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Fault indicator operable from a remote excitation source through a uniformly distributed impedance cable

  • US 4,288,743 A
  • Filed: 10/10/1978
  • Issued: 09/08/1981
  • Est. Priority Date: 10/10/1978
  • Status: Expired due to Term
First Claim
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1. A fault indicator operable from the relatively low voltage secondary circuit of a power distribution transformer for indicating the presence of a fault current in the relatively high voltage primary circuit of the transformer, said indicator including:

  • a housing;

    externally-viewable circuit condition indicating means within said housing having a fault-indicating state and a reset-indicating state, said indicating means being operable from an applied excitation current;

    means comprising an elongated flexible cable extending between said indicating means and the secondary circuit of the transformer for supplying excitation to said indicating means, said cable includingan electrically conductive core portion forming an electrical path having a uniformly distributed impedance many times greater than that of said primary and secondary circuits between said indicating means at one end and said secondary circuit at the other end whereby said core portion, if shorted to ground, results in only an inappreciable current flow in said circuits; and

    an electrically insulating sleeve portion extending around and along said core portion between said housing at one end and said secondary circuit at the other end.

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