Arc stack assembly for a circuit breaker

Information

  • Patent Grant
  • 6624373
  • Patent Number
    6,624,373
  • Date Filed
    Wednesday, September 19, 2001
    23 years ago
  • Date Issued
    Tuesday, September 23, 2003
    21 years ago
Abstract
A circuit breaker for interrupting the flow of current upon the detection of excess current or temperature is provided that contains an arc plate assembly which includes a pair of insulative mounting plates having mounted thereon a set of arc plates arranged in an arcuate array generally tracing the arcuate path of movement of a circuit breaker moveable contact blade. A baffle plate is mounted between the insulative mounting plates and positioned above the uppermost arc plate in the set of arc plates for blocking arc-formed debris from projection into the operating mechanism of said circuit breaker. Mounting tabs, which are extending toward the insulative mounting plates from edges of the arc plates, are being used to connect the mounting plates with the arc plates by passing the tabs through corresponding apertures located in the mounting plates. The tabs are crimped against the exterior surface of the mounting plates.
Description




FIELD OF THE INVENTION




This invention is directed generally to circuit breakers, and, specifically, to an arc stack for a circuit breaker.




BACKGROUND OF THE INVENTION




A circuit breaker generally contains an arc stack assembly which has the purpose of receiving and dissipating electrical arcs that are created when a movable contact separates from a stationary contact.




One particular type of arc stack includes a number of arc plates which are offset at equal distances from one another, being supported on each side by a insulating plate. The plates are generally rectangular in shape, identical to one another, and interconnected. Each plate has an arc throat that creates a path for the blade to open and to close whenever the circuit breaker is tripped and reset, respectively. The path is formed by laterally offsetting the identical arc plates relative to one another in the same direction, tracing the imaginary radius that the blade creates when opening and closing.




A drawback of this type of arc stack is that it is sometimes difficult to manufacture, particularly when dealing with circuit breakers that are relatively small in size where space is tight. Easy and reliable automated installation of the arc plates to the insulating plate would greatly increase efficiency and productivity while lowering production costs.




Another drawback typically encountered in this type of arc stack is that molten debris, which is created when the circuit breaker interrupts current, may interfere with internal components of the circuit breaker by either welding internal parts together or by jamming the operating mechanism.




Accordingly, it is an object of this invention to catch and solidify molten debris that is created when the circuit breaker interrupts current, preventing the debris from welding together internal parts of the circuit breaker or from jamming operating parts of the circuit breaker.




It is another object of this invention to make the connection for the arc plates easier and more reliable, therefore, reducing the labor required to assemble the circuit breaker.




SUMMARY OF THE INVENTION




In accordance with a preferred embodiment of the invention, an arc plate assembly for a circuit breaker is provided. It includes a pair of parallel spaced vertically oriented insulative mounting plates having mounted thereon a set of arc plates arranged in an arcuate array generally tracing the arcuate path of movement of a circuit breaker moveable contact blade. A baffle plate is mounted between the insulative mounting plates and positioned above the uppermost arc plate in the set for blocking arc-formed debris from projection into the operating mechanism of said circuit breaker The arc plate assembly baffle plate is preferably mounted at an angle such that it defines with the uppermost arc plate a wedge-shaped volume for catching and solidifying molten arc-formed debris. The baffle plate is preferably mounted at a downward inclination toward the uppermost arc plate.




In accordance with a further embodiment, an arc plate assembly is provided in which the baffle plate and said arc plates are provided with mounting tabs extending toward the insulative mounting plates. The mounting plates are provided with mounting apertures, and the mounting tabs are passed through said apertures and crimped against the exterior surfaces of said mounting plates.




According to a further preferred embodiment, an arc plate assembly for a circuit breaker is provided with a pair of parallel spaced vertically oriented mounting plates having mounted thereon a set of arc plates arranged in an arcuate array generally tracing the arcuate path of movement of a circuit breaker moveable contact blade, with the arc plates being so mounted by tabs extending through apertures in the mounting plates and being crimped against the exterior surfaces of the mounting plates. Further, in accordance with the invention, a method is provided for blocking arc-formed debris projected from the vicinity of an arc plate array in a circuit breaker toward the operating mechanism of the breaker which includes interposing a downwardly extending baffle plate at the top of the arc plate array between the array and the mechanism.











BRIEF DESCRIPTION OF THE DRAWINGS




In the drawings:





FIG. 1

is an orthogonal view of a high arc stack configuration embodying the invention;





FIG. 2

is an orthogonal view of a medium arc stack configuration embodying the invention;





FIG. 3



a


is a front elevation of the baffle plate used in the high arc stack configuration of

FIG. 1

;





FIG. 3



b


is an end elevation of the baffle plate of

FIG. 3



a;







FIG. 4

is a front elevation of the baffle plate used in the medium arc stack configuration of

FIG. 2

;





FIG. 5

is an enlarged view of one of the tabs on the baffle plate of

FIG. 3



a;







FIG. 6

is a front elevation of a modified arc plate that has three crimp tabs; and





FIG. 7

is a front elevation of a modified arc plate that has four crimp tabs.











DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS




Referring to

FIG. 1

, an arc stack


401


contains a baffle plate


403


, an insulating plate


405


on each side of the arc stack


401


, and a plurality of arc plates


407


.




In a preferred embodiment, shown in

FIGS. 3



a


and


3




b


, the baffle plate


403


is a generally rectangular, steel plate that has top and bottom surfaces


409


and


411


, and a pair of side edges


413


and


415


. A projection


417


is formed at the upper end of each side edge, and a mounting tab


419


is formed near the bottom of each side edge. The lower surface of the baffle plate


403


forms an arc surface


421


, which faces the arc plates


407


, while the lower surface forms a blade surface


423


, which faces towards the blade (not shown) of the circuit breaker.




Each mounting tab


419


is inserted into a pivot hole


425


formed in one of the insulating plates


405


near a baffle stop


427


, and each projection


417


rests its arc surface


421


against the baffle stop


427


. The baffle stop


427


is positioned relative to the adjacent pivot hole


425


to allow the placement of the baffle plate


403


at an angle that forms a V-shaped space


429


between the baffle plate


403


and the uppermost arc plate


407


. Specifically, the baffle plate


403


is disposed at an angle that is more than 90° in a counterclockwise direction from a horizontal plane, as viewed in

FIG. 1

, but not more than 180°, preferably around 120°. The V-shaped space


429


collects any molten debris that would normally fall onto and damage internal parts of the circuit breaker.




In another preferred embodiment, shown in

FIG. 2

, a different method of connecting the baffle plate


403


to the insulating plate


405


is used. A mounting tab


431


, clearly shown in

FIG. 4

, is formed in the center of each of the side edges


413


and


415


. An insulating slot


433


, which is located near the baffle stop


427


, is shaped and dimensioned to allow the mating of the mounting tab


431


to the insulating slot


433


, which, in turn, secures in place the baffle plate


403


to the insulating plate


405


. In addition to provide a secure connection, the mounting of mounting tab


431


produces a V-shaped space that collects molten debris produced by arcing of the circuit breaker.




In another preferred embodiment, a crimp tab


435


, clearly shown in

FIG. 5

, is used to easily and reliably attach the insulating plate


405


to the arc plate


407


. The crimp tab


435


is a generally rectangular protrusion that has a protruding edge


437


, which runs parallel to an insulating edge


439


from which it is protruding, and two extending sides


441


, which run along the length of the crimp tab


435


orthogonal to the protruding edge


437


. A small indentation


443


is located at the intersection of each extending side


441


with the insulating edge


439


. The small indentation


443


provides a collapsing place for the material of the crimp tab


435


when the crimp tab


435


is compressed inwardly, towards the insulating edge


439


, in the final assembly stage. A large indentation


445


is located in the center of the protruding edge


437


, having two sides that are orthogonal to each other and forming a V-shaped contour, with the intersecting point between the two sides being centered along the length of the protruding edge


437


. When the crimp tab


435


is compressed inwardly the sides of the large indentation


445


push the two corners of the crimp tab


435


, which are located at the two intersections between the protruding edge


437


and the extending sides


441


, resulting in a secure connection between the arc plate


407


and the insulating plate


405


.




The length of the crimp tab


435


is a little longer than the thickness of the insulating plate


405


, generally on the order of about one millimeter, allowing the crimp tab


435


to protrude beyond the outside surface of the insulating plate


405


before being permanently attached to the insulating plate


405


. The crimp tab


435


protrudes through a tab hole


447


that is located on the insulating plate


405


and that has a diameter large enough to allow the insertion of the crimp tab


435


through the tab hole


447


.




To provide a good, secure connection between the insulating plate


405


and the arc plate


407


, several crimp tabs


435


may be used. For example, in the preferred embodiment shown in

FIGS. 1 and 6

, three crimp tabs


435


are used. On a right insulating edge


449


, which is near a thick end


451


, two crimp tabs


435


are located on either end of the right insulating edge


449


, being generally equally spaced from the center of the edge. On a left insulating edge


453


, which is near a thin end


455


, one crimp tab


435


is located in the center of the edge.




In another preferred embodiment, shown in

FIGS. 2 and 7

, four crimp tabs


435


are used. Two crimp tabs


435


are located on the right insulating edge


449


and two crimp tabs


435


are located on the left insulating edge


453


, being equally spaced from the center of each respective edge.




While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.



Claims
  • 1. A method for assembling an arc stack assembly for use in a circuit breaker, comprising:providing a plurality of metal arc plates each having a plurality of crimp tabs extending laterally from a pair of opposite edges, each of said crimp tabs having an end cutout preformed in the free end thereof, each of said crimp tabs having a plurality of base cutouts preformed in opposite edges thereof at the base of the tab; providing a pair of insulating support plates each of which has a plurality of apertures for receiving said crimp tabs; mounting said arc plates on said support plates with the crimp tabs of the arc plates extending through the apertures in the support plates, and with the arc plates arranged in a spaced array between said support plates; and crimping the free ends of said crimp tabs against the adjacent portions of said support plates to attach said arc plates to said support plates.
  • 2. The method of claim 1 wherein the crimping of said tabs produces crimped tab ends that are substantially flush with the outer surfaces of said support plates.
  • 3. The method of claim 1 wherein the crimping of said tabs displaces metal in the tabs into said cutouts at the base of each tab and against the adjacent walls of the apertures in said support plates.
  • 4. A method for assembling an arc stack assembly for use in a circuit breaker, comprising:providing a plurality of metal arc plates each having a plurality of crimp tabs extending laterally from a pair of opposite edges, each of said crimp tabs having at least one cutout preformed at the base of the tab; providing a pair of insulating support plates each of which has a plurality of apertures for receiving said crimp tabs; mounting said arc plates on said support plates with the crimp tabs of the arc plates extending through the apertures in the support plates, and with the arc plates arranged in a spaced array between said support plates; and crimping the free ends of said crimp tabs against the adjacent portions of said support plates to attach said arc plates to said support plates, said crimping producing crimped tab ends that are substantially flush with the outer surfaces of said support plates, and said crimping displacing metal in the tabs into said cutout at the base of each tab and against the adjacent walls of the apertures in said support plates.
  • 5. A method for assembling an arc stack assembly for use in a circuit breaker, comprising:providing a plurality of metal arc plates each having a plurality of crimp tabs extending laterally from a pair of opposite edges, each of said crimp tabs having cutouts preformed in opposite edges thereof at the base of the tab; providing a pair of insulating support plates each of which has a plurality of apertures for receiving said crimp tabs; mounting said arc plates on said support plates with the crimp tabs of the arc plates extending through the apertures in the support plates, and with the arc plates arranged in a spaced array between said support plates; and crimping the free ends of said crimp tabs against the adjacent portions of said support plates to attach said arc plates to said support plates.
US Referenced Citations (12)
Number Name Date Kind
4431877 Heft et al. Feb 1984 A
4635011 Leone et al. Jan 1987 A
4644307 Tanimoto Feb 1987 A
4716265 Fujii et al. Dec 1987 A
4791393 Flick et al. Dec 1988 A
4841266 Wulff Jun 1989 A
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5440284 Ferullo et al. Aug 1995 A
5793270 Beck et al. Aug 1998 A
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5926081 DiMarco et al. Jul 1999 A
Foreign Referenced Citations (7)
Number Date Country
2128633 Jan 1973 DE
4404706 Sep 1994 DE
0772195 Nov 1996 EP
04-280026 Oct 1992 JP
09-161641 Jun 1997 JP
2000-003655 Jan 2000 JP
WO 0116986 Mar 2001 WO
Non-Patent Literature Citations (12)
Entry
Description of Terasaki Circuit Breaker—Te21-43, as early as 1995, 1 page.
Description of Fuji Circuit Breaker—F-9-11, as early as 1995, 2 pages.
Description of Mitsubishi Circuit Breaker—M-21-6, as early as 1995, 2 pages.
Description of Toshiba Circuit Breaker—T-9-2, as early as 1995, 1 page.
Patent Abstract for Germany—DE 4404706 A, 1 page. (see B03).
Patent Abstracts for Japan—Publ. No. 04-280026, Oct. 6, 1992, 1 page. (see B04).
Patent Abstracts for Japan—Publ. No. 2000-003655, Jun. 7, 2000, 1 page. (see B06).
Patent Abstract for Japan—JP 9161641 A, 1 page. (see B05).
Photographs of Terasaki Circuit Breaker—Te21-43, Photographs 1-11, 11 pages.
Photographs of Fuji Circuit Breaker—F-9-11, Photographs 12-29, 18 pages.
Photographs of Mitsubishi Circuit Breaker—M-21-6, Photographs 30-48, 19 pages.
Photographs of Toshiba Circuit Breaker—T-9-2, Photographs 49-61, 13 pages.