Method to detect arcing faults using switched elements at outlet

Patent metadata

Field	Value
Publication number	US-10114057-B2
Application number	US-201314898776-A
Country	US
Kind code	B2
Filing date	Jun 21, 2013
Priority date	Jun 21, 2013
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A system and method to detect arc faults in branch wiring. The system includes a line conductor and a neutral conductor. A circuit breaker is connected to an alternating current source via the line and neutral conductors. Electrical outlet devices are coupled to the circuit breaker via the line and neutral conductors. Each of the electrical outlet devices has a neutral shorting switching element coupled between the line and neutral conductors, and a load control switching element in the line conductor. The electrical outlet devices also each include an outlet controller to control the switching elements. The outlet controllers close the neutral shorting switching elements and the master controller determines if high impedance is present to detect a series arc fault. The outlet controllers open the load control switching elements and the master controller determines if any current is flowing on the line conductor to detect a parallel arc fault.

First claim

What is claimed is:

1. An electrical outlet device to detect branch arc faults, comprising:
a line conductor;
a neutral conductor, the line conductor and neutral conductor to provide electrical power to a load connected to the electrical outlet device,
a neutral shorting switching element coupled between the line conductor and the neutral conductor having an open position and a closed position, the closed position coupling the line conductor to the neutral conductor;
a load control switching element in the line conductor, the load control switching element having an open position and a closed position for controlling current through the line conductor, wherein the neutral shorting switching element is in the open position and the load control switching element is in the closed position to provide power from the line conductor; and
an outlet controller coupled to the neutral shorting switching element and the load control switching element, the outlet controller opening the load control switching element for a current sensor upstream of the electrical outlet device to determine whether a current is present on the line conductor to detect a parallel arc fault.

2. The electrical outlet device of claim 1 , wherein a voltage sensor is coupled between the line conductor and the neutral conductor upstream of the outlet device and wherein the outlet controller closes the neutral shorting switching element to detect a series arc fault by determination of whether an impedance determined from the sensed voltage and current exceeds a threshold value.

3. The electrical outlet device of claim 2 , wherein an upstream circuit breaker is coupled to the line conductor and neutral conductor, wherein if a fault is detected, the circuit breaker interrupts power on the line conductor.

4. The electrical outlet device of claim 3 , wherein a master controller is coupled to the voltage sensor and current sensor in the circuit breaker.

5. The electrical outlet device of claim 2 , wherein the neutral shorting switching element and the load control switching element are placed in the open and closed position by the outlet controller based on a periodic cycle.

6. The electrical outlet device of claim 5 , wherein the frequency of the periodic cycle is a function of the magnitude of the current on the line conductor.

7. The electrical outlet device of claim 4 , wherein the neutral shorting switching element and the load control switching element are placed in the open and closed positions under the control of the master controller communicating with the outlet controller.

8. The electrical outlet device of claim 4 , wherein the master controller determines the location of the series arc fault by:
opening the neutral shorting switching element of the electrical outlet device, and
closing the neutral shorting switching element of a second electrical outlet device and determining whether an impedance from the sensed voltage and current exceeds a threshold value.

9. The electrical outlet device of claim 1 , wherein the outlet controller is a microcontroller.

10. The electrical outlet device of claim 1 , wherein the neutral shorting switching element and the load control switching element are solid state devices.

11. The electrical outlet device of clam 1 , wherein the neutral shorting switching element and the load control switching element and outlet controller are in a module connected to a conventional outlet device including the line conductor and neutral conductor.

12. A method of determining arc faults downstream from a circuit breaker coupled to an alternating current power source via a line conductor and a neutral conductor, comprising:
opening a load control switching element controlling current through the line conductor in a first electrical outlet device downstream from the circuit breaker;
determining whether current is flowing on the line conductor;
detecting a parallel arc fault based on whether current is flowing on the line conductor;
closing a neutral shorting switching element in the first electrical outlet device to couple the line conductor to the neutral conductor;
measuring the voltage between the line conductor and the neutral conductor and the current flowing on the line conductor to determine an impedance; and
detecting a series arc fault if the impedance exceeds a threshold value.

13. The method of claim 12 , further comprising interrupting the current to the line conductor via the circuit breaker when either the parallel arc fault or series arc fault is detected.

14. The method of claim 12 , wherein the neutral shorting switching element and the load control switching. element are solid state devices.

15. The method of claim 12 , further comprising:
opening the neutral shorting switching element in the first electrical outlet device;
closing a neutral shorting switching element in a second electrical outlet device downstream from the first electrical outlet device to disconnect the line conductor from a load coupled to the second electrical outlet device;
measuring the voltage between the line conductor and the neutral conductor and the current flowing on the line conductor to determine a second impedance; and
determining the location of a series arc fault based on whether the determined impedances exceed the threshold value when the load control switching element of the first electrical outlet device is closed or when the load control switching element of the second electrical outlet device is closed.

16. The method of claim 15 , further comprising opening a load control switching element in the second electrical outlet device controlling current through the line conductor in the second outlet electrical outlet device simultaneously with opening the load control switching element of the first electrical outlet device.

17. The method of claim 12 , wherein the neutral shorting switching element and the load control switching element are opened and closed on a periodic cycle.

18. The method of claim 12 , wherein the neutral shorting switching element and the load control switching element are opened and closed under the control of a master controller in the circuit breaker.

19. A system to detect arc faults, the system comprising:
a line conductor;
a neutral conductor;
a circuit breaker connected to the line and neutral conductors;
a plurality of electrical outlet devices each being coupled to the circuit breaker via the line and neutral conductors, each of the plurality of electrical outlet devices having a neutral shorting switching element coupled between the line and neutral conductors, and a load control switching element coupled to the line conductor, the plurality of electrical outlet devices each including an outlet controller controlling the neutral shorting switching element and the load control switching element, wherein the outlet controller closes the neutral shorting switching elements to detect a series arc fault and opens the load control switching element to detect a parallel arc fault.

20. The system of claim 19 , wherein the circuit breaker includes a voltage sensor coupled between the line conductor and the neutral conductor, a current sensor coupled to the line conductor, and a master controller is coupled to the voltage and current sensors.

21. The system of claim 19 , wherein the circuit breaker interrupts power on the line conductor if a parallel or series fault is detected.

Assignees

• Schneider Electric Usa Inc

Inventors

• Beierschmitt Joseph
• Schroeder Jeremy

Classifications

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title

• H02H7/26

  Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured (locating faults in cables G01R31/08) · CPC title

• H02H3/16

  responsive to fault current to earth, frame or mass (with balanced or differential arrangement H02H3/26 {; monitoring earth connection H02H5/105}) · CPC title

• H01H83/02

  operated by earth fault currents (H01H83/14 takes precedence) · CPC title

• H02H3/20

  responsive to excess voltage · CPC title