83/MID/AN

Repairs to 2.5 MVA HT Transformer 33/6.6 kV (Unit-I) of LIS Rajal by way of transportation including loading of 2.5 MVA capacity, damaged HT Electric Transformer 33/6.6 kV at site Rajal with the help of suitable capacity Hydra Crane and trailer truck suitable to manoeuvre at site and transport the same through road to workshop, unloading, loading at workshop after repairs, despatch and unloading/stacking at required platform at site Repairs to APEX make 2.5 MVA capacity, three phase, 33KV/6.6KV, oil natural air natural cooling, Vector group Dyn 11, no load voltage (HV-33KV & LV-6.6 KV), current on HV side- 43.738 Amperes & 218.7 Amperes on LV side, Maximum temperature rise in oil 50ºC, frequency 50 HZ, Impedance Voltage 6.556% installed at electric substation of LIS Rajal. The job includes opening of top cover, extraction of transformer assembly out of the housing, Complete dismantling of transformer assembly & allied parts and draining out of insulating oil safely into barrels. Providing & fitting of new coil out of EC grade copper with insulation HT coil (i.e 228 Kg), checking of LT coils, assembling & making of connections by new EC grade copper of new pre-heated coils on HV & LV side as well. Assembly of core, core- coil assembly. Providing and in laying in position of tapping connections by way of brazing with silver brazing rods including properly insulated tap leads dressed with insulation paper. Baking of re-wound transformer assembly in heating chamber till Specified/ proper IR value is achieved. Cleaning of transformer tank from out -side & in- side as well to make it free from slag, dirt, and other unwanted deposits/ suspensions. In-side painting of transformer tank with hot oil resistant paint. Boxing up of Transformer with re-wound transformer assembly and complete connected accessories by providing and fitting of new HT bushings assembly (1 No.), HT terminal plate, gaskets, fasteners, and connected sundries. Out-side painting of transformer tank with two coats of red oxide followed by two coats of synthetic enamel after proper surface preparation. Providing & fitting of new breather assembly including silica gel and oil drain valve in place of old unserviceable one. Filling of new T.oil in transformer (2200 ltrs) after draining out the old/uesd transformer oil from the transformer tank ( approx. 2000 ltrs) with the required BDV value and Di- electric strength upto specified mark inside conservator. Shop testing of transformer for permissible magnitudes of all connected parameters. The job also includes Servicing of oil type OLTC (on load tapping changer) by way of cleaning of contacts and pits if any, oil sludge removal, adjustment of springs, checking of motor drive operation, wiring, insulation rods for its proper mechanical & electrical strength and separation/barrier plates. After cleaning of contacts, the contact resistance to be checked to ensure proper cleaning/contact. All lugs/crimping at OLTC taps to be checked and re-crimped, checking of oil surge relay and papers of all tapping leads. Complete job including cost of material, labour and testing, the complete job includes making of electric connections on HV Side & LV side by way of cleaning of bus-bars at site, providing and fitting of new thimbles, nuts, bolts and washers. Making of earth connections after testing of earth resistance value. Field testing of transformer for all connected functional parameters on no load as well on load conditions, checking for noise/humming Complete job including the cost of material, hire charges of machinery/tools & tackles and labour charges etc

PERFECT ELECTRICAL WORKS

BEE AAR ENTERPRISES