Arc fault detector and method for locating an arc fault

• US 7,253,640 B2
• Filed: 01/13/2003
• Issued: 08/07/2007
• Est. Priority Date: 01/13/2003
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Theisen, Peter J., Parker, Kevin L., Hetzmannseder, Engelbert, Engel, Joseph C., Zuercher, Joseph C.
• Primary Examiner(s): Deb; Anjan
• Assistant Examiner(s): NATALINI, JEFF WILLIAM
• Application Number:
  US10/341,483
• Publication Number:
  US 20040136124A1
• Time in Patent Office: 1,667 Days
• Field of Search: 324/424, 324520-522, 324/536, 324/76.42, 324/512, 324/713, 324/716, 361/80, 361/81, 361/42, 361/47, 702/58, 702/59, 340/638
• US Class Current: 324/622
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/042 combined with means for locating the fault locating faults in cables G01R31/08

Abstract

A circuit breaker for locating an arc fault for a protected circuit includes separable contacts interrupting the protected circuit and an arc fault detector determining an arc fault in the protected circuit. An analog to digital converter circuit measures a value of peak arc current at the arc fault detector. Another analog to digital converter circuit provides a peak line-to-neutral voltage. A memory provides an arc voltage operatively associated with the value of peak current. A microprocessor determines a distance from the arc fault detector to the arc fault from the value of peak arc current, a wire resistance per unit length or a wire conductance per unit length, the peak line-to-neutral voltage and the arc voltage.

Claims

1. A circuit breaker for a protected circuit, said circuit breaker comprising:

means for interrupting said protected circuit;

an arc fault detector determining an arc fault in said protected circuit;

a circuit measuring and storing a plurality of values of peak current for said arc fault; and

means for displaying only the largest one of said measured and stored values of peak current for said arc fault external to said circuit breaker.

2. The circuit breaker of claim 1 wherein said means for displaying is a light emitting diode;

and wherein said circuit measuring and storing a plurality of values of peak current includes a processor having an output driving said light emitting diode.

3. The circuit breaker of claim 1 wherein said means for displaying is a communication port;

and wherein said circuit measuring and storing a plurality of values of peak current includes a processor having an output driving said commumcation port.

4. The circuit breaker of claim 1 wherein said means for displaying is structured to display said only the largest one of said measured and stored values of peak current by sequentially outputting counts of values representing 100 A, 10 A and 1 A.

5. A system for locating an arc fault for a protected circuit, said system comprising:

a circuit breaker for said protected circuit, said circuit breaker comprising;

means for interrupting said protected circuit,

an arc fault detector determining an arc fault in said protected circuit,

a circuit measuring at least a value of peak current for said arc fault, and

means for displaying at least said measured value of peak current for said arc fault external to said circuit breaker;

means for providing a peak line-to-neutral voltage;

a data computation and display circuit remote from said circuit breaker, said data computation and display circuit comprising;

means for providing a wire resistance per unit length or a wire conductance per unit length for said protected circuit,

means for providing an arc voltage operatively associated with said value of peak current, and

means for determining a distance from the arc fault detector to said arc fault from the value of peak arc current, the wire resistance per unit length or the wire conductance per unit length, the peak line-to-neutral voltage, and the arc voltage; and

means for communicating at least said measured value of peak current between said circuit breaker and said data computation and display circuit.

6. The system of claim 5 wherein said means for providing a peak line-to-neutral voltage includes a memory storing a nominal peak line-to-neutral voltage as said peak line-to-neutral voltage.

7. The system of claim 5 wherein said means for providing a peak line-to-neutral voltage includes means for measuring a value of the peak line-to-neutral voltage at about when said value of peak arc current is measured;

and wherein said means for communicating at least said measured value of peak current between said circuit breaker and said data computation and display circuit communicates said value of the peak line-to-neutral voltage to said means for determining a distance of said data computation and display circuit.

8. The system of claim 5 wherein said means for providing an arc voltage includes means for providing an arc voltage as a function of said value of peak current.

9. The system of claim 5 wherein said means for providing an arc voltage includes a memory storing a constant value of said arc voltage.

10. A circuit breaker for locating an arc fault for a protected circuit, said circuit breaker comprising:

means for interrupting said protected circuit;

an arc fault detector determining an arc fault in said protected circuit;

means for measuring a value of peak arc current at said arc fault detector;

means for providing a peak line-to-neutral voltage;

means for providing an arc voltage operatively associated with said value of peak current; and

means for determining a distance from the arc fault detector to said arc fault from the value of peak arc current, a wire resistance per unit length or a wire conductance per unit length, the peak line-to-neutral voltage and the arc voltage.

11. A method for locating an arc fault in an electrical system, said method comprising:

measuring a value of peak arc current at an arc fault detector;

employing a wire resistance per unit length or a wire conductance per unit length;

providing a peak line-to-neutral voltage;

providing an arc voltage operatively associated with said value of peak current;

employing the value of peak arc current, the wire resistance per unit length or the wire conductance per unit length, the peak line-to-neutral voltage and the arc voltage, and calculating a distance from the arc fault detector to said arc fault; and

displaying said distance.

12. The method of claim 11 further comprising:

providing the peak line-to-neutral voltage from a nominal peak line-to-neutral voltage.

13. The method of claim 11 further comprising:

employing a constant value of said arc voltage.

14. The method of claim 11 further comprising:

measuring a value of the peak line-to-neutral voltage at about when said value of peak arc current is measured.

15. The method of claim 14 further comprising:

employing a predetermined relationship between said arc voltage and said value of peak arc current.

16. The method of claim 11 further comprising:

measuring the value of peak arc current at the arc fault detector of a single-pole circuit interrupter.

17. The method of claim 16 further comprising:

calculating said distance in said single-pole circuit interrupter; and

employing a display on said single-pole circuit interrupter to display said distance.

18. The method of claim 11 further comprising:

measuring the value of peak are current at the arc fault detector of a single-pole circuit interrupter;

communicating said measured value of peak are current to a device remote from said single-pole circuit interrupter; and

calculating said distance at said device.

19. The method of claim 11 further comprising:

employing an aircraft circuit breaker as said arc fault detector; and

employing a peak line-to-frame voltage as said peak line-to-neutral voltage.

20. The method of claim 11 further comprising:

employing a circuit breaker as said arc fault detector;

sequentially measuring a plurality of values of arc current at said circuit breaker;

storing said values of are current;

tripping open said circuit breaker in response to said are fault;

selecting at least two largest values of said stored values of arc current;

averaging said selected at least two largest values to provide an average value; and

employing said average value as said value of peak are current.

21. The method of claim 20 further comprising:

sequentially measuring a plurality of values of arc voltage at said circuit breaker;

associating each of said values of arc voltage with a corresponding one of the values of arc current;

storing said values of we voltage;

selecting at least two values of arc voltage associated with said at least two largest values of said stored values of arc current;

averaging said selected at least two values of arc voltage to provide an average voltage value; and

employing said average voltage value as said peak line-to-neutral voltage.

22. The method of claim 11 further comprising:

employing a nominal peak line-to-neutral voltage;

employing a value of impedance upstream of the arc fault detector; and

reducing said nominal peak line-to-neutral voltage by said value of impedance times said value of peak arc current.

23. A method for locating a line-to-line arc fault in an electrical system, said method comprising:

measuring a value of peak arc current at an arc fault detector;

employing a wire resistance per unit length or a wire conductance per unit length for two lines;

providing a peak line-to-line voltage;

providing an arc voltage operatively associated with said value of peak current;

employing the value of peak arc current, the wire resistance per unit length or the wire conductance per unit length, the peak line-to-line voltage and the arc voltage, and calculating a distance from the arc fault detector to said arc fault; and

displaying said distance.

24. The method of claim 23 further comprising:

providing the peak line-to-line voltage from a nominal peak line-to-line voltage.

25. The method of claim 23 further comprising:

employing a predetermined relationship between said arc voltage and said value of peak arc current.

26. The method of claim 23 further comprising:

measuring a value of the peak line-to-line voltage at about when said value of peak arc current is measured.

27. The method of claim 23 further comprising:

employing a constant value of said arc voltage.

28. The method of claim 23 further comprising:

measuring the value of peak arc current at the arc fault detector of a circuit interrupter.

29. The method of claim 28 further comprising:

employing as said circuit interrupter a three-pole circuit interrupter;

calculating said distance in said three-pole circuit interrupter; and

employing a display on said three-pole circuit interrupter to display said distance.

30. The method of claim 23 further comprising:

measuring the value of peak arc current at the arc fault detector of a first single-pole circuit interrupter for a first line;

employing a first wire resistance per unit length or a wire conductance per unit length for said first line;

employing a second single-pole circuit interrupter for a second line;

employing a second wire resistance per unit length or a second wire conductance per unit length for said second line;

communicating said measured value of peak arc current to a device remote from said first and second single-pole circuit interrupters; and

calculating said distance at said device.

31. A circuit breaker for a protected circuit, said circuit breaker comprising:

means for interrupting said protected circuit;

an arc fault detector determining an arc fault in said protected circuit;

a circuit measuring and storing a plurality of values of peak current for said arc fault;

means for selecting at least two largest values of said measured and stored values, a count of said at least two largest values being less than a count of said plurality of values of peak current for said arc fault;

means for averaging only said selected at least two largest values to provide an average value; and

means for employing said average value as one value of peak are current.