Rewinding of 450 KW/ 610 HP, 3.3 kV, 1492 RPM Induction Motor of Dryer-B in NP Plant, FACT-CD, Ambalamedu.

Amount

Motor dismantling and flux loop testing: The work includes removing cooling fan cover and fan, Dismantling the motor, threading out the rotor from the stator core pack, inspection of stator/rotor/end overs/bearing cup assembling parts, stripping out of old stator windings, cleaning the stator slots, conducting flux loop tests on stator and rotor to find out the core damages.

Stator core restacking: The work includes mounting the stator body in hydraulic press, removing the core pack from stator body with special tools and machineries after heating the stator yoke with special heating arrangements, segregating the damaged stator core from core pack, removing the old burnt core plate varnishes by chemical treatment, cleaning, removing the surface kinks, replacing damaged core stampings with new one, varnishing the stampings in re-varnishing cum conveyor oven to cure the core plate varnish, staggering the core with special tools and machineries, locking and repositioning the core pack to the stator body by hydraulic press and finally conducting the flux loop test to ascertain the restacked core healthiness, cleaning and polishing the slots ready to feeding. Insulating and anti-corrosive coating shall be applied on slots, after cleaning. This work shall be executed after analyzing the stator flux loop test report, visual inspection and after getting approval from concerned engineer in charge. If partial re-staggering only required, the payment will be done proportionally.

Stator rewinding (3.3KV): The work includes rewinding the stator using of class `F’ enamelled double fibre glass covered electrolytic grade new copper conductors for rewinding coils as per the original shape and dimension by using special jigs and dies, insulating the slot portions using semicatherm insulating materials, molding the slot portion in hydraulic hot press, applying flexible insulation to the overhang portion, inserting the coils in to the slots, banding the overhang portions in the surge ring, fixing new bush insulator and Brass stud/washers/nut for termination, bracing, tinning, soldering, forming the end connection, preheating, doing vacuum pressure impregnation(VPI), curing, fixing heater coils and heater covers, wiring heater coils to the terminal block, applying finishing varnishes. Good quality, glass laminated (or superior) wedges shall be placed over the coils in slots. Suitable spacer (filler material) shall be inserted between coils at the overhang portion, to avoid vibration of individual coils. The contractor shall arrange new Bush insulator, Brass stud/washers/nut, 230V/250W heater coil and cover, thermal insulated wires for successful completion of the work. The brass nut shall have large contact area for terminating 120Sq.mm copper cable round lug.

Rotor Restacking: This work includes, machining the lock welding, shifting the rotor to hydraulic press, removing the core locks, lifting the core one by one with special fixtures, segregating the damaged rotor core from core pack, removing the old burnt core plate varnishes by chemical treatment, cleaning, removing the surface kinks, replacing damaged core stampings with new one, varnishing the stampings in re-varnishing cum conveyor oven to cure the core plate varnish, staggering the core with special tools and machineries, locking and repositioning the core pack to the rotor shaft, welding the locks in hydraulic press, conducting the flux loop test to ascertain the restacked core healthiness, cleaning and polishing the slots ready to feeding. This work shall be executed after analyzing the rotor flux loop test report, visual inspection and after getting approval from concerned engineer in charge. If partial re-staggering only required, the payment will be done proportionally.

Rotor Re-Barring: This work includes mounting the rotor in lathe, machining both side end ring, stripping out the damaged bars in bar removing machine using special tools and machineries, machining the new rotor bars & end rings made out of electrical conductivity grade copper, inserting the new rotor bars using special tools and machineries, positioning, locking, machining both side rotor bars for proper bedding of bars and end rings, brazing the bars and end rings using silver brazing rods, flux & oxy-acetylene gas and thermal protection materials, verifying the healthiness of the brazed joints before and after machining the excessive materials, cleaning dip varnishing the rotor with class ‘F’ varnish, baking, applying finishing varnish to the overhang portions. Damaged rotor bars and end rings shall not use for doing this work. This work shall be executed after getting approval from concerned engineer in charge.

Machining Rotor, bearing housing and end covers : This work includes inserting sleeves/machining for rotor shaft dimension correction, suiting bearings on end covers, bearing housing, inner grease cups and outer grease cups.

Rotor balancing: The work includes Fixing of inside cooling fan on rotor using new nut/bolt/star washer/spring washer, inserting outer cooling fan/coupling and doing dynamic balancing of rotor to balance quality grade of G2.5 at rated RPM. Anabond thread sealing compound shall be applied to the thread of bolts to avoid loosening due to vibration. This work shall be done after rotor repair work.

Motor cooling tubes repair works: This work includes replacing of damaged cooling tubes, cleaning, painting and testing. This work shall be executed on the basis of requirement and after getting approval from concerned engineer in charge. If partial repair work only required, the payment will be done proportionally.

Assembling, painting and testing of motor: The work includes assembling of motor using the new bearings supplied by FACT(free of cost), painting of motor using two coats of anti-corrosive epoxy paint over suitable primer, conducting routine tests as per relevant IS standers and No-load trial run at the rated voltage of 3.3 KV. All test reports shall be submitted before dispatching the motor. The test results shall be in compliance with applicable standards/ regulations etc. In case of deviations beyond acceptable values, they shall be brought to normal values by carrying out necessary corrective measures without any extra cost to FACT. Mobil Unirex N3 grease shall be used for motor bearing lubrication.

Supply of brass stud assembly unit: The work includes supply of spare stud assembling unit consist of 1 number of suitable brass threaded stud, two number of brass plate washers, two number of brass spring washers, three number of suitable brass nut.

Supply of bush insulator: The work includes supply of spare bush insulator used for fixing the stud in terminal block.

Delta Roto tech Pvt. Ltd.