| 摘要 |
In the overcurrent tripping unit for a circuit breaker, current transformers are provided for detecting currents flowing through respective phases of a main circuit, the secondary outputs of the current transformers are star connected, the primary outputs are polyphase full-wave rectified, the voltage drop based on the rectified positive/negative direct output of each phase is directed by first and second resistances to be applied to the control means, and a ground fault current is detected based on the secondary outputs of the current transformers to be applied to the control means.
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