MID/AN/08

Disconnecting power supply to APEX make 2.5 MVA capacity, three phase, 33KV/6.6KV, ONAN 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 50º C, frequency 50 HZ, Impedance Voltage 6.556% HT Electric Transformer and disconnecting all conductor/cables on its HT & LT sides and loading it onto suitable capacity trailer truck at site with the help of suitable capacity Hydra Crane(s) properly maneuvering at site and transporting the same through road to firm’s works, unloading the same for dismantling & for carrying out repairs to it. The job includes opening of top cover, extraction of transformer assembly out of the housing, complete dismantling of transformer assembly- core & damaged coils and allied parts at firm’s works; Fabrication and fitting of new HV coil out of EC grade copper with insulation (3-leg@228 Kg per leg/limb) in place of damaged coils of the limb/leg and of LV coils (3-legs@157 Kg per leg/limb) of transformer, assembling & making of connections by pre-heated coils on HT & LT side as well. Assembly of core, core-coil assembly. Brazing of coils with silver brazing rods including properly insulated & dressed with insulation paper. Baking of re-conditioned transformer core-coil 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 and In-side painting of transformer tank with hot oil resistant paint. Boxing up of Transformer with new and re-conditioned transformer core-coil assembly and complete connected accessories /gaskets, fasteners and connected sundries. Filling of new oil in transformer 2200 ltr. with the required BDV value and Di-electric strength up to specified mark inside the conservator. Providing & fitting of new breather assembly including silica gel, and oil drain valve in place of old unserviceable ones. Shop testing of transformer for permissible magnitudes of all connected parameters. Dispatching the repaired HT Transformer from firm’s workshop and unloading/stacking the same at designated platform at site, making of electric connections on HT Side & LT side by way of cleaning of bus-bars, providing and fitting of new thimbles, nuts, bolts and washers. Making of earth connections after testing of earth resistance value. Field testing of HT transformer for all connected functional parameters on load as well on no load conditions, checking for noise/humming temperature rise etc. and its commissioning. Complete job includes cost of material after deducting rebate on old unserviceable material, charges for skilled & semi-skilled labour, hire charges of machinery/tools & tackles with to and fro transportation charges etc.