NCTPS I ES Circle EM I Dn ON SITE Rectification of unit II BHEL make 210 MW Turbo Generator Stator winding fault at NCTPS I

Amount

Dismantling of Generator 1. Open bearing pedestal cover front and rear bearing of generator, bearing top half’s. 2. Check bearing clearances, interferences, CRO, decoupled LP generator, check alignment. 3. Dismantled hydrogen seals, seal body, end shields, inner oil catchers. 4. Prepare and thread out generator rotor. 5. Clean the stator and visual inspection. 6. Identification &Rectification of fault.

Partial rewinding of generator stator (Replacement of one defective top bar). 1. De-wedging. 2. Cutting overhang braiding and opening of insulation covers. 3. De-soldering the bar joints. 4. Removing top bars covering up to 3 adjacent bars. 5. Laying of top bars. 6. Re-wedging and wedge tightness check. 7. Soldering of the bar joints. 8. Assembly of insulation covers and braiding of overhang winding. 9. IR, PI and resistance checks on stator winding and HV test/ ELCID test on stator. 10. Epoxy glue injection. 11. Varnishing of stator.

Partial rewinding of generator stator (Replacement of one defective bottom bar) 1. De-wedging. 2. Cutting overhang braiding and opening of insulation covers. 3. De-soldering the bar joints. 4. Removing top bars covering up to 1 pitch coil (app) for facilitating removal of 3 adjacent bottom bars. 5. Removal of defective bottom bar upto 3 nos adjacent. 6. Braiding of bottom bars overhang. 7. Laying of top bar. 8. Re-wedging and wedge tightness check. 9. Soldering of the bar joints. 10. Assembly of insulation covers and braiding of overhang winding. 11. IR, PI and resistance checks on stator winding and HV test/ ELCID test on stator. 12. Epoxy glue injection. 13. Varnishing of stator.

Re-assembly of Generator 1. Revisioning bearings (including DP & UT), seal rings, seal bodies, oil catchers, end shields etc., 2. Prepare and thread in of rotor. 3. Assembly of end shields, seal bodies, seal and oil catchers etc. 4. LP-Generator alignment correction coupling, CRO check etc. 5. Assembly of bearings pedestal no.6 and 7 and brush gear etc. 6. Air tightness test of generator complete assembly & rectification. 7. Assistance in commissioning. 8. Assembly of flexible leads.

Electrical Statutory Testing the Following test should be carried out with latest testing techniques and equipment’s 1. Tan delta test of stator winding. 2. Partial discharge test of stator winding. 3. Hydraulic test of stator winding. 4. Digital wedge mapping test of stator winding (before and after) shall be carried out as per latest testing technic to ensure tightness of all the wedges. 5. IR and DC resistance of rotor winding. 6. RSO test of rotor winding. 7. Conducting purge test of rotor. 8. Gas tightness test of rotor. Note: The testing equipments are under contractor scope.

Supply of consumables, Gaskets & Chemicals needed for the above work.