Systems and methods for stray voltage detection

• US 8,599,031 B2
• Filed: 11/16/2010
• Issued: 12/03/2013
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Nstar Electric Company (Eversource Energy)
• Original Assignee: Nstar Electric Company (Eversource Energy)
• Inventors: Gelbien, Lawrence J., Schweiger, Werner J., Andreas, Philip B.
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US12/947,318
• Publication Number:
  US 20110221602A1
• Time in Patent Office: 1,113 Days
• Field of Search: None
• US Class Current: 340/662
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential
• CPC Class Codes: G01R 29/24 Arrangements for measuring quantities of charge
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks

Abstract

A system for detecting stray voltage in a conductive object is disclosed herein. The system includes a pick-up element, electrical circuitry, a housing for enclosing the circuitry, a support for mounting the housing, and an indicator. The pick-up element is separated from the conductive object and capable of detecting an electric field from the conductive object. The support of the housing is such that the pick-up element remains separated from the conductive object. The electrical circuitry determines a voltage level corresponding to the electric field detected by the pick-up element and generates, based on a comparison of the determined voltage level relative to a reference voltage level, an indicator signal representative of whether stray voltage is present in the conductive object. Based on the indicator signal, the indicator indicates to a user of the system whether stray voltage is present in the conductive object.

Claims

1. A system for detecting stray voltage in a conductive object, comprising

a pick-up element separated from the conductive object and capable of detecting an electric field from the conductive object,

electrical circuitry electrically connected to the pick-up element capable of determining a voltage level corresponding to the electric field detected by the pick-up element, wherein the electrical circuitry generates, based on a comparison of the determined voltage level relative to a reference voltage level, an indicator signal representative of whether stray voltage is present in the conductive object,

a housing for enclosing the electrical circuitry,

a support attached to the housing for mounting the housing on or near the conductive object such that the pick-up element remains separated from the conductive object, and

an indicator for indicating to a user of the system, based on the indicator signal, whether stray voltage is present in the conductive object, wherein the indicator comprises a visual indicator for visually indicating to the user whether stray voltage is present in the conductive object, the visual indicator comprising a first externally visible light which displays a first color when on and a second externally visible light which displays a second color, different from the first color, when on, the first externally visible light turning on when indicating a presence of stray voltage in the conductive object and the second externally visible light turning on when indicating an absence of stray voltage in the conductive object.

2. The system of claim 1, wherein

the conductive object has a cylindrical shape, and

the support has a substantially hemi-cylindrical shape such that it is disposed adjacent to the conductive object for mounting the housing on the conductive object.

3. The system of claim 1, wherein the conductive object is a metal pole.

4. The system of claim 3, wherein the conductive object is a lamp post of a lamp for lighting a public area.

5. The system of claim 1, wherein

the conductive object is a lamp for lighting a public area, and

the support encloses a photodetector for sensing an ambient light level and lamp circuitry in communication with the photodetector for switching the lamp between an on state and an off state according to the sensed ambient light level.

6. The system of claim 1, wherein the electrical circuitry comprises a power supply for powering the electrical circuitry.

7. The system of claim 6, wherein the power supply comprises solar cells.

8. The system of claim 7, wherein the solar cells are disposed on an exterior surface of the housing and substantially facing upwards.

9. The system of claim 6, wherein the power supply comprises a first power source and a second power source, the second power source for supplying power when the first power source is off.

10. The system of claim 9, wherein the electrical circuitry comprises a photodetector for sensing an ambient light level, the first power source switching between on and off according to the sensed ambient light level.

11. The system of claim 6, wherein the power supply comprises a power storage device for storing power from a power source.

12. The system of claim 11, wherein the power storage device comprises a rechargeable battery.

13. The system of claim 1, wherein the indicator comprises an audio indicator for aurally indicating to the user whether stray voltage is present in the conductive object.

14. The system of claim 1, wherein the indicator comprises a network connection for automatically communicating to a remote location whether stray voltage is present in the conductive object.

15. The system of claim 1, wherein the first externally visible light comprises a light-emitting diode.

16. The system of claim 1, wherein the first externally visible light is flashing when indicating the presence of stray voltage in the conductive object.

17. The system of claim 1, wherein

the visual indicator is disposed within the housing, and

the housing has at least a portion through which light passes such that the visual indicator is externally visible.

18. The system of claim 1, wherein the electrical circuitry comprises a timer for switching the electrical circuitry between an on state and an off state.

19. The system of claim 1, wherein the pick-up element is separated from the conductive object by at least one of an insulating layer and an air gap.

20. The system of claim 1, wherein the pick-up element is separated from the conductive object by an insulating layer and an air gap.

21. The system of claim 1, wherein the indicator remains on once a stray voltage has been detected and until reset by a control input.

22. The system of claim 21, wherein the control input is generated by one of a timer and a manual reset input.

23. The system of claim 1, wherein the conductive object is a public utility infrastructure object including one of a lamp post, a manhole, and a utility box.

24. The system of claim 1, wherein the pick-up element is an antenna element.

25. A system for detecting stray voltage in a conductive object, comprising

a pick-up element separated from the conductive object and capable of detecting an electric field from the conductive object,

electrical circuitry electrically connected to the pick-up element capable of determining a voltage level corresponding to the electric field detected by the pick-up element, wherein the electrical circuitry generates, based on a comparison of the determined voltage level relative to a reference voltage level, an indicator signal representative of whether stray voltage is present in the conductive object, wherein the electrical circuitry comprises a sensor for detecting whether the determined voltage level exceeds a predetermined threshold value, the generated indicator signal indicating a presence of stray voltage when the determined voltage level exceeds the predetermined threshold value, the sensor comprising a Hex Schmitt sensor,

a housing for enclosing the electrical circuitry,

a support attached to the housing for mounting the housing on or near the conductive object such that the pick-up element remains separated from the conductive object, and

an indicator for indicating to a user of the system, based on the indicator signal, whether stray voltage is present in the conductive object.