ABSTRACT
Electrical plant can be thermally overloaded either by exceeding the maximum permissible load currents - usually over a prolonged period - and/or by a reduced cooling effectiveness. The magnitude of the NPS component in the stator current of a synchronous generator depends on the configuration of the power system. Ground faults can also occur in ungrounded or high resistance or inductively grounded systems. The latter are systems which are grounded via a Petersen coil tuned to compensate the capacitive ground fault currents. The transient fault current and voltage at the relay location in the case of series compensated line contain a decaying oscillatory component instead of a DC component. The resulting load imbalance on generators and motors leads to an NPS component in the stator current, which rotates at twice the system frequency in the opposite direction in relation to the rotor and causes additional eddy current losses and therefore an additional temperature rise in the rotor.
