Open neutral detector

Patent metadata

Field	Value
Publication number	US-10868417-B2
Application number	US-201715836481-A
Country	US
Kind code	B2
Filing date	Dec 8, 2017
Priority date	Dec 9, 2016
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

An apparatus for detecting an open neutral condition in a split phase power system is described. The apparatus includes two powered lines providing output electricity to an electrical distribution system and a shared neutral line providing a grounded neutral to the first and second powered lines. The apparatus is configured for detecting when an open neutral condition is present in the split phase power system by determining when a power current is present on one or both of the first and second powered lines while a return current is not present on the neutral line; and in response to detecting that the open neutral condition is present, causing an interrupter to interrupt the power supplied by the first and second powered lines or to generate a signal indicating an open condition.

First claim

The invention claimed is:

1. An apparatus for detecting an open neutral condition in a split phase power system for delivering power to an electrical distribution system, the apparatus comprising:
a first powered line configured to output electricity to the electrical distribution system;
a second powered line configured to output electricity to the electrical distribution system;
a shared neutral line configured to provide a grounded neutral to the first and second powered lines;
one or more power monitors configured for measuring the current on the first powered line, second powered line, and shared neutral line;
an interrupter configured to selectively interrupt power supplied by the first and second powered lines; and
a controller comprising a processor in communication with the one or more power monitors and the interrupter, the controller configured for:
detecting when an open neutral condition is present in the split phase power system by determining instances when a power current is present on one or both of the first and second powered lines while a return current is not present on the neutral line; and
in response to detecting that the open neutral condition is present, causing the interrupter to interrupt the power supplied by the first and second powered lines.

2. The apparatus of claim 1 , wherein the one or more power monitors comprise a first transformer connected to the first powered line and a second transformer connected to the second powered line; and
wherein the controller is configured for measuring a first current on the first powered line utilizing the first transformer and for measuring a second current on the second powered line utilizing the second transformer.

3. The apparatus of claim 2 , wherein the controller is configured to determine that the return current is not present on the neutral line by detecting instances when the first current on the first powered line is equal to the second current on the second powered line.

4. The apparatus of claim 2 , wherein the controller is configured to determine that the return current is not present on the neutral line by calculating a neutral current using the first and second current.

5. The apparatus of claim 2 , wherein the one or more power monitors further comprise a third transformer connected to the shared neutral line; and
wherein the controller is configured for measuring a third current on the shared neutral line utilizing the third transformer.

6. The apparatus of claim 2 , wherein the one or more power monitors further comprise a third transformer connected to the first and second powered line; and
wherein the controller is configured for measuring a first current on the first powered line utilizing the first transformer, for measuring a second current on the second powered line utilizing the second transformer, and for measuring a third current on the shared neutral line by determining the difference between current on the first and second power lines via output from the third transformer.

7. The apparatus of claim 1 , wherein the controller is configured to determine that the return current is not present on the neutral line by detecting instances when the measured shared neutral current is approximately zero.

8. The apparatus of claim 1 , wherein the controller is configured to determine that the return current is not present on the neutral line by detecting instances when the measured shared neutral current is below a predefined threshold current value.

9. The apparatus of claim 8 , wherein the predefined threshold current value is 0.5 Amps.

10. The apparatus of claim 1 , wherein the interrupter comprises:
a driver interface in communication the controller; and
a main contactor connected to the driver interface and configured to interrupt power to the first and second powered lines.

11. The apparatus of claim 1 , further comprising a power source plug configured for being mated to a 50 A power pedestal.

12. The apparatus of claim 11 , the further comprising an output power plug configured to accept a 50 A-rated plug from a recreational vehicle (RV) power distribution system.

13. The apparatus of claim 1 , wherein the first powered line, the second powered line, and the neutral line are connected to a power source and wherein the first powered line, the second powered line, and the neutral line are connected to a single appliance.

14. The apparatus of claim 1 , wherein the first powered line, the second powered line, and the neutral line are connected to a recreational vehicle (RV) service configured to supply fifty amps of electrical current and wherein the first powered line, the second powered line, and the neutral line are connected to an RV electrical distribution system.

15. The apparatus of claim 1 , further comprising an open neutral indication light, wherein the controller is configured to illuminate the open neutral indication light in response to detecting that the open neutral condition is present.

16. The apparatus of claim 1 , further comprising a graphical display, wherein the controller is configured to present a graphical indication that an open neutral condition is present via the graphical display in response to detecting that the open neutral condition is present.

17. The apparatus of claim 1 , wherein the processor is configured to, upon determining that the power current is present on at least one of the first and second powered lines, allow a predefined period of time to elapse before determining whether the return current is present on the shared neutral line.

18. An apparatus for detecting an open neutral condition in a split phase power system for delivering power to an electrical distribution system, the apparatus comprising:
a first powered line configured to output electricity to the electrical distribution system;
a second powered line configured to output electricity to the electrical distribution system;
a shared neutral line configured to provide a grounded neutral to the first and second powered lines;
one or more power monitors configured for measuring the current on the first powered line, second powered line, and shared neutral line; and
a controller comprising a processor in communication with the one or more power monitors and the interrupter, the controller configured for:
detecting when an open neutral condition is present in the split phase power system by determining instances when a power current is present on one or both of the first and second powered lines while a return current is not present on the neutral line; and
in response to detecting that the open neutral condition is present, generating a signal indicating the detected open neutral condition.

19. The apparatus of claim 18 , wherein the signal is configured to trigger interruption of the power supplied by the first and second powered lines.

20. The apparatus of claim 19 , wherein the controller is further configured for, in response to detecting that the open neutral condition is present, generating an open neutral condition indication.

21. The apparatus of claim 20 , further comprising an open neutral indication light, wherein the controller is configured to illuminate the open neutral indication light in response to the generation of the open neutral indication.

22. The apparatus of claim 20 , further comprising a graphical user interface, wherein the controller is configured to present a graphical indication that an open neutral condition is present via the graphica

Assignees

• Southwire Co Llc

Inventors

• Oldham Jr Donald Paul
• Moussa Hamze

Classifications

• H02H5/105

  responsive to deterioration or interruption of earth connection (for preventing switching-on H02H11/001) · CPC title

• H02H3/338 Primary

  also responsive to wiring error, e.g. loss of neutral, break · CPC title

• H02H3/20

  responsive to excess voltage · CPC title

• H02H5/10

  responsive to mechanical injury, e.g. rupture of line, breakage of earth connection · CPC title