Appeal No. 96-2838
Application 08/336,721
comparator 97 (Figure 2). The window comparator 97 determines
whether selected thresholds have been reached representative
of sputtering arc faults. Timer 107 produces an output if two
step increases in current (e.g., events) are detected within a
selected time period. If two events have occurred within the
selected time period, SCR 39 is turned on, energizing trip
coil 41 which operates trip mechanism 49 to open contacts 51.
Independent claim 13 is reproduced as follows:
13. A circuit breaker for protecting an electrical
system from ground faults and sputtering arc faults,
comprising current sensing means sensing current flowing in
said electrical system; ground fault sensing means connected
to said current sensing means and operative to generate a trip
signal in response to a ground fault in said electrical
system; sputtering arc fault sensing means connected to said
current sensing means to generate a trip signal in response to
at least two successive step increases in current in said
electrical system above a designated magnitude within a
selected time interval; and trip means responsive to trip
signals generated by said ground fault sensing means and by
said sputtering arc sensing means to interrupt current flowing
in said electrical system.
The references relied on by the Examiner are as follows:
Dewey 3,673,455 June 27, 1972
Moser et al. (Moser) 4,402,030 Aug. 30, 1983
Spencer 4,949,214 Aug. 14, 1990
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