Partial Corona Discharge Detection

• US 20100176816A1
• Filed: 01/15/2009
• Published: 07/15/2010
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Clements, Neal D., Horowy, John
• Granted Patent: US 8,193,818 B2
• Time in Patent Office: Days
• US Class Current: 324/536
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 31/1254 of gas-insulated power appliances or vacuum gaps testing switches G01R31/327; detecting electrical or mechanical defects in encased switchgear H02B13/065

Abstract

A method of detecting partial corona discharge in a targeted circuit of an electrical apparatus, comprises the steps of: wrapping a Rogowski coil around a leg of the targeted circuit to produce a Rogowski coil signal that represents electrical current rate of change in the leg of the targeted circuit; coupling the Rogowski coil signal to a three-dimensional display device that may represent the dimension of time, the dimension of amplitude as a function of a time, and the dimension of duration of amplitude as a function of time in successive periods of that have a preselected duration; monitoring the display device to detect deviations of the duration of amplitude as a function of time from a normal waveform in the leg of the targeted circuit; and correlating ones of the detected deviations of the duration of amplitude as a function of time from a normal waveform that exceed a preselected deviation level as indicative of partial corona discharge within the targeted circuit.

Claims

1. A method of detecting partial corona discharge in a targeted circuit of an electrical apparatus, comprising the steps of:

wrapping a Rogowski coil around a leg of the targeted circuit to produce a Rogowski coil signal that represents electrical current rate of change in the leg of the targeted circuit;

coupling the Rogowski coil signal to a three-dimensional display device that may represent the dimension of time, the dimension of amplitude as a function of a time, and the dimension of duration of amplitude as a function of time in successive periods that have a preselected duration;

monitoring the display device to detect deviations of the duration of amplitude as a function of time from a normal waveform in the leg of the targeted circuit; and

correlating ones of the detected deviations of the duration of amplitude as a function of time from a normal waveform that exceed a preselected deviation level with partial corona discharge within the targeted circuit.

2. The method of claim 1, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a live conductor in the circuit.

3. The method of claim 1, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a ground return for the targeted circuit.

4. The method of claim 1, wherein the step of coupling the Rogowski coil signal to a three-dimensional display comprises coupling the Rogowski coil signal to an oscillographic display.

5. The method of claim 4, wherein the oscillographic display is of the digital phosphor oscilloscope (DPO) type.

6. The method of claim 1, wherein the preselected duration of each period is at least one cycle of the normal waveform in the leg of the targeted circuit.

7. The method of claim 1, wherein the step of monitoring the display device to detect deviations of the duration of amplitude as a function of time from a normal waveform in the leg of the targeted circuit comprises monitoring for at least a preselected number of successive periods.

8. The method of claim 1, further comprising the step of injecting a known corona electrical potential into the targeted circuit to determine the preselected deviation level.

9. A method of detecting partial corona discharge in a targeted circuit of an electrical apparatus, comprising the steps of:

wrapping a Rogowski coil around a leg of the targeted circuit to produce a Rogowski coil signal that represents electrical current rate of change in the leg of the targeted circuit;

coupling the Rogowski coil signal to a three-dimensional oscillographic display device that may represent the dimension of time, the dimension of amplitude as a function of a time, and the dimension of duration of amplitude as a function of time in successive periods that have a preselected duration;

monitoring the display device to detect deviations of the duration of amplitude as a function of time from a normal waveform in the leg of the targeted circuit;

injecting a known corona electrical potential into the targeted circuit to establish a predetermined deviation level for detected deviations of the duration of amplitude as a function of time sufficient to cause at least partial corona discharge in the targeted circuit; and

correlating ones of the detected deviations of the duration of amplitude as a function of time from a normal waveform that exceed the preselected deviation level with partial corona discharge within the targeted circuit.

10. The method of claim 9, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a live conductor in the circuit.

11. The method of claim 9, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a ground return for the circuit.

12. The method of claim 9, wherein the oscillographic display is of the digital phosphor oscilloscope (DPO) type.

13. The method of claim 9, wherein the preselected duration of each period is at least one cycle of the normal waveform in the leg of the targeted circuit.

14. The method of claim 9, wherein the step of monitoring the display device to detect deviations of the duration of amplitude as a function of time level from the level of a normal waveform in the leg of the targeted circuit comprises monitoring for at least a preselected number of successive periods.

15. A method of detecting partial corona discharge in a targeted circuit of an electrical apparatus, comprising the steps of:

wrapping a Rogowski coil around a leg of the targeted circuit to produce a Rogowski coil signal that represents electrical current rate of change in the leg of the targeted circuit;

coupling the Rogowski coil signal to a three-dimensional oscillographic display device of the digital phosphor oscilloscope (DPO) type that may represent the dimension of time, the dimension of amplitude as a function of time, and the dimension of duration of amplitude as a function of time in successive periods that have a preselected duration;

monitoring the display device to detect deviations of the duration of amplitude as a function of time from a normal waveform in the leg of the targeted circuit that each have a duration of at least one cycle of the normal waveform;

injecting a known corona electrical potential into the targeted circuit to establish a predetermined deviation level for detected deviations of the duration of amplitude as a function of time sufficient to cause at least partial corona discharge in the targeted circuit; and

correlating ones of the detected deviations of the duration of amplitude as a function of time level from a normal waveform that exceed the preselected deviation level with partial corona discharge within the targeted circuit.

16. The method of claim 15, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a live conductor in the circuit.

17. The method of claim 15, wherein the step of wrapping a Rogowski coil around a leg of the targeted circuit comprises wrapping the Rogowski coil around a ground return for the circuit.

18. The method of claim 15, wherein the step of monitoring the display device to detect deviations of the duration of amplitude as a function of time level from the level of a normal waveform in the leg of the targeted circuit comprises monitoring for at least a preselected number of successive periods.