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Polyphase fault current flow detecting and resetting means

  • US 3,974,446 A
  • Filed: 04/10/1975
  • Issued: 08/10/1976
  • Est. Priority Date: 04/10/1975
  • Status: Expired due to Term
First Claim
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1. Means for detecting flow of fault current in any phase conductor of a polyphase alternating current transmission system in which normal current flow is substantially less than said fault current flow comprising:

  • a fault responsive device including a magnetic circuit, a trip winding on said magnetic circuit, trip current transformer means and trip rectifier means interconnecting each phase conductor and said trip winding for energizing it with direct current according to the magnitude of the flow of fault current in any of said phase conductors, a reset winding on said magnetic circuit, and reset current transformer and reset rectifier means interconnecting each phase conductor and said reset winding for energizing it with direct current according to the magnitude of the simultaneous flow of normal current in each of said phase conductors.

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