ARC FAULT DETECTION APPARATUS AND CIRCUIT BREAKER INCORPORATING SAME
 Inventors: Robert T. Elms, Monroeville; John C.
Schlotterer, Franklin, both of Pa.
 Assignee: Eaton Corporation, Cleveland, Ohio
 Appl. No.: 691,733
 Filed: Aug. 2, 1996
 Int. CI. H02H 3 16
 U.S. CI 361/45; 361/94; 364/483
 Field of Search 361/42, 44, 45,
361/93-94, 97, 102, 111; 364/483-487
 References Cited
U.S. PATENT DOCUMENTS
4,297,738 10/1981 Lee 361/42
4,402,030 8/1983 Moser et al 361/93
5,121,282 6/1992 White 361/42
5,185,684 2/1993 Beihoff et al 361/45
5,307,230 4/1994 Mackenzie 361/96
5,459,630 10/1995 MacKenzie et al 361/45
5,602,709 2/1997 Al-Dabbagh 361/85
FOREIGN PATENT DOCUMENTS
9004278 4/1990 WIPO .
Texas A & M University—IEEE Transactions on Power Apparatus and Systems, vol. PAS-101, No. 6 Jun. 1982; Distribution High Impedance Fault Detection Utilizing
Arcing-faults in an electric power distribution system are detected by a circuit which includes a band-pass filter generating a low frequency bandwidth limited arcing current signal having a bandwidth above the measurable harmonics of the ac current but below the frequency band of power line communications systems, about 3 KHz to 20 KHz and preferably about 6 KHz to 12 KHz. For each cycle of the ac current that this low frequency bandwidth limited arcing current exceeds a threshold, preferably related to the amplitude of the ac current, for a selected duration of the cycle, a fixed pulse is generated. If a time attenuated accumulation of these fixed pulses reaches a selected level representative of a number of closely spaced cycles in which the arcing current has been detected for the selected duration, an arc indicative signal is output. Preferably, the value of the time attenuated accumulation of pulses at which the arc indicative signal is generated is variable so that fewer pulses are needed to generate the output as the amplitude of the ac current increases.
7 Claims, 4 Drawing Sheets