US2080611A - Circuit breaker - Google Patents

Description

May 18, 1937. F. B. JOHNSON 2,080,511

CIRCUIT BREAKER Filed May 22, 1955 4 Sheets-Sheet l Fig. 1.

INVENTOR Frederzakfl Job/75022.

ATTORNEY May 18, 1937. F. JOHNSON CIRCUIT BREAKER Filed May 22, 1935 4 Sheets-Sheet 2 INVENTOR 1 rederzb/fl .fa/msor'z.

ATTORNEY WWW May 18, 1937. F. B. JOHNSON CIRCUIT BREAKER Filed May 22, 1955 4 Sheets-Sheet 3 1775 zzlafz'an INVENTOR Frederzbkfi Jo/mson.

ATTORNEY WITNESSES y 18, 1937. F. B. JOHNSON 2,080,611

CIRCUIT BREAKER Filed May 22, 1935 4 Sheets-Sheet 4 I BY M 49 Patented May 18,1937

UNITED STATES 2,080,611 PATENT OFFICE CIRCUIT BREAKER Frederick B. Johnson, Murrysville, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 2 2,

34 Claims.

My invention relates to an arc extinguisher for a circuit breaker of the type in which the are is split up into a series of short arcs between conducting plates on which the short arcs are ro- 5 itziatleid about an annular path by a radial magnetic An object of my invention is to provide an arc extinguisher of this type which is capable of extinguishing arcs carrying high currents.

Another object of my invention is to provide an arc extinguisher in which the arc is split longitudinally into a plurality of parallel-connected arcs for; the whole length of the are between its termina s.

A further object of my invention is to provide an arc extinguisher in which the parallel-connected arcs are each divided into a plurality of series-related arcs which are then rotated by a magnetic field about annular paths until the arcs are extinguished.

A further object of my invention is to provide an arc extinguisher comprising a series of spaced plates of conducting material having slots therein in which the arc is moved. These slots have two diverging branches at one end thereof towards which the are is moved and caused to be split into two parallel-related arcs before the arc is split up into series-related arcs between the spaced conducting plates. By first causing the arc to play as two parallel-connected arcs, the arcs may be caused to split up into series-related arcs much more easily without burning the tips of the slots.

This invention is a further improvement on are extinguishers for circuit breakers of the type disclosed in Slepian Patent No. 1,927,904 issued September 26,1933. In arc extinguishers of the type where the arc is moved into a slot in a stack of spaced plates of conducting material and is split up into short series-related ares between the 40 plates when the arc reaches the tips of the slots,

difliculty has been experienced in some cases in interrupting very large currents. .It has been found that the arc does not always readily transfer from a single long are playing through the 45 slot to a series of short arcs playing between the plates. It has sometimes been found that the arc does not transfer to the plates until the current in the arc dies down during the alternating current cycle to some lower value of current. During the 5 time that the arc current is high, it may partially transfer to the plates and then transfer back into the slot through the plates. In some cases, this results in a constant motion of the arc back and forth over the end of the slot through the plates, 5 so as to cause excessive burning of the tip of the slot. After the are has been split up into short arcs between the plates, there is a tendency, when the are carries very large currents, for it to reignite in the entrance slot as the voltage again so builds up after a current zero, even though the 1935, Serial No. 22,778

are which transferred to the plates has been extinguished, due to the fact that there may be ionized gas present in the slots through the plates. That is, the arc may jump back into the slotafter it has once transferred to the plates and been extinguished there.

By making use of this invention, the amount of current which can be made to transfer to the plates can be greatly increased thus making it possible to build a circuit breaker of this type of much higher interrupting ability. This is accomplished by making use of a double plate having two annular paths with a single slot having two diverging branches, each of which leads into one of the annular paths. The are is moved upwardly in the slot and into the diverging branches where the arc plays as two parallel-connected ares. Each of these parallel-connected arcs is then moved further along in its branch of the slot until the tips of the slots are reached when each of the parallel-connected arcs is split up into a plurality of series-connected arcs between the plates. Each of these arcs is then rotated about the annular paths between the plates until they are extinguished.

An unrestricted are playing in air cannot normally be caused to play in two parallel-connected sections due to the fact that such an arc has a drooping voltage characteristic. That is, the arc voltage decreases as the current increases. It has been found possible to make the arc play in a stable condition as two parallel-connected arcs by causing it to have arising voltage characteristic wherein the arc voltage increases as the currentincreases. This rising arc-voltage characteristic causes the arc to divide when it reaches the branching portions of the slots and also tends to make the current divide evenly betweenthe two arcs.

This change from a drooping arc-voltage characteristic to a rising arc-voltage characteristic is accomplished by moving the are into a restricted slot in the plates which reduces the cross section of the arc and causes it to play with a higher current density and a higher are voltage than would an unrestricted arc.

These and other objects of the invention will more fully appear from the following description of the preferred embodiment of my invention 11- lustrated in the drawings in which:

Figure 1 shows a view partly in section and partly in elevation of the are extinguisher of my invention; the section being enlarged and taken through'the stack of plates on the line I--I of Fig. 4.

Fig. 2 is a cross sectional view through the arc extinguisher of Fig. 1 taken on the line II-lI of extinguisher of Fig. 1 taken on the line III11I of Fig. 1.

Fig. 4 is a cross sectional view taken on the line IV-IV of Fig. l, and shows the radial field coils which rotate the arc.

Fig. 5 is a sectional view through one of the radial field coil groups taken on the line VV of Fig. 4.

Fig. 6 is an exploded view of the group of arctransfer plates used with each of the radial-fieldcoil groups; and,

Figs. '7 and 8 are views partly in section and partly in elevation and show the assembly of the conducting plates which provide annular paths about which the arc may be rotated within the iron plates for magnetically moving the arc.

The line terminals H and I3 of the circuit breaker are connected to the stationary arcing contact l5 and the moving arcing contact 1. The moving contact |1 may be actuated to open position by any suitable type of operating mechanism which may be provided with main contacts for normally completing the circuit through the circuit breaker. Directly above the stationary and moving arcing contacts 5 and H are positioned arc horns I9 and 2|. The stationary contact I5 is supported from the arc horn H but insulated therefrom by a block of insulating material 23. The arc horns l9 and 2| are provided with up-standing portions 24 and 25 respectively which form the ends of the arc extinguishing structure. The arc. horns l9 and 2| and their up-standing end portions 24 and 25 are of iron and have copper end plates 21 and 29 positioned on their sides which face each other.

The are extinguishing structure betwen the end plates comprises a plurality of plate groups 3| and 33 which are alternated along the stack. While the drawings show two plate groups 3| with one plate group 33 therebetween, it is understood that for higher voltages a larger number of plate groups will be used. Between adjacent plate groups there are positioned radial-field-coil groups 35 for providing a radial magnetic field for rotating the arcs between the plates Each of the plate groups 3| is made up of an assembly of iron, copper and insulating plates as illustrated in Figs. 2 and 8. A composite plate is formed by positioning a plate-31 of conducting material such as copper within a plate 39 of a magnetic material such as iron. The copper plate 31 is shaped so as to provide a pair of annular portions disposed side by side with round holes 4| through the center of each of the annular portions. The lower portion of each of the conducting plates 31 is provided with a projecting portion 40 extending below the lower edges of all of the other plates in the stack. This extending portion 40 is provided with a slot 42 having two diverging branches 43 and 45 which lead into the annular portion of the plates tangentially thereto. The provision of the extension 40 makes it possible to provide a relatively long slot 42 before the branches 43 and 45 are reached. The slot 42 is narrower than the arc so that the arc is restricted in cross section and caused to have a higher are voltage and a rising arc-voltage characteristic.

The plates 39 of magnetic material have a cutout portion which has the same shape as the outer periphery of the conducting plates 31, so that the conducting plates exactly fit within the iron plates. The iron plates 39 therefore act as an extension of the conducting plates 31 and provide additional heat capacity ior taking up the heat of the arc. The iron plates thus extend around three sides of the copper plates, but have an opening providing an air gap across the lower portion of the slotstherein. The iron plates 39 have extensions 41 (Figs. '1 and 8) in the form of separate iron plates insulated by paper sheets 48 (Figs. 2 and 3). The stack of plates 41 and .48 are faced with a member of arc resisting insulating material 49. The are is drawn by the contacts 5 and I1 between the iron plates 41 and is moved upwardly in the slots in the copper plates due to the distortion of the magnetic field by the generally U-shaped pole pieces formed by the iron plates 39 and their extensions 41.

The composite plates formed by the conduct: ing plates 31 and the magnetic plates 39 are spaced apart by sheets of insulating material such as fish paper which are shaped as illustrated in Fig. 1. There are two sheets of insulation between adjacent conducting and magnetic plates. The complete insulating plates 5| have a pair of annular openings 53 cut therein and diverging slots 55 and 56 leading tangentially into each of the annular openings 53. The annular openings 53 in the complete insulating plates 5| fit over the annular portions of the conducting plates 31 so as to provide a complete annular path about which the arcs may be rotated. The edges of the annular openings 53 extend over the joint between the conducting plates 31 and the magnetic plates 39 so as to prevent the are from playing through the crack between the two plates. The composite plate formed by the conducting plates 31 and the magnetic plates 39 are also spaced apart by vented insulating plates made up of three portions 51, 59 and 5|. The vented plates when assembled together are of the same shape as the complete plates 5|, except that a portion leading from the top of each 01' the annular arc paths to the top of the plates is cut out, so as to provide a vent from the annular arc space, through which the hot arc gases may escape. By having the conducting plates 31 and magnetic plates 39 spaced apart by the two types of plates 01' insulating material, one of which defines the complete annular arc path and the other of which has a ventilating passage extending from each arc path, it is made impossible for the arc to move out of the annular path and into the vent extending from each o1 the annular arc paths.

The plates of the alternate plate groups 33 are of the same general type as those of the plate groups 3|, except that they are designed for rotation oi the arc in the direction opposite to the direction of rotation of the arcs in the plate groups 3|. As shown in Fig. 7, the conducting plates 63 each have two annular portions each having an opening 65 through the center thereof. The slot 66 in the conducting plates 53 extends upwardly between the two annular portions of the plates and has two diverging branches 51 and 59 which extend tangentially into the annular portions of the plates. The slots 51 and 59 lead into the top of the annular portions of the plates whereas the slots 43 and 45 in the con ducting plates 41 of the plate groups 3| lead into the bottom of the annular portions of the plates. It is not necessary that the conducting plates 53 in groups 33 have extensions corresponding to the extensions 40 of conducting plates 31 in the groups 3| since the slot 65 extending between the annular paths to the top portion thereof is suificiently long to reduce the cross section and insulating plates 13 increase the arc voltage of the arc before it is split up.

Each of the conducting plates 63 is surrounded by a plate 1| of magnetic material, such as iron, which has a cutout portion shaped to fit around the outer periphery of the conducting plates 83. The magnetic plates 1| in the plate groups 33 function in the same manner as the magnetic plates 39 in the plate groups 3|.

The conducting plates 83 and magnetic plates 1| of plate-groups 33 are spaced apart by complete insulating plates 13 (shown in Fig. 3) which have a pair of annular cutout portions 15. The also have a slot extending upwardly between the two annular cutout portions 15 with diverging branches 11 which are shaped similarly to but .are wider than the branches 61 and 69 of the slot in the conducting plates 83. The conducting plates 83 and magnetic plates 1| are also spaced apart by vented plates formed of three parts 19, 8| and 83 which together make up a plate of the same shapeas the complete plates portions cut away providing a ventilating passage extending from each of the annular arc paths to the top of the plates.

\ The conducting plates 31 and as of both plate groups are also spaced apart by washers 82 of insulating material positioned around the holes 4| and 85. A slot 84 extends into each of the openings 4| and 65 to reduce eddy current losses. The two slots 84 in each plate are at right angles to each other so that the slots in adjacent plates may be kept out of alignment by reversing adjacent plates.

Each of the radial-field-coil groups 35 is made up of a pair of coils 85 and 81 wound from copper strap, as illustrated in Figs. 4 and 5. The two coils are connected together at one end so as to form a double coil with each half of the coil wound in opposite directions; This double coil is positioned between a pair of coil-end plates 89 and 9| and the free end of one coil is connected to the plate 89 and the free end of the other coil is connected to the plate 9| so that double coil is electrically connected in series between the coil end plates \89 and 9|. Each of the coil end plates is surrounded by a magnetic plate 93. The space between the magnetic plates 93 is filled in at the top of the plates by a rectangular block of insulating material 95 and at the sides by angularly shaped blocks of insulating material 91.

A pluralityof arc-transfer plates (Figs. 1, 4 and'6) are positioned beneath the center of the space between the two coils 85 and 81. The center plate 98 of the group of arc-transfer plates is shaped as shown in Fig. 6, and is unslotted. The arc-transfer plates 99 positioned on the side of the center plate 98 toward the plate groups 3| are provided with double slots I00, while the arc-transfer plates IOI'on the side of the.center plate 98 which face the plate groups 33 are provided with a single slot I02. The end arc-transfer plates I03 and I04 are cut oil at their tops, while the other are transfer plates 98, 99 and have extensions which extend up between the coils 85 and 81. The end are transfer plates I03 and I04 have slots the same as plates |0| and 99. The arc transfer plates are spaced apart by members I05 of sheet insulating material.

The alternate plate groups 3| and 33 with the radial-fleld-coil groups 35 positioned therebetween are assembled between the end plates 23 and 25, and the stack is secured together by inother end of rod 13, except that they have I02 and I00 respectively.

sulating tie rods 9 which have threaded metal end pieces I23 on which are screwed nuts I24. The various conducting, magnetic and insulating plates are held in their proper relations by means of pins |2| of insulating material which extend through suitable openings I22 in all of the plates. An insulating tube I 25 extends through the alined openings and 65 in the conducting plates 31 and 63. Positioned within each of the insulating tubes I25 is a slotted tube I21 of magnetic material such as iron to provide'a core for the magnetizing coils 85 and 81 and thereby aid in distributing the flux along the length of the stack of plates.

A rod I29 of copper extends through the inside of one of the tubes I21 and a rod I3I through the other of the tubes I21. One line terminal II is connected through a conductor I30. as shown in Fig. 1, to the left-hand end of rod I3I. The I3I is connected by means of a conductor I33 to the right-hand end of a rod I35 which extends through an insulating tube I31 extending through the top portions of the insulating blocks 95. The other end of the rod I35 is connected by a conductor I39 to the left-hand end of the red I29 which'has its right-hand end connected by conductors HI and M3 to the arc horn I9. 7

The current normally flows from the line terminal II through the contacts I5 and H to the line terminal I3. When this circuit is broken by the separation of the arcing contacts I5 and I1, the path of the current'is then as indicated by the arrows, with the current flowing during one half cycle of the alternating current wave from line terminal through conductor |30,-rod I3I through the stack of plates, conductor I33, back across the stack through rod I35, to conductor I39 which is connnected to the other rod I29 which carries the current through the center of the .other annular arc path in the same direction as the current flow in the rod I3I. The circuit from the rod I29 is completed by the conductor MI and -|43 to the arc horn I9. The current then flows through the are from the are born I9 to the arc horn 2| which is connected to the other line terminal I3.

It should be noted that the direction of current flow is the same through both of the rods I29 and I3I which, together with the other conductors, form a two-turn coil surrounding the magnetic plates 39 and 1| for setting up a magnetic field in the magnetic plates which moves the arc up into the slots in the conducting plates 31 and 63. Since the direction of current flow in the are from the arc horn I9 to the arc horn 2| is the same as the direction of the current flow through the rods I29 and I3I, the are isattracted to the conductors and moved toward the center of each of the arc paths.

As the arc is moved upwardly on the arc horns I9 and 2| into the stack of plates, the arc first encounters the extensions 40 onplates 3|. As

' the arc moves up the slots42 in the extensions 40,

it is reduced in cross section, thereby causing it to play with a higher current density and a higher are voltage. The arc is then split up into a series of sections between the center unslotted arctransfer plates 98. Each of the arc sections is then moved upwardly. In the plate groups 3| the arc is divided longitudinally into two parallel-related arcs by the two slots I00 in the arc-transfer plates and the slots-43 and 45 in the plates 31, while in the alternate plate groups 33 the arc continues to play for a while as a single arc.

After the arcs reach the tips of the slots I and I02 in the arc-transfer plates, the ends of the arc sections are transferred to the coil-end plates 89 and 9i so that the radial field coils 85 and 81 are electrically connected in series with the arc sections. The coils 85 and .81 then set up a radial magnetic field about each of the annular arc paths and also across the slots 43, 45 in plates 37, and across slots 66, 61 and 69 in plates 63. In each of the plate groups 3! the sense of the radial field is in such direction as to cause the arc to rotate clockwise (Fig. 2) about the lefthand annular path and counter-clockwise about the right-hand annular path. In the plate groups 33 the magnetic field is of opposite sense to the magnetic field in the plate groups 3|, so that the arc will be rotated counter-clockwise (Fig. 3) about the left-hand annular path and clockwise about the right-hand annular path.

In the plate groups 3|, the radial field moves the arc up into the slots 43 and 45 which are of decreasing width so as to further restrict the cross section of the arc and increase its current density and make it play with a higher are voltage and a rising arc voltage characteristic. When the parallel-related arcs reach the tips of the slots 43 and 45, they are each split up into a plurality of short series-related arcs between the plates which are rotated therebetween until extinguished.

In the plate groups 33, the arcis moved upwardly as a single arc in each group in the slots 66 by the radial field. The slots 66 restrict the arc and cause it to play with a rising arc-voltage characteristic so that it will play as two parallelrelated arcs when the junction of the two branches 6'! and 69 are reached. The two parallel-related arcs are moved by the radial field up the slots 6! and 69 and are further restricted in cross section and the current density is increased. This makes it easier for each of the two parallelrelated arcs to be split up into a large number of short series-related arcs when the tips of the slots are reached. These short arcs are rotated between the plates until a current zero is reached when they are extinguished.

From the foregoing detailed description of a specific embodiment of the invention, it is apparent that the structure of this invention provides an arc extinguisher for a circuit breaker which is capable of extinguishing arcs carrying very heavy currents. This is accomplished by first splitting the arc longitudinally into a pair of parallel-connected arcs and then separately extinguishing each of the parallel-connected-arcs. It should be noted that the arc is split into a pair of parallel connected arcs for the whole length 01' the are between its terminals. This is accomplished by providing coil-end plates at the end of each group of plates, which formarc terminal members having two diverging branches along which each 01 the parallel-connected arcs is moved. The plates of insulating material provided between the conducting plates also provide an arc path through the structure having two diverging branches, so that the insulating plates also cause the arc to be split longitudinally into parallel-connected arcs.

Each of the conducting plates is provided with a pair of annular portions defined by the insulating plates. These annular arc paths are positioned side-by-side so that there are two arcs which play on each plate as the arcs are rotated.

The pairs of arc paths between each pair of conducting plates and between each pair of coil-end plates are electrically connected in parallel since the two annular paths are on an integral plate. It would, of course, be possible to have each annular arc path on a separate conducting plate with the plates on which each arc is rotated electrically connected to the plates on which its parallel-related arc is rotated.

The circuit breaker of this invention first establishes a single are which is split longitudinally into parallel-related arcs. These parallel-related arcs are moved in diverging slots having ing arc terminals at the ends thereof. Each of these parellel-connected arcs are then split crosswise into a plurality of series-related arcs. These parallel and series-related arc sections are then moved into the annular arc paths defined on the copper plates by the insulating plates and are rotated. The two parallel-related portions of the arc in each group of plates are rotated in opposite directions by the magnetic field. That is, if the portion of the arc in any one group of plates of the arc extinguisher is rotated clockwise, the parallel portion of the arc in the same group of plates is rotated counter-clockwise. The are is also rotated in opposite directions in alternate groups of plates so that if one section of one of the arcs is rotated clockwise in one group of plates the adjacent sections of the arc in the groups of plates on each side thereof, which are in series with the portion which is rotated clockwise, are rotated counter-clockwise. It is apparent that the arc extinguisher of this invention divides the are into a multitude of very small sections which are rotated in different directions in contact with a large area of cool material, so that the arc is readily extinguished.

There is also an important advantage in splitting the arc longitudinally into a plurality of parallel-related arcs prior to splitting up the arc cross-wise into short arcs. This is due to the fact that it is very difiicult to move a heavy current are into a series of spaced plates between which the arc is to be split into a plurality of seriesrelated arcs without burning the edge. of the is moved into them. By first splitting the arc longitudinally into two parallel-related arcs, each of these arcs carries only half the current and may be split up into short series-related arcs much more easily without damage to the plates.

While a specific embodiment of the invention has been described in detail, it is apparent that various modifications can be made without 'de parting from the spirit of the invention.

I claim as my invention:

1. In a circuit interrupter, means for estab lishing a single arc, means for splitting the arc lengthwise into a plurality of parallel-related arcs and means for splitting each of the plurality or arcs crosswise into a plurality of series-related arcs. I

2. In a circuit interrupter, means for establish ing a single arc, means for splitting the arc lengthwise into a plurality oi parallel-related arcs and means for splitting each of the plurality of arcs crosswise into a plurality of series-related arcs, and means for moving a plurality of the parallel and series-related arcs over recurrent paths.

3. In a circuit interrupter, means for establishing a single are, means for splitting the arc lengthwise into a plurality of parallel-related arcs and means for splitting each of the plurality of arcs crosswise into a plurality of series-related arcs, and means for setting up a magnetic field for rotating a plurality of the parallel and seriesrelated arcs about annular paths.

4. In an arc extinguisher, means providing a terminal for the arc,. said are terminal means providing a path for one end of the arc, said terminal means having at least two branches leading therefrom, and means for moving the arc along said arc terminal means and onto said branches and causing the arc to split into two separate parallel-connected arcs.

5. In an arc extinguisher, means providing a terminal for the arc, said arc terminal means providing a path for one end of the. arc and having at least two branches leading therefrom, and means for moving the are along said are terminal means and onto said branches and causing the arc to split into, two separate parallelconnected arcs, and are extinguishing means for the separate are playing on each branch.

6. In an arc extinguisher, means providing a -terminal for the arc, said are terminal means providing a path for one end of the arc and having at least two branches leading therefrom, and means for moving the arc along said are terminal means and onto said branches and causing the arc to split into two separate parallel-connected arcs, and a plurality of conductconnected arcs, and a plurality of cooling members into which the arc playing on each branch is moved.

8. In a circuit interrupter, means having a plurality of passages therein, said passages being joined together at one end and diverging at the other end, arc terminal means for said passages, means for causing an arc to play adjacent the juncture of said passages, means for moving the ends of the are on said are terminal means toward the diverging ends of the passages and causing the arc to play along its whole length as a plurality of parallel-connected arcs.

9. In a circuit interrupter, means having a plurality of passages therein, said passages being joined together at one end and diverging at the other end, are terminal means for each of said passages, means for causing an arc to play adjacent the juncture of said passages, means for moving the ends of the arc on said are terminal means toward the diverging ends of the passages and causing the arc to play along its whole length as a plurality of parallel-connected arcs, and means for splitting up each of said parallelconnected arcs into a plurality of series-connected arcs.

10. In a circuit interrupter, means having a plurality of passages there said passages being joined together at one end and diverging at the other end, are terminal means for each of said passages. means for causing an arc to play adjacent the juncture of said passages, meansror moving the ends of the arc on said are terminal means toward the diverging ends of the passages and causing the arc to play along its whole length as a plurality of parallel-connected arcs, and means for splitting up each or said parallel-connected arcs into a plurality of seriesconnected arcs, and means for rotating said plurality of series and parallel-connected arcs over recurrent annular paths.

11. In an arc extinguisher, a plurality of sheet membershaving slots therein, each of said slots having a plurality of diverging branches, and means for causing movement of the arc in said slots up said diverging branches to form a plurality of separate arcs.

12. In an arc extinguishing structure, means providing a single are path, means providing a pair of arc paths including terminal means at the ends of each arc path electrically connected in parallel with the terminal means of the other arc path, means for causing a single are playing in said single arc path to divide to form a pair of parallel-connected arcs and to play with one are in each of said parallel paths, and means for causing a radial magnetic field of opposite sense across each of said pair of paths for rotating the arcs.

13. In an arc extinguishing structure, means providing a pair of arc paths each having terminal means at the ends thereof electrically connected in parallel with the terminal means of the other are path, and means for establishing an arc and causing it to be split into a plurality of arcs playing between said parallel connected terminal means.

14. In an arc extinguisher, a plurality of conducting members, each of said conducting members having a pair of annular portions disposed side by side, means for establishing an arc, means for causing the arc to play in two parts, and means for causing each part of the arc to rotate about one of the annular portions of the conducting members.

15. In an arc extinguisher, a plurality of conducting members, each of said conducting members providing a pair of arc paths thereon disposed side by side, means for establishing a single arc, means for causing said are to split and play in each of said are paths as separate arcs and means for moving each are along its arc ath. p 16. In an arc extinguisher, a plurality of conducting members, each of said conducting members having a pair of annular portions disposed side by side, and means of magnetic material extending-around three sides or both of said annular portions for moving the arc thereinto.

17. In an arc extinguisher, a plurality of conducting members, each of said conducting members having a pair of annular portions disposed side by side, and means of magnetic material extending around three sides of both of said annular portions for moving the arc thereinto and conducting means extending through the center of each of said annular portions for energizing said means of magnetic material;

18. In an arc extinguisher, a plurality of conducting members, each 01 said conducting members having a pairof annular portions disposed side by side, and each of said conducting members having a slot therein, said slots having diverging branches each or which extends toward one of said annular portions of the conducting members.

19. In an arc extinguisher, a plurality of conducting members, each of said conducting members having a pair of annular portions disposed side by side, and each of said conducting members having a slot therein, said slots having diverging branches each of which extends toward one of said annular portions of the conducting members, means for moving the arc along said slot and into said diverging branches and splitting it into parallel connected sections, and means for rotating each of said are sections around one of the annular portions of the conducting members.

20. In an arc extinguisher, a plurality of sheet members of insulating material having an opening therein in which the arc is caused to play, said opening having a plurality of slots leading therefrom, andmeans for moving the are into said slots and causing it to play as a plurality of parallel connected arcs.

21. In an arc extinguisher, a plurality of sheet members ofinsulating material having an opening therein in which the arc is caused to play, said opening having a plurality of slots leading therefrom, each of a plurality of said sheet members having a plurality of annular openings therethrough into each of which one of said slots ex-' tends, and means for rotating the are about said annular openings.

22. In an arc extinguisher, a plurality of sheet members of insulating material having an opening therein in which the arc is caused to play, said opening having a plurality of slots leading therefrom, and ventilating spaces extending from between said members of insulating material to the outside thereof.

23. In an arc extinguisher, a plurality of sheet members of insulating material having an opening therein in which the arc is caused to play, said opening having a plurality of slots leading therefrom, for splitting the are into a plurality of parallel connected parts, and each of a plurality of said members of insulating material having a plurality of annular openings therethrough into each of which one of said slots extends, conducting means in each of said annular openings for splitting up the arc therein into a plurality of series connected parts, and means for rotating all of said arcs in said annular openings.

24. The method of extinguishing an are which comprises separating the are into a plurality of parallel arcs and moving each arc in a direction different from another of said parallel arcs.

25. The method of extinguishing an are which comprises separating the arc into a plurality of parallel arcs and moving each arc along a diflerent recurrent path.

26. The method of extinguishing an arc which comprises drawing said are between a pair of members, splitting said are into two parallel arc sections, splitting each of said parallel arc sections into a series of shorter arcs and moving the shorter arcs of each section along curved paths, the direction of movement of the shorter arcs of one section being opposite to the direction of movement of the shorter arcs of the other section.

27. The method of extinguishing an arc which comprises splitting the arc lengthwise into a plurality of parallel related arcs, splitting each parallel related arc crosswise into a plurality of series related arcs and rotating the series related arcs of each parallel related are over different recurrent paths.

28. The method of extinguishing an are which comprises drawing said are between a pair of members, increasing the current density of said arc, moving said are along diverging paths to form two parallel arcs and rotating one of the arcs in a direction opposite to the other 01' said arcs.

29. The method of extinguishing an arc which comprises drawing said are between a pair of members, increasing the current density of said arc, moving said are along diverging paths to form two parallel arcs, splitting each of said parallel arcs into a plurality of serially related arcs and rotating said serially related arcs over recurrent paths, the direction of rotation of some of said serially related arcs being opposite to that of other of said serially related arcs.

30. An arc extinguisher comprising a pair of movable members between which an arc may be drawn, a plurality of spaced conducting plates having slots therein terminating in a pair of diverging branches, said slots being alined to form a Y-shaped groove, means to drive the arc into said groove in a direction toward the diverging branches for causing it to separate into two parallel arc sections, and means for moving each arc section from the terminating end of its respective branch into said conducting plates to sub-divide each arc section into a plurality of serially related arcs playing between said plates.

31. An arc extinguisher comprising a pair of movable members between which an arc may be drawn, a plurality of spaced conducting plates having a pair of annular are conducting portions disposed side by side, each of said conducting plates having a slot therein, said slots having diverging branches, each of which extends toward one of said. annular arc conducting portions, means to drive the are into said slots and into said diverging branches for splitting it in two parallel connected sections, and means to produce radial magnetic fields in said plates for rotating each of said are sections around one of said annular conducting portions.

32. An arc extinguisher comprising a pair of movable members between which an arc may. be drawn, a plurality of spaced conducting plates having a pair of annular arc conducting portions disposed side by side, each of said conducting plates having a slot therein, said slots having diverging branches, each of which extends toward one of said annular are conducting portions, means to drive the are into said slots and into said diverging branches for splitting it in two parallel connected sections, and means to produce radial magnetic fields of opposite polarity about the annular conducting portions for rotating each of said arc sections around one of said conducting portions to thereby separate said are sections into a plurality of serially related arcs.

33. In combination with means for establishing an arc between'a single pair of terminals, means defining a path for constricting said arc, means defining other paths into which portions of said arc may be moved and which also tend to constrict the arc portions playing therein, and means for moving said are into said path and for causing it to split longitudinally into parallel portions which play respectively within said other paths.

34. In combination with a single pair of terminals adapted to draw an are, side walls forming a constricting slot having a main portion and a plurality of branches, means for forcing said arc to play within said main portion and to then split longitudinally and its subdivisions to play separately within said branches.

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