Wiring device with multi-shot miswire

• US 7,298,598 B1
• Filed: 09/28/2005
• Issued: 11/20/2007
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Pass & Seymour Incorporated (Legrand SA)
• Original Assignee: Pass & Seymour Incorporated (Legrand SA)
• Inventors: Morgan, Kent, Richards, Jeffrey C., Packard, Thomas N.
• Primary Examiner(s): Sherry; Michael
• Assistant Examiner(s): Benenson; Boris
• Application Number:
  US11/237,399
• Time in Patent Office: 783 Days
• Field of Search: 361/42, 361/45, 361/77, 307/127, 324/424, 324/521
• US Class Current: 361/45
• CPC Class Codes: H02H 3/338 also responsive to wiring error, e.g. loss of neutral, break

Abstract

The present invention is directed to a protective wiring device that includes a plurality of line terminals coupled to a plurality of load terminals by way of at least one conductive path. A miswire detection circuit is coupled to the at least one conductive path. The miswire detection circuit is configured to monitor signal propagation characteristics on the at least one conductive path and generate a miswire detection signal based on the signal propagation characteristics commencing each time source power is applied to either the plurality of line terminals or the plurality of load terminals. A fault detection circuit is coupled to the at least one conductive path. The fault detection circuit is configured to detect a fault condition propagating on the at least one conductive path. The fault detection circuit is configured to generate a trip signal in response to either the fault condition or the miswire detection signal. A circuit interrupter is coupled to the fault detection circuit. The circuit interrupter is configured to introduce an electrical discontinuity in the at least one conductive path in response to the trip signal.

Claims

1. A protective wiring device comprising:

a plurality of line terminals coupled to a plurality of load terminals by way of at least one conductive path;

a miswire detection circuit coupled to the at least one conductive path, the miswire detection circuit being configured to monitor signal propagation characteristics on the at least one conductive path and generate a miswire detection signal based on the signal propagation characteristics commencing each time source power is applied to either the plurality of line terminals or the plurality of load terminals;

a fault detection circuit coupled to the at least one conductive path, the fault detection circuit being configured to detect a fault condition propagating on the at least one conductive path, the fault detection circuit being configured to generate a trip signal in response to either the fault condition or the miswire detection signal; and

a circuit interrupter coupled to the fault detection circuit, the circuit interrupter being configured to introduce an electrical discontinuity in the at least one conductive path in response to the trip signal.

2. The device of claim 1, wherein the signal propagation characteristics include a line voltage polarity and a load current polarity.

3. The device of claim 2, wherein the miswire detection circuit includes a comparator circuit configured to compare the line voltage polarity and the load current polarity, the miswire detection circuit generating the miswire detection signal based on the comparison of line voltage polarity and the load current polarity.

4. The device of claim 1, wherein the miswire detection circuit further comprises:

a current sensor coupled to the at least one conductive path, the current sensor being configured to monitor a load current polarity;

a voltage sensor coupled to the at least one conductive path, the voltage sensor being configured to monitor a line voltage polarity; and

a processor coupled to the current sensor and the voltage sensor, the processor being configured to generate the miswire detection signal based on a comparison of the line voltage polarity and the load current polarity.

5. The device of claim 4, wherein the current sensor includes a shunt and/or current transformer.

6. The device of claim 4, wherein an electric load is coupled to the plurality of line terminals, and wherein the processor is configured to generate the miswire detection signal when the line voltage polarity and the load current polarity are opposite to each other during a predetermined time interval.

7. The device of claim 4, further comprising an internal electric load disposed between the current sensor and the circuit interrupter, whereby the processor is configured to generate the miswire detection signal when the current flowing through the internal electric load not being sensed by the current sensor.

8. The device of claim 7, wherein the processor is configured to generate the miswire detection signal when a load current polarity flowing through an external load connected to the line terminals and the line voltage polarity are opposite to each other.

9. The device of claim 4, further comprising an internal electric load disposed between the current sensor and the plurality of line terminals, whereby a miswire detection signal is not generated when the current flowing through the internal electric load is not sensed by the current sensor.

10. The device of claim 9, wherein the processor is configured to generate the miswire detection signal when a polarity of a current flowing through the internal load and the line voltage polarity oppose each other.

11. The device of claim 1, wherein the fault detection circuit further comprises:

a sensor coupled to the at least one conductive path, the sensor being configured to sense differential current propagating on the at least one conductive path;

a detector circuit coupled to the sensor, the detector being configured to detect a fault condition propagating on the at least one conductive path if the differential current exceeds a predetermined amount and generate the trip signal in response thereto;

a switch element coupled to the detector and the processor, the switch element being configured to provide a switching current in response to the trip signal and the miswire detection signal; and

a solenoid element coupled to the switch element, the solenoid being configured to actuate the circuit interrupter in response to the switching current.

12. The device of claim 6, further comprising an internal electric load, wherein the miswire detection circuit further comprises a processor circuit configured to direct a pulsed current into the internal electric load, the processor being configured to generate the miswire detection signal based on a polarity of the pulsed current flowing through the internal electric load compared to the line voltage polarity.

13. The device of claim 12, further comprising a transistor coupled between the internal electric load and the processor, the pulsed current being propagated by the transistor in response to the processor pulsing the transistor into an ON state at a predetermined repetition rate.

14. The device of claim 12, wherein the internal electric load includes a solenoid element.

15. The device of claim 12, wherein the internal electric load includes a resistance.

16. The device of claim 1, wherein the signal propagation characteristics include an electrical current.

17. The device of claim 16, wherein the miswire detection circuit includes a reclosable fuse.

18. The device of claim 17, wherein the reclosable fuse is configured to remain closed whenever the source voltage is connected to the plurality of load terminals, and wherein the reclosable fuse is configured to open whenever the source voltage is connected to the plurality of line terminals for a predetermined period of time.

19. The device of claim 17, wherein the reclosable fuse is configured to close each time that the device is removed from and/or installed in the electrical distribution system.

20. The device of claim 17, further comprising:

a housing configured to accommodate the plurality of line terminals, the plurality of load terminals, and the circuit interrupter;

a printed circuit board including the miswire detection circuit and the fault detection circuit at least partially disposed thereon, the reclosable fuse being mounted on the printed circuit board; and

an actuator probe coupled to the reclosable fuse and partially accessible from an exterior portion of the housing, the actuator probe being configured to close the reclosable fuse.

21. The device of claim 20, wherein the actuator probe is prevented from closing the reclosable fuse when a wall plate is attached to the housing.

22. The device of claim 20, wherein the actuator probe maintains the reclosable fuse in a closed state if a wall plate is not attached to the housing, and wherein the circuit interrupter is prevented from resetting after the discontinuity is introduced.

23. The device of claim 17, wherein the reclosable fuse closes in response to a removal of a wall plate from the device.

24. The device of claim 17, wherein the miswire detection circuit includes a heating element that generates heat to open the reclosable fuse within a predetermined period of time.

25. The device of claim 1, wherein the miswire detection circuit includes

a voltage sensor that generates a voltage signal in response to the source voltage;

a current sensor that generates a current signal in response to the load current; and

a processor that compares the voltage signal to the current signal to generate the trip signal based on a predetermined relationship between the voltage signal and the current signal.

26. The device of claim 25, wherein the predetermined relationship includes polarity comparison between the voltage signal and the current signal.

27. The device of claim 25, wherein the predetermined relationship includes a phase comparison between the voltage signal and the current signal.

28. The device of claim 25, wherein the device further includes a first internal load such that the current sensor generates a current signal in response to the first internal load current but only when the source voltage is connected to the plurality of line terminals.

29. The device of claim 28, wherein the processor is configured to enable current flow through the first internal load for a predetermined period of time.

30. The device of claim 29, wherein the predetermined period of time occurs a predetermined interval of time after a voltage zero crossing.

31. The device of claim 28, wherein the first internal load includes a trip solenoid that causes the circuit interrupting assembly to enter the tripped state in response to the trip signal.

32. The device of claim 28, wherein the device further includes a second internal load, such that the current sensor generates a current signal in response to second internal load current but only when the source voltage is connected to the plurality of load terminals.

33. The device of claim 1, wherein the circuit interrupter includes isolating contacts that disconnect one or more sets of the plurality of line terminals from the plurality of load terminals when the circuit interrupter is in the tripped state.

34. The device of claim 1, wherein the miswire detection circuit includes isolating contacts that disconnect one or more sets of the plurality of line terminals from the plurality of load terminals when the miswire detection circuit detects that source voltage has been connected to the plurality of load terminals.

35. The device of claim 1, wherein the miswire detection circuit includes an indicator that visibly and/or audibly indicates when the miswire detection circuit detects that source voltage has been connected to the plurality of load terminals.

36. The device of claim 1, wherein the detected condition includes a ground fault condition, an arc fault condition, a grounded neutral condition, a miswire fault condition, and/or a simulated test fault condition.

37. A method for wiring a protective device in an electrical circuit, the protective device including a plurality of line terminals coupled to a plurality of load terminals by way of at least one conductive path, the method comprising:

(a) connecting the plurality of load terminals to source voltage;

(b) monitoring signal propagation characteristics on the at least one conductive path, the step of monitoring commencing each time source voltage is applied to the plurality of load terminals;

(c) generating a miswire trip signal based on a predetermined signal propagation characteristic; and

(d) introducing an electrical discontinuity in the at least one conductive path in response to the trip signal.

38. The method of claim 37, further comprising:

(e) resetting the protective device, whereby electrical continuity in the at least one conductive path is restored;

(f) monitoring the signal propagation characteristics;

(g) generating the miswire trip signal based on a predetermined signal propagation characteristic;

(h) introducing an electrical discontinuity in the at least one conductive path in response to the miswire trip signal; and

(i) repeating steps (e)-(i) until the plurality of load terminals are disconnected from the source voltage.

39. The method of claim 37, further comprising:

(j) connecting the plurality of line terminals to the source voltage;

(j) disabling steps (a) through (d) after a predetermined time interval elapses.