Arc fault circuit breaker and apparatus for detecting wet track arc fault
First Claim
1. A circuit breaker for interrupting current in an electrical system, said circuit breaker comprising:
- separable contacts adapted to interrupt said current in said electrical system;
a trip mechanism adapted to trip open said separable contacts in response to a trip signal; and
a trip circuit outputting said trip signal, said trip circuit comprising;
a circuit adapted to generate a current signal representative of said current in said electrical system, to rectify said current signal to provide a rectified current signal and to track an envelope of said rectified current signal,a first arc fault detector circuit including a first output,a second arc fault detector circuit comprising;
a first circuit adapted to detect when an absolute value of said current signal is less than a first predetermined value and output a signal after a first time period,a comparator adapted to compare said signal after a first time period to the envelope of said rectified current signal, in order to provide a second output with a pulse, which persists for a relatively longer time for a relatively small value of said envelope, and which persists for a relatively shorter time for a relatively large value of said envelope, anda second circuit adapted to enable the second output of said comparator if said rectified current signal exceeds a second predetermined value, and to disable the second output of said comparator after said rectified current signal is below said second predetermined value for a second time period, andan accumulator including an output having said trip signal, the output of said accumulator being responsive to the first output of said first arc fault detector circuit and to the second output of said comparator.
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Accused Products
Abstract
An apparatus includes a first circuit detecting when an absolute value of a current signal is less than a first predetermined value and outputting a signal after a first time period. A comparator compares that signal to an envelope of a rectified current signal, in order to provide an output with a plurality of pulses that persist for a relatively longer time for a relatively small value of the envelope, and persist for a relatively shorter time for a relatively large value of the envelope. A second circuit enables the comparator output if the rectified current signal exceeds a second predetermined value, and disables the comparator output after the rectified current signal is below the second predetermined value for a second time period. A third circuit accumulates the pulses and outputs a signal representative of a wet track arc fault.
29 Citations
20 Claims
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1. A circuit breaker for interrupting current in an electrical system, said circuit breaker comprising:
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separable contacts adapted to interrupt said current in said electrical system; a trip mechanism adapted to trip open said separable contacts in response to a trip signal; and a trip circuit outputting said trip signal, said trip circuit comprising; a circuit adapted to generate a current signal representative of said current in said electrical system, to rectify said current signal to provide a rectified current signal and to track an envelope of said rectified current signal, a first arc fault detector circuit including a first output, a second arc fault detector circuit comprising; a first circuit adapted to detect when an absolute value of said current signal is less than a first predetermined value and output a signal after a first time period, a comparator adapted to compare said signal after a first time period to the envelope of said rectified current signal, in order to provide a second output with a pulse, which persists for a relatively longer time for a relatively small value of said envelope, and which persists for a relatively shorter time for a relatively large value of said envelope, and a second circuit adapted to enable the second output of said comparator if said rectified current signal exceeds a second predetermined value, and to disable the second output of said comparator after said rectified current signal is below said second predetermined value for a second time period, and an accumulator including an output having said trip signal, the output of said accumulator being responsive to the first output of said first arc fault detector circuit and to the second output of said comparator. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit breaker for interrupting current in an electrical system, said circuit breaker comprising:
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separable contacts adapted to interrupt said current in said electrical system; a trip mechanism adapted to trip open said separable contacts in response to a trip signal; and a trip circuit outputting said trip signal, said trip circuit comprising; a first circuit adapted to generate a current signal representative of said current in said electrical system, a second circuit adapted to rectify said current signal and provide a rectified current signal, a third circuit adapted to track an envelope of said rectified current signal, a first arc fault detector circuit including a first input of said rectified current signal, a second input of said envelope of said rectified current signal and a first output, a second arc fault detector circuit comprising; a window comparator circuit adapted to detect when an absolute value of said current signal is less than a first predetermined value and output a signal, a first time delay adapted to delay the signal output by said window comparator and output a first delayed signal, a comparator adapted to compare the first delayed signal of said first time delay to the envelope of said rectified current signal, in order to provide an output with a pulse, which persists for a relatively longer time for a relatively small value of said envelope, and which persists for a relatively shorter time for a relatively large value of said envelope, a threshold detector circuit including an output with a signal, said threshold detector circuit adapted to detect if said rectified current signal exceeds a second predetermined value, a second time delay adapted to delay the signal of the output of said threshold detector circuit after said rectified current signal is below said second predetermined value and output a second delayed signal, and an and circuit outputting a second output responsive to said pulse and said second delayed signal, and an accumulator including an output having said trip signal, the output of said accumulator being responsive to the first output of said first arc fault detector circuit and to the second output of said and circuit. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for detecting a wet track arc fault for a current in an electrical system including a circuit providing a current signal from said current, a circuit providing a rectified current signal from said current signal, and a circuit providing an envelope of said rectified current signal, said apparatus comprising:
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a first circuit adapted to detect when an absolute value of said current signal is less than a first predetermined value and output a signal after a first time period; a comparator adapted to compare said signal after a first time period to the envelope of said rectified current signal, in order to provide an output with a plurality of pulses, said pulses persisting for a relatively longer time for a relatively small value of said envelope, and persisting for a relatively shorter time for a relatively large value of said envelope; a second circuit adapted to enable the output of said comparator if said rectified current signal exceeds a second predetermined value, and to disable the output of said comparator after said rectified current signal is below said second predetermined value for a second time period; and a third circuit adapted to accumulate said pulses from the output of said comparator and output a signal representative of said wet track arc fault.
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Specification