SELECTIVE GROUND-FAULT PROTECTIVE DEVICE OF STATOR WINDING FOR GENERATORS OPERATING IN ENLARGED UNIT Russian patent published in 2006 - IPC H02H7/06 H02H3/16 

FIELD: ground-fault relay protective gear.

SUBSTANCE: proposed device has reference current supply; first and second arc-control reactors; first and second zero-sequence current filters installed at generator first and second leads, respectively; first and second starting elements whose first inputs are connected to secondary windings of first and second arc-control reactors, respectively, and second inputs, to measuring winding of reference current supply; first and second logic units whose first inputs are connected to outputs of first and second starting elements, respectively; first and second selective elements whose outputs are connected to second inputs of first and second logic units, respectively; newly introduced in device are first and second current transformers connected in series with first and second arc-control reactors, respectively, on neutral ends of first and second generators, respectively; these current transformers are connected to reference current supply and input of first low-pass filter, to output of first zero-sequence current filter and to secondary winding of first current transformer and output, to first inputs of first and second selective elements, respectively; first zero-sequence current filter and first current transformer are connected into differential circuit; second low-pass filter has its input connected to output of second zero-sequence current filter and to secondary winding of second current transformer and output, to second inputs of second and first selective elements, respectively; first zero-sequence current filter and second current transformer are connected into differential circuit.

EFFECT: enhanced reliability of selective protection against both steady ground faults and intermittent arcing shorts.

1 cl, 1 dwg