Circuit interrupter with ground fault self-test and associated method

Patent metadata

Field	Value
Publication number	US-2018366291-A1
Application number	US-201715625230-A
Country	US
Kind code	A1
Filing date	Jun 16, 2017
Priority date	Jun 16, 2017
Publication date	Dec 20, 2018
Grant date	—

Abstract

A circuit interrupter is structured to protect a protected circuit. The circuit interrupter includes a ground fault current sensor structured to sense a ground fault current in the protected circuit and a processor including a routine structured to perform a ground fault output self-test. The ground fault output self-test includes to output a trip signal within a predetermined phase angle of a zero-crossing of current flowing through the protected circuit, to stop outputting the trip signal before the zero-crossing, to determine whether the trip signal caused a pulse in the ground fault current, and to determine whether the circuit interrupter passed the ground fault output self-test based on whether the trip signal caused a pulse in the ground fault current.

First claim

What is claimed is:

1 . A circuit interrupter structured to protect a protected circuit, the circuit interrupter comprising:
a ground fault current sensor structured to sense a ground fault current in the protected circuit; a processor including a routine structured to perform a ground fault output self-test, the ground fault output self-test including:
to output a trip signal within a predetermined phase angle of a zero-crossing of current flowing through the protected circuit;
to stop outputting the trip signal before the zero-crossing;
to determine whether the trip signal caused a pulse in the ground fault current; and
to determine whether the circuit interrupter passed the ground fault output self-test based on whether the trip signal caused a pulse in the ground fault current.

2 . The circuit interrupter of claim 1 , wherein the processor is structured to determine that the circuit interrupter passed the ground fault output self-test when it is determined that the trip signal caused the pulse in the ground fault current; and wherein the processor is structured to determine that the circuit interrupter failed the ground fault output self-test when it is determined that the trip signal did not cause the pulse in the ground fault current.

3 . The circuit interrupter of claim 2 , wherein the processor is structured to repeat the ground fault output self-test if the circuit interrupter fails the ground fault output self-test; and wherein the processor is structured to output an error signal if the circuit interrupter fails the ground fault output self-test a predetermined consecutive number of times.

4 . The circuit interrupter of claim 3 , further comprising:
an indicator structured to activate in response to the processor outputting the error signal.

5 . The circuit interrupter of claim 1 , wherein the ground fault output self-test further includes:
to perform a first integration on the ground fault current for a first predetermined period of time where the pulse is expected to be present; to perform a second integration on the ground fault current for a second predetermined period of time where the pulse is not expected to be present; and to compare the first and second integrations, and wherein the processor is structured to determine that the trip signal caused the pulse in the ground fault current if a difference between the first and second integrations is above a threshold level.

6 . The circuit interrupter of claim 1 , wherein the processor is structured to determine whether the trip signal caused a pulse in the ground fault current by tracking a peak value of the ground fault current.

7 . The circuit interrupter of claim 1 , further comprising:
separable contacts; a solenoid structured to activate to trip open the separable contacts; and a silicon controlled rectifier (SCR) structured to allow current from the protected circuit to flow through a coil of the solenoid when the processor outputs the trip signal, wherein the current flowing through the protected circuit within the predetermined phase angle of the zero-crossing is insufficient to cause the solenoid to activate and trip open the separable contacts.

8 . The circuit interrupter of claim 7 , wherein the predetermined phase angle is about 15 degrees.

9 . The circuit interrupter of claim 1 , wherein the processor is structured to perform the ground fault output self-test at predetermined intervals.

10 . The circuit interrupter of claim 1 , wherein the processor is structured to perform a ground fault input self-test prior to performing the ground fault output self-test.

11 . A method of performing a ground fault output self-test in a circuit interrupter, the method comprising:
outputting a trip signal within a predetermined phase angle of a zero-crossing of current flowing through a protected circuit; stopping output of the trip signal before the zero-crossing; determining whether the trip signal caused a pulse in the ground fault current; and determining whether the ground fault output self-test has been passed based on whether the trip signal caused a pulse in the ground fault current.

12 . The method of claim 11 , further comprising:
determining that the ground fault output self-test has been passed when it is determined that the trip signal caused the pulse in the ground fault current; and determining that the ground fault output self-test has been failed when it is determined that the trip signal did not cause the pulse in the ground fault current.

13 . The method of claim 12 , further comprising:
repeating the ground fault output self-test if the ground fault output self-test has been failed; and outputting an error signal if the ground fault output self-test has been failed a predetermined consecutive number of times.

14 . The method of claim 13 , further comprising:
activating an indicator in response to outputting the error signal.

15 . The method of claim 11 , wherein determining whether the trip signal caused a pulse in the ground fault current includes:
performing a first integration on the ground fault current for a first predetermined period of time where the pulse is expected to be present; performing a second integration on the ground fault current for a second predetermined period of time where the pulse is not expected to be present; and comparing the first and second integrations; and determining that the trip signal caused the pulse in the ground fault current if a difference between the first and second integrations is above a threshold level.

16 . The method of claim 11 , wherein determining whether the trip signal caused a pulse in the ground fault current includes:
determining whether the trip signal caused a pulse in the ground fault current by tracking a peak value of the ground fault current.

17 . The method of claim 11 , wherein the current flowing through the protected circuit within the predetermined phase angle of the zero-crossing is insufficient to cause a solenoid to activate and trip open separable contacts of the circuit interrupter.

18 . The method of claim 17 , wherein the predetermined phase angle is about 15 degrees.

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 performing a ground fault output self-test in a circuit interrupter, the method comprising:
outputting a trip signal within a predetermined phase angle of a zero-crossing of current flowing through a protected circuit; stopping output of the trip signal before the zero-crossing; determining whether the trip signal caused a pulse in the ground fault current; and determining whether the ground fault output self-test has been passed based on whether the trip signal caused a pulse in the ground fault current.

20 . The non-transitory computer readable medium of claim 19 , wherein the method further comprises:
determining that the ground fault output self-test has been passed when it is determined that the trip signal caused the pulse in the ground fault current; and determining that the ground fault output self-test has been failed when it is determined that the trip signal did not cause the pulse in the ground fault current.

Assignees

• Eaton Corp

Inventors

• Jiao Jian
• Anderson Adonna Angelika

Classifications

• H01H71/04

  Means for indicating condition of the switching device {(by means of an auxiliary contact H01H71/46)} · CPC title

• H02H3/335

  the main function being self testing of the device · CPC title

• H01H71/24

  Electromagnetic mechanisms · CPC title

• H02H3/021

  concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order (disconnection at zero value in general H03K17/18) · CPC title

• H01H2071/044

  Monitoring, detection or measuring systems to establish the end of life of the switching device, can also contain other on-line monitoring systems, e.g. for detecting mechanical failures · CPC title