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Publication numberUS3582966 A
Publication typeGrant
Publication dateJun 1, 1971
Filing dateDec 30, 1969
Priority dateDec 30, 1969
Publication numberUS 3582966 A, US 3582966A, US-A-3582966, US3582966 A, US3582966A
InventorsAlbert Strobel
Original AssigneeIte Imperial Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Venting means for circuit breaker arc quencher
US 3582966 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Inventor Appl. No.

Filed Patented Assignee VENTING MEANS FOR CIRCUIT BREAKER ARC Albert Strobel Cherry Hill, NJ.

Dec. 30, 1969 June 1 l 971 l-T-E Imperial Corporation Philadelphia, Pa.

QUENCHER 10 Claims, 9 Drawing Figs.

US. Cl Int. Cl Field of Search References Cited UNITED STATES PATENTS 6/1958 Edmunds 200/144(R) 200/144 H01h 9/30 200/ l 44 3,005,892 10/1961 Yarrick 200/144(R) 3,025,376 3/1962 Yarrick 200/144(R) 3,031,552 4/1'962 Stewart .i. 200/144(R) 3,265,842 8/l966 P0korny.... 200/l44(R) 3,374,332 3/1968 Bould 200/144(R) Primary Examiner-H. 0. Jones Attorney-Ostrolenk, Faber, Gerb & Soffen VIEN'IENG MEANS FOR CIRCUIT BREAKER ARC QUENCEIEIR This invention relates to circuit breakers in general, and more particularly relates to means for controlling deflection of a flexible arc shield which normally blocks gases from leaving the arc chute.

U.S. Pat. No. 2,839,641 to W. H. Edmunds for An Arc Shield for Circuit Breaker Arc Quencher discloses a flexible are shield which is normally urged against the rear wall of the arc shield which is normally urged against the rear wall of the arc chute housing to block vent openings therein. During high current interruption, the pressure of the gases developed in the arc chute causes the shield to flex away from the rear wall to crease some openings around the arc shield edges thereby relieving some of the pressure within the arc chute. However,

this without flexing of the shield does not pennit a sufficient quantity of ionized gases to escape and cause a rotating to the line terminal.

While the construction set forth in the aforesaid U.S. Pat. No. 2,839,641 proved satisfactory for interruption at the current and voltage limits set forth in the patent, such construction has proven inadequate when interrupting as much as 50,000 amperes at 600 volts. Under these conditions, failure appears to result from the fact that deflection of the arc shield blocks the vent opening in the housing to prevent relief of pressure buildup within the arc chamber. Blocking of the cover vent openings resulting in failures appears to be caused by the fact that in U.S. Pat. No. 2,839,641 the arc shield assumes a slightly curved configuration around the arc chute and retains somewhat of a permanent set in that configuration.

In order to overcome the above-noted problem, the instant invention provides a support plate or strip to prevent transverse curving of the arc shield so that deflection thereof is essentially in the direction of movement of arcing gases as they leave the arc chute through openings in the backwall thereof. The support plate acting in conjunction with ribs in the cover adjacent to the cover vent openings prevents the arc shield from blocking the vent openings even under conditions of extremely high current interruption.

Accordingly, a primary object of this invention is to provide novel means for controlling deflection of an arc shield during current interruption to prevent such shield from closing off vent openings in the housing adjacent to the arc chute.

Another object is to provide an arc chute having vent openings at the rear thereof, with an arc shield normally closing the vent opening region and a support positioned to limit bending of the shield generally in the direction of flow of arcing gases leaving the arc chute through the openings in the rear wall thereof.

Another object is to provide an arc shield of this type, and means to limit deflection thereof under conditions of circuit interruption such that the arcing gases are directed through the housing openings adjacent to the arc chute.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a side elevation of a circuit breaker partially cross sectioned to show the operative position of the baffle assembly constructed in accordance with the instant invention.

FIG. 2 is an enlarged fragmentary portion of FIG. 1, show ing the baffle in its normal position.

FIG. 3 is a partial cross section of the cover taken through line 3-3 of P16. 2, looking in the direction of arrows 33.

FIG. 41 is a plan view of the arc chute and baffle assembly.

FIG. 5 is a view similar to that of FIG. 2.. showing the baffle deflected during current interruption.

FIG. ti is a side elevation of the baffle assembly.

FIG. 7 is a front elevation of the baffle assembly, looking in the direction of arrows 7-7 of FIG. 6.

FIG. 8 is a front elevation of the baffle.

FIG. 9 is a front elevation of the baffle support.

Now referring to the figures. FIG. 1 is a partially sectioned view of a molded case circuit breaker 10 which, except for the arc shield means and its cooperating elements of the instant invention, is of a construction well known to the art. Circuit breaker 10 includes a housing comprising base 11 and removable cover 12 having auxiliary covers 13, 14 at opposite ends thereof.

Circuit breaker 10 is a three-phase unit, only one pole of which is partially shown in FIG. 1. In the pole illustrated, line terminal portion 15 of conducting strap 16 is fixedly secured to base 11 by screw 17. Stationary contacts l8, 19 are mounted to the upper surface of strap 16 at the end thereof remote from line terminal 15. Movable contacts 28, 29, engageable with the respective stationary contacts 18, 19, are mounted to contact arms 22, 23, respectively, carried by bracket 24 secured to interphase tie bar 25. In a manner well known to the art, tie bar 25 is connected to operating mechanism 26 which is manually operable by handle 27 to operate the pairs of cooperating contacts 18, 28 and 19, 29 into and out of engagement. In addition, a fault responsive means (not shown) is provided for automatic operation mechanism 26 to separate the pairs of contacts 18, 28 and 19, 29.

In a manner well known to the art, circuit breaker 10 also includes arc chute 30 disposed above strap 16. Chute 30 comprises a series of generally horizontal spaced metal plates 31, 31, etc. each having a notch 32 (FIG. 4) at its forward end, to provide a passage through which contact arm 23 moves for engagement and disengagement of movable arcing contact 29 with stationary arcing contact 19. Edge projections 33 from the sides of each arc plate 31 extend into notches in the insulating sidewalls 34, 35 of the arc chute housing for positioning of plates 31. The are chute housing is generally rectangular and also includes front wall sections 36, 37 and rear wall 38, each constructed of insulating material.

Screw 39 extends through clearance aperture 40 in the horizontal leg metal bracket 41 of baffle assembly (FIGS. 6 and 7) and a clearance aperture in the bottom plate or are runner 42 of arc chute 30, and is received by a threaded aperture in strap 16 to secure baffle assembly 45 and are chute 30 with baffle assembly 45 opcratively positioned to the rear of arc chute 30 and forward of line terminal 15. Baffle assembly 45 also includes arc shield or baffle 50, constructed of relatively flexible insulating sheet material (FIG. 8) and baffle support 55 (FIG. 9) constructed of relatively stiff insulating material. The lower ends of both shield and support are secured to the upwardly extending leg 44 of bracket 41 by a pair of rivets 46, 47. As best seen in FIGS. 6 and 7, support 55 is positioned immediately behind baffle 50, with the former being only slightly more than half the height of the latter.

With cover 12 installed on base 11, cover ribs 56, 57 (FIGS. 2 and 3) engage oppositely extending cars 48 of bame support 55 to deflect the upper edge thereof slightly in a forward direction into engagement with the midportion of baffle 50. This causes the upper edge 59 to baffle 50 to bear against the rear surface of the rear wall 38 of the arc chute housing to deflect the upper portion of baffle 50 slightly in the rearward direction.

Ribs 56, 57 are parts of the cover formation which positions arc quenching screen assembly 60 over the arcing gas exhaust vent in cover 12 adjacent to the rear of arc chute 30. Assembly 60 consists of three rectangular metal screens 61, separated by insulating rectangular frames 62.

When arcing contacts 19, 29 are separated under normal current conditions, the arcing gases are confined, essentially, within the housing 34-38 of arc chute 30. These gases seep slowly out of are chute 30 at the upper end thereof and escape from circuit breaker 10 through screen assembly 60 and the holes in insulating sheet 64 at the rear of circuit breaker 10.

When arcing contacts 19, 29 separate under extremely high current conditions, the arcing gases generated cause large pressures to be built up within arc chute housing 34-38. The arcing gases leave arc chute 30 through holes in wall 38 and force the upper portion of baffle 50 to deflect to the rear. If the gas pressure is high enough, baffle 511, in its fully deflected position, engages cover ribs 56, 57 (FIG. 5). The construction and positioning of. cover ribs 56, 57 limits rearward deflection of baffle 50 to a point spaced from screen assembly 60, so that a substantial passage remains open for arcing gases to pass from are chute 30 to and through screen assembly 60, to be exhausted from circuit breaker through the openings in insulating sheet 64.

. It is noted that relatively stiff baffle support 55 limits deflection of baffle 50in the direction of gas flow leaving arc chute 30. That is, support 55 prevents baffle 50 from curving or bending about a generally vertical axis. lf baffle 50 were to bend about a generally vertical axis, cover ribs 56, 57 would be ineffective in preventing baffle 50 from blocking off substantial portions of screen assembly 60 and current interruption would be interfered with.

Thus, the instant invention provides a novel construction for a baffle assembly positioned at the rear of an arc chute. The assembly is so constructed that deflection of the baffle is controlled in a manner such that during high current interruption the baffle does not block off the deionizing screen assembly. 1

It is noted that the use of terms such as above" and horizontal" is intended only as a device to simplify the description and claims. Such terms have been used in their relative senses and are not to be deemed as strict limitations.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to limited notby the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.


1. A circuit interrupter comprising cooperating relatively movable and relatively stationary contacts; operating means to open and close said contacts; an arc chute including a plurality of spaced plates constructed and positioned to receive electric current arcs drawn between said contacts upon separation thereof and assist in extinguishing such arc; a first vent means at the rear of said are chute to permit gases created by said arcs to escape from said are chute; housing means wherein said contacts, said operating means and said are chute are disposed; second vent means formed in said housing and operatively positioned at the rear of said chute to exhaust said gases from said housing; a flexible baffle means interposed between said first and said second vent means to control flow of said gases therebetween; control means cooperating with said baffle means to direct deflection of said baffle means and limit said deflection to a fully deflected position wherein said baffle means does not close off said second vent means.

2. A circuit interrupter as set forth in claim 1, in which said control means includes internal formations of said housing positioned forward of said second vent means to engage and limit deflection of said baffle means to said fully deflected position.

3. A circuit interrupter as set forth in claim 1, in which said bafile means comprises a sheet member in a plane generally perpendicular to flow of said gases as they exit from said first vent means; means anchoring the lower end of said sheet member; said control means engageable with said baffle means to limit deflection thereof to a direction parallel to direction of said flow.

4. A circuit interrupter as set forth in claim 3, in which said control means includes a relatively stiff member positioned to engage said sheet member at a region intermediate the ends thereof.

5. A circuit interrupter as set forth in claim 4, in which said stiff member comprises a sheet at the rear of said sheet member in juxtaposition with substantially the lower half thereof.

6. A circuit interrupter as set forth in claim 5, in which the arc chute is provided with a generally flat rear wall; said first vent means comprising apertures in said rear wall; the upper edge of said sheet member normally enga es said rear wall.

. A circuit interrupter as set forth in c arm 6, in which said control means includes internal formations of said housing positioned forward of said second vent means to engage and limit deflection of said baffle means to said fully deflected position.

8. A circuit interrupter as set forth in claim 7, also including deionizing screen means over said second vent means.

9. A circuit interrupter as set forth in claim 8, in which there is a subassembly comprising said sheet member, said stiff member, a bracket, and means fixedly securing the lower edges of said members to said bracket, said bracket constructed of metal and said members constructed of insulating material.

10. A circuit breaker as set forth in claim 9, in which there is a common means operatively positioning said are chute and said baffle means.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2839641 *Sep 30, 1954Jun 17, 1958Ite Circuit Breaker LtdArc shield for circuit breaker arc quencher
US3005892 *Mar 19, 1957Oct 24, 1961Ite Circuit Breaker LtdArc chute design for circuit breakers
US3025376 *May 13, 1958Mar 13, 1962Ite Circuit Breaker LtdArc chute for circuit breakers
US3031552 *May 28, 1959Apr 24, 1962Gen ElectricElectric circuit interrupter
US3265842 *Jul 18, 1963Aug 9, 1966Ite Circuit Breaker LtdArc chute mixing chamber for cooling exiting gases employing a reflective screen arc barrier
US3374332 *Jul 16, 1965Mar 19, 1968Square D CoArc chute for a circuit breaker
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3780249 *Apr 28, 1972Dec 18, 1973Airpax ElectronicsDust seal high performance breaker
US3784775 *Jul 27, 1972Jan 8, 1974Ite Imperial CorpArc runner between stationary contacts
US3997746 *Mar 19, 1975Dec 14, 1976Airpax Electronics, IncorporatedCircuit breaker with arc chamber screen
US4011425 *Jan 3, 1975Mar 8, 1977I-T-E Imperial CorporationArc chute extension for increased interruption rating
US4107497 *Jul 15, 1976Aug 15, 1978General Electric CompanyArc chute assembly
US4737606 *Oct 24, 1986Apr 12, 1988Square D CompanyCircuit breaker arc stack assembly
US4877929 *Aug 17, 1988Oct 31, 1989Merlin GerinBreaking device for multipole electrical circuit breaker with multiple contacts
US5172088 *Feb 6, 1992Dec 15, 1992General Electric CompanyMolded case circuit breaker combined accessory actuator-reset lever
US5753878 *Apr 23, 1996May 19, 1998General Electric CompanyCircuit breaker having variable arc gas venting
US5780800 *Aug 7, 1996Jul 14, 1998General Electric CompanyCircuit breaker contact arm and spring shield
US6703576 *Feb 13, 2003Mar 9, 2004Eaton CorporationArc chute with valve and electric power switch incorporating same
US6844514 *Jul 5, 2001Jan 18, 2005Siemens AktiengesellschaftArc extinguisher with an attachment for low voltage switchgear
US6960736 *Apr 20, 2000Nov 1, 2005Siemens AktiengesellschaftSwitching gas damper for low-voltage power circuit breakers
US9064648 *Apr 27, 2011Jun 23, 2015Schneider Electric Industries SasValve system for an arc extinguishing chamber and circuit breaker comprising same
US20040026377 *Jul 5, 2001Feb 12, 2004Michael BachArc extinguisher with an attachment for low voltage switchgear
US20110259852 *Oct 27, 2011Schneider Electric Industries SasValve system for an arc extinguishing chamber and circuit breaker comprising same
CN102129925A *Apr 2, 2011Jul 20, 2011常熟开关制造有限公司(原常熟开关厂)Arc-extinguishing chamber of circuit breaker with free-eliminating device
CN102129925BApr 2, 2011Dec 5, 2012常熟开关制造有限公司(原常熟开关厂)Arc-extinguishing chamber of circuit breaker with free-eliminating device
EP0212197A2 *Jul 8, 1986Mar 4, 1987Westinghouse Electric CorporationCircuit breaker with arc gas vent baffle
EP0306382A1 *Aug 11, 1988Mar 8, 1989Merlin GerinBreaker arrangement for an electric multipolar circuit breaker with many contacts
EP0437151A1 *Nov 27, 1990Jul 17, 1991Schneider Electric SaMultipolar circuit-breaker with a gas filter which is common to different poles
EP2871656A1 *Jul 31, 2014May 13, 2015LSIS Co., Ltd.Molded case circuit breaker
WO1988003323A1 *Oct 23, 1987May 5, 1988Square D CoCircuit breaker arc stack assembly
WO2014138557A1 *Mar 7, 2014Sep 12, 2014Carling Technologies, Inc.Arc shield
U.S. Classification218/149
International ClassificationH01H9/34
Cooperative ClassificationH01H2009/343, H01H9/342
European ClassificationH01H9/34C
Legal Events
Jan 30, 1984ASAssignment
Effective date: 19830131