US3649791A

US3649791A - Arc chute for electrical switch apparatus

Info

Publication number: US3649791A
Application number: US60218A
Authority: US
Inventors: Wilfried Kruckewitt
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1969-07-02
Filing date: 1970-07-01
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14
Also published as: DE1933529A1; FR2053977A5; GB1281299A

Abstract

An arc chute for an electrical switch apparatus includes sidewalls which converge together toward the top and which are perforated ceramic plates arranged on each side of the electrodes forming the arc. The plates form a wedge-shaped arc space within the electrode space and also on the exterior of the plates and vertical fire walls. Each of the exterior wedge-shaped arc spaces is divided by intermediate substantially vertical division walls or webs which extend substantially perpendicular to the fire walls. The interior wedge-shaped arc space is closed preferably by a perforated plate made of ceramic material. The two plates forming the interior wedge-shaped arc space either converge to a point or they are spaced apart at their tops by a crossmember or horizontal plate.

Description

United States Patent Kruckewitt Mar. 14, 1972 [54] ARC CHUTE FOR ELECTRICAL 2,836,683 5/ 1958 Souchet ..200/ 144 SWITCH PPARATUS A FOREIGN PATENTS OR APPLICATIONS [72] Invent Lg? 51,348 1/1942 France ..2o0/|44 [73] Assignee: Brown, Boveri & Cie Aktlengesellacluft, Primary Examiner-Robert S. Macon Mannheim-Kafertal, Germany Attorney-McGlcw and Toren [72] Filed: July 1, 1970 [57] I ABSTRACT U x [21] Appl 60318 An arc chute for an electrical switch apparatus includes sidewalls which converge together toward the top and which [30] Foreign Application Priority Data are perforated ceramic plates arranged on each side of the electrodes forming the arc. The plates form a wedge-shaped July 2,1969 -Cermany ..P 19 33 529.6 are space wimin the electrode Space and also on the exerior of the plates and vertical fire walls. Each of the exterior {In-$.81. g p arc spaces is intermediate substan [58] Fie'ld Search 200/144 148 C tially vertical division walls or webs which extend substantially perpendicular to the tire walls. The interior wedge-shaped arc space is closed preferably by a perforated plate made of [56] Cited ceramic material. The two plates forming the interior wedge- UNITED STATES PATENTS shaped arc space either converge to a point or they are spaced apart at their tops by a crossmember or horizontal plate. 1,944,403 1/1934 Clerc ..200/ 148 C 2,302,592 11/1942 Amer ..200/148 C 7 Claims,4Drawing Figures ARC C IIUTE FOR ELECTRICAL SWITCH APPARATUS SUMMARY OF THE INVENTION This invention relates in general to the construction of electrical switching apparatus and in particular, to a new and useful arc chute for an electrical switching device which includes perforated sidewalls which form one or more wedge-shaped chambers for containing the are.

It is known to employ arc chutes having sidewalls which'are formed'of flat perforated plates for small switches, particularly for one pole circuit breakers. They have the advantage that the ionized gases developing in the arc space can penetrate throughthe perforated ceramic walls so that they are cooled and deionized. The perforated ceramic walls permit pressure equalization at times on both sides of the traveling are so that the arc travel is not impeded by the subpressure region which develops on the rear side. Arc chutes of this kind have thus far. not been used for high power switches particularly for multipole switches apparently because the measures required for the phase break were considered to be too expensive and because the arc chute having high break capacities did not seem to offer any particular advantages over the other known are chutes. The are gases which penetrate through the perforations of the sidewalls often become ignited outside of the arc spaces itself, particularly, when the plates are narrowly spaced in order to obtain a high are gradient.

In accordance with the present invention, an arc chute is provided which is an improvement over the prior art and which includes perforated sidewalls which are arranged to make the construction more advantageous for use with higher capacities and with multipole switches. For this purpose, the perforated plates are inclined toward one another in the direction of the travel of the are so that a wedge-shaped space is created in the arc chamber and preferably an additional wedge-shaped space is created on the exterior of the perforated walls between the perforated walls and a fire wall or partition wall on each'side of the device. The wedge-shaped spaces between the perforated plates and the fire walls are also advantageously divided by vertical webs or partitions which extend perpendicular to the side fire walls.

In a further embodiment of the invention, a lower closure for the arc chutechamber is effected by a substantially flat horizontally extending perforated plate which facilitates the intake of fresh'air from the lower switch space. It has proved to be particularly advantageous to make the perforated plates of a screen-ceramic material since this material is very are re sistant. Tominimize the risk of arc ignitions with the adjacent phases it is advantageous to have the fire walls project beyond the height of the arc space formed by the perforated plates.

Accordingly, it is an object of the invention to provide an improved arc chute for electrical switches which include sidewalls formed of perforated plates which are inclined toward each other in the direction of arc travel to'form a wedge-shaped arc space and which includes a fire wall arranged exteriorly of the plates and forming additional wedgeshaped intermediate spaces on the exteriors of the plates which are advantageously subdivided by partition'webs which are arranged substantially vertically.

A further object of the invention is to provide an arc chute for-electrical switches which is simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIG. I is a transverse sectional view of an arc chute constructed in accordance with the invention;

FIG. 2 is a section taken along the line 2-2 of FIG. 1; FIG. 3 is a top plan view; and

FIG. 4 is a section similar to FIG. 2 of another'embodiment of the invention.

GENERALDESCRIPTION'OF THE PREFERRED EMBODIMENTS Referring to thedrawings in particular, theinvention embodied therein in FIGS. l'to 3, comprises an arc chute which comprises two screen-

ceramic walls

1 and 2 which are inclined toward each other in the direction of arc travel and which are arranged in abutting relationship at theirtops in the embodiment shown. At the interior, the plates 1 and .2 fonn an arc space 3 of wedge-shaped configuration. whichnarrows in the direction of travel of the arc. Fire walls6 and 7 are arranged exteriorly of the

walls

1 and 2 and they extend substantially vertically and define-withithe walls-l and 2- a wedgeshaped intermediate space 4 on one side and 5 on the opposite side. The

intermediate spaces

4 and 5 are subdividedby vertical webs 8.

The electrodes 9 and 10 project into the arc chutes inthe space 3 and the electrode 10 is provided with a relieving electrode 18. The are 12 is shown between the electrodes9 and 10. The space 3 is closed at the lower end by a screen ceramic plate 13.

The are chute formed in accordance with the invention; provides a pressure equalizing flow chamber by the arc space 3 and the arc burns at 12 at its upper side and discharges the hot ionized gases in the direction of the arrows 14 into the

intermediate spaces

4 and 5. Fresh air is drawn in

fromthe spaces

4 and 5 in the direction of the arrows 15 at the-lower.

ends of the spaces. Since the bottom 13 is'also'a perforated plate, additionalfresh'air can be sucked-in from the outside in the direction of the arrows l6.- lgnition of the are outside of the arc space 3 is prevented by'the potential separation webs 8 which extends: through the

spaces

4 and 5. In addition; for better separation from neighboring

phases thefire walls

6 and 17 to form a truncated wedge. The plate 17 is also preferably-a.

perforated ceramic plate. Fire wall 6' and 7'. are also provided as well as a bottomperforated platewall l3. The spaces-4-'- and 5 are also divided by vertically extending potential separation webs 8'.

The advantages achieved by the invention primarily consist in that the arc chute, because of the wedge-shaped'arrangement of the perforated plates in conjunction withthe outer fire walls, can act as a pressure equalizing'flow chamber and provides optimumcooling of the arc. When the arc is ignited at the bottom in the widest part of the arc chute; it'can move upwardly in a relatively easy manner, and the pressure wave forming at its front side is equalized through the

perforated plates

2 and 3, with simultaneous-deionization; Furthermore, the subpressure area developing on the backside of the arc can be refilled through the perforated plates. Thewedge-

shaped spaces

4 and 5 between the perforated plates 2 'and 3 and the

fire walls

6 and 7 supports this process of pressure equalizing flow. The are space narrowing in the direction of travel en.- larges the surface of the arc, thereby increases the arc voltage and'also supports the equalizing'flow. Lest'the ionized hot gases which, due to the wedge-shaped'narrowing of the arc space, escape through'the perforation to a higher degree lead to ignitions outside the arc space, the intermediate spaces between the perforated plates and the fire walls are subdivided by-the webs 8. This further measure has provedto be very significant in connection with the wedge-shaped arc space, which is importantfor a high arc gradient. The'webs 8 and 8-, in addition, provide" for better mechanical strength of the perforated plates, so that breaking of the'plates' as a result of the overpressure caused by the arc in the interior of the arc space' need not be expected. Tests have shown that it may be advantageous for higher capacities to not have the upper arc space run out to a complete point but to cover it by a nonperforated plate. It is then easier to drive the powerful arc to the upper limit of the arc space and to completely utilize-the volume of the arc space.

What is claimed is:

1. An arc chute for an electrical switch comprises a first sidewall and a second sidewall each being perforated across its width and length, said first and second sidewalls extending upwardly and disposed in converging relationship in the upward direction, each said first and second sidewalls having an inner surface facing the other said sidewall and an outer surface directed oppositely from the other said sidewall and a closedwedge-shaped space formed between the inner surfaces of said sidewalls, a substantially vertically extending fire wall positioned outwardly from the outer surface of each of said first and second sidewalls and forming an intermediate space between each said fire wall and the adjacent said sidewall, and least one substantially vertically extending web extending between each said fire wall and the adjacent said sidewall subdividing the intermediate space therebetweeni 2. An arc chute, according to claim 1, wherein the lower parts of said first and second sidewalls are disposed in diverging relationship, and a cover plate extends transversely between the lower ends of said sidewalls, said cover plate is perforated across its width and length and forms a bottom closure for the wedge-shaped space between said sidewalls.

3. An arc chute, according to claim 1, wherein said sidewall plates are made of a screen-ceramic material.

4. An arc chute, according to claim 1, wherein a perforated top plate extends between the upper ends of said sideplates and forms a closure for the upper end of the space therebetween, and the space between said sideplates and said top plate being of a substantially truncated wedge shape.

5. An arc chute, according to claim 1, wherein said fire walls project upwardly beyond the upper extent of said sidewalls.

6. An arc chute, according to claim 1, wherein said sidewalls converge to a point at their upper ends, said fire walls being of a height such that they extend upwardly above the converging upper ends of said sidewalls, a perforated bottom plate closing the lower end of the wedge-shaped space between said sideplates, an electrode disposed within the space between said sideplates and including first and second spaced contacts arranged to form an arc therebetween centered in the upper portion of the wedge-shaped space formed between said sideplates.

7. An arc chute, according to claim 6, wherein each of the intermediate spaces defined between said sideplates and said fire walls is divided by a plurality of said vertically extending webs so that said webs act as potential separation webs.

Claims

1. An arc chute for an electrical switch comprises a first sidewall and a second sidewall each being perforated across its width and length, said first and second sidewalls extending upwardly and disposed in converging relationship in the upward direction, each said first and second sidewalls having an inner surface facing the other said sidewall and an outer surface directed oppositely from the other said sidewall and a closedwedge-shaped space formed between the inner surfaces of said sidewalls, a substantially vertically extending fire wall positioned outwardly from the outer surface of each of said first and second sidewalls and forming an intermediate space between each said fire wall and the adjacent said sidewall, and least one substantially vertically extending web extending between each said fire wall and the adjacent said sidewall subdividing the intermediate space therebetween.

2. An arc chute, according to claim 1, wherein the lower parts of said first and second sidewalls are disposed in diverging relationship, and a cover plate extends transversely between the lower ends of said sidewalls, said cover plate is perforated across its width and length and forms a bottom closure for the wedge-shaped space between said sidewalls.