Non-contact current measurement system

Patent metadata

Field	Value
Publication number	US-10591515-B2
Application number	US-201715604320-A
Country	US
Kind code	B2
Filing date	May 24, 2017
Priority date	Nov 11, 2016
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

Systems and methods provide a non-contact current measurement system which operates to measure alternating current flowing through an insulated wire without requiring galvanic contact with the insulated wire. The measurement system may include a magnetic field sensor that is selectively positionable proximate an insulated wire under test. In operation the magnetic field sensor detects a magnetic field generated by the current flowing in the insulated wire. Using an adjustable clamp assembly, the measurement system provides control over the mechanical positioning of the insulated wire relative to the magnetic field sensor to ensure consistent measurements. The non-contact current measurement system may determine information relating to the physical dimensions (e.g., diameter) of the insulated wire. Using the detected magnetic field, the known mechanical positioning, and the determined information relating to the physical dimensions of the insulated wire, the measurement system accurately determines the magnitude of the current flowing through the insulated wire without galvanic contact.

First claim

The invention claimed is:

1. A non-contact current measurement system, comprising:
a slider clamp assembly having a clamp member and a first clamp surface, the slider clamp assembly being adjustable to selectively clamp and locate an insulated wire at a defined position;
a position feedback sensor that, in operation, senses an extension of the clamp member, determines a diameter of the insulated wire clamped in the slider clamp assembly, and generates a position feedback sensor signal indicative of the diameter of the insulated wire;
a magnetic field sensor positioned proximate the slider clamp assembly, wherein in operation the magnetic field sensor detects a magnetic field generated by a current flowing in the insulated wire, and generates a magnetic field sensor signal that is indicative of at least one characteristic of the current flowing through the insulated wire clamped in the slider clamp assembly; and
at least one processor communicatively coupled to the position feedback sensor and the magnetic field sensor, wherein in operation the at least one processor:
receives the position feedback sensor signal from the position feedback sensor;
determines a clamp position of the insulated wire clamped in the slider clamp assembly based on the position feedback sensor signal, wherein the clamp position is indicative of the diameter of the insulated wire;
receives the magnetic field sensor signal from the magnetic field sensor; and
determines at least one characteristic of the current flowing through the insulated wire based at least in part on the received position feedback sensor signal and the magnetic field sensor signal by accounting for an impact of the diameter of the insulated wire has on a relationship between the detected magnetic field and the current flowing in the wire, the at least one characteristic including at least one of a magnitude or frequency of the current flowing through the insulated wire.

2. The non-contact current measurement system of claim 1 wherein the position feedback sensor generates a linear position feedback signal indicative of a linear position of the slider clamp assembly.

3. The non-contact current measurement system of claim 1 , further comprising a user interface operatively coupled to the at least one processor, wherein in operation the at least one processor causes the user interface to display the determined at least one characteristic of the current flowing through the insulated wire.

4. The non-contact current measurement system of claim 1 wherein the at least one characteristic of the current flowing through the insulated wire comprises a magnitude of the current flowing through the insulated wire.

5. The non-contact current measurement system of claim 1 wherein the position feedback sensor comprises a resistive sensor, a magneto-resistive sensor, a Hall Effect sensor, a capacitive sensor, an inductive sensor, or an optical sensor.

6. The non-contact current measurement system of claim 1 wherein the slider clamp assembly comprises a second clamp surface, the second clamp surface faces the first clamp surface, and at least one of the first and second clamp surfaces is movable in a direction toward and away from the other of the first and second clamp surfaces to selectively clamp the insulated wire between the first and second clamp surfaces at the defined position.

7. The non-contact current measurement system of claim 6 wherein the first clamp surface comprises a front end surface of a front end of a housing of the non-contact current measurement system, and the second clamp surface is disposed on a clamp member that is selectively movable with respect to front end surface.

8. The non-contact current measurement system of claim 7 wherein the magnetic field sensor is positioned proximate the front end surface of the front end of the housing.

9. The non-contact current measurement system of claim 1 wherein the clamp member is a first clamp portion and the slider clamp assembly comprises the first clamp portion having a first clamp surface and a second clamp portion having a second clamp surface that faces the first clamp surface, and a biasing member biases the first clamp portion toward the second clamp portion.

10. The non-contact current measurement system of claim 9 wherein at least one of the first clamp surface and the second clamp surface operates as a shield for the magnetic field sensor.

11. The non-contact current measurement system of claim 1 , further comprising:
a reference signal type sensor that, in operation, senses a reference signal in the insulated wire without galvanically contacting the insulated wire,
wherein the at least one processor receives the reference signal and determines the at least one characteristic of the current flowing through the insulated wire based at least in part on the received reference signal.

12. The non-contact current measurement system of claim 11 wherein the at least one processor further determines at least one physical dimension of a conductor inside the insulated wire based at least in part on the received reference signal, wherein the at least one physical dimension is indicative of a distance between the conductor and the magnetic field sensor.

13. The non-contact current measurement system of claim 11 wherein the at least one processor further determines at least one physical dimension of a conductor inside the insulated wire based at least in part on the received reference signal and the received position feedback sensor signal.

14. A method of measuring current in an insulated wire without galvanically contacting a conductor in the insulated wire, the method comprising:
clamping, via slider clamp assembly, the insulated wire between first and second clamp surfaces;
determining a clamp distance between the first and second clamp surfaces, wherein the clamp distance is indicative of a diameter of the insulated wire clamped between the first and second clamp surfaces;
sensing, via a magnetic field sensor positioned proximate the insulated wire clamped between the first and second clamp surfaces, a magnetic field generated by the current flowing through the insulated wire, the magnetic field being indicative of at least one characteristic of the current flowing through the insulated wire; and
determining, via at least one processor, at least one characteristic of the current flowing through the insulated wire based at least in part on the determined clamp distance and the sensed magnetic field generated by the current flowing through the insulated wire by accounting for an impact of the diameter of the insulated wire has on a relationship between the detected magnetic field and the current flowing in the wire, the at least one characteristic including at least one of a magnitude or frequency of the current flowing through the insulated wire.

15. The method of claim 14 wherein determining the clamp distance comprises determining a linear position of the slider clamp assembly.

16. The method of claim 14 wherein the first clamp surface is positioned on a first clamp portion and the second clamp surface is positioned on a second clamp portion, and the method further comprises biasing the first clamp portion toward the second clamp portion.

17. The method of claim 14 , further comprising:
displaying, via a user interface, the determined at least one characteristic of the current flowing through the insulated wire.

18. The method of claim 14 wherein determining the at least one characteristic of the current flowing through the insulated wire compr

Assignees

• Fluke Corp

Inventors

• Rodriguez Ricardo
• Epperson David L
• Steuer Ronald
• Worones Jeffrey

Classifications

• G01R15/146

  Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop (if no voltage isolation is involved G01R1/203 or G01R19/0092) · CPC title

• G01R15/148

  involving the measuring of a magnetic field or electric field (G01R15/18, G01R15/20, G01R15/24, G01R15/26 take precedence) · CPC title

• G01R19/0092

  Measuring current only · CPC title

• G01R15/207 Primary

  Constructional details independent of the type of device used · CPC title

• G01R19/00

  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