| 摘要 |
PURPOSE: To enable swift transition to a stable separated system operation by, if a large current passes through a private electric wire and further current frequency is reduced, immediately opening a circuit breaker so that power from a private generator be supplied only to the loads on the private generator side. CONSTITUTION: A frequency relay device 200 is composed by AND-connecting an overcurrent relay 51L connected to the secondary side of a current transformer CTG and a frequency relay 95L connected to the secondary side of a voltage transformer PTG. If a fault occurs on the system side, a large current passes through a private generator G. The overcurrent relay 51L detects the current and issues a trip command T1 . Since a fault on the system side also lowers frequency, the frequency relay 95L issues a trip command T2 . When the AND circuit A receives the trip commands T1 , T2 simultaneously, it opens a circuit breaker 52B so that the private generator G supplies power only to significant loads 103, 104. This enables transition to a stable separated system operation without damage the generator G. |
