Method and apparatus for detecting arcing in alternating-current power systems by monitoring high-frequency noise
OwnerFrederick K. Bladesinventor
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Abstract
An arc detector for detecting potentially hazardous arcing in electrical connections comprises detection and signal processing circuitry for monitoring high-frequency noise characteristic of arcing on the power line and distinguishable from other sources of high-frequency noise.
Claims24
In an electrical network having AC power supply lines, such that any electrical contact arcing in the network superimposes sharply-defined bursts of wide bandwidth high-frequency noise on the power supply lines, a method for determining that such bursts of high-frequency noise are produced by electrical contact arcing as opposed to an external disturbance, said method comprising the steps of:
- monitoring the high-frequency components on the power line waveform to detect bursts of wide bandwidth high-frequency noise having detectable characteristics that differ from other typical electrical disturbances;
- said detectable characteristics including one or more of current rise times at the ends of said bursts being less than a predefined value, the rate of change of the current waveform exceeding a predetermined minimum level during said bursts, and the frequency content of said bursts including components of frequency greater than 10 MHz;
- and
- determining that arcing exists on the power line when a plurality of the detected bursts satisfy a predetermined algorithm for examining the pattern of detected bursts as a function of time.
A method for detecting the presence of electrical arcing on an AC power line of frequency F and period T=1/F, comprising the following steps:
- monitoring the line voltage, the load current, or energy radiated from the power line, as a waveform;
- examining the monitored waveform for detecting the presence of high-frequency noise, said high-frequency noise being substantially higher in frequency than F;
- and
- monitoring the detected noise present on the waveform for the occurrence of one or more predefined features in the noise characteristic of arcing, said features including discrete bursts of wide bandwidth high-frequency noise;
- and
- determining that arcing exists if said features occur only at substantially nonuniform intervals.
Apparatus for detecting the presence of electrical arcing on an AC power line of frequency F and period T=1/F, comprising:
- means for monitoring one of the line voltage and the load current and for extracting high-frequency noise therefrom, said high-frequency noise being substantially higher in frequency than F;
- means for monitoring the extracted noise for detecting the occurrence of one or more bursts in the noise, said bursts having detectable properties characteristic of arcing, said detectable properties including one or more of rapid current rise time, frequency components in excess of 10 MHz, and broad frequency bandwidth;
- means for determining that arcing exists if said detected bursts, and/or a sequence of said bursts, satisfy one or more additional predetermined conditions;
- and
- means activated to produce an output signal responsive to the determination that arcing exists.
A method for detecting the presence of electrical arcing on a power line powered by an AC source, comprising the following steps:
- monitoring the line voltage, the line current, or energy radiated from the power line, as a waveform;
- examining the waveform for detecting the presence of discrete, well-defined bursts of wide bandwidth noise including frequency components above 10 MHz;
- monitoring the time of detection of said bursts with respect to the zero-crossings of the current waveform;
- and
- determining that arcing exists on the power line when a plurality of the detected bursts are detected other than during portions of the waveform surrounding the zero-crossings of the current waveform.
Dependencies are inferred from the claim text.