Patent ID: 8373570
Filing Date: 2013-02-12
Classification: H02H

Abstract:
1. A method for determining when an arc fault occurs and thereafter disconnecting a supply voltage from the arc fault, said method comprising the steps of: a) sampling a load current with a current sampling circuit to produce a sampled current signal; b) processing the sampled current signal to produce a low frequency current signal having frequency components less than about one kilohertz; c) processing the sampled current signal to produce a band pass frequency current signal having frequency components from about ten kilohertz to about one hundred kilohertz; d) calculating an energy value of the band pass frequency current signal; e) calculating a root-mean-square (RMS) current value of the low pass frequency current signal; f) determining whether the RMS current value of the low pass frequency current signal is greater than an RMS threshold value, wherein if not greater then returning to step a) and if greater then going to step g); g) determining whether the energy value of the band pass frequency current signal is greater than a high energy threshold value, wherein if not greater then returning to step f) and if greater then going to step h); h) assigning a score to an arc event; i) incrementing an arc event count in an arc event counter; j) starting an arc event time in an arc event timer; k) determining whether the arc event time is greater than a time threshold value, wherein if greater then resetting the arc event count and returning to step a) and if not greater then going to step l); l) determining whether the arc event count is greater than an arc event count threshold value, wherein if not greater then returning to step a) and if greater then going to step m); and m) generating a trip signal for disconnecting the supply voltage from the arc fault.