TRIGGERED ARC FLASH ARRESTER AND SWITCHGEAR SYSTEM INCLUDING THE SAME

• US 20130120879A1
• Filed: 11/15/2011
• Published: 05/16/2013
• Est. Priority Date: 11/15/2011
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: John J. Shea
• Inventors: SHEA, JOHN J., Rosenkrans, Benjamin A., Smith, Robert Kirkland, Campbell, Louis G.
• Granted Patent: US 8,861,144 B2
• Time in Patent Office: Days
• US Class Current: 361/13
• CPC Class Codes: H01H 33/66 Vacuum switches
• CPC Class Codes: H01H 33/664 Contacts; Arc-extinguishing means, e.g. arcing rings
• CPC Class Codes: H01H 33/6643 having disc-shaped contacts subdivided in petal-like segments, e.g. by helical grooves
• CPC Class Codes: H01T 2/02 comprising a trigger electrode or an auxiliary spark gap
• CPC Class Codes: H02H 3/00 Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems H02H7/00; systems for change-over to standby supply H02J9/00 ; integrated protection for motors H02H7/0822

Abstract

A triggered arc flash arrester includes an envelope structured to operate at: a pressure less than about 1.33 Pa; or a pressure greater than 0.10857 MPa; a plurality of conductors partially disposed within the envelope; a number of gaps disposed between the plurality of conductors within the envelope; and a shorting structure selected from the group consisting of a triggered gap and a fuse. The shorting structure is operatively associated with the number of gaps. The shorting structure is structured to electrically short the plurality of conductors either together or to ground, in order to create an arc within the envelope which is electrically in parallel to an arc fault causing the arc fault internal to switchgear to be extinguished.

Claims

1. A triggered arc flash arrester comprising:

an envelope structured to operate at;

a pressure less than about 1.33 Pa;

or a pressure greater than 0.10857 MPa;

a plurality of conductors partially disposed within said envelope;

a number of gaps disposed between said plurality of conductors within said envelope; and

a shorting structure selected from the group consisting of a triggered gap and a fuse,

wherein said shorting structure is operatively associated with said number of gaps, and

wherein said shorting structure is structured to electrically short said plurality of conductors either together or to ground, in order to create an arc within said envelope which is electrically in parallel to an arc fault causing the arc fault internal to switchgear to be extinguished.

2. The triggered arc flash arrester of claim 1 wherein said shorting structure is said triggered gap;

and wherein said triggered gap is formed by one of said plurality of conductors and an electrode disposed within and insulated from said one of said plurality of conductors.

3. The triggered arc flash arrester of claim 2 wherein said electrode is an elongated electrode having a first end and an opposite second end;

wherein said one of said plurality of conductors has a first opening proximate the first end of said elongated electrode and proximate another one of said plurality of conductors, and a second opening, larger than the first opening, proximate an insulator disposed between said elongated electrode and said one of said plurality of conductors; and

wherein said insulator has a third opening, larger than and proximate the second opening, in order to prevent metal deposition on a surface of said insulator within said envelope between said elongated electrode and said one of said plurality of conductors.

4. The triggered arc flash arrester of claim 2 wherein said electrode is an elongated electrode having a first end and an opposite second end;

wherein said one of said plurality of conductors has an opening proximate the first end of said elongated electrode and proximate another one of said plurality of conductors; and

wherein the first end of said elongated electrode has a profile selected from the group consisting of a rounded end, a flat end and a pointed end.

5. The triggered arc flash arrester of claim 4 wherein said elongated electrode has a generally cylindrical shape;

wherein said pointed end is a cone having a surface disposed at an angle with respect to the generally cylindrical shape of said elongated electrode; and

wherein said angle is between about 15 degrees and about 30 degrees.

6. The triggered arc flash arrester of claim 1 wherein said envelope comprises a ring electrode;

wherein said shorting structure is said triggered gap; and

wherein said triggered gap is formed by a gap between said ring electrode and a cylindrical portion of one of said plurality of conductors.

7. The triggered arc flash arrester of claim 6 wherein the cylindrical portion of said one of said plurality of conductors has a first planar surface;

wherein another one of said plurality of conductors has a second planar surface parallel to and proximate the first planar surface;

wherein said ring electrode has a third planar surface co-planar with the first planar surface.

8. The triggered arc flash arrester of claim 7 wherein said ring electrode further has a fourth planar surface parallel to the third planar surface;

wherein a cross section of said ring electrode has a first square corner at the third planar surface and a rounded corner at the fourth planar surface;

wherein a cross section of the cylindrical portion of said one of said plurality of conductors has a second square corner proximate the first square corner; and

wherein said first and second square corners form part of said triggered gap.

9. The triggered arc flash arrester of claim 1 wherein said envelope comprises a shield and a trigger rod electrode having a first end electrically connected to said shield and an opposite second end;

wherein said shorting structure is said triggered gap; and

wherein said triggered gap is formed by a gap between the opposite second end of said trigger rod electrode and a portion of one of said plurality of conductors.

10. The triggered arc flash arrester of claim 9 wherein the portion of said one of said plurality of conductors has a first planar surface;

wherein another one of said plurality of conductors has a second planar surface parallel to and proximate the first planar surface;

wherein said trigger rod electrode is generally co-planar with the first planar surface;

wherein the opposite second end of said trigger rod electrode is a point proximate said one of said plurality of conductors; and

wherein said triggered gap is formed by a gap between the point of the opposite second end of said trigger rod electrode and a portion of the first planar surface of said one of said plurality of conductors.

11. The triggered arc flash arrester of claim 1 wherein said envelope comprises a shield;

wherein said shorting structure is said fuse; and

wherein said fuse is electrically connected between said shield and one of said plurality of conductors.

12. The triggered arc flash arrester of claim 11 wherein said fuse is selected from the group consisting of a fuse wire and a fuse ribbon.

13. The triggered arc flash arrester of claim 1 wherein said shorting structure is said fuse;

wherein said envelope comprises a ring electrode having a first portion disposed external to said envelope and a second portion disposed internal to said envelope; and

wherein said fuse is electrically connected between said ring electrode and one of said plurality of conductors.

14. The triggered arc flash arrester of claim 11 wherein said one of said plurality of conductors has a first cylindrical shape with a first planar surface;

wherein another one of said plurality of conductors has a second cylindrical shape with a second planar surface parallel to and proximate the first planar surface;

wherein said fuse is generally co-planar with the first planar surface; and

wherein the first cylindrical shape is smaller than the second cylindrical shape.

15. The triggered arc flash arrester of claim 11 wherein said one of said plurality of conductors has a first cylindrical shape with a first size and a first planar surface;

wherein another one of said plurality of conductors has a second cylindrical shape with a second size and a second planar surface parallel to and proximate the first planar surface;

wherein said fuse is generally co-planar with the first planar surface; and

wherein the first size is the same as the second size.

16. The triggered arc flash arrester of claim 11 wherein said envelope further comprises an insulative cylinder disposed therein between said shield and said one of said plurality of conductors;

wherein said one of said plurality of conductors has a cylindrical shape with a planar surface;

wherein said insulative cylinder has an annular end parallel to said planar surface; and

wherein said annular end supports said fuse.

17. The triggered arc flash arrester of claim 16 wherein said annular end has an outer edge proximate said shield and an inner edge proximate said one of said plurality of conductors;

and wherein said fuse is disposed in a linear segment directly between the outer edge and the inner edge.

18. The triggered arc flash arrester of claim 16 wherein said annular end has an outer edge proximate said shield and an inner edge proximate said one of said plurality of conductors;

and wherein said fuse is disposed in a generally circular segment beginning at the outer edge, disposed over and around the annular end, and ending at the inner edge.

19. The triggered arc flash arrester of claim 16 wherein said annular end has an outer edge proximate said shield and an inner edge proximate said one of said plurality of conductors;

wherein said insulative cylinder is supported by a first conductive member disposed between said shield and the outer edge and a second conductive member disposed between the inner edge and said one of said plurality of conductors;

wherein said first conductive member is electrically connected to said shield;

wherein said second conductive member is electrically connected to said one of said plurality of conductors; and

wherein said fuse is electrically connected between said first conductive member and said second conductive member.

20. The triggered arc flash arrester of claim 1 wherein said plurality of conductors are three conductors structured to be energized by a three-phase medium voltage.

21. The triggered arc flash arrester of claim 1 wherein said envelope is a vacuum envelope structured to operate at the partial vacuum.

22. The triggered arc flash arrester of claim 1 wherein said envelope is structured to operate at the pressure less than about 1.33 Pa.

23. The triggered arc flash arrester of claim 1 wherein said shorting structure is said triggered gap;

and wherein said triggered gap is structured to be actuated by a number of voltage pulses having a voltage magnitude structured to breakdown the triggered gap.

24. The triggered arc flash arrester of claim 23 wherein said envelope comprises a shield disposed within said envelope;

and wherein said triggered gap is partially disposed within said shield.

25. The triggered arc flash arrester of claim 24 wherein said number of gaps are disposed between said plurality of conductors and between said shield and said plurality of conductors;

and wherein said gaps meet BIL spacing requirements.

26. The triggered arc flash arrester of claim 1 wherein said shorting structure is said triggered gap;

and wherein said triggered gap is partially disposed within one of said plurality of conductors.

27. The triggered arc flash arrester of claim 1 wherein said triggered arc flash arrester is encapsulated in an insulator for increased BIL.

28. The triggered arc flash arrester of claim 1 wherein said plurality of conductors are four conductors for three phases and a ground;

and wherein said four conductors are partially disposed within said envelope.

29. The triggered arc flash arrester of claim 1 wherein said envelope comprises a shield partially disposed within said envelope;

wherein said shorting structure is said triggered gap;

wherein said triggered gap is partially disposed within said shield; and

wherein said triggered gap includes a plasma exhaust disposed within said shield proximate said number of gaps and a trigger electrical connection disposed external to said envelope.

30. The triggered arc flash arrester of claim 1 wherein said envelope comprises a ceramic tube having a ceramic surface therein and a shield partially disposed within said envelope;

wherein said shorting structure is said triggered gap;

wherein said triggered gap is partially disposed within said shield; and

wherein one of said plurality of conductors has a shape structured to prevent metal deposition on the ceramic surface within said envelope.

31. The triggered arc flash arrester of claim 1 wherein one of said plurality of conductors carries a fixed contact and another one of said plurality of conductors carries a movable contact movable between a first position separated from said fixed contact and a second position electrically engaging said fixed contact.

32. The triggered arc flash arrester of claim 1 wherein said envelope comprises a shield and a trigger rod electrode having a first end electrically isolated from said shield and an opposite second end;

wherein said shorting structure is said triggered gap; and

wherein said triggered gap is formed by a gap between the opposite second end of said trigger rod electrode and a portion of one of said plurality of conductors.

33. The triggered arc flash arrester of claim 32 wherein said shield has an opening;

and wherein said trigger rod electrode is electrically isolated from said shield by an insulator within the opening of said shield.

34. The triggered arc flash arrester of claim 1 wherein said shorting structure is said fuse;

wherein said envelope comprises shield and a ring electrode having a first portion disposed external to said envelope and a second portion disposed internal to said envelope;

wherein said fuse is electrically connected between said ring electrode and one of said plurality of conductors; and

wherein said fuse and said ring electrode are electrically isolated from said shield.

35. A system comprising:

switchgear including a power circuit;

a triggered arc flash arrester comprising;

an envelope structured to operate at;

a pressure less than about 1.33 Pa;

or a pressure greater than 0.10857 MPa,

a plurality of conductors partially disposed within said envelope,

a number of gaps disposed between said plurality of conductors within said envelope, and

a shorting structure selected from the group consisting of a triggered gap and a fuse,

wherein said shorting structure is operatively associated with said number of gaps, and

wherein said shorting structure is structured to electrically short said plurality of conductors either together or to ground, in order to create an arc within said envelope which is electrically in parallel to an arc fault causing the arc fault internal to said switchgear to be extinguished;

a current sensor sensing current flowing through said power circuit including a plurality of power conductors corresponding to said plurality of conductors;

a light sensor sensing light operatively associated with said arcing fault for said power circuit; and

a trigger circuit structured to trigger said shorting structure when the sensed current is greater than a first predetermined threshold and when the sensed light is greater than a second predetermined threshold.

36. The system of claim 35 wherein an upstream circuit breaker is operatively associated with said power circuit;

and wherein said trigger circuit is further structured to trip said upstream circuit breaker responsive to said trigger of said triggered gap.