MG-TRIPPING ON UNDER/OVER FREQUENCY PROTECTION

Motor generator set MG no. 1 tripped on 30-2 relay indication. EMTR was initiated and class II and class III tie breaker 5231 CB 8 closed as per design intent and supply was restored to class II bus. The unit continued to operate at 145 MWe.

BASIS FOR RATING: A-2R. In this event the tie breaker between Class II and Class III closed restoring supply to class II bus-S. There was only 300 m/sec interruption of supply to Bus-S. Had the power supply to class II bus not been restored by EMTR, there would have been degradation of defence in depth. Hence level I is selected.
DIFFICULTIES IN RATING: None.

Location: 
KALPAKKAM-1
Event date: 
Tue, 1990-10-23
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