S.56 NCTPS II ES Circle EM I Division Turbine Motors Complete stator rewinding and rotor rebarring of two numbers of failed 12MW 11 KV MDBFP HT Motor Ms BHEL 28 Tonnes each

STATOR REWINDING (11 KV) GVPI : Dismantling the motor, threading out the rotor from the stator core pack, stripping out of old windings, cleaning the slots, conducting hot spot tests to find out the core damages, removing the stator core pack from the stator yoke by hydraulic press using special jigs and fixtures, rewinding the stator using class F enameled POLYMICA covered electrolytic grade rectangular copper conductors for rewinding coils as per the original shape and dimension by using special jigs and dies, pre-staggering the coil with thermopreg, insulating the slot portions using SAMICAPOR insulating materials, applying corona protection tapes and stress grading tapes, inserting the coils in to the slots, banding the overhang portions in the surge ring, forming the end connection, fixing RTDs, preheating, Global Vacuum Pressure Impregnating the winding with core pack in vacuum chamber using suitable poly epoxy resin, baking, testing, refixing the core pack into the stator yoke with special jigs and fixtures in hydraulic press, providing flexible silicon cables, applying finishing varnishes including assembling.

STATOR CORE RESTACKING: 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, 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.

ROTOR CORE RESTACKING: 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, 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 and finally conducting the flux loop test to ascertain the restacked core healthiness, cleaning and polishing the slots ready to feeding.

ROTOR RE-BARRING: Mounting the rotor in the lathe, machining both side enduring, stripping out the bars in bar removing machine using special tools and machineries, machining the rotor bars & 2 Nos. end rings made out of electrical conductivity grade copper using copper bars & copper end rings, inserting the 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, conducting 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 varnishes to the overhang portions.

Dynamically balancing the rotor to grade G2.5

Fabrication and fixing of new terminal cover at CT end of Size: Length:970mm X Breadth:740mm X Depth:440mm ; Thickness:5 mm

Fabrication of shroud for all the three phases, 11KV bushing and bushing rods with brass nuts and washer for take-off leads & CT terminals and new epoxy separators for take of leads (3 nos. for one motor) (Removed 3 Nos. shrouds, 3 Nos. bushing & bushing rods and 3 Nos. epoxy separators to be handed over to the TNPGCL.)

Blue matching of 12MW MDBFP motor weighing 28 ton with motor frame.

Machining, grinding and polishing the DE& NDE side rotor shaft labyrinth step

Replacing the DE & NDE side labyrinth seal