Multi-winding high sensitivity current transformer

Patent metadata

Field	Value
Publication number	US-10090093-B2
Application number	US-201715854231-A
Country	US
Kind code	B2
Filing date	Dec 26, 2017
Priority date	Jan 28, 2014
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

A system includes a sensor configured to detect an electrical leakage current associated with an operation of an industrial machine. The sensor includes a core and a first winding encircling a first portion of the core. The first winding includes a first number of turns. The first winding is configured to obtain a set of electrical current measurements associated with the operation of the industrial machine. The sensor includes a second winding encircling a second portion of the core. The second winding includes a second number of turns. The second winding is configured to obtain the set of electrical current measurements associated with the operation of the industrial machine. The first winding and the second winding are each configured to generate respective outputs based on the set of electrical current measurements. The respective outputs are configured to be used to reduce the occurrence of a distortion of the set of electrical current measurements based on a temperature of the core.

First claim

The invention claimed is:

1. A non-transitory computer-readable medium having computer executable code stored thereon, the code comprising instructions configured to cause one or more processing systems to:
receive a line voltage measurement associated with a first set of windings and a second set of windings coiled around a core of a current sensor;
receive a plurality of electrical leakage current measurements via the current sensor;
calculate an amplitude and a phase angle of a respective output voltage of each of the first set of windings and the second set of windings, wherein the amplitude and phase angle of the respective output voltages are referenced to the line voltage measurement;
calculate a phase-shift angle and a magnetic permeability value corresponding to each of the first set of windings and the second set of windings based at least in part on the phase angle of the respective output voltages;
derive one or more correction factors based on the phase-shift angles and the magnetic permeability values, wherein the one or more correction factors are configured to correct a temperature-based or aging-based distortion of the plurality of electrical leakage current measurements;
utilize the one or more correction factors to correct the temperature-based or the aging-based distortion of the plurality of electrical leakage current measurements to generate corrected electrical leakage current measurements; and
utilize the corrected electrical leakage current measurements to control a current and or voltage of stator windings of an industrial machine comprising the first set of windings and the second set of windings.

2. The non-transitory computer-readable medium of claim 1 , wherein the code comprises instructions to cause the one or more processing systems to receive the plurality of electrical leakage current measurements via a high sensitivity current transformer (HSCT).

3. The non-transitory computer-readable medium of claim 1 , wherein the code comprises instructions to cause the one or more processing systems to calculate the respective output voltage of each of the first set of windings and the second set of windings based on a transfer function corresponding to each of the first set of windings and the second set of windings.

4. The non-transitory computer-readable medium of claim 1 , wherein the code comprises instructions to cause the one or more processing systems to derive the one or more correction factors based on the phase-shift angles and the magnetic permeability value to correct a distortion based on a temperature variation of the core of the current sensor.

5. The non-transitory computer-readable medium of claim 1 , wherein the code comprises instructions to cause the one or more processing systems to derive the one or more correction factors based on the phase-shift angles and the magnetic permeability value for each of a plurality of current sensors.

6. The non-transitory computer-readable medium of claim 1 , wherein the code comprises instructions to cause the one or more processing systems to process the respective output voltages once per time period.

7. A system, comprising:
a processor configured to:
receive a line voltage measurement associated with a first set of windings and a second set of windings coiled around a core of a current sensor;
receive a plurality of electrical leakage current measurements via the current sensor;
calculate an amplitude and a phase angle of a respective output voltage of each of the first set of windings and the second set of windings, wherein the amplitude and phase angle of the respective output voltages are referenced to the line voltage measurement;
calculate a first phase-shift angle corresponding the first set of windings and a second phase-shift angle corresponding to the second set of windings based at least in part on the phase angle of the respective output voltages;
calculate a magnetic permeability value of the core of the current sensor based at least in part on the phase angle of the respective output voltages; and
derive one or more correction factors based on the phase-shift angles and the magnetic permeability value, wherein the one or more correction factors are configured to correct a temperature-based or aging-based distortion of the electrical leakage current measurements; and
utilize the one or more correction factors to correct the temperature-based or the aging-based distortion of the plurality of electrical leakage current measurements to generate corrected electrical leakage current measurements; and
utilize the corrected electrical leakage current measurements to control a current and or voltage of stator windings of a machine comprising the first set of windings and the second set of windings.

8. The system of claim 7 , wherein the processor is configured to provide an indication of whether the electrical leakage current measurements comprise a capacitive leakage current or a resistive leakage current based at least in part on the first phase-shift angle and the second phase-shift angle.

9. The system of claim 7 , comprising the current sensor, wherein a first number of turns corresponding to the first set of windings does not equal a second number of turns corresponding to the second set of windings.

10. The system of claim 9 , wherein the first number of turns corresponding to the first set of windings and the second number of turns corresponding to the second set of windings comprises a ratio of approximately 3:2 or approximately 2:1.

11. The system of claim 9 , wherein the sensor comprises a high sensitivity current transformer (HSCT).

12. The system of claim 9 , wherein the core comprises a high-permeability magnetic core.

13. The system of claim 12 , wherein the high-permeability magnetic core comprises, high nickel, iron, a supermalloy, or any combination thereof.

14. The system of claim 9 , comprising a second sensor configured to detect an electrical voltage associated with the operation of an industrial machine.

15. The system of claim 14 , wherein the industrial machine comprises a synchronous motor, an induction motor, or a generator.

16. The system of claim 9 , comprising a second sensor and a third sensor each corresponding to a respective conductor coupled to an industrial machine, and wherein each of the second sensor and the third sensor comprises a respective first set of windings and a respective second set of windings.

17. The system of claim 7 , comprising a signal conditioning circuit coupled to the first set of windings and the second set of windings, wherein the signal conditioning circuit comprises a multiplexer configured to transmit the respective output voltages to the processor one at a time for processing.

18. The system of claim 7 , wherein the first set of windings and the second set of windings are configured to operate independently with respect to one another.

Assignees

• Gen Electric

Inventors

• Lu Dan Tho

Classifications

• H01F2038/305

  with toroidal magnetic core · CPC title

• H01F27/24 Primary

  Magnetic cores · CPC title

• G01R15/183 Primary

  using transformers with a magnetic core · CPC title

• H01F38/28

  Current transformers · CPC title

• G01R31/343

  in operation · CPC title