NLC India Ltd, Neyveli
Online published on 18 September, 2018.
In Hydrogen Cooled 210 MW Turbo Generator of BHEL make, there is always a possibility of dislodging end core lamination strip due to looseness and loss of integrity of core. This dislodged lamination strip vibrates due to the alternating electromagnetic forces in the stator core which in turn start to cut the nearby wedge and then the conductor placed in the slot leading to Stator earth fault warranting a forced shut down ultimately. Re- synchronising of Unit after shut down due to Stator winding earth fault requires at least 20 to 30 days depending upon type of fault in the winding and availability of spare materials to attend the repair and how quickly the award of contract is taking place. Hence proportionate huge loss of revenue is easily understandable and therefore preventive action for such earth fault not to occur becomes of paramount importance. This paper deals with the preventive techniques to be carried out in the area of Generator Stator end core so that Stator winding earth fault and its associated heavy revenue loss do not happen.
