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Method of an apparatus for detecting ground faults in electrical systems

  • US 3,975,663 A
  • Filed: 01/10/1975
  • Issued: 08/17/1976
  • Est. Priority Date: 06/13/1972
  • Status: Expired due to Term
First Claim
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1. A method of detecting ground faults in ungrounded equipment having an electrical supply, the method comprising the steps of;

  • connecting either side of the supply to a chassis ground terminal of the equipment;

    impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply;

    detecting and monitoring with respect to this side of the supply, the resulting potential between this side and the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak; and

    monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential;

    establishing ground faults by changes in the magnitude of the varying potential; and

    locating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values.

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