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Arc fault circuit interrupter and circuit breaker having the same

  • US 6,532,139 B2
  • Filed: 05/10/2001
  • Issued: 03/11/2003
  • Est. Priority Date: 05/12/2000
  • Status: Expired due to Fees
First Claim
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1. An arc fault circuit interrupter (AFCI) in an electrical wiring system that can shut an AC (Alternating Current) source off from a phase conductor and a neutral conductor when an arc fault occurs in the AC source, said AFCI comprising:

  • a current transformer for producing an arc voltage in accordance with the variation of current in the phase conductor and in the neutral conductor;

    an arc fault detector for limiting the arc voltage to a specified level and producing an arc fault indicative signal when the arc voltage is higher than a reference arc signal with predetermined level;

    a trip signal generator which is capable of charging the arc fault indicative signal, and if the charged arc fault indicative signal corresponds to a reference trip level, then producing a trip signal; and

    a trip circuitry coupled to the phase conductor and the neutral conductor, for shutting the AC source off from the phase conductor and the neutral conductor in response to the trip signal wherein said arc fault detector comprises;

    a filter for diminishing a harmonic frequency (i.e., overtone) component from the arc voltage and limiting the arc voltage to a specified level; and

    a comparator for comparing the limited arc voltage with the reference arc signal and producing the arc fault indicative signal when the limited arc voltage is larger than the reference arc signal;

    wherein said filter comprises;

    a level limiter for limiting the arc voltage to the specified level; and

    a rectifier for half or full wave rectifying the limited arc voltage;

    wherein said rectifier comprises;

    a first plurality of diodes coupled between the resistor of said level limiter and ground; and

    a second plurality of diodes coupled between the resistor of said level limiter and said comparator.

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