| 摘要 |
PURPOSE:To prevent the partial commutation failure and the breakdown of a thyristor element by constituting the device so that a GP and a PHS of a normal timing and an asynchronous GP are discriminated, and reset is not executed in the case of others than the GP of a normal timing. CONSTITUTION:The device is provided with a circuit for making a flip-flop reset circuit of an opposite phase operable under the condition of a fact being a gate pulse signal (GP) of the own phase generated within a prescribed time after a phase control signal (PHS) from a controller 7 is inputted. Accordingly, even if such a conventional reset condition as both of FV(U) and FV(X) signal do not exist exceeding a prescribed time after the GP of an opposite phase is outputted is established, unless the GP of an opposite phase is not that of the normal timing, flip-flops 8U, 8X come not to be reset. In such a way, a partial commutation failure and a breakdown of a thyristor element can be prevented. |
