ARC DETECTION USING DETAILED AND APPROXIMATE COEFFICIENTS FROM DISCRETE WAVELET TRANSFORMS
First Claim
1. An apparatus for facilitating interruption of current in an electrical circuit, the apparatus comprising:
- a current sensing device disposed in the electrical circuit to service an electrical load, the current sensing device being productive of an output signal representative of a load current passing therethrough;
a detection unit, in signal communication with the current sensing device such that the output signal produced by the current sensing device is received by the detection unit, the detection unit being configured and disposed to output a secondary signal based on the output signal; and
a microcontroller, coupled to the detection unit, being responsive to computer executable instructions which, when executed by the microcontroller, cause the microcontroller to receive and to decompose the secondary signal into detailed and approximate coefficients, and to generate a trip signal for use in interrupting an operation of the electrical circuit when a current of the sensed load is above a predetermined threshold and the detailed and approximate coefficients cooperatively indicate that threshold conditions for trip signal generation are satisfied.
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Accused Products
Abstract
An apparatus for facilitating interruption of current in an electrical circuit is provided and includes a current sensing device in the electrical circuit to service an electrical load, the current sensing device being productive of an output signal representative of a load current passing therethrough, a detection unit, in signal communication with the current sensing device such that the output signal is received by the detection unit, the detection unit being configured and disposed to output a secondary signal based on the output signal, and a microcontroller to receive and to decompose the secondary signal into detailed and approximate coefficients, and to generate a trip signal for use in interrupting an operation of the electrical circuit when a current of the sensed load is above a predetermined threshold and the detailed and approximate coefficients cooperatively indicate that threshold conditions for trip signal generation are satisfied.
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Citations
17 Claims
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1. An apparatus for facilitating interruption of current in an electrical circuit, the apparatus comprising:
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a current sensing device disposed in the electrical circuit to service an electrical load, the current sensing device being productive of an output signal representative of a load current passing therethrough; a detection unit, in signal communication with the current sensing device such that the output signal produced by the current sensing device is received by the detection unit, the detection unit being configured and disposed to output a secondary signal based on the output signal; and a microcontroller, coupled to the detection unit, being responsive to computer executable instructions which, when executed by the microcontroller, cause the microcontroller to receive and to decompose the secondary signal into detailed and approximate coefficients, and to generate a trip signal for use in interrupting an operation of the electrical circuit when a current of the sensed load is above a predetermined threshold and the detailed and approximate coefficients cooperatively indicate that threshold conditions for trip signal generation are satisfied. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer implemented method of performing arc fault current interruption (AFCI) for a circuit, the method comprising:
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sensing a load current at a current sensing device in electrical communication with the circuit; generating a secondary signal reflective of a current of the sensed load current at a detection unit in signal communication with the current sensing device; sampling the secondary signal at a first predetermined frequency at a microcontroller coupled to the detection unit; when the sampling of the secondary signal is determined to be complete and when a zero cross of the secondary signal is determined to have been sampled, computing detailed coefficients from first components of the secondary signal and approximate coefficients from second components of the secondary signal; determining if threshold criteria are determined to have been met based on the first coefficients or, if the sensed load current is below a predetermined threshold, based on the detailed and approximate coefficients; and
, if so, issuing a trip signal to interrupt an operation of the circuit. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A computer implemented method of performing arc fault current interruption (AFCI) for a circuit, the method comprising:
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decomposing first and second portions of a secondary signal, which is generated at a detection unit as being based on a load current sensed by a current sensing device with which the detection unit is in signal communication, into detailed and approximate coefficients, respectively, using discrete wavelet transforms; with the first portion of the secondary signal determined to have been zero cross sampled, computing a sum of absolute values of the detailed coefficients and computing absolute values and a ratio of sums thereof of the approximate coefficients for first and second windows of the secondary signal; comparing the sum of the absolute values with a first predetermined threshold or, if a current of the sensed load is below a pre-selected magnitude, comparing a product of the sum of the absolute values and the ratio of sums with a second predetermined threshold; and issuing a trip signal to interrupt an operation of the circuit if a result of the comparison indicates that the corresponding one of the first and second predetermined thresholds is exceeded with a predetermined frequency over a given period of time.
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Specification