| 摘要 |
PURPOSE:To suppress the generation of a surge by controlling to interrupt a field switch after a field current is reduced at stop controlling time. CONSTITUTION:An AC switch 2 is opened at the stop control starting time due to the recovery of a master relay, and starting resistors 41-43 are then sequentially closed. Here, a relay 12 is reset by the opening of the master relay and the switch 2, and the outputs of amplifiers 112, 113 become zero. Then, a relay 13 is reset by the opening of a contactor 93, and the output of the amplifier 114 becomes zero. Thus, the output of a thyristor converter 116 is controlled to be reduced, i.e., the field current is reduced. After the time limit T of a timer relay is elapsed, a field switch 6 is controlled to be opened. Thus, the load capacity of a surge protecting element can be alleviated. |
