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Fault indicator and means for resetting the same

  • US 4,086,529 A
  • Filed: 07/26/1976
  • Issued: 04/25/1978
  • Est. Priority Date: 07/26/1976
  • Status: Expired due to Term
First Claim
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1. A fault indicator responsive to the occurrence of an alternating fault current of predetermined minimum amplitude in a conductor and means for resetting the same, comprising in combination:

  • a generally cylindrical housing;

    a target mounted at one end of said housing for rotation in a plane generally perpendicular to the axis of said housing between a fault indicating position and a reset position, at least a portion of said target being visible from the exterior of said housing to indicate the position of said target;

    a target permanent magnet having diametrically opposed magnetic poles of like gender mounted for rotation with said target;

    a stationary permanent magnet of high coercive force disposed in magnetic communication with said target magnet, and having magnetic poles arranged for biasing said target magnet to position said target in said fault indicating position;

    a pair of pole pieces extending longitudinally in generally parallel-spaced relationship within said housing from said one end of said housing to the other end thereof, each of said pole pieces being formed of a magnetizable material of low coercive force subject to being demagnetized upon occurrence of a current in the conductor in excess of said predetermined minimum level, said pole piece each including an end portion projecting from said other end of said housing and defining therewith means for receiving the conductor, the other ends of said pole pieces being disposed in magnetic communication with opposing poles of said target magnet;

    and reset means comprising a receptacle dimensioned for telescopic engagement with said housing and including winding coaxially disposed therein for magnetic communication with said pole pieces when said housing is seated in said receptacle for magnetizing said pole pieces whereby said other ends thereof bias said target magnet to position said target in said reset position.

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