| 摘要 |
PURPOSE:To prevent the partial commutation failure and the breakdown of a thyristor element by resetting a flip-flop circuit after confirming a fact that a sufficient turn-off time is secured at the time of operation stop of a thyristor switch TSC. CONSTITUTION:After a stop signal GB and a reverse voltage signal FV(X) are brought to AND by an AND circuit, and after it is confirmed that a state of AND is continued exceeding a prescribed time by a time delay circuit 16, a reset signal is inputted to a flip-flop circuit 8U through an OR circuit 11U. By outputting a protective pulse GP(U), whenever a forward voltage is applied until a sufficient turn-off time is secured even after the signal GB is outputted, the element can be protected from the partial commutation failure and the breakdown, therefore, the reliability can be improved. |
