)

Cable Switch Module

:21 KA for 3 sec.

Vacuum Circuit Breaker Module:21 KA for 3 sec.

1.5

Insulation Level

:95/28 kV (peak/r.m.s.)

1.8

Breaking Current

:To be indicated at 11KV

1.9

Making Current

:To be indicated at 11KV

ANNEXURE-III

SINGL LINE DIAGRAM FOR SF6 INSULATED RING MAIN UNITS

SF6 RMU HAVING 4 NOS. CABLE SWITCHES

SF6 RMU HAVING 1 NO. CABLE SWITCH & 1 NO. VCB MODULE