e-NIT no.20 od 2023-24 dt. 31.08.2023

Amount

Replacement of worn-out components of 2.5 MVA 6.6 KV HT step less rolling type Regulator (AVR) by way of drawing out VCB from the breaker units for Isolating all the units from power supply. Disconnecting controlling supply and discharging stored power (if any). Draining out transformer oil from regulating unit. Dismantling top tank cover, extracting out hand wheel after disengaging the motor driver from the regulator disconnecting flexible cables from the tank terminal, lifting all the three limbs along with contact bar with the help of Crane and unloading the same to a safe working place near pump house, on the drop tray and allowing it to drain reasonably. Cleaning and smoothening the marked/pitted portion on the coils surface with ‘0’ grade emery cloth by rubbing gently around the coils surface in the direction of winding. Every precaution be taken that no copper /carbon dust is lodged between the turns of coils and that all copper/carbon dust produced is removed from coils surface and frame work with clear rags and white sprit. Refilling the drained transformer oil after de-moisturizing and topping upto required level by Providing/Filling of additional transformer oil (approx-240ltr.). Making all connection of flexible cables. Refitting of tank cover, motor box after replacing gasket. Draining out transformer oil from tank of main transformer (buck boost & step up / step down transformer) of AVR unit disconnecting all the connections of the control circuits. Dismantling explosion unit, conservation tank and top lid of the tank. Replacing the damaged insulators bush rods, bush cups etc. De-moisturizing of T-oil + topping with additional T-oil-160 ltr. (approx.) Refitting the top cover of explosion unit and conservation tank. Making all the connections of control unit circuit after proper thimbling inter connecting cables of main transformer and regulator unit. Replacement of 1 No. damaged electric relay for automatic sensing (PCB) with new one as per sample (provided) and P/F of new Limit switches B4C-2nos., Aux contactor-01 no, delay relay (TDR) in place of defective relay in the controller unit. Servicing/repairs to 6.6kv VCB of 2500KVA AVR by way of dismantling control circuit coupler connections, removing cover of breaker, servicing hand driven spring charging mechanism. Servicing of pilot motor of spring charging mechanism cleaning and smoothening of contact points, finger contact adjustment, oiling and greasing of mechanical moving parts. Replacement of 01 No. tripping coil with P/F of new coil as per sample. Complete checking of tripping & closing mechanism. Lubrication of gear teeth, contact surface of guide cam and trip latch, motor eccentric and eccentric roller. P/F of motor relay -01 No. in place of damaged relay. Job also includes replacement of damaged roller of breaker trolley. Job includes providing and fitting of 03 nos. 12 V battery cell and UPS for operating control panel of AVR Inserting breaker in its position properly. Improvement to reversing panel/ control panel by way of replacement of damaged indicators and defective wiring, and burnt/blown up HRC fuses. Tightening all the connection of control circuit. Complete job includes cost of material charges including additional oil provided for topping and parts replaced, labour charges, hire charges of Crane and other tools & tackles required for execution of job. Testing the AVR on full load.

M/S UK MECH AND ELECT ENGG WORKS

BEE AAR ENTERPRISES