8362 REPAIR/OVERHAULING OF FREQUENCY CONVERTOR NO.1, 1000KW/1250KVA AT C NO 67 FOR CRUISER WHARF AT NAVAL DOCKYARD UNDER GE (NW) KUNJALI, MUMBAI

M&L for decoupling of motor and generator at site by disconnecting incoming and outgoing cable of capacity 1250 KVA, 1800 RPM, 6.6 KV set. The work envolves removal of pedestral bearing machines including shims ie thin liners of sheet metals of various thickness under pedestral bearing and the feet of the stator frames. Proper diagrams and marking on the shims should be recorded as a guide. Levelling must be carried out very accurately, as the success full operation of the machine depending largely on the correct installation of the bearing/machine complete all as specified and directed.

M&L for shifting of motor and generator of capacity 1250 KVA, 6.6KV set from dockyard to workshop within 100 km on heavy duty loader for complete overhauling of FC set complete all as specified and directed by Engr-in-Charge.

M & L for dismantling of motor and generator and excitor stator rotor for repairing/ overhauling. Removal of the bearing pedestral from its position after putting the necessary shims. Removal of the upper half of the bearing, the rotor will be supported by the crane hook on the coupling side till the nuts are loosened carefully removal of the oil rings, the rotor will be carefully removed. Proper cleaning of the pedestral bearing oil well before reinstallation and lower half of the bearing should be cleaned properly, The bearing will be placed in position and coated with oil complete all as specified. Note: (i) During working on stator frames comprising of the following: The appropriate shims in the feet of the stator frames will be placed in position, dismantling/reinstalled of stator frames insttalled from the base plate as per record/drawings. Placing of board packing in the air gap between rotor and stator in order to avoid damages to them while transportation.(ii) During working on dowel pins and comprising of the following: While reinstallation of machines on site it will be ensure that the existing dowel holes in the stator frames and bearing pedestral to the base plate will be in the correct position and alignment.It will be ensure that all dowel holes are in one line for correct alignment of the parts. (iii) During working on bearing and rotor which comprising of following: To prevent the damage of the bearing insulating shims under the padestral will be provided to avoid damages due to shaft currents. The insulating shims will be placed next to steel shims. The FC should be provided with insulating holding down steel bolts of appropriate size.

The M&L for overhauling of 1250 KVA, 1800 RPM, 6.6 KV FC set by the authorised dealer/OEM as per the following maintanance schedule:- (i) Check all fans/blowers for proper working/functioning. (ii) Check all the door locks/interlocking system for proper functioning. (iii) Check all the indication lamps/lights working or not. (iv) Check the emergency stop switched. (v) Check any abnormal sound/noise from the rectifier. (vi) Cleaning of the equipment and associated switchgear. (vii) Check all the sensors. (viii) Clean the equipment carry out dust cleaning with blower. (ix) Check ACB/MCCB contactors and tight. (x) Check and clean all the contacts with CTC for proper working/functioning. (xi) Check voltage and current potentiometer for proper working. (xii) Check all the bus bar fittings. (xiii) check and tighten the rectifier bridge fittings. (xiv) Check built in meter, SPP, OL system etc.(xv) calibration of the meters. All electrical meter are to be calibrated by authorised agency and certificate to be produce to user. (xvi) All safety equipment to be calibrated and tested for its satisfactory functioning.

M&L for following static test of winding using special tools test jigs as per manufacturer recommendation: (i) Insulation resistance of winding (ii) Winding resistance (iii) surge comparision test (iv)Polarization index test etc

M&L for conducting of following test on all winding of motor generator, exciter stator and rotor of 1250 KVA FC Set, 6.6KV, 1800RPM, complete all as specified and directed by Engr-in-Charge. (i) Dry ice (CO2) cleaning of winding of FC motor generator, exciter stator and rotor. (ii) pre-heating of windings in oven of FC motor generator, exciter stator and rotor. (iii) varnishing of all windings of FC motor generator, exciter, stator and rotor . (iv) curing of winding in oven of FC motor generator, exciter, stator, stator and rotor,

M&L for dynamic balancing of generator rotor, synchronous motor rotor and exciter rotor, record of reading on all sides of rotor for proper alignment complete all as specified and directed by Engr-in-Charge.

M&L for white metal relining of 01 Nos pedestal type journal sleeve bearing with spherical seating . The thickness of white liner is 3.1 mm complete all as specified and directed by Engr-in-Charge.The white lining process for bearing is a meticulous procedure that envolves preparation tin plating, melting and pouring the white metal, cooling machining and thorough inspection. The composition of white metal alloy is critical and varies depanding on the application with tin based. It ensuring the longevity and efficiency of the bearing by providing low friction surface.

M&L for repair of slip ring for generator and motor of current rating 230 Amps made out of mild steel shrunck on to an epoxy glass insulated steel sleeve which is pressed on to the shaft. The brush gear is fixed to the adjuscent bearing pedestral. The bushes are held in contact with the slip ring under adjustable spring pressure suitable for FC 860KW, 600RPM, 6.6KV as per the existing gauge and size including cutting of helical grooves on the surface of sliprings complete all as specified and directed by Engr-in-Charge.

M&L for Re-assembly of motor generator & exciter unit of FC convertor 6.6KV, complete all as specified and directed by Engr-in-Charge. Note: (i) During assembling the machines, the air gap must be checked very carefully for eccentricity which should not be more than 5% of the avarage air gap.(ii) The frame should be effectively earthed by a connection of substantial cross section which should be mechanically and electrically sound.(iii) A careful inspection of the machine should be made before first running up. The connection should be tallied with the connection diagram supplied with each machine and all electrical connection tightened firmly. Checking of all clearance between live parts and earth. The bearing should be filled with oil to the correct level and oil ring should be revolves freely when the machine is running.(iv) The pedestral bearing oil well should be cleaned before reinstallation and lower half of the bearing should be cleaned, placed in position. The oil ring should be put in position and the top halves of the bearing liner should be oiled and assemble after checking that the oil rings revolve freely, insert the coupling bolts into the half cuplings and tighten the coupling side till the nuts are tightened.