SPECIFICATION FOR 220 kV STATION CLASS SURGE …

1 _____ 220kV Page 1 of 8 SPECIFICATION FOR 220 kV STATION CLASS SURGE ARRESTERS A. system information A-1 system conditions The networks are mainly of outdoor type. The basic parameters are set out below: Nominal system voltage between phases kV 220 Earthing of neutral at transformers Solid system earthing Effectively earthed system Frequency Hz 50 system highest voltage kV 245 Symmetrical short circuit current at rated voltage RMS (ultimate) kA 25/40 Impulse withstand voltage Main Transformer kV 950 Impulse withstand voltage Other Equipment kV 1050 Power frequency voltage (1 min.)- Main Transformer kV 395 Power frequency voltage (1 min.)- Other Equipment kV 460 A-2 Minimum Substation Clearances Air insulated outdoor and indoor busbars and connections shall have electrical clearances as listed in the following table.

2 - Highest system voltages between phases kV 245 Minimum clearance between live metal and earth mm 2200 Minimum clearance between live metal of different phases mm 2200 Minimum safety clearance between the nearest point not at earth potential of an insulator to ground (Pedestrian Access) mm 2300 Minimum safety clearance between live metal and positions to which access is permissible with other conductive equipment mm 4500 _____ 220kV Page 2 of 8 A-3 Pollution levels of Insulators and Bushings 25 mm/kV (Pollution CLASS III) A-4 Service conditions The following service conditions shall be taken into account in designing of material and equipment. (a) Altitude above sea level < 1000 m (b) Max. ambient air temperature 40 C (c ) Max average daily temperature 30 C (d) Lowest Ambient temperature +5 C (e) Max.

3 Solar radiation 1000 W/m2 (f) Mean monthly solar radiation 425 W/m2 (g) Max. Relative humidity ( 24 hrs) 90 % (h) Isokeraunic level 60 -80 days/an (i) Mean wind velocity (24 hours) 65 km/hours (j) Annual rainfall up to 5250 mm (k) system Highest voltage 245 kV {as applicable} (l) system Earthing , 132kV Direct B. MINIMUM REQUIREMENTS FOR MANUFACTURERS The bidder shall ensure, that each equipment offered , is manufactured by a manufacturer with a minimum of ten (10) years successful experience in manufacturing comparable equipment, in rated voltage and capacity, to the equipment offered under the contract.

4 If the offered equipment is manufactured under license, the service experience of equipment manufactured by the parent company shall not be counted as service experience of the licensee equipment. Bidder shall provide adequate evidence of compliance to above requirements to the satisfaction of the C E B . Bids non-complying with above requirements or with incomplete evidence of compliance would be rejected. _____ 220kV Page 3 of 8 C. TECHNICAL SPECIFICATIONS C-1 The 220 kV STATION CLASS Gapless SURGE Arrestors (for outdoor use) shall be of the metal oxide type using Zinc oxide resistor blocks of non linear characteristic without air gap. They shall comply IEC 99-4 and shall be entirely suitable for operation under the system conditions specified; including system voltage rises on unloading long transmission lines and shall have sufficient capacity to discharge system charging currents without damage.

5 C-2 it is expected to use these SURGE arrestors at the line end and near the HV power transformers. The present SURGE arrestors have a center to center distance of 3m in the switch yard and transformer bay. The SURGE arrestor shall be capable or resealing against the maximum transient over voltage (TOV). C-3 The SURGE arrestors shall be connected between each phase and earth in a three-phase system . C-4 The active element shall be housed in a gas tight insulator of polymer compound. The creepage distance shall be minimum 25 mm/kV phase to phase based on the rated voltage of the system . C-5 The SURGE arrestors shall be equipped with a grading ring. If necessary, an internal grading system may control the voltage distribution along the metal oxide resistor stack.

6 C-6 A pressure relief device shall prevent damage by overpressure and discharge counters shall be provided to indicate number of operations for each arrestor. C-7 SURGE arrestor shall be of heavy duty type. Connection to ground shall be by copper cable via a SURGE counter. A suitable SURGE counter shall be provided with the arrestor. C-8 SURGE arrestor shall withstand maximum local wind force and conductor forces. The arrestors will be mounted vertical upright. C-9 The quality of design and manufacturing process shall be assured in accordance with the ISO 9000 series standards. Relevant ISO certificates shall be furnished with the offer. _____ 220kV Page 4 of 8 D. APPLICABLE STANDARDS The equipment and the components supplied shall generally be in accordance with the standards specified below or later editions and/or amendments thereof: D-1 IEC 99-4 - Metal oxide SURGE arrestors without gaps for ac system .

7 D-2 ISO 9000 series for design, manufacture and quality control. D-3 IEC 61166/IEE693 - Seismic acceleration withstand E. TERMINAL & NAME PLATE E-1 Suitable terminals shall be provided to connect to the existing line. Existing system has two wires of 30mm at each terminal end. Standard type of terminal shall be offered. E-2 All the rated data of the complete SURGE arrestor shall be given on the main rating plate. The individual unit shall have individual rating plate with rated data of that unit. The rating plate shall be attached to the SURGE arrestor base. E-3 If the supplier is granted the offer, the General Arrangement Drawings including nameplate drawing shall be produced for review, before starting the manufacturing process.

8 F. TESTS. F-1 Type tests. Following Type test reports of similar SURGE arrestors according to the requirements set out by the latest edition of IEC recommendations 99-4 shall be forwarded with the offer. 1. Insulation withstand test 2. Residual voltage test 3. Long duration current impulse withstand test 4. Operating duty test 5. Pressure relief test 6. Tests of arrestor disconnections 7. Artificial pollution test 8. Partial discharge test _____ 220kV Page 5 of 8 9. Seal leakage test 10. Current distribution test for multi column arrestor The type tests shall be carried out for a sample manufactured at the same workplace where the offered equipments are manufactured. The type tests shall be carried out by an independent and internationally recognized testing institute for HV equipments.

9 F-2 Routine Tests In addition the manufactured arrestors shall be routine tested according to the IEC standard 99-4 and shall be forwarded with the delivery. All the test reports shall be in English. G. PACKING AND DELIVERY G-1 Packing. G-1-1 Precautions shall be taken to ensure that the equipment is safe for transportation by sea. G-1-2 Packing in cases shall be so carried out that there will be no movements of the contents. G-1-3 Each crate or package shall contain a packing list in a waterproof envelop and copies in triplicate shall be forwarded to CEB prior to dispatch. G-2 Delivery Delivery period shall be approximately 16 weeks after opening the LC. Clearing and transport to the site will be done by CEB. H. ERECTION AND MAINTENANCE. H-1 Erection and Commissioning of the SURGE arrestors will be done by CEB staff.

10 H-2 A complete erection manual in English which shall comply with IEC/ IEEE standard together with drawings of the complete SURGE arrestor and counters shall be supplied. Any clarification that will be required during erection shall be provided free of charge. _____ 220kV Page 6 of 8 H-3 Complete erection, operation, maintenance and dismantling instructions including mechanical drawings with details such as high voltage terminal drawings, earth terminal details, details of the mounting plate, details of the name plate, bolt torque, etc. shall be furnished with the offer. H-4 The operating and maintenance manuals together with all relevant drawings and circuit diagrams shall be supplied. I. VALUES AND DATA. Attached as Annex A. J. WARRANTY Warranty period of at least 18 months after delivery or one year after commissioning against design and manufacturing defects shall be applied for all the equipment supplied under the Bid.