Residential circuit arc detection
AssigneeGeneral Electric Company
InventorJohn James Dougherty
Life of this patent
Estimating the term…
Abstract
An electronically controlled circuit breaker for detecting arc and a method for detecting arc conditions are disclosed. The circuit breaker and method uses digital Fourier transformation on sampled line current signals and bins the even, odd, and fundamental transforms. Even arc signals and non-harmonic arc signals are calculated from the values in the bins and used within an expert arc algorithm which uses an accumulator to sum an increment based on whether the even arc signals and non harmonic arc signals exceed a fixed threshold. A trip signal is issued when the increment exceeds a predetermined value.
Claims27
An electronically controlled circuit breaker comprising:
- a line current sensor sensing line current signals;
- a processor for determining the fundamental frequency of the current signals, wherein the processor processes a preselected number of multiples of the fundamental frequency, and squares and sums the multiples to yield even, odd, and fundamental values;
- even, odd, and fundamental bins within the processor for receiving the even, odd, and fundamental values, wherein the processor processes even arc signals and non-harmonic arc signals from the even, odd, and fundamental values in the bins;
- and,
- an expert arc algorithm within the processor having an accumulator for calculating an incremental value based on even arc signal and non-harmonic arc signal input, and additionally wherein the processor applies an acceleration factor to the incremental value when both an even arc threshold and a non-harmonic arc threshold are exceeded by the even arc signal and the non-harmonic arc signal, respectively, and a fixed threshold for which to compare the incremental value;
- wherein the processor issues a trip signal when the fixed threshold is exceeded by the incremental value.
An electronically controlled circuit breaker comprising:
- a line current sensor sensing line current signals;
- a processor for determining the fundamental frequency of the current signals, wherein the processor processes a preselected number of multiples of the fundamental frequency, and squares and sums the multiples to yield even, odd, and fundamental values;
- even, odd, and fundamental bins within the processor for receiving the even, odd, and fundamental values, wherein the processor processes even arc signals and non-harmonic arc signals from the even, odd, and fundamental values in the bins;
- and,
- an expert arc algorithm within the processor having an accumulator for calculating an incremental value based on even arc signal and non-harmonic arc signal input and a fixed threshold for which to compare the incremental value;
- wherein the incremental value is calculated using the equation:
- Increment=(EA*T1)+(NHA*T2)+(n*(EA+NHA)*(T1*T2))−(m*(not T1* not T2))
- where thresholds T1 and T2 are binary signals which represent that the EA even harmonic signal or NHA non harmonic signal, respectively, is greater than a predetermined proportion of load current of the circuit breaker and where n is an acceleration factor applied when both thresholds T1 and T2 are exceeded and m is a linear factor used to decrease the Increment when neither threshold T1 nor T2 is exceeded;
- and
- wherein the processor issues a trip signal when the fixed threshold is exceeded by the incremental value.
A method for detecting arc conditions in an electronically-controlled circuit breaker, the method comprising:
- providing an even arc threshold and a non-harmonic arc threshold;
- calculating an incremental value based on even arc signals and non-harmonic arc signals, wherein calculating the incremental value comprises comparing the even arc signals with the even arc threshold and the non-harmonic arc signals with the non-harmonic arc threshold, applying an acceleration factor to the incremental value if both the even arc threshold and the non-harmonic arc threshold are exceeded, and decreasing the incremental value if neither the even arc threshold nor the non-harmonic arc threshold is exceeded;
- comparing the incremental value to a fixed threshold;
- and,
- issuing a trip signal indicating an arc fault condition when the fixed threshold is exceeded by the incremental value.
Dependencies are inferred from the claim text.