Patent ID: 7268989

Claim:
An arc fault circuit interrupter comprising: a line terminal adapted to receive a line voltage including a zero crossing; a load terminal; separable contacts electrically connected between said line terminal and said load terminal; a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said sensed current including a line cycle; an arc fault detection circuit adapted to collect a plurality of samples of said sensed current for said line cycle, determine a first slope of said sensed current at about the zero crossing of said line voltage, determine a magnitude of one of said samples at about said zero crossing, determine a second slope of said sensed current at another one of said samples having about said magnitude, said first slope being opposite in polarity with respect to said second slope, calculate a difference between said first and second slopes, and generate a trip signal as a function of said difference; and an operating mechanism adapted to open said separable contacts responsive to said trip signal.