techinical specification for 33/11kv onan power ... - Cescoorissa.com

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) By direct metal to metal contact with the tank base.c) By a connection to the structure on the same side of the core as the main earth connectionto the tank.7.5.3 The magnetic circuit shall be connected to the clamping structure at one point only and thisshall be brought out of the top cover of the transformer tank through a suitably rated insulator.A disconnecting link shall be provided on transformer tank to facilitate disconnections fromground for IR measurement purpose.7.5.4 Coil clamping rings of metal at earth potential shall be connected to the adjacent coreclamping structure on the same side as the main earth connections.7.6 WINDING7.6.1 Winding shall be subjected to a shrinking and seasoning process, so that no further shrinkageoccurs during service. Adjustable devices shall be provided for taking up possible shrinkagein service.7.6.2 All low voltage windings for use in the circular coil concentric winding shall be wound on aperformed insulating cylinder for mechanical protection of the winding in handling andplacing around the core.7.6.3 Winding shall not contain sharp bends which might damage the insulation or produce highdielectric stresses. No strip conductor wound on edge shall have width exceeding six times thethickness.7.6.4 Materials used in the insulation and assembly of the windings shall be insoluble, non catalyticand chemically inactive in the hot transformer oil and shall not soften or the otherwiseaffected under the operating conditions.7.6.5 Varnish application on coil windings may be given only for mechanical protection and not forimprovement in dielectric properties. In no case varnish or other adhesive be used which willseal the coil and prevent evacuation of air and moisture and impregnation by oil.7.6.6 Winding and connections shall be braced to withstand shocks during transport or short circuit.7.6.7 Permanent current carrying joints in the windings and leads shall be welded or brazed.Clamping bolts for current carrying parts inside oil shall be made of oil resistant materialwhich shall not be affected by acidity in the oil steel bolts, if used, shall be suitably treated.7.6.8 Terminals of all windings shall be brought out of the tank through bushings for externalconnections.7.6.8.1 The completed core and coil assemble shall be dried in vacuum at not more than 0.5mm ofmercury absolute pressure and shall be immediately impregnated with oil after the dryingprocess to ensure the elimination of air and moisture within the insulation. Vacuum may beapplied in either vacuum over or in the transformer tank.7.6.8.2 The winding shall be so designed that all coil assembles of identical voltage ratings shall beinterchangeable and field repairs to the winding can be made readily without specialequipment. The coils shall have high dielectric strength.7.6.8.3 Coils shall be made of continuous smooth high grade electrolytic copper conductor, shapedand braced to provide for expansion and contraction due to temperature changes.7.6.8.4 Adequate barriers shall be provided between coils and core and between high and low voltagecoil. End turn shall have additional protection against abnormal line disturbances.46
7.6.8.5 The insulation of winding shall be designed to withstand voltage stress arising from surge intransmission lines due to atmospheric or transient conditions caused by switching etc.7.6.8.6 Tapping shall not be brought out from inside the coil or from intermediate turns and shall beso arranged as to preserve as far as possible magnetic balance of transformer at all voltageratios.7.6.8.7 Magnitude of impulse surges transferred from HV to LV windings by electro magneticinduction and capacitance coupling shall be limited to BILL of LV winding.7.6.8.8 The current density adopted in all winding shall not exceed 2.4 A/mm2. The total netcross sectional area of the strip conductors for calculating current density for eachwinding shall be obtained after deducting the copper area lost due to rounding up of thesharp edges at the rectangular conductors.7.7 INSULATING OIL7.7.1 The insulating oil for the transformer shall be of EHV grade, generally conforming to IS: 335.No inhibitors shall be used in the oil.7.7.2 The quantity of oil required for the first filling of the transformer and its full specificationshall be stated in the bid. The bidder shall quote the price of transformer complete withall fittings, accessories and new transformer oil required for first filling plus 10% extraoil. The extra quantity of oil shall be supplied in non-returnable drums along with the oilrequired for the radiator banks.7.7.3 The design and materials used in the construction of the transformer shall be such as to reducethe risk of the development of acidity in the oil.7.7.4 The contractor shall warrant that oil furnished is in accordance with the followingspecifications.S.No Characteristic Requirement Method of Test01 Appearance The oil shall be clear &transparent & free fromsuspended matter or sediment02 Density at 20 0 C 0.89 g/cm 3 Max. IS:1448...... Kinematic Viscosity at 27 deg. 27 CST IS:1448C Max04 Interfacial tension at 27 0 C 0....... N/m IS:6104Min.05 Flash Point 136 0 C IS:144806 Pour Point Max. -6 0 C IS:144807 Nautralisation Value (Total 0....... mg KOH/gm IS:335Acidity) Max.08 Electric strength Breakdown 72.5 KV IS:6792(voltage) Min.09 Dielectric dissipation factor tan 0....... Max IS:6262delta at 90 0 C10 Min specificresistance(resistively) at 90 0 C35X10 12 ohm cm (min.) IS:61......47A representative sample ofoil shall be examined in a100 mm thick layer atambient temp.
Page 2: CENTRAL ELECTRICITY SUPPLY UTILITY
Page 6 and 7: ,5.0 Schedule of Requirements & Del
Page 8 and 9: SECTION -IIINSTRUCTION TO BIDDERS (
Page 10 and 11: 5. BIDDING DOCUMENTS:5.1 The Scope
Page 12 and 13: 9.2.3 The bid security shall be in
Page 14 and 15: 16.3 The Bid shall contain no inter
Page 16 and 17: 24. PRELIMINARY EXAMINATION OF BIDS
Page 19 and 20: SECTION -IIIGENERAL TERMS AND CONDI
Page 21 and 22: 2.06 “Month” shall mean the cal
Page 23 and 24: 8.0 QUALITY ASSURANCE PLAN:8.1 The
Page 25 and 26: 10.0 PACKING AND FORWARDING:The equ
Page 27 and 28: 15.0 Deviation from Specification:I
Page 29 and 30: 22.02 The bidder shall quote the ba
Page 31 and 32: Force Majeure shall not include occ
Page 33 and 34: SECTION- IVTECHINICAL SPECIFICATION
Page 35 and 36: 6 Type of mounting On Wheels, Mount
Page 37 and 38: iii) Transformer shall under except
Page 39 and 40: performance of power transformers a
Page 41 and 42: 6.6 Internal design of transformer
Page 43 and 44: 6.13.7.2 Each coat of paint shall a
Page 45: 7.4.4 ( C ) For those bidders, who
Page 49 and 50: vii) All applicable routine and typ
Page 51 and 52: iii) The marshalling box shall acco
Page 53 and 54: xxiv)xxv)xxvi)xxvii)b) Air release
Page 55 and 56: Govt. Approved Laboratory, if the t
Page 57 and 58: 8.2.1 Type Testb) Oil leakage test
Page 59 and 60: The Engineer authorized from CESU a
Page 61 and 62: 9 LIQUIDATED DAMAGES FOR EXCESSIVE
Page 63 and 64: SECTION -VLIST OF ANNEXURES( SCHEDU
Page 65 and 66: ANNEXURE - IIPROFORMA FOR COMPOSITE
Page 67 and 68: Annexure- IIIPrice Schedule for 5 M
Page 69 and 70: Tender Specification No. . CESU /P&
Page 71 and 72: Tender Specification No . CESU /P&S
Page 73 and 74: Tender Specification No . CESU /P&S
Page 77 and 78: Sl.NO.Tender Specification No. CESU
Page 81 and 82: ANNEXURE V (A)(TECHNICAL DEVIATION
Page 83 and 84: ANNEXURE VI(PERFORMANCE OF MATERIAL

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