| 摘要 |
PURPOSE:To smoothly protect a controlled rectifier by cooperatively protecting a gate shift to a gate block or bypass pair of a defective controlled rectifier group of parallel-connected controlled rectifier groups and operating the effective rectifier groups in forward conversion range. CONSTITUTION:A controlled rectifier for supplying polyphase current to a load is composed by connecting a plurality of controlled rectifier groups formed by connecting in cascade one or more unit controlled rectifiers in parallel. The respective groups are controlled by the firing pulses from a phase controlling circuit 13 operated by the output from the current control circuit 8 corresponding to the respective groups. When a malfunction of a certain group is detected by a malfunction detecting circuit 10, a malfunction time fire deciding circuit 9 is operated, and the malfunctioned group is controlled to cooperatively protect from the gate shift to the gate block or gate shift to the bypass pair, and the effective groups are controlled to operated in the forward conversion range. |
