SPECIAL REPAIR/ REPLACEMENT OF CERTAIN (E/M) EQUIPMENT AGAINST BER UNDER GE (AF) SURATGARH

Disconnect the existing transformer from both HT and LT sides after obtaining the necessary shutdown. Carefully dismantle and lift the existing transformer using a suitable capacity crane, transport it, and deposit it at the designated MES yard. Demolish the existing reinforced cement concrete (RCC)/PCC transformer foundation, remove all demolished debris from the substation premises to an approved dumping location, and clean, dress, and level the area, making it ready for construction of the new transformer foundation. The quoted rate shall include all labour, T&P, lifting equipment, transportation, loading, unloading, disposal of debris, and all incidental works required for complete execution of the job

Supply, installation, testing and commissioning of platform mounted outdoor type Step-down Power Transformer, copper wound, as per IS:2026 & IEC:60076-1:2000, 33/11 kV, 5 MVA, ONAN, 3 Phase, 50 Hz, double copper wound, core type with low loss, non-ageing, high permeability, prime grade CRGO core material, better with BIS Certification, having Dyn11 vector group and Off Circuit Delta/Star vector. Equipped with ON LOAD Tap Changer (OLTC) on HV side to vary secondary voltage from (+5)% to (-10)% in 12 steps @ 1.25%. The OLTC shall conform to IS 8468 / IEC 60214 (Part 1 & 2). The 33 kV HT and 11 kV LT bushings shall be provided. The transformer shall be compatible to get the data on SCADA through communication port. The insulating oil shall be unused inhibited Type-A, High Grade conforming to IS 335 / IEC 60396:2020. The transformer shall be designed with particular attention to the suppression of voltage distortions induced in the windings by external disturbances and any possibility of high frequency disturbances, inductive effects or circulating currents between neutral points of different transformer stations reaching such a magnitude as to cause interference with communication circuits. The transformer shall be provided as specified, installed, tested and commissioned complete.

(i) Float Feed Type Buchholz Relay (gas operated) with shut-off valves at both ends, complying with IS:3637, 50 mm, with two pairs of electrically separated contacts, one pair for alarm and other pair for tripping. The angle of inclination shall be 3° to 7°. (ii) Range temperature indicator 150 mm diameter for top oil temperature indication with angular sweep of 270°. Temperature range shall be 0–150°C with accuracy of ±1.5% (or better) of full-scale deflection, with alarm and trip contact. (iii) Winding temperature indicator about 150 mm diameter for measuring the hot spot temperature of each winding (HV, IV & Tertiary if applicable). It shall have angular sweep of 270°. Range of temperature shall be 0–150°C with accuracy of ±1.5% (or better) of full-scale deflection, with electrical contacts for alarm and trip contacts. (iv) Sheet steel weather proof Marshalling box of IP-55 construction and shall have following load disconnect switch for incoming power supply from auxiliaries, wiring and termination individually for Buchholz relay alarm for main tank, winding temp high alarm, oil temp high alarm, tank oil level low alarm, tap changer complete alarm, wiring and termination individually of remote trip alarm, winding temp high trip, oil temp high trip, Buchholz relay trip or sudden gas and sudden oil pressure relay trip, cubicle illumination lamp with door switch and space heater with thermostat and ON/OFF switch. (v) Magnetic oil level gauge with low level alarm contact.

(vi) Pressure release valve (PRV) with trip contacts. (vii) Conservator with oil filling hole with cap and drain plug and with built-in diaphragm to avoid direct air contact with transformer oil & diaphragm rupture detection relay. Conservator tank shall be provided with two separate compartments (with partition barrier), one for main transformer tank and other for OLTC compartment. (viii) Magnetic oil level indicator, 150 mm dia with minimum level marking. (ix) Thermometer pockets with thermometer. (x) Silica gel breather with silica gel. (xi) Air release plug. (xii) Lifting lugs. (xiii) Earthing terminals. (xiv) Bi-directional rollers – 4 Nos. (xv) Anodized aluminum rating and diagram plate. (xvi) Top filter valve. (xvii) Bottom drain-cum-filter valve. (xviii) Jacking lugs. (xix) Insulation level / KV Peak – HV: 325 KV and LV: 75 KV. (xx) Insulation level (power frequency withstand) – HV: 140 KV, LV: 28 KV. (xxi) Impedance losses at rated voltage. (xxii) Single float Buchholz relay / oil surge relay with alarm contact for OLTC.

(xxiii) No load losses and load losses at rated voltage and frequency. Not more than 40 kW. (xxiv) % Impedance at 75°C (Refer Clause 3.3.1.4.1 and refer Table 7.15). (xxv) For electrical operation of OLTC from local as well as remote, motor operated mechanism shall be provided. The tap changer shall be provided with over-current protection to prevent the tap-change operation during a system fault. The motor drive mechanism shall be designed to ensure that once OLTC control and indication. The diverter switch or arcing switch shall be designed to ensure that its operation once commenced shall be completed independently of the control relays or switches, failure of auxiliary supplies etc. to prevent any contingency which may result in incomplete operation of the current switch, adequate means shall be provided to safeguard the transformer and its ancillary equipment. The current diverter contacts shall be housed in a separate oil chamber not communicating with the oil in main tank of the transformer and the chamber shall be designed to withstand the vacuum. It shall be complete with the following: (a) Circuit breaker/Contactor with thermal overload devices for controlling the AC Auxiliary supply to the OLTC motor. (b) Emergency Push Button to stop OLTC operation. (c) Cubicle light with door switch. (d) Anti-condensation metal clad heaters to prevent condensation of moisture. (e) Pad locking arrangement. (f) All contacts, relay coils and other parts shall be protected for long-term operation against corrosion, deterioration due to condensation, fungi etc. (g) The cabinet shall be tested at least IP55 protection class.

(xxvi) Remote tap changer control panel (RTCC). (xxvii) Automatic voltage regulator relay (AVR). (xxviii) Differential protection with LV side CT. (xxix) Installation outdoor type including plinth as per recommendation of OEM along with oil soak pit as per the latest IE Rules.

Earthing complete all shown as electrical plate No -05 of MES Sch part -I as specified with testing and as directed including the following. (i) Copper earth plate of size 600 x 600 x 3.0 mm thick burried directly in ground vertically to a depth not less than 2.25 mtr below ground level with top edge of earth plate at a depth not less than 1.50 metre below ground level. (ii) Earth plate surrounded by and packed with charcoal and common salt in alternative layers ( n.exc 15 cms each layer). (iii) 32x6mm copper strip from earth plate to test point by means of brazing, bolts, nut washers and check nut of brass and connected with test point of bronze all as directed. (iv) 20mm bore, medium grade, GI pipe for watering including GI funnel and wire mesh. Pipe shall be provided vertically upto top level of earth pit and then taken horizontaly to the earth pit. (v) 40 mm dia bore G. I. light grade pipe for protection of copper strip. (vi) Cement concrete chamber of PCC (1:3:6) type C-2 using 40mm graded crushed stone aggregate. The chamber shall be constructed one metre away from edge of earth pit. (vii) 50mm thick precast cover of cement concrete(1:2:4) type B-1 using 20mm graded crushed stone aggregate and MS angle iron 50x50x6mm frame including two coats of synthetic enamel painting over a coat of red oxide to exposed steel surfaces with suitable handle to lift the cover. (viii) Excavation in soft/loose soil, returning filling & removal of surplus soil to a distance of 50m as directed .Note :- Copper strip 32x6 mm at 7.5 mtr included in quoted rates.