Circuit interrupter with temperature compensation and method of operating a circuit interrupter

Patent metadata

Field	Value
Publication number	US-10622801-B2
Application number	US-201715659927-A
Country	US
Kind code	B2
Filing date	Jul 26, 2017
Priority date	Jul 26, 2017
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

A circuit interrupter for protecting a protected circuit includes separable contacts, an operating mechanism structured to trip open the separable contacts, a current sensor structured to sense a current flowing through the protected circuit, a temperature sensor structured to sense a temperature of the protected circuit proximate the current sensor, and a processor configured to select a trip time based on the sensed current, to adjust the selected trip time based on the sensed temperature, and to cause the operating mechanism to trip open the separable contacts when the adjusted selected trip time is reached.

First claim

What is claimed is:

1. A circuit interrupter for protecting a protected circuit, the circuit interrupter comprising:
separable contacts;
an operating mechanism structured to trip open the separable contacts;
a current sensor structured to sense a current flowing through the protected circuit;
a temperature sensor structured to sense a temperature of the protected circuit proximate the current sensor; and
a processor configured to select a trip time based on the sensed current, to adjust the selected trip time based on the sensed temperature, and to cause the operating mechanism to trip open the separable contacts when the adjusted selected trip time is reached.

2. The circuit interrupter of claim 1 , wherein the selected trip time is selected from a predetermined trip time curve.

3. The circuit interrupter of claim 1 , wherein the processor is configured to adjust the selected trip time based on the sensed temperature by reducing the selected trip time when the sensed temperature is above a predetermined temperature.

4. The circuit interrupter of claim 1 , wherein the processor is configured to determine which one of a plurality of ranges of temperature the sensed temperature is within.

5. The circuit interrupter of claim 4 , wherein the processor is configured to adjust the selected trip time by an adjustment amount associated with the one of the plurality of ranges of temperature the sensed temperature is within; and wherein each of the plurality of ranges of temperature are associated with a different adjustment amount.

6. The circuit interrupter of claim 4 , wherein the processor is configured to determine that the adjusted selected trip time is reached when a counter reaches a trip time counter based on the selected trip time; wherein the processor is configured to periodically increment the counter; and wherein the processor is configured adjust an amount the counter is incremented by based on the one of the plurality of ranges of temperature the sensed temperature is within.

7. The circuit interrupter of claim 1 , wherein the current sensor includes a shunt.

8. The circuit interrupter of claim 7 , wherein the shunt has a variation of less than 8%.

9. The circuit interrupter of claim 1 , wherein the temperature sensor is a thermistor.

10. A method of operating a circuit interrupter, the method comprising:
sensing a current flowing through a circuit protected by the circuit interrupter with a current sensor;
sensing a temperature of a conductor proximate the current sensor with a temperature sensor;
selecting a trip time based on the sensed current;
adjusting the selected trip time based on the sensed temperature; and
causing the circuit interrupter to trip when the adjusted selected trip time is reached.

11. The method of claim 10 , wherein the selected trip time is selected from a predetermined trip time curve.

12. The method of claim 10 , wherein adjusting the selected trip time includes adjusting the selected trip time based on the sensed temperature by reducing the selected trip time when the sensed temperature is above a predetermined temperature.

13. The method of claim 10 , further comprising:
determining which one of a plurality of ranges of temperature the sensed temperature is within.

14. The method of claim 13 , wherein adjusting the selected trip time includes adjusting the selected trip time by an adjustment amount associated with the one of the plurality of ranges of temperature the sensed temperature is within; and wherein each of the plurality of ranges of temperature are associated with a different adjustment amount.

15. The method of claim 13 , further comprising:
determining that the adjusted selected trip time is reached when a counter reaches a trip time counter based on the selected trip time;
periodically incrementing the counter; and
adjusting an amount the counter is incremented by based on the one of the plurality of ranges of temperature the sensed temperature is within.

16. The method of claim 10 , wherein the current sensor includes a shunt.

17. The method of claim 16 , wherein the shunt has a variation of less than 8%.

18. The method of claim 10 , wherein the temperature sensor is a thermistor.

19. A non-transitory computer readable medium storing one or more programs, including instructions, which when executed by a computer, causes the computer to perform a method of operating a circuit interrupter, the method comprising:
sensing a current flowing through a circuit protected by the circuit interrupter with a current sensor;
sensing a temperature of a conductor proximate the current sensor with a temperature sensor;
selecting a trip time based on the sensed current;
adjusting the selected trip time based on the sensed temperature; and
causing the circuit interrupter to trip when the adjusted selected trip time is reached.

20. The non-transitory computer readable medium of claim 19 , wherein adjusting the selected trip time includes adjusting the selected trip time based on the sensed temperature by reducing the selected trip time when the sensed temperature is above a predetermined temperature.

Assignees

• Eaton Corp
• Eaton Intelligent Power Ltd

Inventors

• Jimenez Sandy
• Jiao Jian

Classifications

• H02H6/005

  using digital thermal images · CPC title

• H01H71/125

  characterised by sensing elements, e.g. current transformers (for differential protection H01H83/144) · CPC title

• H02H3/10 Primary

  additionally responsive to some other abnormal electrical conditions · CPC title

• H02H3/085

  making use of a thermal sensor, e.g. thermistor, heated by the excess current (also responsive to the temperature of the protected device H02H5/041, thermal images H02H6/00) · CPC title

• H01H71/22

  with compensation for variation of ambient temperature {(H01H71/162 takes precedence)} · CPC title