| 摘要 |
PURPOSE:To monitor the operating states of motor group with a simple structure by dividing monitoring unit into three equivalent motor groups, measuring the currents of the respective groups in different power phases and adding the currents. CONSTITUTION:Electric power from a power source bus is supplied through a switci 1 to a motor 2. The current of the motor 2 in the same groups to be monitored is measured in the sum by one current transformer 3 for the phase R of the motor 2-1, the phase S of the motor 2-2 and the phase T of the motor 2-3. The current which flow through the current transformer 3 to a malfunction discriminator 4 is almost nearly zero in the ordinary state without malfunction, but when a malfunction occurs in the motor 2, the motor current will vary. Accordingly, the current is flowed to the discriminator 4 in the varied amount, thereby detecting the malfunction. |
