Non-contact voltage measurement system using multiple capacitors

Patent metadata

Field	Value
Publication number	US-10281503-B2
Application number	US-201715412891-A
Country	US
Kind code	B2
Filing date	Jan 23, 2017
Priority date	Nov 11, 2016
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

Systems and methods for measuring alternating current (AC) voltage of an insulated conductor (e.g., insulated wire) are provided, without requiring a galvanic connection between the conductor and a test electrode or probe. A non-galvanic contact (or “non-contact”) voltage measurement system includes a plurality of conductive sensors which capacitively couple with the insulated conductor. At least one processor receives signals indicative of the voltages at the conductive sensors due to the AC voltage in the insulated conductor, and determines the AC voltage in the insulated conductor based at least in part on the received signals.

First claim

The invention claimed is:

1. A system to measure alternating current (AC) voltage in an insulated conductor, the system comprising:
a housing;
a sensor assembly physically coupled to the housing, the sensor assembly selectively positionable proximate the insulated conductor without galvanically contacting the conductor, the sensor assembly comprising a first conductive sensor, a second conductive sensor, and a third conductive sensor, wherein the first, second and third conductive sensors each capacitively couple with the insulated conductor when the sensor assembly is positioned proximate the insulated conductor, and each of the first, second and third conductive sensors differs from the other of the conductive sensors with respect to at least one characteristic which affects capacitive coupling;
a voltage measurement subsystem electrically coupled to the first, second and third conductive sensors, wherein the voltage measurement subsystem, in operation, generates first, second and third sensor voltage signals that are indicative of voltages at the first, second and third conductive sensors, respectively; and
at least one processor communicatively coupled to the voltage measurement subsystem, wherein, in operation, the at least one processor:
receives the first, second and third sensor voltage signals from the voltage measurement subsystem; and
determines the AC voltage in the insulated conductor based at least in part on the received first, second and third sensor voltage signals.

2. The system of claim 1 wherein the at least one characteristic which affects capacitive coupling comprises at least one physical dimension.

3. The system of claim 1 wherein the at least one characteristic which affects capacitive coupling comprises at least one of physical area, physical orientation, or physical separation from the insulated conductor when the sensor assembly is positioned proximate the insulated conductor.

4. The system of claim 1 wherein each of the first and second conductive sensors has a planar right triangular shape which defines a first edge and a second edge that form a right angle, and a hypotenuse edge opposite the right angle, and the hypotenuse edges of the first conductive sensor and the second conductive sensor are positioned proximate each other.

5. The system of claim 4 wherein the third conductive sensor has a planar rectangular shape.

6. The system of claim 5 wherein the first and second conductive sensors are positioned in a first plane and the third conductive sensor is positioned in a second plane, and the first plane is disposed at an acute angle with respect to the second plane.

7. The system of claim 6 wherein the first plane is disposed at an angle with respect to the second plane which is between 20 degrees and 50 degrees.

8. The system of claim 1 wherein the sensor assembly comprises:
a first insulation layer which insulates the first and second conductive sensors from the insulated conductor when the sensor assembly is positioned proximate the insulated conductor, the first insulation layer having a first thickness; and
a second insulation layer which insulates the third conductive sensor from the insulated conductor when the sensor assembly is positioned proximate the insulated conductor, the second insulation layer having a second thickness that is different from the first thickness.

9. The system of claim 8 wherein the first thickness of the first insulation layer is less than the second thickness of the second insulation layer.

10. The system of claim 1 , further comprising at least one internal ground guard which at least partially surrounds each of the first, second and third conductive sensors.

11. The system of claim 1 wherein the at least one processor determines at least one of:
the first sensor voltage signal divided by the second sensor voltage signal;
the sum of the first sensor voltage signal and the second sensor voltage signal; and
the sum of the first sensor voltage signal, second sensor voltage signal and the third sensor voltage signal.

12. The system of claim 11 wherein the at least one processor determines the sum of the first sensor voltage signal and the second sensor voltage signal divided by the third sensor voltage signal.

13. The system of claim 1 wherein the at least one processor compares at least one value derived from the first, second and third sensor voltage signals to a lookup table to determine the AC voltage in the insulated conductor based at least in part on the received first, second and third sensor voltage signals.

14. The system of claim 1 wherein the at least one processor evaluates at least one equation using at least one value derived from the first, second and third sensor voltage signals to determine the AC voltage in the insulated conductor based at least in part on the received first, second and third sensor voltage signals.

15. A method of operating a system to measure alternating current (AC) voltage in an insulated conductor, the system comprising a housing, a sensor assembly physically coupled to the housing, the sensor assembly selectively positionable proximate the insulated conductor without galvanically contacting the conductor, the sensor assembly comprising a first conductive sensor, a second conductive sensor, and a third conductive sensor, wherein the first, second and third conductive sensors each capacitively couple with the insulated conductor when the sensor assembly is positioned proximate the insulated conductor, and each of the first, second and third conductive sensors differs from the other of the conductive sensors with respect to at least one characteristic which affects capacitive coupling, the method comprising:
generating, via a voltage measurement subsystem electrically coupled to the first, second and third conductive sensors, first, second and third sensor voltage signals that are indicative of voltages at the first, second and third conductive sensors, respectively;
receiving, by at least one processor communicatively coupled to the voltage measurement subsystem, the first, second and third sensor voltage signals from the voltage measurement subsystem; and
determining, by the at least one processor, the AC voltage in the insulated conductor based at least in part on the received first, second and third sensor voltage signals.

16. The method of claim 15 wherein determining the AC voltage in the insulated conductor comprises determining at least one of:
the first sensor voltage signal divided by the second sensor voltage signal;
the sum of the first sensor voltage signal and the second sensor voltage signal; and
the sum of the first sensor voltage signal, second sensor voltage signal and the third sensor voltage signal.

17. The method of claim 15 wherein determining the AC voltage in the insulated conductor comprises determining the sum of the first sensor voltage signal and the second sensor voltage signal divided by the third sensor voltage signal.

18. The method of claim 15 wherein determining the AC voltage in the insulated conductor comprises comparing at least one value derived from the first, second and third sensor voltage signals to a lookup table to determine the AC voltage in the insulated conductor based at least in part on the received first, second and third sensor voltage signals.

19. The method of claim 15 wherein determining the AC voltage in the insulated conductor comprises evaluating at least one equation using at least one value derived from the first, second and third sensor voltage signa

Assignees

• Fluke Corp

Inventors

• Steuer Ronald
• Radda Peter

Classifications

• G01R19/00 Primary

  Arrangements for measuring currents or voltages or for indicating presence or sign thereof (G01R5/00 takes precedence; for measuring bioelectric currents or voltages A61B5/24) · CPC title

• G01R15/14

  Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks · CPC title

• G01R15/142

  Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26 · CPC title

• G01R1/22 Primary

  Tong testers acting as secondary windings of current transformers · CPC title

• G01R15/16

  using capacitive devices · CPC title