Method and apparatus for detecting arcing in electrical connections 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 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 occurs every half-cycle of the power frequency, arcing is determined to be present, and an alarm is given.
Claims48
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 or the line current 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 for a gap of duration t.sub.b wherein substantially no high-frequency noise is present, t.sub.b being less than or equal to T/4;
- determining that arcing exists if high-frequency noise is substantially continuously present except for one such gap during any time interval equal in duration to T/2;
- and
- providing an output responsive to said determination that arcing exists.
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 or the load current 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 for the occurrence of a pattern, the pattern comprising:
- a first interval of duration t.sub.a, t.sub.a being less than T/2, wherein high-frequency noise is substantially present, and followed immediately by
- a second interval of duration t.sub.b, t.sub.b being less than T/2, wherein high-frequency noise is substantially absent, and followed immediately by
- a third interval of duration t.sub.c wherein high-frequency noise is substantially present, t.sub.a +t.sub.b +t.sub.c being no greater than T/2;
- determining that arcing exists if said pattern occurs only once in any interval equal in duration to T/2;
- and
- providing an output responsive to said determination that arcing exists.
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 measuring the amplitude of said noise and comparing the amplitude to a predetermined value to determine if high-frequency noise is present;
- means for determining whether a pattern is exhibited by said noise in any interval equal in duration to T/2, said pattern comprising at least one interval wherein high-frequency noise is present and another interval wherein high-frequency noise is absent, and, if so, determining that arcing exists;
- and
- means activated to produce an output signal responsive to the determination that arcing exists.
Dependencies are inferred from the claim text.