ARC FAULT DETECTOR

• US 20070262780A1
• Filed: 04/23/2007
• Published: 11/15/2007
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Mernyk, Ross, Bradley, Roger
• Granted Patent: US 7,535,234 B2
• Time in Patent Office: Days
• US Class Current: 324/509
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/44 responsive to the rate of change of electrical quantities

Abstract

An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault interrupter (GFCI), protects from potentially dangerous arc fault conditions. The device utilizes a line side or load side series connected inductance having an air or magnetic core to generate the derivative di/dt signal of the arc current in the conductor. The derivative signal is fed to an arc fault detector where it is analyzed for the presence of arcing. The device can have two series connected inductors inductively coupled to each other such that the signal from one inductor is inductively coupled into the other inductor for coupling to the arc fault detector.

Claims

1. Apparatus for detecting arcs on an electrical power distribution network having at least one conductor comprising:

series inductance means adapted to be coupled in series with a conductor of the network wherein a voltage is produced across the series inductance means having a waveform which relates to the derivative of current flow in the conductor; and

arc detection means coupled to identify when the waveform of the voltage across the series inductance means is representative of arcing on the network and to generate an arc detection signal when the waveform is representative of arcing on the network.

2. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and a phase conductor.

3. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and two phase conductors.

4. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and three phase conductors.

5. The apparatus of claim 1 wherein the at least one conductor comprises two phase conductors.

6. The apparatus of claim 1 wherein the at least one conductor comprises a single conductor with return current carried through a ground or frame.

7. The apparatus of claim 1 wherein the series inductance means is adapted to be coupled to be in series with all current in the at least one conductor.

8. The apparatus of claim 1 wherein the series inductance means is adapted to be coupled in series with part of the current in the at least one conductor.

9. The apparatus of claim 1 wherein the series inductance means is an inductor.

10. The apparatus of claim 1 wherein the series inductance means is at least one winding of a transformer.

11. The apparatus of claim 10 wherein the transformer is coupled to a current measuring means to measure current in at least one conductor of the network.

12. The apparatus of claim 10 wherein the transformer forms part of a ground fault means to measure ground fault differential current flow in at least two conductors of the network.

13. The apparatus of claim 10 wherein the transformer forms part of a ground fault means to measure ground fault grounded neutral current flow in at least one conductor of the network.

14. The apparatus of claim 1 wherein the series inductance means has an inductance of between 0.1 and 1,000,000 nanohenries.

15. The apparatus of claim 1 wherein the series inductance means comprises a conductor having a bend between 15 degrees and a turn of 360 degrees.

16. The apparatus of claim 1 wherein the series inductance means comprises a conductor having between one and six turns.

17. The apparatus of claim 1 further comprising clamping means coupled in parallel with the series inductance means.

18. The apparatus of claim 17 wherein the clamping means comprises at least one diode.

19. The apparatus of claim 17 wherein the at least one diode comprises a first diode coupled in parallel with a second diode head-to-toe.

20. The apparatus of claim 17 wherein the clamping means comprises at least one Zener diode.

21-46. -46. (canceled)