| 摘要 |
A current direction indicator including control means for performing a predetermined operation in a poly-phase electrical power system independently of the magnitude of current flow in the polyphase system. A separate current direction indicating circuit is provided for each phase and includes a first circuit for producing a signal in response to a change in polarity of current in one of the phases of the system, a second circuit for producing a signal functionally related to the polarity of the voltage between two of the phases of the system and a third circuit which produces an output signal when both signals of the first and second circuits occur simultaneously. The control means operates in response to the output signal to initiate the predetermined operation in the system.
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