| 摘要 |
PROBLEM TO BE SOLVED: To prevent an unnecessary operation of a circuit for detecting abnormality of circuits which detect a forward voltage and a reverse voltage of a thyristor.SOLUTION: A voltage detection abnormality detection circuit includes: an OR circuit 12a which inputs signals of detection circuits FV and RV for detecting a forward voltage and a reverse voltage of a thyristor, a signal of a one-shot circuit 11 that outputs a gate block signal for a predetermined period after reception, a by-pass pair signal and a breaker open state detection signal and outputs a signal if these signals are not inputted; an inverter circuit 32 for inverting a signal of the OR circuit 12a; circuits 17 and 18 for inverting the signals of FV and RV; AND circuits 13 to 16 which input output of the circuit 32, the signal of FV, the signal of RV and output of the circuits 17 and 18 and output signals if AND is established; delay circuits 19 to 22 which input output of the circuits 13 to 16, delay the output just for a time shorter than a delay time of the circuit 11 and output them; and flip-flops 23 to 26 which input the output of the circuits 19 to 22 to set terminals, output various voltage signal abnormality signals and eliminate output signals when reset signals are inputted. |
