Mobile electric power supply system with deactivatable GFCI protection

• US 6,788,504 B2
• Filed: 06/26/2002
• Issued: 09/07/2004
• Est. Priority Date: 06/26/2002
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Vanderkolk, Richard John
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): Nguyen, Danny
• Application Number:
  US10/184,600
• Publication Number:
  US 20040001292A1
• Time in Patent Office: 804 Days
• Field of Search: 361/42, 361/43, 361/44, 361/45, 361/46, 361/47, 361/48, 361/49, 361/50, 361/114, 361/115
• US Class Current: 361/42
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence

Abstract

A mobile system for use in supplying AC power to different types of electrical loads including those having grounded neutrals as well as those having neutrals that are electrically isolated from ground. The system includes a GFCI circuit and can be switched between a first mode, in which the circuit provides AC power with ground fault protection for those loads having ungrounded (isolated) neutrals, and a second mode, in which the GFCI is deactivated so that it will not experience false tripping due to the intentional grounding of the neutral at the load. Both single and multi-phase systems are disclosed which can be incorporated into a vehicle, towed trailer, or portable generator. The system is useful for providing AC power to various types of electrical loads at locations where public utility power is not readily available.

Claims

1. A mobile system for supplying electric power to an electrical load, comprising:

a vehicle;

an electric power source in said vehicle comprising a battery;

a first receptacle electrically coupled to said electric power source via a plurality of power line conductors;

a second receptacle electrically coupled to said electric power source via said power line conductors;

a ground fault circuit interrupter electrically connected to said power line conductors, said ground fault circuit interrupter having an output for providing a trip signal used by the mobile system to interrupt current flow over said power line conductors to thereby provide ground fault protection of said second receptacle against a current imbalance in said power line conductors;

a switch device electrically coupled between said electric power source and said first and second receptacles, with said switch device being connected in series with said ground fault circuit interrupter such that current flowing through said ground fault circuit interrupter flows through said switch device;

wherein said switch device can be switched between a first state, in which said first receptacle receives power from said electric power source that is unprotected by said ground fault circuit interrupter, and a second state, in which said second receptacle receives power from said electric power source that is protected by said ground fault circuit interrupter against a current imbalance in said power line conductors.

2. The mobile system of claim 1, wherein said power line conductors provide alternating-current electrical power and include a neutral conductor.

3. The mobile system of claim 2, wherein said power line conductors comprise said neutral conductor and a single 115 VAC conductor, whereby said electric power source supplies single phase power.

4. The mobile system of claim 2, wherein said power line conductors comprise said neutral conductor and two 115 VAC conductors, each of which are 180 degrees out of phase with the other, whereby said electric power source supplies two-phase power.

5. The mobile system of claim 2, wherein said electric power source includes a ground, and wherein said first receptacle is designated for and capable of electrically interfacing with a first type electrical load having a grounded neutral conductor, and said second receptacle is designated for and capable of electrically interfacing with a second type electrical load having an ungrounded neutral conductor.

6. The mobile system of claim 2, wherein said switch device is connected in series with all of said power line conductors except said neutral conductor, and wherein said switch device switches alternating-current power to only one of said first and second receptacles at a time.

7. The mobile system of claim 2, wherein said ground fault circuit interrupter includes a circuit breaker element that is connected in series with said switch device such that current flowing through said circuit breaker element flows through said switch device, said circuit breaker element being capable of open-circuiting at least one of said power line conductors in response to said trip signal.

8. The mobile system of claim 2, wherein said ground fault circuit interrupter includes a control circuit that can be selectively enabled or disabled by said switch device and that, when enabled, produces the trip signal on said output in response to a current imbalance between said power line conductors.

9. The mobile system of claim 8, wherein said control circuit includes a data input coupled to said switch device, wherein said control circuit can be selectively enabled or disabled via said data input based on the state of said switch device;

and

wherein, when said switch device is placed in a first state, said control circuit is disabled via said data input with said first receptacle being electrically connected to said power line conductors and said second receptacle being electrically isolated from at least one of said power line conductors, and, when said switch device is placed into a second state, said control circuit is able to produce the trip signal on said output in response to a current imbalance between said power line conductors, with said first receptacle being electrically isolated from at least one of said power line conductors and said second receptacle being electrically connected to said power line conductors.

10. The mobile system of claim 9, wherein said mobile system further comprises a disable circuit coupled between said switch device and said data input, said disable circuit being operable to disable said control circuit via said data input when said first receptacle is powered via said switch device.

11. The mobile system of claim 2, wherein said switch device comprises a manually activated switch connected in series with at least one of said power line conductors.

12. The mobile system of claim 2, wherein said switch device comprises a manually activated switch and a relay connected to at least one of said power line conductors and both said first and second receptacles, with said relay including normally open contacts connected to one of said first and second receptacles and normally closed contacts connected to the other of said first and second receptacles, and including a coil that can be selectively energized using said switch to thereby switch power from said power line conductors to one or the other of said first and second receptacles.

13. The mobile system of claim 2, wherein said electric power source further comprises:

an electronic power conversion circuit electrically coupled to said at least one battery, wherein said electronic power conversion circuit is capable of converting the direct-current electric power into the alternating-current electric power supplied by said power line conductors.

14. The mobile system of claim 13, wherein said output of said ground fault circuit interrupter is connected to said electric power conversion circuit, and wherein said trip signal is used by said electric power conversion circuit to disable itself from supplying alternating-current electric power to said power line conductors.

15. The mobile system of claim 2, further comprising an automotive vehicle, wherein said electric power source, said ground fault circuit interrupter, said switch device, and said first and second receptacles are situated onboard said automotive vehicle.

16. The mobile system of claim 15, wherein said electric power source and said ground fault circuit interrupter are located in close proximity together on said vehicle, and wherein at least one of said receptacles is located on said vehicle remotely from said electric power source and said ground fault circuit interrupter.

17. The mobile system of claim 15, wherein said vehicle includes an enclosed cabin space and said mobile system further comprises a third receptacle coupled to said electric power source via said ground fault circuit interrupter and said switch device to receive power from said electric power source;

and

wherein said first and second receptacles are located outside said cabin space.

18. A mobile system for supplying electric power to an electrical load, comprising:

a vehicle having an internal combustion engine;

an electric power source in said vehicle comprising at least one battery and a power inverter receiving power via a generator from said internal combustion engine;

at least two line conductors connected to said electric power source;

a ground fault circuit interrupter electrically connected to said line conductors and capable of interrupting current flow through said conductors in response to a current imbalance between said conductors;

a first receptacle designated for and capable of electrically interfacing with a first type electrical load having a grounded neutral conductor;

a second receptacle designated for and capable of electrically interfacing with a second type electrical load having an ungrounded neutral conductor; and

a switch device connected in series with said ground fault circuit interrupter between said electric power source and said first and second receptacles such that power from said electric power source is provided to only one of said first and second receptacles at a time;

wherein said switch device is capable of electrically switching said electric power source between said first and second receptacles and wherein said second receptacle is protected by said ground fault circuit interrupter against a current imbalance between said conductors and said first receptacle is unprotected by said ground fault circuit interrupter.

19. The mobile system defined in claim 18,

wherein said electric power source and said ground fault circuit interrupter are located in close proximity together on said vehicle, and wherein at least one of said receptacles is located on said vehicle remotely from said electric power source and said ground fault circuit interrupter.

20. The mobile system defined in claim 18,

wherein said vehicle includes an enclosed cabin space and said mobile system further comprises a third receptacle coupled to said electric power source via said ground fault circuit interrupter and said switch device to receive power from said electric power source;

and

wherein said first and second receptacles are located outside said cabin space.

21. The mobile system defined in claim 18, wherein said switch device is electrically connected in series between said ground fault circuit interrupter and said first and second receptacles such that power supplied to said first and second receptacles passes through said ground fault circuit interrupter, and wherein said ground fault circuit interrupter is disabled whenever power from said electric power source is supplied to said first receptacle.

22. The mobile system defined in claim 21, wherein said ground fault circuit interrupter includes a data input and can be selectively disabled via said data input, and wherein said mobile system further comprises a disable circuit coupled between said switch device and said data input, said disable circuit being operable to disable said ground fault circuit interrupter via said data input when said first receptacle is powered via said switch device.

23. The mobile system defined in claim 21, wherein said switch device includes a manually activated switch that can be moved between a first position, in which said first receptacle is connected via said ground fault interrupter circuit to said electric power source, and a second position, in which said second receptacle is connected via said ground fault interrupter circuit to said electric power source.

24. The mobile system defined in claim 21, wherein said switch device comprises:

a relay connected in circuit between said ground fault circuit interrupter and said first and second receptacles; and

a manually activated switch that can be moved between first and second positions, said manually activated switch being coupled to said ground fault circuit interrupter and said relay;

wherein, when said switch is in said first position, said ground fault circuit interrupter is disabled and said first receptacle receives power from said electric power source via said ground fault circuit interrupter and said relay, and, when said switch is in said second position, said ground fault circuit interrupter is enabled and said second receptacle receives power from said electric power source via said ground fault circuit interrupter and said relay.

25. The mobile system defined in claim 21, further comprising an indicator circuit electrically coupled to said switch device and being capable of providing a visual indication when said ground fault circuit interrupter is disabled.

26. The mobile system defined in claim 18, wherein said electric power source comprises:

at least one battery capable of providing direct-current electric power; and

an electronic power conversion circuit electrically coupled to said at least one battery, wherein said electronic power conversion circuit is capable of converting the direct-current electric power into alternating-current electric power.

27. The mobile system defined in claim 26, wherein said ground fault circuit interrupter has an output connected to said electric power conversion circuit, and wherein said ground fault circuit interrupter is capable of supplying a trip signal on said output in response to a current imbalance on said line conductors, with said trip signal being used by said electric power conversion circuit to disable itself from supplying alternating-current electric power to said line conductors.

28. The mobile system defined in claim 18, wherein said electric power source further comprises:

a phase line conductor; and

a neutral line conductor;

wherein said phase line and neutral line conductors supply alternating-current electric power to said first receptacle via said switch device when said switch device is in a first state and to said second receptacle via said switch device and said ground fault circuit interrupter when said switch device is in a second state.

29. The mobile system defined in claim 28, wherein said switch device is electrically connected in series between said ground fault circuit interrupter and said first and second receptacles such that said phase line and neutral line conductors supply alternating-current electric power to said first receptacle via both said switch device and said ground fault circuit interrupter.

30. The mobile system defined in claim 28, wherein said switch device includes a single-pole, double-throw type configuration having two fixed contacts, each coupled to one of said first and second receptacles, and a movable contact that is coupled to said phase line conductor.

31. The mobile system defined in claim 28, wherein said switch device comprises:

a relay that includes a coil, two fixed contacts with each coupled to one of said first and second receptacles, and a movable contact that is coupled to said phase line conductor; and

a manually activated switch electrically coupled to said coil;

wherein said movable contact moves between said fixed contacts upon energization of said coil; and

wherein said manually activated switch controls operation of said coil.

32. The mobile system defined in claim 28, wherein said phase line conductor comprises a first phase line conductor and wherein said electric power source further comprises a second phase line conductor which supplies alternating-current electric power that is 180 degrees out of phase with the alternating-current electric power supplied by said first phase line conductor;

and

wherein said first receptacle is one of a first plurality of receptacles designated for and capable of electrically interfacing with the first type electrical load having a grounded neutral conductor;

wherein said second receptacle is one of a second plurality of receptacles designated for and capable of electrically interfacing with the second type electrical load having an ungrounded neutral conductor;

wherein said first phase line conductor supplies alternating-current electric power via said switch device to at least one of said receptacles when said switch device is in a first state and to at least one other of said receptacles when said switch device is in a second state; and

wherein said second phase line conductor supplies alternating-current electric power via said switch device to at least one of said receptacles when said switch device is in the first state and to at least one other of said receptacles when said switch device is in the second state.

33. The mobile system defined in claim 32, wherein said switch device includes a double-pole, double-throw configuration having:

a first set of contacts that includes two fixed contacts, each coupled to at least one of said receptacles, and a movable contact that is coupled to said first phase line conductor; and

a second set of contacts that includes two fixed contacts, each coupled to at least one of said receptacles, and a movable contact that is coupled to said second phase line conductor.

34. The mobile system defined in claim 32, wherein said switch device comprises:

a relay that includes;

a first set of contacts that includes two fixed contacts, each coupled to at least one of said receptacles, and a movable contact that is coupled to said first phase line conductor; and

a second set of contacts that includes two fixed contacts, each coupled to at least one of said receptacles, and a movable contact that is coupled to said second phase line conductor; and

a coil that causes movement of said movable contacts upon energization of said coil; and

a manually activated switch electrically coupled to said coil;

wherein said manually activated switch controls operation of said coil.

35. The mobile system defined in claim 19, wherein said ground fault circuit interrupter is incorporated into said electric power source.