US3749867A

US3749867A - Spaced-metallic-plate-type of arc-chute for a switch

Info

Publication number: US3749867A
Application number: US00135107A
Authority: US
Inventors: J Rexroad
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1971-04-01
Filing date: 1971-04-19
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31
Also published as: AU4019472A; AT312736B; AU472522B2; AT311469B; CA984436A; JPS4735761A; AU3992672A; BE781360A; CA944798A; DE2215885C3; AU474143B2; DE2218420A1; AR194094A1; GB1383954A; IT950754B; FR2133596A1; CH531785A; ES401327A1; DE2215885A1; DE2215885B2

Abstract

An improved spaced metallic plate-type of arc chute construction is provided for a switch, in which the spaced metallic plate structure is in close proximity to both the main separable contacts, as well as to the separable arcing contacts. In one construction, the inner edges of the spaced metallic plates are generally parallel to the one, or several main contacts of the switch, with an elongated slot provided in the central portion of the plate structure to accommodate the protruding movable tip portion of the centrally-located separable main arcing contacts. In a modification of the spaced metallic plate arc-chute structure, minor closed-end slots are, additionally, provided in the plate structure to tend to promote arc transfer movement from the separable main contacts into the spaced plate structure, to thereby provide additional cooling and deionization effects. In a third modification of the spaced metallic plate structure of the present invention, curved minor closed-end slots are provided adjacent the main separable contact structure to additionally magnetically promote arc transfer movement from the main separable contacts into the plate structure for increased cooling and deionization effects.

Description

United States Patent 1191 Rexroad [451 July'3l, l973 I SPACED-METALLIC-PLATE-TYPE OF ARC-CHUTE FOR A SWITCH [75] Inventor: James O. Rexroad, Beaver, Pa.

[73] Assignee: Westinghouse Electric Corporation, Pittsburgh, Pa.

[22] Filed: Apr. 19, 19 71 .[21] Appl. No.: 135,107

[52] US. Cl.....'.. 200/146 R, 200/144 R, 200/147 R [51] Int. Cl. H0lh 33/12 [58] Field of Search 200/147 R, 146 R,

[56] 7 References Cited UNITED STATES PATENTS 2/1939 Baker 2001146 R 5/1970 Cellerini et al. 200/146 R Primary Examiner--R0bert S. Macon Attorney-A. T. Stratton, Clement L. McHale and Willard R. Crout [57] ABSTRACT An improved spaced metallic plate-type of arc chute construction is provided for a switch, in which the spaced metallic plate structure is in close proximity to both the main separable contacts, as well as to the separable arcing contacts. In one construction, the inner edges of the spaced metallic plates are generally parallel to the one, or several main contacts of the switch,

' with an elongated slot provided in the central portion of the plate structure to accommodate the protruding movable tip portion of thecentrally-located separable main arcing contacts.

In a modification of the spaced metallic plate arc chute structure, minor closed-end slots are, additionally, provided in the plate structure to tend to promote arc transfer movement from the separable main contacts into the spaced plate structure, to thereby provide additional cooling and .deionization effects.

In a third modification of the spaced metallic plate structure of the present invention, curved minor closed-end slots are provided adjacent the main separable contact structure to additionally magnetically promote arc transfer movement from the main separable contacts into the plate structure for increased cooling and deionization effects.

7 Claims, 12 Drawing Figures PAIENIED M3 1 I975 sum 1 or 5 INVENTOl-QSv James O. Rexrood FIG. I

f DM' ATTORNEY SPACED-METALLIC-PLATE-TYPE OF ARC-CHUTE FOR A SWITCH CROSS-REFERENCE TO RELATED APPLICATIONS scribes and claims an improved'operating mechanism 7 for an improved switch structure of high currentcarrying capacity, which switch effectively utilizes the improved arc-chute'structu'res of the present-invention".

BACKGROUND OF THE INVENTION D.C. and 600-voltA.C. application. Main switches and branch switches may be used together, the main switches, of course, carrying a greater load current. The particular switch application, with which the present application is concerned, is adapted for800, or lZOO-ampere current ratings, at a voltage, for example, of 600-volts A.C.

It is desirable, as well as known by those skilled in the art, to provide arc-chutes, which are highly effective in cooling and deionizing the established arcs to quickly bring about circuit interruption. The use of spaced metallic magnetic plates is, of course, well known in the art.

Reference may be had, for example, to the following United States Patents, all of whichhave been assigned to the assignee of the instant application, for a theoretical discussion of the magnetic movement of the arcs into the spaced metallic plate structure for effective arc extinction: Ellsworth et al. 3,071,666, issued Jan. 1, 1963; Cellerini 2,687,462, issued Aug. 24, 1954; Cel-' lerini 2,769,066, issued Oct. 30, 1956; Cellerini 2,707,218, issued Apr. 26, 1955; Cellerini 2,684,462, issued Aug. 24, 1954; Cellerini 2,654,012 issued Sept. 29, 1953; Kalaway 2,590,543, issued Mar. 25, 1952; and Bingenheimer et al. 2,551,822, issued May 8, 1951.

SUMMARY OF THE INVENTION According to a preferred embodiment of the present invention, there is provided an improved spaced metallic plate-type of arc-chute for a switch having a relatively high-ampere current-carrying capacity. Such a type of switch may have main separable contacts as well as separable arcing contacts. In a switch having main separable contacts as well as separable arcing contacts, the interruption of high currents can result in arcing on both the main separable contacts, as wellras on the separable arcing contacts.

1 have found that in a 1,200-.ampere switch, for example, the effect of arcing on the main separable contacts is kept within acceptable limits by applying an arcchute with a spaced metallic plate grid structure to help extinguish the arc. According to the improved arc chute structure of the present invention, the spaced metallic plates are provided in close proximity to the main separable contacts, as well as providing a centrally-provided slot portion in the plates to accommodate the protruding tip portion of the centrally-located main arcing contacts. In a modification of the present improved arc-chute structure, minor closed-end slots the separable contactswith the spaced metallicplates may, additionally, be provided at the inner corners of the plates adjacent the separable main contacts to promote and assist arc transfer into the spaced metallic plates for effective cooling and deionizing action. Thus, there is provided effective are extinction on both the main and arcing contacts. In the improved arc-chute structure of the present invention, the same grid plate structure functions for both the arcing on the main as well as arcing on the separable arcing contacts.

In .a modification of the present invention, curved closed-end minor slots are provided at the inner corners of the plates to expedite arc transfer fromthe main separable contacts intothe plate structure, as well as promoting the rapid transfer of the arc at the main separable arcing contacts.

Accordingly, it is a general object of the present invention to provide an improved arc-chute structure, which will effect a rapid deionization of the arcing, which is established at the main separable contacts, as well as at the arcing contacts during highcurrent interruption. I

Still a further object of the present invention is to provide an improved arc-chute structure, in which the spaced metallic plate structure is provided in close proximity to the main separable contacts.

I Still a further object of the present invention is the provision of an effective arc-chute, in which special configuration of the spaced plates is utilized to promote transfer of the arcs from the main separable contacts into the plate structure, by the use of one or more minor closed-end slots provided in inner corners of the plate structure, in addition to the main centrallyprovided slot for the accommodation of the protruding movable arcing contact.

Still a further object of the present invention is the provision of an improved arc-chute structure, which accommodates arcing at both the main and arcing sets of contacts on high-current interruption, and facilitates movement and transfer of the arcing into and through the spaced metallic plate structure.

Further objects and advantages willreadily become apparent upon reading the 'following specification taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS tops of the three pole-units, and showing a top plan view of the improved arc-chutes of the present invention, the contacts being illustrated in the fully opencircuit position; l

FIG. 3 is an enlarged top plan view of one of the arcchutes of "FIG. 2, illustrating the inter-relationship of x of the arc-chute, and showing the close proximity of platernaterial to the main separable contacts;

FIG. 4 is a view illustrating the position of the several contact parts, and also the mechanism parts in the fully open-circuit position;

FIG. 5 is a view similar to that of FIG. 4, but illustrating the closed position of the switch;

FIG. 6 illustrates, fragmentarily, a side elevational and partly sectional view taken through the improved arc-chute structure and the manner of arc interruption, with the contacts shown in the closed position;

FIG. 7 is a perspective view of the stationarycontact support plate, or terminal plate, together with the stationary arcing horn affixed thereto. The view also shows the stationary main contacts for the two pairs of movable main contacts;

FIG. 8 illustrates, in perspective, the fiber insulating enclosure or wrapper for positively positioning the several spaced metallic arc plates of the improved arc chute structure for the switch contacts;

FIG. 9 illustrates one of severalarcing metallic plates used in the arc-chute structure of the improved Switch;

FIG. 10 illustrates an alternate type of metallic arcing plate, which may be used in substitution of the arcing plate of FIG. 9; I

FIG. 11 illustrates, in plan, the top arcing, or cover plate of the arc-chute structure; and,

FIG. 12 illustrates another type of arcing plate, which may be used in substitution for the plates of FIGS. 9 and 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates panelboard equipment comprising, forexample, a main-line switch, generally designated by the reference numeral 2, and controlling a number of branch feeder switches, designated by the reference numerals 3-9. The branch feeder switches, designated by the reference numerals 3-9, are not a part of the present invention, but may be referred to in U.S. Pat. No. 3,525,835, issued Aug. 25, I970, to Alexander R. Norden, and US. Pat. application filed Dec. 12, I969, Ser. No. 889,804 (W.E. 41,480) by Alexander R. Norden, and also in the US. Pat. application filed Dec. 12, I969, Ser. No. 889,803, by Alexander R. Norden (WE. 41,481), all of the foregoing patents and applications being assigned to the assignee 0F the instant application.

The bus connections between the several switches are not illustrated in FIG. 1, but it may be assumed that the line-bus connections are controlled by the lowerdisposed main panelboard switch 2, which, through feeder-bus connections, are fed to the other branch switches 3-9, which may control various sub-branch circuits.

The improved switch construction 10 of the present invention is embodied in the main panelboard switch 2. FIGS. 2-6 illustrate, in detail, the construction and operation of the improved switch construction 10 of the present invention.

Referring again to FIG. 1 of the drawings, it will be observed that there is provided an external operating handle 11, which may be grasped by a station attendant, and physically rotated to the ON" and OFF" positions, as will be apparent from FIG. 1. The switch box enclosure 12 has a cover 13, which is hinged, as at 14, and may be opened or closed, a hasp 15 being provided. The cover 13 may, of course, be padlocked in the open" or closed" positions.

The rotation of the manually operable handle 11 effects, through a shank portion 1 la, the rotation of a rotatable plate 16 (FIG. 4), which has an offcenter pivotal connection 17 to a link 18, which operates a reciprocally-operable slide, designated by the reference numeral 19. The slide 19 is captive within four guides 20, as shown in FIG. 4, and may be reciprocally operated to effect the respective opening and closing operations of the switch mechanism 22.

As illustrated in FIGS. 4 and 5 of the drawings, it will be apparent that an overcenter-type toggle mechanism 22 is provided to effect the opening and closing move,

'C of the switch 10, as illustrated in more detail in FIG.

2 of the drawings.

Thus, with reference to FIGS. 4 and 5, it will be observed that the main arcing movable contact 25c ofeach'pole-unit is spring-biased in a counterclockwise direction about its pivot rod 31, so that when the switch 10 is closed, as illustrated in FIG. '5, the contactcompression spring 35, individual to each contact finger, is compressed. Also, the main contact finger 27, 28-

have their own individual compression springs 36, the upper ends of which seat within cupshaped spring holders 36a affixed to the movable contact support '33.

Briefly, the overcenter-type toggle mechanism 22, comprises a pair of pivotally-connected toggle links 37, 38, which, in fact, comprise pairs of links 37a,f38a. FIGS. 4 and 5 show only a

single toggle link

37 or 38,

but, in fact, there are two adjoining links 37a or 38a for each toggle-

leg

37 or 38, respectively.

As shown more clearly in FIG. 4 of the drawings, the toggle-leg 37, comprising the two links 37a, is pivotally connected to a pair of spaced operating brackets 40, which are affixed by mounting screws 41 to the insulating tie-bar 34. A pivot pin 42 extends through the rear portions of the operating brackets 40, and connects to the left-hand ends of the toggle-leg 37. The two .toggle links, or

legs

37, 38 are pivotally connected together to a knee-pin 44, which additionally serves as spring support for one end of each of two toggle-tension springs, designated by the reference numeral 46. The other ends of the two toggle-tension springs 46 are connected to a rod 48, which bears within slots 49 providedin the ends of legs 50b of angularly-shaped operatinglevers 50, which are pivotally-supported on stationary pivots 51. The stationary pivot-51, in fact, comprises a rivet, which extends through the sidewall53a of asideframe supp rt 53. I a

From the foregoing discussion, it will be apparent that rotation of the operating handle 11 will, through the linkage of 16-18, effect right-ward opening motion of the slide 19, which through the interposition of the side slots 19a, will carry the actuating rod 56 toward 7 the right, as viewed in FIG. 4, thereby carrying the anguIarly-shaped rotatable operating arms 50 and the right-hand ends of the toggle-tension springs 46 downwardly to the position illustrated in FIG. 4. The line of i action of the force, exerted by the two toggle-tension springs 46, moves below the toggle pivot 58, and thereby effects collapsing of the toggle-

legs

37, 38 to the position illustrated in FIG. 4, thus opening the

switch contacts

24, 25. I

Similarly, to effect closing operation of the switch 10, rotation of the operating handlel 1 will move the actupoint 58, thereby closing the

switch contacts

24, 25, as

' illustrated in FIG. 5.

ating slide 19 toward the left, carrying the upper ends 50a of the angularly-shaped arms 50 toward the left,- and also moving the line of force of the toggle springs 46 upwardly over the'toggle pivot 58 toeffect a straightening of the

toggle legs

37, 38, thereby closing the

switchcontacts

24, 25, as illustrated in FIG. 5.

FIG. 2 illustrates, in more detail, the structural frame A rotatable releasable toggle pivot support,or trigger 65 is provided. A rod 66 passes through the tubular sleeve 67, which is affixed to the central main body portion of the rotatable toggle pivot support, or'trig'ger 65. The pivot rod 66 passes through suitably-provided apertures in the side walls of the side-frame supports 53, 54. It will be observed in FIG. 2 that the knee-pin 44 of the toggle linkage 39 has extended portions 44a,

which serve as the left-hand spring-supports for the two toggle-tension springs 46. Again, FIG. 2 illustrates this more clearly. a

In the closedposition of the

switch contacts

24, 25, wherein the

toggle legs

37, 38 are straightened,'it will be observed that a portion b of the body portion of the rotatable toggle support 65 serves as an overcenter stop. This posisiton is illustrated more clearly in FIG. 5 of the drawings. Additionally,- another portion 650 of the rotatable toggle support 65 serves a resetting function. Thus, for remote electrical tripping, an electrically-actuated tripping lever is provided, of channelshaped configuration, having a 'roller 72 passing through one end theereof. The tripping lever 70 is piv-v otally mounted on a rod 69 journaled in apertures of the frame 60. This roller 72 normally maintains the toggle support 65 in a fixed latched position, as shown in FIGS. 4 and 5. Following energization of the solenoid 73, the latching lever 70 is released to thereby permit the toggle springs 46 to effect a counterclockwise rotation of the toggle support 65. In this position, the

switch contacts

24,25 are, of course, open. To effect a resetting and a subsequent closing operation of the

switch contacts

24, 25, the oerating' handle 11 is moved toward 'a fully-open position, as shown in FIG. 4. This forcibly causes interengagement between the rod 48, carrying the right-hand ends of the toggle-tension springs 46,'against the resetting portion 65c .of the body portion of the rotatable toggle-pivot 65, and carries the rotatable toggle-pivot 58 about its fixed pivot point 66,

as shown in FIG. 5, to its reset position, as illustrated in FIGS. 4 and 5 of the drawings, l

j Following the resetting of the rotatble toggle-pivot 58, the operator may, at this time, move the operating handle 11 toward the closed-switch position, which, as previously described, carries the line of action of the toggle springs 46 upwardly across" the toggle-pivot In will be observed from a study of FIG. 2 of the drawings that each of the pole-units A, B and C has its -

own fuse

82A, 82B and 82C. The

fuses

82A, 82B and 82C may be of l,200-amperes, 600-volts A.C., for example. Thus, the fuses provide fault, or overcurrent protection for the switch.

By way of recapitulation, the three line connectors, L1, L2 and L3, affixed to the three

line contact plates

84, 85 and 86, pass the current through the stationary 7 main and movable main contacts 24a,2 4b and 25a, 25bto the shunt connectors .88 to the movable-contactsup-'

port plates

90, 91 and 92. As observed in FIG. 2, the moving

contact support plates

90, 91 and 92 have extensions, constituting fuse-terminal plates a, 91a and 92a, which are secured by bolts 94 to the blades 95 of the

fuses

82A, 82B and 82C. The current, consequently, passes through the fuses, and through the other fuse blades, which are bolted to the fuse contact bases, or terminals A, 1008 and 100C. Situated at the right-hand ends of the three

fuse contact bases

100A, 100B and 100C, as viewed in FIG. 2, are the load-terminal connectors F,, F and F which may connect to the branch circuits controlled by the branch switches 3-9, as illustrated in FIG. 1.

ARC-CHUTE STRUCTURES 102) FIGS. 2, 3 and 6 illustrate, in more detail, the arcchute structures 102, which are associated with each pair of

separable switch contacts

24, 25. As previously mentioned, the stationary contact structure comprises stationary main contact plates 24a, 24b (FIG. 7), and an upwardly-protruding stationary arcing contact 240, which overlies an arc-horn plate 24d. During the opening operation, arcing may take place between both the main contacts 24a, 24b and also the arcing contacts 24c. The arc-chute structure 102 is adapted to accomplates 104 closely surrounds the extending tip 25c of the movable arcing contact 25c (FIG. 6). Thus, arcing is accommodated at both the main contacts and also at the separable arcing contacts. It is an established test fact that a plurality of shutning arcs 107, 108, (FIG. 7) may be established, both at the main contacts and also at the arcing contacts. The provission of the body portions, designated by the reference numeral 104a, 10% in FIG. 9, provides anentrance for the arcs 107, 109

established at the main contacts 24a, 24b. These arcs 107, 109 are split upv into a plurality of serially-related arcsbetween the plates 104, and are cooled anddeion ized'until arc extinction ensues. V t 3 Alternate arcing plates 11], 112, such as illustrated in FIGS. 10 and 12, may be substituted for the arcing plates 104 of FIG. 9 in the lower portion of the arcchute stack 102. This will facilitate thpe transfer and entrance of the main arcs 107, 109 from the main contacts 24a, 24b into the plate structure. i I

In more detail, plate 104 was developed because of arcing on the main contacts and proved to be all right for normal use of the switch, but not for generalapplication with a shunt trip. There is a range of current values, for which the arc will develop in the corners 104e, 104d, and in using the plate 104, the arc stayed in the corners 104e, 104d. To avoid this difficulty, the meta1 lic plate, designated by the reference numeral 111, and illustrated in FIG. 10, was developed to get the arc to move out of the corners due to the magnetic forces. The moving arc would cool more, and thus the interrupting ability of the switch, as a whole, would be enhanced. It was found by test that a set of arc chutes 102 with the plates modified by the use of plates 11! was tested, and interrupted, whereas the standard plates I04 had failed in previous tests. The arcs were found to move away from the corners of the plate.

From the foregoing description, it will be apparent that there has been provided improved arc-chute structures, in which by the use of spaced-plate metallic material, close to the main separable arcing contacts an improved deionization effect has been achieved. In addition, by the use of minor slots Illa, 111b, 112a, ll2b in thee plate structure, the promotion and transfer of the arcs from the main separable contacts into the plate structure has been encouraged.

Although there has been illustrated and described various embodiments of the invention, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

I claim:

1. A switch structure including a pair of separable arcing contacts and two pairs of main contacts situated on both sides of said separable pair of arcing contacts, means establishing three arcs at both the two pairs of separable main and also at the separable arcing contacts, means defining a spaced metallic plate structure closely confining the separable arcing contacts as well .as confining the two pairs of main contacts, whereby the three parallel arcs are moved into the plate structure for arc-extinction purposes. 7 2. The combination according to claim 1, wherein a centrally-arranged main arcing slot is provided to accommodate the separable arcing contacts, the latter protruding into the plate structure.

3. The combination according to claim 1, wherein minor slots are provided in-the spaced plates adjacent the two pairs of separable main contacts to encourage v arc movement into'the plate structure from the two the plates have outer leg portions and centrallyprovided notches, and additionally the plate structure has minor notches provided in the inner side comers of the plates to prevent arc termination at the corners, and instead to promote arc movement away from the said inner corners of the plates.

7. The combination to claim 6, wherein the minor notches are curved.

Claims

1. A switch structure including a pair of separable arcing contacts and two pairs of main contacts situated on both sides of said separable pair of arcing contacts, means establishing three arcs at both the two pairs of separable main and also at the separable arcing contacts, means defining a spaced metallic plate structure closely confining the separable arcing contacts as well as confining the two pairs of main contacts, whereby the three parallel arcs are moved into the plate structure for arcextinction purposes.

2. The combination according to claim 1, wherein a centrally-arranged main arcing slot is provided to accommodate the separable arcing contacts, the latter protruding into the plate structure.

3. The combination according to claim 1, wherein minor slots are provided in the spaced plates adjacent the two pairs of separable main contacts to encourage arc movement into the plate structure from the two pairs of separable main contacts.

4. The combination according to claim 1, wherein curved minor slots are additionally provided in the plate structure adjacent the two pairs of separable main contacts to encourage arc movement into the plate structure.

5. The combination according to claim 2, wherein additional minor slots are provided in the spaced plates adjacent the two pairs of main contacts to encourage arc movement from the three pairs of separable contacts into the plate structure.

6. The combination according to claim 1, wherein the plates have outer leg portions and centrally-provided notches, and additionally the plate structure has minor notches provided in the inner side corners of the plates to prevent arc termination at the corners, and instead to promote arc movement away from the said inner corners of the plates.

7. The combination to claim 6, wherein the minor notches are curved.