US2285316A - Switch construction - Google Patents

Description

June 1942- H. A. TRIPLETT ETAL 2,285,316

SWITCH CONSTRUCTION Filed July 10, 1940 2 Sheets-Shet l wsum T/O/V Va 1/37 fave/$0219: {/qg/z 1% 2229mm zgum [Landau Hit/ 5 Patented June 2, 1942 SWITCH CONSTRUCTION Hugh A. Triplett, Wilmette, and Sigurd I. Lindell, Chicago, 111., assignors to Schweitzer & Conrad,

Inc., Chicago, 111.,

a corporation of Delaware Application July 10, 1940, Serial No. 344,688

22 Claims.

This invention relates, generally, to electric switches, and it has particular relation to switches adapted to interrupt the normal load current that flows in a relatively high voltage circuit such as a circuit energized at a voltage of 2300 volts and upward.

An object or" this invention is to provide means for breaking up the arc, formed between a pair of switch members when they are separated, into a number of short arcs in order to interrupt current flow in an electric circuit in a new and im proved manner.

Another object of this inventicn'is to cause the short arcs to be formed between metallic plates.

A further object of this invention is to confine the small arcs between the plates.

It is another object or this invention to provide for drawing two arcs in series in interrupting current flow in an electric circuit and. for breaking up each are into a number of short arcs.

Other objects of ti?" uvention will, in part, be obvious and in part appear hereinafter.

For a more complete understanding of the nature and scope of this invention, reference may be had to the following detailed description to= gethcr with the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view of the principal parts illustrating one embodiment of this invention, the switch being shown in the circuit closed position;

Figure 2 is a view, similar to Figure l, but showing one of the switch members in elevation and the switch mcmbersin the relative positions.

which they occupy while the circuit is being opened therethrough;

Figure 3 is a view in side elevation showing how the stack of metallic plates, illustrated in Figures 1 and 2, can be stationarily mounted;

Figure 4 is a plan view showing the relative locations of the metallic plates and insulating rings; and

Figure 5 is a longitudinal sectional view of anotier embodiment of the invention.

Referring now particularly to Figure 1 of the drawings, it will be observed that the reference characters in and H designate, generally, relativcly movable switch members. Each of the switch members in and H is arlanged to be connectcd to one terminal of an electric circuit in which current normally flows and which current it is intended shall be interrupted on movement apart of the switch members and l l with an are being drawn therebetween. Either of the switch members 10 or 1! may be stationary and the other movable, or both of them may be arranged for movement. As will hereinafter appear, in the embodiment shown herein, the switch member 16 is stationary and the switch member ii is movable.

The switch member it comprises a stack of metallic plates 12 in the form of washers which are spaced apart by insulating rings 13. The plates or washers 52 may be formed of any suitable conducting material, such as brass, while the insulating rings 53 are formed of suitable in-= sulating material such as fiber or Bakelite. Obviously, other materials can be employed if desired.

As shown in Figure 4, are located about the outer periphery of the metallic plates or washers l2, and the latter are stacked so as to provide a generaly cylindrical opening i l therethrough for receiving the switch member H which is generally cylindrical in shape.

Referring again to Figure l of the drawings, it will be noted that the arrangement of the insulating rings 13 is such that radial arc gaps it are provided therebetween which open inwardly into the cylindrical space M in which the switch member it moves. This construction is important, as will hereinafter appear.

During the circuit opening operation, or during relative movement apart of the switch members it and ii, relatively short arcs i6, Figure 2, are formed between adjacent plates or washers i2. By breaking up the single arc which would otherwise be formed between the switch members Ill and it into a number of short arcs between. the plates or washers it, it is much easier to extinguish the are formed which is incident to the circuit opening operation.

The means for stationarily mounting the switch member 113 are illustrated in Figure 3 of the drawings. It will be noted that the stack of metallic plates or washers l2, spaced apart by the insulating rings 13, is mounted between end bracket members 11, which may be generally rectangular in shape and which have oppositely turned ends for receiving screws 18 for mounting them on a suitable insulating support IS. The end bracket members I! are formed of suitable metal, such as brass, and are held in proper relation with respect to each other by insulating spacers 20 and are secured thereto by means of screws 21. A terminal 22 may be secured to the under side of the lower end bracket 11 for carrying a conductor 23 which is connected to one the rings 53 of insulation position, as shown in Figure three Sides by terminal of the electric circuit in which the switch is connected.

The switch member II, Figure 1, comprises a base portion 26 that is formed of suitable metal, such as brass, which has depending therefrom contact fingers 21 .each having a projecting portion 28 for engaging the inner sulation. A conductor 32 is secured by means a bolt 33 to the base member 25, and it extends out of an opening 34 in the side wall of the tube 29 for connection to another circuit terminal.

It will be understood that, when the switch members It and H occupy the switch closed 1 of the drawings, the switch member I I is connected through contact fingers 21 to the end plate or washer I2 periphery of the metallic plates or washers I2 when the switch With a view to closing the open side of the a air gaps I5 between the plates or washers I2, a generally cylindrical trailer 35 is provided. The trailer 35 is formed of insulating material, such as fiber, which is capable-oi evolving a gaseous medius, i. e. water vapor, when exposed to the heat of an electric are. This vapor tends to repel the arcs I6 drawn in proximity to the surface of the trailer 35 thereby causing them to be confined in the spaces or air gaps I5. This vapor also assists in the. extinction of the arcts. The insulating trailer 35 may be in the form of a tube which is secured at its upper end by screws 36 to a metallic adapter plate 31 through which the bolt 33 projects and which serves to hold tube 35 in place so that it moves conjointly with the switch member II. The outer diameter of the insulating trailer 35 is such that a minimum of space is provided between its outer periphery and the inner periphery of the plates or washers I2. When the insulating rings I3 are formed of fiber or like material, they will contribute which is directly connected to one terminal of an' electric circuit, the other terminal of the circuit being connected to the switch member II.

As soon as relative movement is caused between the switch members II) and 'I I, as by the movement of the switch member II upwardly through the opening 94 provided by-the plates or washers I2, this circuit is no longer completed when the contact fingers 21 move out of engagement with the lowe. most plate or washer I2. The contact fingers 21 immediately engage the inner periphery of the next above plate or washer I2, and a short arc I8, Figure 2, is formed between the bottom two plates or washers I2. Additional arcs I6 are formed between additional plates or washers I2, as shown in Figure 2, as the switch member II moves upwardly. A sufficient number of metallic plates or washers by the time the contact fingers 21 disengage the uppermost plate or washer I2, all of the relatively short arcs I6 will have been extinguished. The number of plates or washers that is employed depends upon the circuit in which the switch is connected. Instead of a single' are being formed between the contact fingers 21 and the lowermost plate or washer I2, a number of short arcs are formed. These short arcs are or require a higher voltage to maintain them, than a single are maintained between the contact fingers 21 and the lowermost plate or washer I2.

In order to break upthe single are into the numerous short arcs, it is essential that the short arcs I6 be confined within the air gaps I5. These radial air'gaps I5 are confined on the plates or washers I2 and the insulating rings I3. However, these air gaps I5 are open on their inner sides. As a result, unless means are taken to close this open side or to repel the arcs from the inner edges of the plates or washers I2, instead of several short arcs I6 being formed, it is likely that a single arc will be drawn between the lowermost plate or washer I2 and the contact fingers 21 of the switch member H or that the series of short arcs that have combine to form a single continuous are.

I2 is provided'so that r voltage of the electric some are extinguishing gas when exposed to the heat of the arcs I6. I

As shown in Figure 2 of the drawings, the insulating trailer 35 efiectively serves to close the inner open side of the air gaps I5 between the metallic plates or washers I2, and thus confines the short arcs I6 therein. As a result, there is little likelihood of a fiashover directly between the lowermost plate or washer I2 and the contact fingers 21 of the switch member II. Because of the relatively higher voltage required to maintain the series of short arcs I6 as compared to a single arc of the samev total length, and the I drawings, it will be observed that another embodiment of the invention is there disclosed. A generally cylindrical insulating housing 40 is provided. Preferably the housing 40 is formed of porcelain. At its ends, line terminals 4| and 42 are provided. Each of the terminals 4I and 42 is provided with a line conductor receiving aperture 43 and 44, respectively, into which screws 45 and 46 project for securing the line conductors therein. Flexible contact fingers 41 and 48 project from each of the line terminals III and 42, and they are urged inwardly at their outer ends by garter springs 49 and 5D.

The insulating housing 50 is adapted to receive a bayonet, type connecting member through its upper end forinterconnecting the line termi-- tion is enlarged for contact engagement with the flexible contact fingers 41 in the switch closed position. A connecting member- 55, formed of good conducting material, such as copper, is threaded into the lower end of the support member 54, and it carries adjacent its upper end a plurality of metallic plates or washers 51. The plates or washers 51 are formed of good conducting material, such as brass. They are spaced apart by insulating rings 58 which are preferably formed of fiber. The plates or washers 51 are insulated from the connecting member 56 by means of a sleeve 59 of suitable insulation, such as mica. The lowermost plate,

or washer 60 of the stack of plates or washers is considerably thicker than the remaining plates or washers 51, and is chamfered in order to facilitate its entry between the flexible contact fingers 41. A sleeve 6| of insulating material, such as fiber, telescopes with the sleeve 59 and with the lowermost plate or washer 60 to provide additional insulation between the connecting member 56 and the plate or washer 60.

It will be observed that the arrangement of the plates or washers 51 and the insulating rings 58 is such that air gaps 62 are provided therebetween. The air gaps 62 are radial in form and are closed along their inner side and open along their outer side.

The lower end portion 64 of the connecting member 56 is enlarged for contact engagement with the flexible contact fingerst 48 on the lower line terminal 42. A pin 65, of suitable insulating material, such as Bakelite, is secured to the enlarged portion 64 by'a transverse pin 66. The pin 55 carries a stack of plates or washers B1 that are formed of suitable conducting material such as brass. The plates or washers 61 are spaced apart by insulating rings 68 that may be formed of fiber. The lower end of the pin 5.55 is provided with a head portion 89 which inten'lts h a plate or washer EH3 that is con siclerably B ser than the other plates or washers and chamfered in to facilitate insertion b the flexible contact fingers 3 8. served that he or wash ed apart the insulating rings radial air therebe side and. open on outer side. The 11 ity of this constrlucpresently be lll lower end of the insulating hot closed by cap 12 that is threaded, as s--o.1n, onto the lower line terminal and is provided with a vent l3 for gases that may be evolved in operation of the switch. The cap is preferably forme of insulating material such as so as to isin Bakelite. I

m the circuit closed. position, previously indicated, the enlarged lower portion of the support member 55 engages the contact fingers At the some timthe enlarged lower portion 84 or the connecting member 56 engages the contact fingers d8. It will then be apparent that a circuit completed between the line terminals El and through the connection member 56. When the circuit is opened between the line terminals ll and 42, two arcs will be drawn, in the event that current is flowing in the circuit, one are being formed between the enlarged portion 5'5 of the support member 5 and the contact fingers all, and the other are being formed between the enlarged portion 64 of the connecting member 56 and the contact fingers 8.

As the handle 53 is withdrawn, carrying with it the two stacks of plates or washers 51 and 61, these two arcs are each broken up into several short arcs between the plates or washers 51 and 61. For circuit interrupting purposes, the enlarged portion 55 of the support member 54 can be considered as one of the plates or washers of the upper stack, while the enlarged portion 64 of the connecting member 56 is a part of the stack of plates or washers 61.

It is, of course, desirable that the short arcs formed between the plates or washers of each of the two stacks be confined in the radial air gaps 62 and 1|. For this purpose, insulating sleeves 13 and 14 are provided. The sleeve 13 is carried by the line terminal 4|, while the sleeve 14 is carried by the line terminal 42. The inner diameters of the insulating sleeves 13 and 14 are such that they closely fit around the plates or washers making up their respective stacks, so that the radial air gaps in which the short arcs are formed are substantially closed at their outer side. This arrangement efiectively prevents a single are being formed which would span several of the plates or washers of each stack.

The sleeves 13 and 14 are preferably formed of material which will evolve an arc extinguishing medium under the heat of the arcs so as to assist in confining them by repulsion between the plates or washers 51 and 61 as previously set forth and extinguishing the same. For this purpose the sleeves 13 and 14 may be formed of fiber.

Since certain further changes can be made in the foregoing constructions and different embodiments of the invention can be made without departing from the scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be in terpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof to open an electric circu. in which current flows; one of said switch members including a stack of metallic plates, and means for maintaining said plates in insulated spaced relation with air gaps therebetween; and means oil til

for connecting an end plate of said stack to one terminal of said electric circuit, the other of said switch members being adapted to be connected. to another terminal of said electric circuit and to engage said end plate in the switch closed posi tion and on relative movement thereof to successively engage the remaining plates, the air gap spacing, between said plates being such that arcs are formed therebetw-een when the switch is coerated to the switch open position whereby said are is broken up into a plurality of short arcs.

2. A switch comprising relatively movable switch members between. which an arc is drawn on movement thereof apart to open an electric circuit in which current flows, one of said switch members including a plurality of metallic plates insulated from each other with air gaps therebetween and one of said plates being adapted to be connected to one terminal or" said electric circuit, the other of said switch members being adapted to be connected to another terminal of said electric circuit and to engage said one plate in the switch closed position and on relative movement thereof to successively engage the remaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and insulating means cooperating with said metallic plates and acting as a barrier with respect thereto in confining said short arcs between said plates.

3. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members including a stack of metallic plates, and means for maintaining said plates in insulated spaced relacessively engage the remaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said arc is broken up into a plurality of short arcs, and generally cylindrical insulating means adapted to evolve an arc extinguishing medium when subjected to are heat and disposed to cooperate with said metallic plates and serve as a barrier withrrespect thereto in confining said short arcs between said plates.

4. A switch comprising generally cylindrical interfitting relatively movable switch :members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members including a stack of metallic plates, and means for maintaining the same in insulated spaced rela-. tion with radial air gaps therebetween closed along one side with the other side remaining open; means connecting an end plate of said stack to one terminal of said electric circuit, the other of said switch members being adapted to be connected to another terminal of said electric circuit and to engage said end plate in the switch closed position, and on relative movement thereof to successively engage theremaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said arc is broken up into a plurality of short arcs, and generally cylindrical insulating means relatively movable with respect to said plates in close proximity thereto for closing the open sides of said air gaps to confine said short arcs between said plates.

5. A switch comprising relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows, one or said'switch members including a plurality oi stationary metallic plates insulated from each other with air gaps therebetween and one of said plates being adapted to be connected to one terminal of said electric circuit, the other of said switch members being movable and adapted to be connected to another terminal of said electric circuit and to engage said one plate in the switch closed position and on movement thereof to successively engage the remaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs.

6. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members ineluding a stationary stack of metallic washers in' the switch closed position and on movement thereof through said cylindrical opening to successively engage the remaining washers, the air gap spacing between said washers being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said arc is broken up into a plurality of.

short arcs.

'7. A switch comprising relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows, one of said switch members including a plurality of stationary metallic plates insulated from each other with air gaps therebetween and one of said plates being adapted to be connected to one terminal of said electric circuit, the other of said switch members being movable and adapted to be connected to another terminal of said electric circuit and to engage said one plate in the switch closed position and on movement thereof to successively engage the remaining plates, the air gap spacing'between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and

insulating means movable with said other switch thereof apart to open an electric circuit in which current flows; one of said switch members including a stationary stack of metallic washers defining a cylindrical opening therethrough, and means for maintainingsaid washers in insulated spaced relation with air gaps therebetween; means connecting an end washer oi. said stack to one terminal of said electric circuit, the other of said switch members being movable and adapted to be connected to another terminal of said electric circuit and to engage said end washer in the switch closed p sition and on movement thereof through said cylindrical opening to shocessively engage the remaining washers, the air gap spacing between said washers being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and generally cylindrical insulating means movable with said other switch memher and adapted to evolve an arc extinguishing medium when subjected to are heat and disposed to cooperate with said metallic washers and serve as a barrier with respect thereto in confining said short arcs between said washers.

9. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members including a stationary stack of metallic washers defining a cylindrical opening therethrough, and insulating rings interposed between said washers adjacent their outer peripheries to maintain them in insulated spaced relation with radial air gaps therebetween opening inwardly; means connecting an end washer of said stack to one terminal of said electric circuit, the other of said switch members being movable and in the form of a plug having contact fingers adapted to be connected to another terminal of said electric circuit and to engage said end washer in the switch closed position and on movement thereof through said cylindrical opening to successively engage the remaining washers, the air gap spacing between said washers being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and generally cylindrical insulating means movable with said other switch member and substantially filling said cylindrical opening as said movable switch member moves through the same and closing the inner open side of said air gaps for confining said short arcs between said washers.

10. A switch comprising relatively movable set in the switch closed position and on relative movement thereof to successively engage the remaining plates or each set, the air'gap spacin between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby each of said two arcs is broken up into a plurality of short arcs.

11. A switch comprising generally cylindrical interfitting relatively movable switch members between which two arcs are drawn in series on movement thereof apart to open an electric circuit in which current flows; one of said switch members including two spaced apart stacks of metallic plates, and means for maintaining the plates of each stack in insulated spaced relation with air gaps therebetween; and means for connecting an end plate of each stack to a-terminal of said electric circuit, the other of said switch members being adapted to engage and interconnect said end plate oi. each stock in the switch closed position and on relative movement thereof to successively engage the remaining plates 01' each stack, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby each of said two arcs is broken up into a plurality of short arcs.

12. A switch comprising relatively movable switch members between which two arcs are drawn in series on movement thereof apart to open an electric circuit in which current fiows, one of said switch members including two sets oi metallic plates, the sets of plates being spaced apart and the plates 01! each set being insulated from each other with air gaps therebetween and one plate of each set being adapted to be connected to a terminal of said electric circuit, the other of said switch members being adapted to engage and interconnect'said one plate of each set in the switch closed position and on relative movement thereof to successively engage the remaining plates 01 each set, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby each or said two arcs is broken up into a plurality of short arcs, and insulating means cooperating with air gaps therebetween, one of said plates with each set of metallic plates and acting as a barrier with respect thereto in confining said short area between said plates.

13. A switch comprising generally cylindrical interfitting relatively movable switch members between which two arcs are drawn in series on movement thereof apart to open an electric circuit in which current flows; one of said switch members including two spaced apart stacks of metallic plates, and means for maintaining. the plates of each stack in insulated spaced relation with air gaps therebetween; means for connecting an end plate of each stack to a terminal of said electric circuit, the other of said switch members being adapted to engage and interconnect said end plate of each stack in the switch closed position and on relative movement thereof to successively engage the remaining plates of each stack, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby each of said two arcs is broken up into a plurality of short arcs, and generally cylindrical insulating means cooperating with each of said stacks and serving as a barrier with respect thereto in confining said short arcs between said plates.

14. A switch comprising generally cylindrical interfitting relatively movable switch members between which two arcs are drawn in series on movement thereof apart to open an electric circuit in which current fiows; one of said switch members including two spaced apart stacks of metallic plates, and means for maintaining the plates of each stack in insulated spaced relation with radial air gaps therebetween closed along one side with the other side remaining open; means for connecting an end plate of each stack to a terminal of said electric circuit, the other of said switch members being adapted to engage and interconnect said end plate of each stack in the switch closed position and on relative movement thereo! to successively engage the remaining plates of each stack, the air gap spacing between the plates of each stack being such that arcs are formed therebetween when the switch is operated to the switch open position whereby each of said two arcs is broken up into a plurality of short arcs, and generally cylindrical insulating means relatively movable with respect to each of said stacks in close proximity thereto for closing the open sides of said air gaps to confine said short arcs between said plates.

15. A switch comprising relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current fiows, one of said switch members including a plurality of metallic plates movable as a unit and insulated from each other being adapted to be connected to one terminal 0! said electric circuit, the other of said switch members being stationary and adapted to be connected toanother terminal of said electric circuit and to engage said one plate in the switch closed position and on movement of said oneswitch member to the switch open position to successively engage the remaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said arc is broken up into a plurality of short arcs.

16. A switch comprising generally cylindrical between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members including a movable stack of metallic washers, and means for maintaining said washers in insulated spaced relation with air gaps therebetween; and means for .connecting an end washer of said stack to one terminal of said electric circuit, the other of said switch members being stationary and adapted to be connected to another terminal of said electric circuit and to engage said end washer in the switch closed position and on movement of said stack to the switch open position to successively engage the outer periphery of the remaining washers, the air gap spacing between said washers being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said arc is broken up into a plurality of short arcs.

1'7. A switch comprising relatively movable switch members between which an arc is drawn on movement thereof apart to open an electriccircuit in which current flows, one of said switch members including a plurality of metallic plates of said electric circuit, the other of said switch members being stationary and adapted to be connected to another terminal of said electric circuit and to en; ige said one plate in the switch closed position and on movement of said one switch member to the switch open position to successively engage the outer periphery of the remaining plates, the air gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and insulating means cooperating with said metallic plates and acting as a barrier with respect thereto in confining said short arcs between said plates.

18. A' switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit inwhich current flows; one of said switch members including a movable stack of metallic washers, and means for maintaining said washers in insulated .spaced relation with air gaps therebetween;

means connecting an end washer of said stack to one terminal of said electric circuit, the other of said switch members being stationary and adapted to be connected to another terminal of said electric circuit and to engage said end washer in the switch closed position and on movement of said. stack to the switch open position to successively engage the outer periphery of the remaining washers, the air gap spacing between said washers being such that arcs .are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and generally cylindrical stationary insulating means adapted to evolve an arc extinguishing medium when subjected to are heat and disposed to cooperate with said metallic washers as the same are moved therepast and acting as a barrier with respect thereto in confining said short arcs between said washers.

19. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which eluding a movable stack of metallic washers, and insulating rings interposed between said washers adjacent their inner peripheries to maintain them in insulated spaced relation with radial air gaps therebetween opening outwardly; means connecting an end washer of said stack to one terminal of said electric circuit, the other of said switch members being stationary and in the form of a socket having contact fingers adapted to be connected to another terminal of said electric circuit and to engage said end washer in the switch closed position and on movement of said stack to the switch open position to successively engage the outer periphery of the remaining washers, the air gap spacing between said washers being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a pluralityof short arcs, and generally cylindrical stationary insulating means through which said stack of metallic plates moves to the switch open position cooperating with said washers to close the outer open side of said air gaps for confining said short arcs between said .washers.

20. A switch comprising generally cylindrical interfitting relatively movable switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows; one of said switch members including a stack of metallic plates, and means for maintaining said plates in insulated spaced relation with gaps therebetween; means connecting an end plate of said stack to one terminal of said electric circuit, the other of said switch members being adapted to be connected to another terminal of said electric circuit and to engage said end plate in the switch closed position and on relative movement thereof to move past the remaining plates, the gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are isbroken up into a plurality of short arcs, and generally cylindrical insulating means movable with said other switch member relative to said metallic plates to cooperate with the same and serve as thereof apart to open an electric circuit in which current flows; one of said switch members incurrent flows; one of said switch members including a stack of metallic plates, and means for maintaining the same in insulated spaced relation with radial gaps therebetween closed alon one side with the other side remaining open; means connecting an end plate of said vvstack to one terminal of said electric circuit, the other of said switch members being adapted to be connected to another terminal of said electric circuit and to engage saidend plate in the switch closed position, and on relative movement thereof to move past the remaining plates, the gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and generally cylindrical insulatin means movable with said other switch member relative to said plates in close proximity thereto for closing the open sides of said gaps to confine said short arcs between said plates.

switch members between which an arc is drawn on movement thereof apart to open an electric circuit in which current flows, one of said switch members including a plurality of stationary metallic plates insulated from each other with gaps therebetween and one of said. plates being adapted to be connected to one terminal of said electric circuit, the other of said switch members being movable and adapted to be connected to another terminal of said electric circuit and to engage said one plate in the switch closed position and on movement thereof to move past the remaining plates, the gap spacing between said plates being such that arcs are formed therebetween when the switch is operated to the switch open position whereby said are is broken up into a plurality of short arcs, and insulating means movable with said other switch member and cooperating with said metallic plates and acting as a barrier with respect thereto in confining said short arcs between said plates.

HUGH A. 'IRIPLET'I'.

SIGURD I. LINDELL.

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