STRAY VOLTAGE DETECTING

• US 20070279067A1
• Filed: 06/02/2006
• Published: 12/06/2007
• Est. Priority Date: 06/02/2006
• Status: Active Grant

• Current Assignee: Cal-Tek 2000, Inc.
• Original Assignee: Cal-Tek 2000, Inc.
• Inventors: Sun, Jianping, Peterson, Meredith P., Wiswell, Daniel C.
• Granted Patent: US 7,449,892 B2
• Time in Patent Office: Days
• US Class Current: 324/457
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential
• CPC Class Codes: G01R 31/083 in cables, e.g. underground
• CPC Class Codes: G01R 31/088 Aspects of digital computing

Abstract

A stray voltage detector has a portable housing carrying a pair of electrostatic charge sensors spaced apart along an axis, and a pair of field intensity indicators, each indicator connected to an associated one of the charge sensors and constructed to indicate a relative electric field intensity at its associated sensor. The voltage detector is constructed to provide simultaneous electric field intensity feedback from both indicators to an operator moving the housing along the axis over a surface with a localized region at an elevated voltage, to assist in locating the localized elevated voltage region. The detector is useful for locating high-voltage regions, even when there is little or no current flowing through such regions to generate a magnetic field.

Claims

1. A stray voltage comprising

a housing carrying a pair of electrostatic charge sensors spaced apart along an axis;

and

a pair of field intensity indicators, each indicator operably connected to an associated one of the charge sensors and constructed to indicate a relative electric field intensity at its associated sensor;

the voltage detector thus being constructed to provide simultaneous electric field intensity feedback from both indicators to an operator moving the housing along the axis over a surface with a localized region at an elevated voltage, to assist in locating the localized electric voltage region.

2. The stray voltage detector of claim 1 wherein the electrostatic charge sensors each comprise a conductor positioned and configured to define a capacitor in cooperation with the localized elevated voltage region.

3. The stray voltage detector of claim 2 wherein the conductor comprises a substantially flat plate.

4. The stray voltage detector of claim 3 wherein the flat plate has a thickness of less than about 0.005 inch (0.13 millimeter).

5. The stray voltage detector of claim 2 wherein the conductor comprises a portion of a conductive layer of a printed circuit board.

6. The stray voltage detector of claim 1 wherein the electrostatic charge sensors each comprise a plate of conductive material on a circuit board.

7. The stray voltage detector of claim 6 wherein the plates comprise portions of an etched copper layer of the circuit board.

8. The stray voltage detector of claim 7 wherein the plates are electrically connected to electrical components on the circuit board through vias.

9. The stray voltage detector of claim 6 further comprising a conductive shield trace extending between the electrostatic charge sensors and connected to an electrical ground potential of the circuit board.

10. The stray voltage detector of claim 9 wherein the conductive shield trace lies directly between, and is coplanar with, the plates.

11. The stray voltage detector of claim 1 further comprising a pair of amplification circuits, each amplification circuit having an input connected to a respective one of the electrostatic charge sensors.

12. The stray voltage detector of claim 11 wherein each amplification circuit comprises first and second amplification stages connected in series.

13. The stray voltage detector of claim 12 wherein the second amplification stage provides an adjustable gain.

14. The stray voltage detector of claim 11 wherein each amplification circuit provides an overall effective gain of between about 1 and 10,000.

15. The stray voltage detector of claim 1 wherein the indicators comprise left an right audio speakers.

16. The stray voltage detector of claim 15 wherein the left and right audio speakers are of a headset wearable by the operator.

17. The stray voltage detector of claim 15 further comprising visual field intensity displays, each display operably connected to an associated one of the field sensors, such that the indicators and displays provide simultaneously left and right audio-visual feedback indicative of relative field intensity.

18. The stray voltage detector of claim 1 wherein the indicators are visual field intensity display arranged to be viewed simultaneously by the operator.

19. The stray voltage detector of claim 18 wherein the displays each comprise a series of lights that sequentially illuminate with increasing field intensity.

20. The stray voltage detector of claim 1 wherein the housing is hand-portable.

21. The stray voltage detector of claim 20 wherein the housing is elongated, with a lower end carrying the sensors laterally spaced apart, and an upper end having a handle graspable by the operator to move the lower end of the housing across the surface while walking erect along the surface.

22. The stray voltage detector of claim 21 wherein the handle is arranged to define a forward direction perpendicular to the axis along which the sensors are spaced apart, such that the sensors and their associated indicators comprise left and right sensor-indicator pairings.

23. The stray voltage detector of claim 22 wherein the left sensor-indicator pairing includes a left audio speaker operably connected to the sensor of the left sensor-indicator pairing, and wherein the right sensor-indicator pairing includes a right audio speaker operably connected to the sensor of the right sensor-indicator pairing.

24. The stray voltage detector of claim 1 further comprising a GPS receiver carried by the housing and having a display visible by the operator to indicate position of the stray voltage detector.

25. The stray voltage detector of claim 24 further comprising a wireless transmitter operable to send a signal indicating detector position to a remote receiver.

26. The stray voltage detector of claim 24 further comprising stray voltage location memory storage contained within the housing.

27. The stray voltage detector of claim 26 wherein the memory storage is configured to save sets of data, each set including an indication of test date and time, location latitude and longitude, and whether a stray voltage fault was detected.

28. The stray voltage detector of claim 1 further comprising a data port disposed on the housing and connectable to a data storage medium for storing stray voltage location data.

29. The stray voltage detector of claim 28 wherein the data storage medium is configured to time stamp stored stray voltage location data.

30. A method of detecting stray mains voltage, the method comprising

providing a portable detector with a housing carrying a pair of electrostatic charge sensors spaced apart along an axis, and a pair of field intensity conductors, each indicator operably connected to an associated one of the electrostatic charge sensors and constructed to indicate a relative electric field intensity at its associated sensor;

moving the housing along the axis over a surface with a localized region at an elevated voltage, such that the elevated voltage region passes under a first, then a second of the pair of sensors, while monitoring the indicators;

in response to the indicators indicating a high maximum field intensity from the first to the second sensor, moving the housing back along the axis until the indicators indicate approximately an equal field intensity at the sensors; and

recording housing position as a location of a stray mains voltage.

31. The method of claim 30 further comprising adjusting an amplification of a signal from one of the electrostatic charge sensors to its associated field intensity indicator.

32. The method of claim 30 wherein monitoring the indicators comprises listening to left and right audio speakers, each speaker associated with a respective charge sensor.

33. The method of claim 30 wherein monitoring the indicators comprises observing left and right visual indicators, each visual indicator associated with a respective charge sensor.

34. The method of claim 30 wherein the housing is moved by hand.

35. The method of claim 30 wherein recording housing position comprises determining housing position by global satellite positioning and digitally recording the determined housing position in a memory storage.

36. The method of claim 35 further comprising wirelessly transmitting housing position to a remote receiver.