Patent ID: 6300766
Filing Date: 2001-10-09
Classification: H02H

Abstract:
Apparatus for detecting arcing faults in an ac electrical system, said apparatus comprising:current sensing means generating a signal containing a current pulse for each step increase in current of at least a predetermined amplitude detected in said ac electrical system, said current pulses having an amplitude which is a function of the amplitude of said step increase;randomness detecting means for detecting randomness in said current pulses and comprising first tracking means with a first time constant integrating said current pulses to generate a first tracking signal, and second tracking means with a second time constant shorter than said first time constant integrating said current pulses to generate a second tracking signal, and means generating a charge pulse having a value which is a function of the amplitude of a most recent of said step increases in current when the second tracking signal falls to a selected fraction of said first tracking signal; andoutput means maintaining a time attenuated accumulation of said charge pulses and generating an arcing fault indication when said time attenuated accumulation reaches a predetermined value.