High-voltage indicating apparatus and method
A digital voltage indicator includes a probe having a first electrode including a hollow portion and a probe tip projecting from the hollow portion, a second electrode extending into the hollow portion and spaced therefrom, and dielectric material disposed between the second electrode and the hollow portion. The indicator may include a reference conductor connected to the second electrode and detection circuitry connected between the probe and the reference conductor for detecting a voltage difference therebetween, and an annunciator connected to the detection circuitry for displaying the measured voltage.
1. A high-voltage indicator for use with an AC electric field source near ground comprising:
a probe including a probe tip for coupling to the source,
a reference conductor,
detection circuitry connected between the probe and the reference conductor for detecting the voltage difference therebetween, the detection circuitry being calibrated for electric fields typical of sources remote from ground,
an annunciator connected to the detection circuitry for indicating the voltage magnitude of the source, and
a substantial impedance connected between the probe tip and the detection circuitry sufficient to compensate for the greater field strength of the source near ground so as to indicate the source voltage with an accuracy comparable to that achievable when the detection circuitry is used with sources remote from ground.
2. The indicator of claim 1 , and further comprising a housing enclosing the reference conductor, the detection circuitry and the annunciator.
3. The indicator of claim 2 , wherein the housing is formed of plastic and the reference conductor comprises a conductive shield on an inner surface of the housing.
4. The indicator of claim 1 , wherein the detection circuitry includes a voltage divider.
5. The indicator of claim 1 , wherein the impedance is capacitive.
6. The indicator of claim 5 , wherein the probe includes first and second electrodes respectively connected to the probe tip and the detection circuitry, and dielectric material disposed between the electrodes for cooperation therewith to define a capacitor in series with the probe tip.
7. The indicator of claim 1 , wherein the detection circuitry includes a rectifier.
8. The indicator of claim 1 , wherein the annunciator includes a digital display.
9. The indicator of claim 1 , wherein the impedance is sufficient to provide insulation from an inadvertent bridging of the probe and voltage indicator from an energized terminal to a grounded conductor causing a short circuit or electric arc.
10. A high-voltage indicator for use with an AC electric field source near ground comprising:
a probe including a probe tip for coupling to the source,
a reference conductor,
detection circuitry connected between the probe and the reference conductor for detecting the voltage difference therebetween, the detection circuitry being calibrated for electric fields typical of sources remote from ground,
an annunciator connected to the detection circuitry for indicating the voltage magnitude of the source, and
a substantial impedance connected between the probe tip and the detection circuitry sufficient to provide insulation from an inadvertent bridging of the probe and voltage indicator from an energized terminal to a grounded conductor causing a short circuit or electric arc.