Circuit interrupter with arcing fault protection and PTC (positive temperature coefficient resistivity) elements for short circuit and overload protection

• US 5,999,384 A
• Filed: 08/05/1998
• Issued: 12/07/1999
• Est. Priority Date: 08/25/1997
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Gregory, George D., Scott, Gary W., Chen, William W., Haun, Andy A.
• Primary Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US09/129,156
• Time in Patent Office: 489 Days
• Field of Search: 361/42-50, 361/93.1, 361/93.6, 361/93.7, 361/93.8, 361/99, 361/100, 361/102, 361/106, 361/93.9
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/025 Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence
• CPC Class Codes: H02H 9/026 Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Abstract

A circuit protection apparatus employs a PTC element for overload and/or short circuit protection and an arcing fault interruption arrangement. The circuit protection apparatus may be employed in a ground fault receptacle for interrupting the flow of electrical current in a line in response to any of a plurality of different types of fault conditions on the line. The circuit protection apparatus may include a set of contacts connected in series with the line, and having an open position and a closed position, a trip device coupled to the contacts, adapted to be actuated by a trip signal, to move the contacts from the closed position to the open position and an element having a positive temperature coefficient of resistivity (PTC) connected in series with the contacts. The PTC element is connected to the trip device to provide the trip signal to the device in response to overload or short circuit conditions in the line. A switching element is operatively coupled with the trip device for providing the trip signal to said device in response to an actuating signal. An arcing fault circuit is adapted for detecting an arcing fault in the line and producing the actuating signal when the arcing fault is detected.

Claims

1. A circuit protection apparatus for interrupting the flow of electrical current in a line in response to any of a plurality of different types of fault conditions on the line, said apparatus comprising:

a set of contacts connected in series with the line, and having an open position and a closed position;

a device coupled to the contacts, adapted to be actuated by a trip signal, to move the contacts from the closed position to the open position;

an element having a positive temperature coefficient of resistivity (PTC) connected in series with the contacts, said PTC element being connected to said device to provide said trip signal to the device in response to overload or short circuit conditions in the line;

a switching element operatively coupled with said device for providing said trip signal to said device in response to an actuating signal; and

a circuit adapted for detecting an arcing fault in the line and producing said actuating signal when the arcing fault is detected.

2. The apparatus of claim 1 wherein said circuit is further adapted for detecting a ground fault current in the line and producing said actuating signal when the ground fault current is detected.

3. The apparatus of claim 1 wherein said device comprises a coil operatively associated with said contacts.

4. The apparatus of claim 1 wherein said switching element has an open position and a closed position and wherein the switching element is adapted to move from the open position to the closed position in response to said actuating signal.

5. The apparatus of claim 4 wherein the switching element is an SCR.

6. The apparatus of claim 4 further compnsing a diode arrangement adapted to direct current through the device and to prevent a current from flowing through the PTC element when the switching element is in the closed portion.

7. The apparatus of claim 1 and further including a voltage limiting element coupled in circuit for protecting the PTC element during a short circuit interruption.

8. The apparatus of claim 7 wherein said voltage limiting element comprises one of a metal oxide varistor (MOV) or a silicon avalanche suppressor diode (SASD) coupled in parallel with said PTC element for providing a shunt path for extra current.

9. The apparatus of claim 7 wherein said voltage limiting element comprises one of a metal oxide varistor (MOV) or a silicon avalanche suppressor diode (SASD) coupled in parallel with the series combination of the PTC element and the load.

10. The apparatus of claim 3 and further including a second coil coupled in series with said PTC element and wound around a common core with said coil for more rapidly opening said switch during a short circuit condition.

11. The apparatus of claim 1, wherein said apparatus is housed in an electrical receptacle.

12. The apparatus of claim 1, wherein said apparatus is housed in a power strip.

13. The apparatus of claim 11 wherein said electrical receptacle is part of a power strip.

20. The receptacle of claim 12 and further including one of a metal oxide varistor (MOV) or a silicon avalanche suppressor diode (SASD) coupled in circuit for providing a shunt path for extra current during short circuit interruption for protecting the PTC element.

21. The receptacle of claim 20 wherein said MOV or SASD is coupled in parallel with said PTC element.

14. A ground fault receptacle having a circuit protection apparatus for interrupting the flow of electrical current in a line in response to any of a plurality of different types of fault conditions on the line, said receptacle comprising:

a set of contacts connected in series with the line, and having an open position and a closed position;

a device coupled to the contacts, adapted to be actuated by a trip signal, to move the contacts from the closed position to the open position;

an element having a positive temperature coefficient of resistivity (PTC) connected in series with the contacts, said PTC element being connected to said device to provide said trip signal to the device in response to overload or short circuit conditions in the line;

a switching element operatively coupled with said device for providing said trip signal to said device in response to an actuating signal; and

a circuit adapted for detecting an arcing fault in the line and producing said actuating signal when the arcing fault is detected.

15. The receptacle of claim 14 wherein said circuit is further adapted for detecting a ground fault current in the line and producing said actuating signal when the ground fault current is detected.

16. The receptacle of claim 14 wherein said device comprises a coil operatively associated with said contacts.

17. The receptacle of claim 14 wherein said switching element has an open position and a closed position and wherein the switching element is adapted to move from the open position to the closed position in response to said actuating signal.

18. The receptacle of claim 15 wherein the switching element is an SCR.

19. The receptacle of claim 17 further comrising a diode arrangement adapted to direct current through the device and to prevent a current from flowing through the PTC element when the switching element is in the closed portion.

22. The receptacle of claim 18 wherein said MOV or SASD is coupled in parallel with the series combination of the PTC element and the load.

23. The receptacle of claim 14 and further including a second coil coupled in series with said PTC element and wound around a common core with said coil for more rapidly opening said switch during a short circuit condition.

24. The receptacle of claim 14 wherein said ground fault receptacle is part of a power strip.