Non-contacting method and apparatus for determining contact voltage sources and providing a warning for same
First Claim
1. A hand held contact voltage source detection apparatus for identification of hazardous contact voltages on energized objects or surfaces, comprising:
- (a) an electric field sensor structured to sense an electric field;
(b) an amplifier electrically connected to the electric field sensor to amplify electric signals from the electric field sensor;
(c) a signal conditioning circuit adapted to process the amplified electric signals and form time-coordinated signals, wherein the time-coordinated signals formed by the signal conditioning circuit are a third derivative (f0′
″
) signal of the amplified electric field signal, a third harmonic frequency to fundamental frequency comparison signal (H3/f0) from the amplified electric field signal, and a signal formed from the signal representing the percent total harmonic distortion (% THD) of the fundamental frequency of the amplified electric field signal; and
(d) a signal processor adapted to evaluate the time-coordinated signals and provide a user with a status of a contact voltage source by activating an appropriate status indicator.
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Accused Products
Abstract
This invention relates to non-contact measurement methods and an apparatus for the identification of hazardous contact voltages on energized objects and surfaces. The apparatus includes an electric field sensor structured to sense an electric field and a gain amplifier electrically connected to the electric field sensor to amplify electric signals from the electric field sensor. The apparatus further includes a signal conditioning circuit adapted to process the amplified electric signals and form time-coordinated signals and a digital signal processor adapted to evaluate the time-coordinated signals and provide a user with a status of a contact voltage source by activating an appropriate status indicator.
29 Citations
18 Claims
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1. A hand held contact voltage source detection apparatus for identification of hazardous contact voltages on energized objects or surfaces, comprising:
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(a) an electric field sensor structured to sense an electric field; (b) an amplifier electrically connected to the electric field sensor to amplify electric signals from the electric field sensor; (c) a signal conditioning circuit adapted to process the amplified electric signals and form time-coordinated signals, wherein the time-coordinated signals formed by the signal conditioning circuit are a third derivative (f0′
″
) signal of the amplified electric field signal, a third harmonic frequency to fundamental frequency comparison signal (H3/f0) from the amplified electric field signal, and a signal formed from the signal representing the percent total harmonic distortion (% THD) of the fundamental frequency of the amplified electric field signal; and(d) a signal processor adapted to evaluate the time-coordinated signals and provide a user with a status of a contact voltage source by activating an appropriate status indicator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of detecting a hazardous contact voltage on energized objects or surfaces comprising the steps of:
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(a) providing a hand held contact voltage source detection apparatus, having; (i) an electric field sensor; (ii) an amplifier; (iii) a signal conditioning circuit; and (iv) a digital signal processor; (b) receiving an electric field signal using the electric field sensor; (c) amplifying the electric field signal using the amplifier; (d) conditioning the amplified signal using the signal conditioning circuit and forming time-coordinated, distinct source type identifier signals; (e) comparing the time-coordinated signals using the signal processor to evaluate a state of the time-coordinated signals and determine if a hazardous contact voltage is present; and (f) activating an indicator on the handheld contact voltage source detection apparatus that provides a user with a source type identification of the detected contact voltage. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A hand held contact voltage source detection apparatus for identification of hazardous contact voltages on energized objects or surfaces, comprising:
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(a) an electric field sensor structured to sense an electric field; (b) an amplifier electrically connected to the electric field sensor to amplify electric signals from the electric field sensor; (c) a signal conditioning circuit adapted to process the amplified electric signals and form time-coordinated, distinct source type identifier signals, the identifier signals including neutral-earth (NEV) contact voltage source, intermittent arcing condition fault source, and induced contact voltage source; and (d) a signal processor adapted to evaluate the time-coordinated signals and provide a user with a source identification of a contact voltage source by activating an appropriate light emitting diode (LED) indicator representative of one of the time-coordinated, distinct source type identifier signals.
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Specification