| 摘要 |
PURPOSE:To rapidly continue a motor in operation by disconnecting a defective bank from the circuit when the defect occurs in one bank of multiplexing configuration, decreasing the speed reference signal, and setting the motor current value to the remaining power converter capacity or lower. CONSTITUTION:AC commercial power is supplied from an input switch 1 through an input transformer 2, rectifiers 3A, 4A and DC reactors 3B, 4B to power inverters 3C, 4C, and fed to a thyristor motor 5. When a defect occurs in the device 3, a voltage control circuit 11 outputs a phase reduction command to the rectifier 3A, and outputs an OFF command from a phase controller 13 to the inverter 3C. Simultaneously, a defect signal is applied to a current value memory comparator 15. The comparator 15 stores the detected input current value, and compares the total input current value immediately before the defect and rated current value per one bank applied from the rated current setter 14. When exceeding the rated constant value, one bank is disconnected, the comparator compares, and controls so that the rotating speed of the motor 5 decreases through a speed limiter 16. |
