Multifunction single core sensor for ground fault application

Patent metadata

Field	Value
Publication number	US-11799279-B2
Application number	US-202117375142-A
Country	US
Kind code	B2
Filing date	Jul 14, 2021
Priority date	Jul 14, 2021
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

A ground fault sensing circuit system includes a current transformer having a first winding and a second winding on opposite halves of the current transformer, outputting first and second signals, each winding coupled to a processor that determines information about respective currents in conductors monitored by the current transformer, based on a combination of the first and second signals. In another embodiment, the current transformer has a third winding wrapped continuously around both halves of the current transformer, overlapped with the first and second windings, the third winding outputting a third signal coupled to the processor, which determines information about respective currents in conductors monitored by the current transformer, based on a combination of the first, second, and third signals.

First claim

What is claimed is:

1. A ground fault sensor for a circuit, comprising:
a current transformer having a body with an opening having a central axis running along a length of the opening, the current transformer having a first winding and a second winding wrapped around the body and through the opening, the first winding configured to output a first signal and the second winding configured to output a second signal, the body surrounding two parallel conductors that pass through the opening parallel with the central axis and occupy a conductor plane that is coincident with the central axis, the two parallel conductors being substantially equidistant from the central axis;
wherein the first signal corresponds to a first secondary current in the first winding induced by a magnetic flux in the first winding that is magnetically coupled with a first current in a first conductor of the two parallel conductors;
wherein the second signal corresponds to a second secondary current in the second winding induced by a magnetic flux in the second winding that is magnetically coupled with a second current in a second conductor of the two parallel conductors; and
wherein the first winding is wrapped around a first half of the body and the second winding is wrapped around a second half of the body, and the first winding is non-overlapped with the second winding.

2. The ground fault sensor of claim 1 , wherein information about a combination of the first signal in the first winding and the second signal in the second winding is determined by a combined signal circuit.

3. The ground fault sensor of claim 1 , wherein the body surrounds a third conductor that passes through the opening of the body and is coincident with the central axis;
wherein a third winding is wrapped continuously around both halves of the body, through the opening, overlapped with the first and second windings and configured to output a third signal; and
wherein the first winding is configured to output the first signal on a first signal chain, the second winding is configured to output the second signal on a second signal chain, the third winding is configured to output the third signal on a third signal chain, and the first signal chain, second signal chain, and third signal chain are connected to a combined signal circuit.

4. The ground fault sensor of claim 1 , wherein the first half of the body and the second half of the body are symmetrically opposed about an orthogonal plane that is substantially perpendicular to the conductor plane; and
wherein the first conductor of the two parallel conductors is closer to the first winding than to the second winding, and the second conductor of the two parallel conductors is positioned closer to the second winding than to the first winding.

5. The ground fault sensor of claim 1 , wherein the first winding is configured to output the first signal on a first signal chain, the second winding is configured to output the second signal on a second signal chain, the first signal chain and second signal chain are connected to a combined signal circuit, and wherein the combined signal circuit is an averaging circuit that determines an average of the first and second signals.

6. The ground fault sensor for a circuit of claim 1 , wherein the first signal is output on a first signal chain, wherein the second signal is output on a second signal chain, and wherein the first signal chain and the second signal chain are independent with respect to one another.

7. A ground fault sensing circuit system, comprising:
a current transformer having a body with an opening having a central axis running along a length of the opening, the current transformer having a first winding and a second winding wrapped around the body and through the opening, the first winding configured to output a first signal and the second winding configured to output a second signal, the body surrounding two parallel conductors that pass through the opening parallel with the central axis and occupy a conductor plane that is coincident with the central axis, the two parallel conductors being substantially equidistant from the central axis;
wherein the first signal corresponds to a first secondary current in the first winding induced by a magnetic flux in the first winding that is magnetically coupled with a first current in a first conductor of the two parallel conductors;
wherein the second signal corresponds to a second secondary current in the second winding induced by a magnetic flux in the second winding that is magnetically coupled with a second current in a second conductor of the two parallel conductors; and
wherein the first winding is wrapped around a first half of the body and the second winding is wrapped around a second half of the body, and the first winding is non-overlapped with the second winding; and
a processor coupled to the first winding to receive the first signal and coupled to the second winding to receive the second signal, the processor configured to determine information about at least one of a first current in a first conductor or a second current in a second conductor of the two parallel conductors, based on a combination of the first signal and the second signal.

8. The ground fault sensing circuit system of claim 7 , wherein the body surrounds a third conductor that passes through the opening of the body and is coincident with the central axis;
wherein a third winding is wrapped continuously around both halves of the body, through the opening, overlapped with the first and second windings and configured to output a third signal; and
wherein the first winding is configured to output the first signal on a first signal chain, the second winding is configured to output the second signal on a second signal chain, the third winding is configured to output the third signal on a third signal chain, and the first signal chain, second signal chain, and third signal chain are connected to the processor.

9. The ground fault sensing circuit system of claim 7 , wherein the first winding is configured to output the first signal on a first signal chain, the second winding is configured to output the second signal on a second signal chain, the first signal chain and second signal chain are connected to the processor, and wherein the processor determines an average of the first and second signals.

10. The ground fault sensing circuit system of claim 7 , wherein the first signal is output on a first signal chain, wherein the second signal is output on a second signal chain, and wherein the first signal chain and the second signal chain are independent with respect to one another.

11. The ground fault sensing circuit system of claim 7 , wherein a difference between the first signal in the first winding and the second signal in the second winding determined by the processor, indicates a ground fault in at least one of the two parallel conductors.

12. The ground fault sensing circuit system of claim 7 , wherein a load current in at least one of a first conductor or a second conductor of the two parallel conductors is determined by the processor based on the first signal in the first winding and the second signal in the second winding.

13. The ground fault sensing circuit system of claim 7 , wherein a ground fault is determined by the processor based on at least one of an absolute difference between the first signal in the first winding and the second signal in the second winding or when the first signal is greater than the second signal.

14. The ground fault sensing circuit system of claim 7 , wherein the first half of the body and the second half of the body are symmetrically opposed

Assignees

• Schneider Electric Usa Inc

Inventors

• Schroeder Jeremy D
• Melecio Juan Ignacio

Classifications

• H02H1/0007 Primary

  concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445) · CPC title

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title

• H01F27/28

  Coils; Windings; Conductive connections · CPC title

• H01F38/28 Primary

  Current transformers · CPC title

• H02H3/16

  responsive to fault current to earth, frame or mass (with balanced or differential arrangement H02H3/26 {; monitoring earth connection H02H5/105}) · CPC title