Method for determining a circuit element parameter

• US 9,330,875 B2
• Filed: 01/29/2013
• Issued: 05/03/2016
• Est. Priority Date: 10/02/2009
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Beck, Riley D., Layton, Kent D., Tyler, Matthew A., Grange, Scott R.
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): McDonnough, Courtney
• Application Number:
  US13/752,596
• Publication Number:
  US 20140210484A1
• Time in Patent Office: 1,190 Days
• Field of Search: 324/509, 361/42
• US Class Current: 1/1
• CPC Class Codes: G01R 31/62 Testing of transformers
• CPC Class Codes: H01H 83/02 operated by earth fault currents H01H83/14 takes precedence
• CPC Class Codes: H02H 3/044 Checking correct functioning of protective arrangements, e.g. by simulating a fault for differential current circuit breakers H02H3/335
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence

Abstract

A method for determining a circuit element parameter in a ground fault circuit interrupter circuit. An electrical signal provided to a first node is used to generate another electrical signal at a second node. The electrical signal at the second node is multiplexed with a modulation signal to generate a modulated signal that is then filtered and converted into a digital representation of a portion of the circuit element parameter. The electrical signal at the second node is multiplexed with the modulation signal after it has been phase shifted to produce a modulated signal that is filter and converted into a digital representation of another portion of the circuit element parameter. In another aspect, a slope based solenoid self-test method is used for self-testing in a GFCI circuit. Alternatively, a method for determining a wiring fault is provided using a digital filter.

Claims

1. A method for determining a fault in a transformer, comprising:

providing the transformer having primary and secondary sides;

in a first configuration, determining the occurrence of a ground-to-neutral fault; and

in a second configuration determining the occurrence of a differential ground fault, wherein determining the occurrence of the differential ground fault includes;

generating an input current to the transconductance amplifier in response to a value of the reflected impedance;

generating a first copy of the input current;

using the first copy of the input current to determine a value of the impedance, wherein using the first copy of the input current to determine the value of the impedance includes determining a real component of the impedance;

generating a second copy of the input current; and

using the second copy of the input current to determine a reactive component of the impedance.

2. The method of claim 1, wherein determining the occurrence of the ground-to-neutral fault includes:

coupling a bias voltage to an input of a transconductance amplifier; and

detecting a reflected impedance at an output of the transconductance amplifier.

3. The method of claim 2, wherein determining the occurrence of the ground-to-neutral fault includes:

generating an input current to the transconductance amplifier in response to a

value of the reflected impedance.

4. The method of claim 1, wherein using the first copy of the input current to determine the value of the impedance includes determining a real component of the impedance.

8. The method of claim 1, wherein determining the occurrence of the ground-to-neutral fault comprises detecting a reflected impedance at the secondary side of the transformer.

5. A method for determining a fault in a transformer, comprising:

providing the transformer having primary and secondary sides;

in a first configuration, determining the occurrence of a ground-to-neutral fault, wherein determining the occurrence of the ground-to-neutral fault includes;

coupling a bias voltage to an input of a transconductance amplifier; and

detecting a reflected impedance at an output of the transconductance amplifier; and

in a second configuration determining the occurrence of a differential ground fault, wherein determining the occurrence of the differential ground fault includes;

generating an input current to the transconductance amplifier in response to a value of the reflected impedance;

generating a first copy of the input current; and

using the first copy of the input current to determine a value of the impedance, wherein using the first copy of the input current to determine the value of the impedance includes determining a real component of the impedance; and

further including;

generating a second copy of the input current; and

using the second copy of the input current to determine a reactive component of the impedance.

6. The method of claim 5, further including:

generating a third copy of the input current; and

using the third copy of the input current to detect a differential current.

7. A method of for determining a fault in a transformer, comprising:

providing the transformer having primary and secondary sides;

in a first configuration, determining the occurrence of a ground-to-neutral fault, wherein determining the occurrence of the ground-to-neutral fault includes;

coupling a bias voltage to an input of a transconductance amplifier; and

detecting a reflected impedance at an output of the transconductance amplifier; and

in a second configuration determining the occurrence of a differential ground fault, wherein determining the occurrence of the ground-to-neutral fault includes;

generating an input current to the transconductance amplifier in response to a value of the reflected impedance;

generating a first copy of the input current;

using the first copy of the input current to determine a value of the impedance, wherein using the first copy of the input current to determine the value of the impedance includes determining a reactive component of the impedance;

generating a second copy of the input current; and

using the second copy of the input current to determine a reactive component of the impedance.