US2338715A - Arc splitting plate - Google Patents

Description

Jan. 1 1344- H. c. GRAVES, JR

ARC SPLITTING PLATE Filed March 20, 1941 4 Sheets-Sheet 1 IN VE N TOR 'H'arfierfi C. afi' BY ,lfi

ATTORNEY.

1944- H. c. GRAVES, JR

ARC SPLITTING PLATE Filed March 20, 1941 4 Sheets-Sheet 2 F 20 jambqza FIC5.2.

INVENTORJ Merl C. rat e5, f BY 61.! M ATTORNEY.

Jan. 11, 1944. C R-,;VE ,JR 2,338,715

ARC SPLITTING PLATE Filed March 20, 1941 v 4 Sheets-Sheet 3 ATTORNEY.

Patented Jan. 11, 1944 UNITED STATES PATENT OFFICE ortol.

T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 20, 1941, Serial No. 384,245

12 Claims.

This invention relates to circuit interrupting apparatus and are quenching means therefor, and more particularly to an arc quencher having a series of parallel plates so arranged that the arc may be forced longitudinally between them for extinguishment.

The type of apparatus involved includes power switching equipment that may be required automatically to interrupt fault currents of great magnitude. These arcing currents. unless extinguished quickly, will seriously damage metallicparts with which they come in contact.

Further, the type of power-switching apparatus to which this invention may be applied is frequently enclosed in compact metallic cubicles as a protection for the operator and the surrounding apparatus.

It is important, in connection with apparatus of this type, that the are, which may be drawn between the contacts when they are open, be rapidly extinguished. Accordingly. my invention provides for an arc quenching device, consisting preferably of plates of insulating material emitting little or no gas or vapor when in contact with an are, between which the ionized gases forming the arc are squeezed and brought into intimate contact with cooling surfaces which thus serve to de-ionize the gases to extinguish the arc.

An important object of the present invention, therefore, is the arrangement of an arc quencher having a series of parallel plates in such a manner that the arc may be forced longitudinally between them for the de-ionization of the gases and theextinguishment of the arc.

There are other objects and uses of the present invention and of the combinations and elements herein set forth. Many of these will in part be apparent and, where this is not the case, they will be pointed out in the following description and drawings, in which:

Figure 1 is a side elevation of the circuit breaker of my invention.

Figure 2 is a front view of the circuit breaker arrangement of Figure 1.

Figure 3 is a cross-sectional view on line 3-3 of Figure 2 showing the circuit breaker in closed circuit position, and showing slightly modified spacing washers,

Figure 4 is a view corresponding to that of Figure 3 showing the circuit breaker in open circuit position.

Figure 5 is a cross-sectional view on line 5-5 of Figure 4 showing the arrangement of the arc quencher.

Figure 6 is an end view taken along line 6-6 of Figure 4 showing a slight modification of the structure of the arc quencher.

' Figures 7, 8 and 9 are cross-sectional views, each corresponding to the cross-sectional view of Figure 5 but showing variations in the number of parallel spaced plates in the arc quencher and in the arrangement thereof.

Figure 10 is a cross-sectional view of the arc quencher showing the slightly modified form of Figure 6 and taken along line I0|0 of Figure 1.

Referring now to the figures, I have here shown a three-pole circuit interrupter having a plurality of arc chutes I50, each comprising side plates Iii which support a plurality of shorter spaced parallel plates I52; the lower edges of each of which are curved to form the downwardly depending cusps I92,

Since the function of the arc chute is the rapid extinguishment of an are drawn between the contacts of a circuit interrupter, the structure and operation thereof can best be understood from a preliminary description of the relevant portions of a type of interrupter in connection with which the same may be used.

In Figures 1 to 4, I have shown a circuit interrupter having the pole units 20. 2| and 22 mounted on the face of an insulating panel 23.

The bracket which supports the operating members is secured to the panel 23 by means of screws 25 and comprises two flanged side plates 28 and 29 which extend on each side of a horizontal shelf 30 to which they are welded. The operating mechanism 3|, comprising the toggles and other elements, is bolted to the lower side of the shelf 30. Link 34 connects the operating mechanism 3| to the lever 35 which is secured to the shaft and is rotatable therewith.

The stationary contacts 36 and their back connection stud assembly are mounted on the panel above the bracket 24 and support the inner ends of the arc chutes in the manner hereinafter described. A bridge 31 of insulating material secured to the outer end of the bracket 24 supports the outer end of the arc chutes.

The stationary main contacts 36 are bolted to the connecting stud 42 which passes through the panel 13. The path of the main current when the contacts are closed (Figure 3) is through the connection stud 42, the stationary contact 36, the stationary contact tip 40, the movable contact tip 4| mounted on the contact lever which carries the flexible connection 43, the opposite end of which is connected to the member 44.

The movable contact lever is pivotal about the pin 53 on the contact carrying arm 48 which is secured by the clamp to the rotatable shaft 45. The lever 60 is resiliently secured to the arm 48 by the link 68 extending through the perforation 61 of the arm, and by the spring 89 mounted on the link and compressed between the recess 68 of the arm and the cup I0 on the end of the link.

' When the main contacts are disengaged (Figure 4) the lower end I2 0! the main contact lever 80 presses against the contact arm 48 in the manner shown. As the contacts are engaged,

then end I2 of the lever is forced away from the arm 48 (Figure 3) and contact pressure is obtained by compression of spring 59.

The arcing contact members 81 are mounted in the upper part of the contact arm 48 and are supported by arcing contact levers 15 which pivot on pin I8. A second pin I8 is mounted in the top of the contact arm 48 between two upwardly extending flanges 19 thereof. Link BI is connected to pin I8 and extends beyond the back of the arcing contact levers I5. Spring 84 is compressed between spring cup 85 on the free end of the link 8| and sliding spring cup 83 which is pressed against the back of the lever.

The lower end of the arcing contact lever 15 is oil-set to receive the end of a flexible conductor 03 which is connected to the terminal block 44.

The flexible lead I00 from the arcing horn I80 herinai'ter described is also connected to the terminal block 44. It will thus be seen that the three flexible conductors I00, 93 and 43 are all led from the contact structure to the lower terminal 44 to which all three are or may be secured by the same screws and lock washers.

The lower terminal or pigtai1" posts may have connected thereto a terminal of coil IIO which may energize an over-current magnet, the opposite end of the coil being connected at II2 to the back connection stud I I I.

Since the leads 43, 33 and I00 are each thus connected to the pigtail post 44, the over-current coil I I0' will thus be in series with the main contacts: and, after these are opened, with the arcing contacts: and finally with the arcing horns.

When the circuit breaker is fully closed, the resistance of the circuit through the main contacts 38 and 60 is low as compared with the resistance through the arcing circuit so that a relatively small current flows through the latter.

The movable arcing contact 88 (when the arcing contacts are engaged and the main contacts are notengaged) engages the stationary arcing contact I2I. Current is led to the stationary arcing contact I2I through the blow-out coil in the following manner:

Current from the upper'connection stud 42 flows into the lower terminal block I25 of the blow out magnet coil I22 around the coil to its upper terminal I29 and thence to the stationary arcing horn I23 which is secured thereto. From the stationary arcing horn, the current flows to the stationary arcing contact I2I, thence to the movable arcing contact 88, thence through the arcing contact lever 15, flexible lead 93,-the ter minal block 44, the coil H0, and the connection stud III in the manner hereinbefore described.

The coil I22 is wound so that current flowing from the lower coil terminal to the upper coil terminal flows around the slotted cylindrical iron core I30 in a clockwise direction in the views of Figures 3 and 4. A fiber tube I 3I insulates the core I30 from the coil I22.

The upper part I38 of the arcing horn I23 is extended along the panel and forms a hook I39 for anchoring the arc chute in the manner hereinafter described.

The arcing horn I23 curves around the blowout coil as seen in Figures 3 and 4, and forms a path for one of the arc terminals. The arcing horn is preferably wider than the coil I22 and as seen in Figures 3 and 4, its under surface rests against the edges of insulating side plates I32 which extend on either side of the coil I22.

In the actual operation of the contact assemblies, when the contacts are fully closed and the breaker is then tripped, the contact shaft 45 and the contact arm 48 rotate in a counterclockwise direction in the views of Figures 3 and 4. As the arm and the contact pivot pins I8 and 63 move away from the stationary contacts, the springs 89 and maintain the moving contacts in engagement with the stationary contacts until in the rotation of the contact levers, these levers I5 and 60 strike their respective stops.

During this movement, the lower end 12 of the contact lever 60 strikes the part of the contact arm 48 which surrounds the shaft 45. At this point in the movement, the main contacts separate while the arcing contacts are still engaged. It is thus seen that the circuit through the main contacts is interrupted and all the current is transferred to the circuit of the blow-out coil I22 and the arcing contacts. The core I30 therefore and its associated pole pieces are magnetized in proportion to the current flowing.

When the arcing contacts are fully opened, the end of the arc is transferred from the movable arcing contact to the arcing horn and the arc is drawn between the horn I60 and the termina1 I23.

The are chute The are chute I50 comprises side plates l5I and five shorter parallel spaced arc splitting plates I52. Both the side plates and the arc splitters are of arc resistantinsulating material. The entire group is held together preferably by rivets I53, I53, ill, I" making a rigid assembly. Preferably, the rivets comprise, as seen in Figure 5, a central metal tube-like part I54 and'carry insulating spacing washers I55 which space the arc splitting plates.

The portions of the inside plates I52 near the panel 23 (Figures 4 and 5) are separated by members I56 of insulating material which prevent the arc gases from coming in contact with the panel and which also comprise hooks I51 engaging under the hook or lip I39 of the stationary arcing horn I23 in order to assist in supporting the arc quencher assembly. Near the front of the arc chute is secured a metal arcing horn I60 which is connected to metal angle clip IBI, by the screw 1I162 passing through the flange I63 of the arcing As seen in Figures 6 and 10 the mounting hole I'IIa of arcing horn I 60 may be counterbored over size and additional insulating bushings I 'I'Ib may be used for spacing the arc horn from the side walls of the-arc quencher. This serve to increase the leakage distance between the arcing horns.

As is seen in the slightly modified form of Fig. 3, instead of using spacing washers I55 to space the plates of the arc quencher of Fig. 3, from each other, a series of strips I55a or I55b of insulating material extending out radiall from the rivets may be used. These strip may be streamlined as shown to afford minimum resistance to th flow of arc gases, and serve as crossbarriers to restrict the movements of spaced parts of any are that may have been moved this distance from the arcing horns.

The metallic clip I8I is secured by the screw I54 and lock washer I55-to the bridge 31 of molded insulating material. This metallic clip I6I is electrically connected to the flexible conductor I which in turn connects it to the lower pigtail terminal 44. At the end of the opening movement of the arcing contact the tip 81 of the movable arcing contact 81 moves under the stationary arcing horn I80 in the manner shown in Figure 4 so that the arc terminal is transferred to the stationary arcing horn I50 and the current flows through the conductor I00 to the lower terminal block ll.

The blow-out core I30 extends beyond the sides of the blow-out coil I22 a distanc equal to the thickness of the side plates I I The side plates are notched at I (Figure 1) so that they may embrace the core I30 while their edges rest against the panel 23. The inner surfaces of the magnetic poles I18 bear against the ends of the core. By this arrangement, any possible impediment to the flow of magnetic fluxe from the core into the pole pieces hereinafter described is obviated.

Ferrous blow-out plates or pole pieces I18 (Figs. 1, 2 and 5) are secured to the outer surfaces of the side plates I5I of the arc chute by means of rivets or other suitable attaching means I11. These blow-out plates .orpole pieces (see Fi 1) cover a part of th notch I15 in the plates I5I s that when the arc chutes are in position against the panel 23 and in proper relation to the contact assembly, the surface of each end of the core I30 is in contact with a corresponding iron blow-out plate or pole piece I18. The rivets for securing the iron plates to the arc chute are relatively remote from the blow-out core so that a slight spring of the plates may be used to assure intimate contact. The edges of the iron are flared slightly to provide for easy engagement.

The notch I15 which engages the blow-out coil core I30 (Fig. 1) and the lip I33 on the stationary arcing con'tact I23 which engages the hook I51 of the fiber spacer I55 of the arc chute I50 (Fig. 3) cooperate to position the back end of th arc chute in proper relation to the panel, 23 and to the various other portions of the contact assembly.

The front end of the arc quencher is supported and locked in place by means of the screw I62 which passes through the angle clip I8I and the end I63 of the arcing horn I50. The angle clip IGI is secured to the insulating bridge 31 by screws-I64.

Rotation of the screw I82 will permit the with- --"d rawal of the entire arc chute from the contact assembly without requiring the disassembly of any other portion of the circuit breaker. The

' movement of withdrawal is entirelyhorizontal,

no vertical motion being required.

The are splitting plates I52 (five in number in the preferred embodiment) have, as seen in Figs. 3 and 4, their lower edges shaped in two concave arcs I90 and HM, with the rounded cusp I92 between them. This cusp lies between the stationary arcing horn I23 and the front arcing horn I80. The downwardly extending cusps I facilitate the entrance of the are into the slots between the plates and are so arranged that a relatively small longitudinal length of the arc is first forced between the plates and o that as the arc is blown upwardly, progressively greater lengths of the arc are forced between the plates. I

As is also seen in Figs. 3, 4 and 5, the lower edges of the plates I52 are of different heights, the middle one I52a being the highest and the outer plates I520 being the lowest, that is, ex tending downwardly a greater distance. The intermediate plates I52b are of a height so that the lower edges extend in planes substantially between the position of the edges of the middle and outer members.

As is also seen in Figs. 3 and 4, the five plates here shown have perforations I95 of suitable size and shape, spaced and arranged to permit the flow of arc gases from the slot I08 (Fig. 5) between One pair of plates to the slot between another. In order to provide a more turbulent condition of the arc gases and in order to ensure contact of the arc gases with the various plates, the holes or perforations I95 of each of the plates may be in staggered relation with respect to those in adjacent plates.

Upon opening of the main contacts and formation of the are between the arcing contacts 14 and I23, the arc is immediately transferred from the arcing tip 81 to the arcing horn I80.

Th current flowing through the coil I33 energizes the magnet comprising core I30 and ferrous plates I15 producing a flux across the arc space. This flux forces the arc upwards towards and into the arc chute I50. ;When the arc reaches the lower edges of the arc splitters or plates I52. it is squeezed or flattened to be forced between the two outer plates I520 and I520. Further movement forces the arc between the intermediate plates I52-b--I52b further reducing its horii zontal width. i

As the arc is pushed further, it may enter one of the slots I88 or it may be divided longitudi-v nally in two or more slots. In either case, the arc gases have an opportunity to expand through the holes I35 in the plates I52. This provision iorpermitting the arc gases to expand from slot to slot reduces the back pressure and hence permits the blow-out magnet to force the arc upward at full speed.

The tendency of the ionized gases discharged from one slot to enter another through the perforations I permits parallel aims to exist over sections of the arc. This causes greater instability and increased tendency to speed the extinquenched within 1/120 of a second of the formation thereof.

The construction and operation of th arc quencher is not limited to the particular form of arc quencher shown in Figures 1 to 5 inclusive, or to the particular number of plates therein shown, but as is seen in Figures '1, 8 and 9, any number of plates may be used. Thus the arc quencher I50a oi- Figure 7 has seven spaced plates I52, each of which vary in height in the manner therein shown. This provides for a progressive squeezing of the arc and a probable separation thereof into at least two parallel arcs. Or, as is seen in Figure 8, the arc quencher I501) therein shown may have as little as four or fewer spaced parallel plates I52" which will operate in the manner hereinabove described. Or as is seen in Figure 9, the arc quencher I500 therein shown may have nine spaced parallel plates l52, consisting of two sets each of which is arranged and function in the same manner as the single set of plates as shown in Figure 5.

This arrangement ensures the breaking up of the are into at least a pair of parallel arcs and probably into a greater number of unstable parallel arcs.

Sufiicient interphase barriers are provided by the side plates l5l of the arc chute. However,

additional interphase barrier plates I45 (Figures 1 to 4 inclusive) may be placed between the arc chutes and carried up so that they are aligned with the top of the panel 23.

As will also be seen in Figure l, the inter-phase barrier I45 extends beyond the arc chute both at the top and the front. The front lower corner rests on the insulation bridge 31 while the back end bears against the panel and extends down between the shaft insulation disks |43--I43.

Lower interphase barriers llllla (Figure 1) may be aligned with the upper interphase barriers and secured to the panel 23 by screws Mia and H121; thus preventing any tendency of the flexible leads to approach each other or any current at that point from arcing over.

The arrangement of all of the parts of the circuit breaker is such that the assembly thereof is extremely simple:

The entire arc quencher I50 including the arcing horn I60 may be removed from the circuit breaker assembly by a single movement after the rotation of a single screw I 62.

The removal of screw 201 permits the interphase barrier to be withdrawn. These operations expose the whole contact structure for inspection.

Assembly replacement and repair are thus greatly facilitated. Separation of the various parts for any purpose whatever is made easy and simple and the general arrangement of the members on the panel 23 facilitates the mounting of thi panel in a switch board with other similar circuit breakers or other switch devices.

In the foregoing, I have described only those parts of the circuit breaker necessary to fully understand the operation of the arc quencher and the arc-splitting plates. The various constructions herein described may be modified in many ways which will now be obvious to those skilled in the art.

I claim:

1. In an electrical switching apparatu a fixed and cooperating movable contact; a stationary arcing horn; a front arcing horn; a plurality of arc extinguishing plates mounted between said arcing horns, the lower edges of said plates forming two concave arcs with a rounded cusp between the ends, said cusp lying between said arcing horns.

2. In an electrical switching apparatus, a fixed and cooperating movable contact; a stationary arcing horn; a front arcing horn; a plurality of arc extinguishing plates mounted between said arcing horns, the lower edges of said plates forming edges curved upwardly from the center toward the arcing horns to form a central cusp therebetween.

3. In a circuit interrupter, a stationary contact and a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn associ-- ated with said stationary contact and in electrical communication therewith, a stationary arcing horn as ociated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheets of insulating material enclosing said contacts and said arcing horns, a plate of insulating material supported between said sheets parallel thereto, the boundary of said plate toward said arcing horns having a form approximating that of said arcing horns.

4. In a circuit interrupter, a stationary contact and a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn associated with said stationary contact and in electrical communication therewith, a stationary arcing horn associated with aid movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheets of insulating material enclosing said contacts and said arcing horns, a plate of insulating material supported between said heets parallel thereto, the boundary of said plate toward said arcing horns having a form approximating that of said arcing horns, the distance between said boundary and said horns being greater near said contacts and at any point remote from said contacts.

5. In a circuit interrupter, a stationary contactand a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn associated with said stationary contact and in electrical communication therewith, a stationary arcing horn associated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheets of insulating material enclosing said contacts and said arcing horns, a plurality of spaced plates of insulating material supported between said sheets parallel thereto, the boundary of each of said plates toward said arcing horns having a form approximating that of said arcing horns.

6. In a circuit interrupter, a stationary contact and a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn associated with said stationary contact and in electrical communication therewith, a stationary arcing horn associated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheets of insulating material enclosing said contacts and said arcing horns, a plurality of spaced plates of insulating material supported between said sheets parallel thereto, the boundary of each of said plates toward said arcing horns having a form approximating that of said arcing horns, the boundaries of said plates toward said arcing horns being at different distances therefrom.

7. ma circuit interrupter, a stationary contact and a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn assoaassms ciated with said stationary contact and in electrical communication therewith, a stationary I arcing horn associatedv with said movable contheir boundaries at a lesser distance from said arcing horns than said middle plate.

8. In a circuit interrupter, a stationary con-,- tact and a movable contact, magnetic means for moving an are drawn between said contacts away from its initial position, an arcing horn associated with said stationary contact and in elec trical communication therewith, a stationary arcing horn associated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheetsof insulating material enclosing said contacts and said arcing horns, a plurality of spaced plates of insulating material supported between said sheets parallel thereto, the boundary of each of said plates toward said arcing horns having a form approximating that of said arcing horns, said plates extending in planes parallel to the axis of the arc, the free edges of said plates being stepped with relation to each other, the edges of the outermost plates being closest to thearc path, the edges or the remaining plates being progressively raised from the arc path, and the edge of the central plate being furthest removed from the arc path.

9. In a circuit interrupter, a stationary contact and a movable contact, magnetic means for moving an arc drawn between said contacts away from its initial position, an arcing horn associated with said stationary contact and in electrical communication therewith, a stationary arcing horn associated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact tosaid associated arcing horn, an arc chute comprising two sheets 0! insulating material enclosing said contacts and said arcini horns, a plurality of groups of spaced plates of insulating. material supported between said sheets parallel thereto, the boundary of each of said plates toward said arcing horns having a form approximating that of .said arcing horns.

10. In a circuit interrupter, a stationary con-' tact and a movable contact, magnetic means for moving an. arc drawn between said contacts away from its initial positon, an arcing horn associated with said stationary contact and in electrical communication therewith, a stationary arcing horn associated with said movable contact and in electrical communication therewith, means for transferring an arc terminal from said moving contact to said associated arcing horn, an arc chute comprising two sheets of insulating material enclosing said contacts and said arcing horns, a plurality of spaced plates of insulating material supported between said sheets parallel thereto, the boundary of each of said plates toward said arcing horns having a form approximating that 01. said arcing horns, said stationary arcing horn being in electrical communication with said movable contact and rigidly supported between said enclosing sheets in spaced relation thereto,

11. In electrical, switching apparatus, a pair of contacts, a plurality of spaced plates of insulatingmaterial in parallel planes, said plates being at least three in number, the lower edges of each of said plates being in stepped relation at progressively greater distances from the contacts; means for drawing an are between the contacts, means for moving said are in a plane parallel to those of the plates and causing said are to enter the space between adjacent plates.

12. In electrical switching apparatus, a pair of contacts, a plurality of spaced plates of insulating material in parallel planes, said plates being at least three in number, the lower edges of each of said plates being in stepped relation at progressively greater distances from the contacts; and an additional plate adjacent the plate most remote from the contacts and having its lower edge less remote therefrom, means for drawing an are between the contacts, means for moving said are in a plane parallel to those oi the plates and causing said are to enter the space between adjacent plates. I

HERBERT C. GRAVES, Ja.

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