| 摘要 |
PURPOSE:To obtain a protective relay unit provided with a function for dealing with non-operation of circuit breaker in which a circuit breaker non-operation detection signal is not produced for ground fault on the secondary of current transformer. CONSTITUTION:A ratio differential relay 87 is inserted to the secondaries of first and second current transformers CT1, CT2 provided, respectively, on the input and output sides of an object to be protected, while an overcurrent relay 51F1 is inserted into the secondary circuit of the second current transformer CT2 and a voltage transformer PT1 is provided on one end side of the object to be protected. An undervoltage relay 27 is inserted into the secondary circuit and a circuit for delivering a circuit breaker non-operation command upon function of the ratio differential relay 87, the overcurrent relay 51F1 and the undervoltage relay 27 is also provided. |
