Method and apparatus for detecting arcing in alternating current power systems by monitoring high-frequency noise
First Claim
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1. 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 line current, or energy radiated from the power line, as a waveform;
monitoring the waveform for the presence of high-frequency noise, said high-frequency noise being substantially higher in frequency than F;
monitoring the waveform to detect gaps wherein said high-frequency noise is substantially attenuated;
measuring the time between successive detected gaps in the high-frequency noise;
determining that arcing exists if at least a predetermined number of said detected gaps occur at intervals substantially equal to integral multiples of T/2; and
providing an output signal responsive to said determination that arcing exists.
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Abstract
An arc detector or detecting potentially hazardous arcing in electrical connections comprises detection and signal processing circuitry for monitoring high-frequency noise on the power line characteristic of arcing and distinguishable from other sources of high-frequency noise. If high-frequency noise is present and a gap is detected at intervals synchronous to the power frequency, arcing is determined to be present, and an alarm is given.
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Citations
38 Claims
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1. 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:
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monitoring the line voltage, the line current, or energy radiated from the power line, as a waveform; monitoring the waveform for the presence of high-frequency noise, said high-frequency noise being substantially higher in frequency than F; monitoring the waveform to detect gaps wherein said high-frequency noise is substantially attenuated; measuring the time between successive detected gaps in the high-frequency noise; determining that arcing exists if at least a predetermined number of said detected gaps occur at intervals substantially equal to integral multiples of T/2; and providing an output signal responsive to said determination that arcing exists. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. 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:
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monitoring the line voltage, the load current, or energy radiated from the power line, as a waveform; examining the monitored waveform to detect the presence of high-frequency noise, said high-frequency noise being substantially higher in frequency than F; monitoring said high-frequency noise in the waveform for the occurrence of one or more predefined features characteristic of arcing, said characteristic features including predetermined variations of the amplitude of said noise occurring during periods of length T/2; and determining that arcing exists if said feature occurs repetitively at integral multiples of T/2. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. Apparatus for detecting the presence of electrical arcing on an AC power line of frequency F and period T=1/F, comprising:
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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 said extracted noise for detecting the occurrence of one or more predefined features in the noise characteristic of arcing, said features comprising one or more of minimum randomness of said noise, minimum bandwidth of said noise, or predetermined patterns of variation in the amplitude of said noise; means, responsive to said means for monitoring said extracted noise, for determining that arcing exists in response to detection of the occurrence of said one or more features repetitively at substantially integral multiples of T/2; and means, responsive to said means for determining, activated to produce an output signal responsive to the determination that arcing exists. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for detecting the presence of electrical arcing on an AC power line, comprising the following steps:
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monitoring the line voltage, the line current, or energy radiated from the power line, as a waveform; monitoring the waveform for the presence of noise having frequency components in excess of 10 kHz; monitoring the waveform to detect gaps wherein said high-frequency noise is substantially attenuated; and determining that arcing exists on the power line when a plurality of the detected gaps as a function of time satisfy a predetermined algorithm for determining whether the detected gaps follow a predetermined pattern. - View Dependent Claims (28, 29, 30, 31, 32)
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33. In an electrical network having AC power supply lines and wherein electrical contact arcing in the network superimposes high frequency components on the power supply line, a method for determining that the high frequency components are produced by electrical contact arcing as opposed to an external disturbance, said method comprising the steps of:
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monitoring the high-frequency components to detect gaps in said high frequency components on the line, wherein said high-frequency components are substantially attenuated during said gaps; and determining that arcing exists on the power line when a plurality of the detected gaps as a function of time satisfy a predetermined algorithm for evaluating the pattern of said gaps. - View Dependent Claims (34, 35, 36, 37, 38)
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Specification