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Circuit breaker responsive to repeated in-rush currents produced by a sputtering arc fault

  • US 5,940,256 A
  • Filed: 11/09/1994
  • Issued: 08/17/1999
  • Est. Priority Date: 02/26/1993
  • Status: Expired due to Term
First Claim
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1. A circuit breaker for protecting an ac electrical system from sputtering arc faults, comprising:

  • current sensing means sensing current flowing in said electrical system;

    event signal generating means responsive to said current sensing means comprising means generating a bandwidth limited rate of change of current (di/dt) signal having a bandwidth selected to pass step increases in current, and means comparing said bandwidth limited di/dt signal to threshold values and generating an event signal when said threshold values are exceeded;

    means generating a trip signal in response to a plurality of event signals within a preselected time interval; and

    means responsive to said trip signal interrupting current flowing in said electrical system.

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