To carryout urgent repairs to CRS Sub Station step down transformer of capacity 500KVA

M&L for disconnecting carefully electrical connection from both HT/ LT (primary & secondary) sides of the transformer, keeping them at safe side and taking out the transformer of capacity 500 KVA, 11 KV/ 0.433 KV, step down transformer for carrying out complete overhauling which shall comprise of the following:- a) M&L for lifting, transporting, handling, the transformer to workshop and opening top cover of the transformer by unscrewing nuts, bolts, washers etc. including disconnecting core assembly from HT/ LT bushing and lifting the same gently and taking out from the shell (container/ body) of the transformer. b) M&L for draining out transformer oil from the above said transformer in the suitable capacity of container /drums and keeping it in safe custody for reuse. c) M&L for cleaning the transformer body from inside, removing deposited dirt/ sludge/ foreign particles etc. from the bottom/ body of the transformer and drying up the shell from inside before refilling of the transformer oil. d) M&L for cleaning and washing thoroughly core and windings of the transformer by hosing down with clean dry oil( without moisture) conforming to IS 335/1983, removing deposited dirt/sludge/foreign particles from the windings/ core, thorough inspection of windings, providing insulations to leads and terminals, heating/ drying/ baking complete carefully and thoroughly inside the heating chamber at suitable temperature to obtain required value of insulation resistance etc. all as directed by Engr-in- charge. e) Lifting and refixing core assembly inside the transformer shell gently and carefully, connecting primary/ secondary/ Neutral connections to the bushings assembly, fixing of tap change over including tightening of nuts, bolts, washers of the core to reduce humming noise all as directed. f) Refilling the filtered transformer oil in the shell of transformer complete & topping up of the transformer oil complete. g) Refixing the top cover including replacement of cork sheet/ gasket 8mm thick, tightening of nuts/ bolts/ washers etc. and replacement of breather with silica gel crystal type all as directed by Engr-in charge. h) Lifting/ shifting to the place from where removed or to any location as directed and re-installing the transformer including connecting primary/ secondary/ neutral and earthing connections etc. all as directed by Engr-in-Charge. j) The inspection of transformer shall involve:- i) Checking of all clamps, nuts, bolts including core bolts & cover fixing bolts. ii) Checking all brazings, joints, tap heads and connection joints. iii) Checking all jumpers, terminations/ connections inside the transformer. iv) Painting of transformer complete with two coats of synthetic enamel paint externally transformer shell complete all as directed by Engr-in-Charge. (v) Inspection of tap changer, checking the moving and fixed contacts for contact wear and connection to winding. k) Conducting the tests on core and windings as per IS like ratio, short circuit etc. in presence of Engr-in-Charge. Note:- (i) Any damage to insulators/ bushes/ windings etc. while in the custody of the contractor shall be made good at no extra cost to Department. The serviceability of the transformer shall be checked and confirmed by the contractor before taking into his custody. (ii) M&L for rewinding/ re-insulation of HT/ LT (primary/ secondary) coils, bushes, studs, top up of Transformer oil if any etc will be measured and paid separately.

M & L for Filtration of transformer oil of transformers to achieve di-electric strength not less than 60 KV at 2.5mm gap as per relevant IS with portable filtration plant, testing of the oil for the di-electric strength before filtration and after filtration and submit the same signed by both contractor and Engineer in Charge and kept on record complete all as directed.

Supply and topping up of transformer oil with di-electric strength not less than 60 KV in to the conservator tank/ body tank of the transformer complete all as directed. [Make: Poweroil/ Transol/ Sabitha Chemicals]

M&L for rewinding of distribution (HT/LT) transformers of capacity 315 KVA by winding the defective coils with new copper wire as per I.S. of same gauge and existing size together with new insulated materials/ bracings before placing in to the transformer and assembling the coil with new insulation and fitting the coils in the chamber, testing and commissioning the transformer and recording the test results complete all as directed. [Note: M&L for re-insulation of serviceable coils will be measured & paid separately under relevant items.]

M&L for re-insulating windings of distribution transformers of capacity 315 KVA, removing the old defective insulation paper and replacing with new DPC insulation to the copper conductor, re-varnishing of the windings with super varnish including heating/ drying/ backing complete carefully and thoroughly inside the heating chamber at suitable temperature to obtain required value of insulation resistance etc. all as per IS 1986-87 and as directed.