| 摘要 |
PROBLEM TO BE SOLVED: To ensure a back-up protection at the time of a fault of a generator main circuit by externally outputting a normal service protective output and a back-up protective output from a generator protective relay unit and a main transformer protective relay, respectively. SOLUTION: In the case that the protective relaying apparatus is normal when a short-circuit fault occurs, fault currents flow from transformers CT3, CT5 for instruments to a generator protective relay unit 7, and a generator protective relay normal service output 201M is operated. Then, a parallel circuit breaker 4 is opened in a protective sequence, water flowing to a waterwheel is shut off, and a generator 1 is safely stopped. If the relay unit 7 is faulted, a generator protective back-up protective relay is operated under an AND operation of a fault signal and a back-up protective output 101B from a main transformer protective relay unit 6. Then the breaker 4 is opened in the protective sequence, the water flowing to the waterwheel is shut off, the generator 1 is safely stopped, and the back-up protection of the generator 1 main circuit at the time of the fault can be conducted.
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