US2037418A

US2037418A - Circuit breaker

Info

Publication number: US2037418A
Application number: US510981A
Authority: US
Inventors: Frederick B Johnson
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1931-01-24
Filing date: 1931-01-24
Publication date: 1936-04-14
Anticipated expiration: 1953-04-14
Also published as: GB388519A; GB388175A; GB394740A; DE592684C; US1927904A; US1896779A; FR750505A; DE591597C; GB399695A; US2100743A; US1927888A; FR730297A

Description

April 14, 19 36. 3 JOHNSON 2,037,418

CIRCUIT BREAKER Original Filed Jan. 24, 1931 3 Sheets-Sheet l INVENTOR (Z d. I fFaen'cKE//7050l7.

BY ATTORNEY April 14, 1936. B, JOHNSON 2,037,418

CIRCUIT BREAKER Original Filed Jan. 24, 1931 3 Sheets-Sheet 2 @2. 171' 9' WITNESSES. I57 5/ INVENTOR (5 4w fFder/cAB Jhhson.

g I 1 Y fw I l ATTORNEY April 14, 1936. F, JOHNSON 2,037,418

CIRCUIT BREAKER Original Filed Jan. 24, 1951 '3 Sheets-Sheet 3 0 42 o o 9 o 9! IRON COPPER INVENTOR /7dend5ffa7nsan AT'i'ORNEY Patented Apr. 14, 1936 UNITED STATES CIRCUIT BREAKER Frederlck B. Johnson, Murrysville, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application January 24, 1931, Serial No. 510,981 Renewed February 2, 1934 48 Claims.

My invention relates to circuit breakers and more particularly to an arc-extinguishing structure therefor having the capability of opening high-voltage, large-current arcs in air or gas.

. The. circuit. breaker of my invention is of the Deion type in which an arc is drawn and moved into a converging slot in a plurality of spaced conducting plates and split up into a plurality of short arcs. The short arcs are rotated at a high velocity between the conducting plates by reason of the force exerted upon them by a radial field set up by coils between spaced groups of the plates.

My invention is a further development of circuit a breakers of the type shown in the copending application of R. C. Dickinson, Serial No. 511,010, filed Jan. 24, 1931, and assigned to the assignee of this application.

' An object of my invention is to provide a blowin field for moving the are into the spaces between the plates without the provision of heavy multi-turn blow-in coils. This is accomplished by providing a plurality of iron yokes in planes perpendicular to the arc current and surrounding the deionizing plates to provide a path for the flux caused by the arc current and concentrate it at the entrance to the deionizing structure to move the arc thereinto. This construction is advantageous in that it eliminates the heating losses which occur when series blow-in windings are used. The insulation of the structure is also much simplified, since all of the parts adjacent to each end of the structure are at.the same potential.

A further object of my invention is to provide a plurality of deionizing plates, each of which is surrounded by an iron plate of approximately the same thickness as the deionizing plate and in the same plane therewith. This makes it possi- 40 ble to leave ventilating passages between both the iron and the copper plates and to allow the iron plates to function as extensions oi the copper plates to provide additional metal for deionizing the arc gases and, at the same time, to provide an increased amount of heat-dissipating surface and to reduce the cost of the structure by reason of the smaller amount of copper required.

A further object of my invention is to provide sheets of insulating material, spacing apart both the iron and the copper plates and to have the insulation so overlap the qoints between the plates as to prevent any possibility of the are playing in the small spaces between the plates.

A further object of my invention is to provide a magnetic core member for supplying an entering field for a deionizlng structure having a narrowed portion adjacent to the entrance to the structure so as to ensure a field of increased strength for moving the are into the structure and which has a wide portion adjacent to the main deionizing structure so that the strength of the field thereacross shall be so reduced as not to interfere with the radial field which rotates the arc.

A further object of my invention is to provide a deionizlng structure in which the force necessary to move the are into the structure and split it into a plurality of short arcs is reduced. This is accomplished by making the converging slots in some of the plates of different lengths from those in the other plates. This causes the arc to be first split into a plurality of sections between the plates having the shorter slots, while each section is in those portions of the other slots which are relatively wide in order that there shall be less resistance to movement of the arc. As the arc is further moved in the relatively wide portions of the longer slots, the radial field coils are energized as the arc is moved over the coilend plates. Burning of the coil-end plates is avoided, since the arc may be moved rapidly because of the widths of the longer slots. As the arc is moved into the tips of the longer slots, each section thereof is then split into a plurality of short arcs.

A further object of my invention is to provide means whereby the force necessary to split each of the sections into a plurality of shorter arcs is provided by the radial field which makes it possible to use a relatively weak entering field.

A further object of my invention is to provide a dcionizing structure having an annular'path for the arc and a. straight blow-in path symmetrically placed in relation to the annular path but in which the arc is moved into the annular path at a tangent thereto because of the provision of a curved arc path connecting the straight and annular paths.

These and other objects and advantages of my invention will be made apparent and more fully understood from the following description of the specific embodiment of my invention illustrated in the drawings, in which:

Figure 1 is a diagrammatic view, partially in section, of my circuit interrupter,

Fig. 2 is a sectional view, through the circuit interrupter, taken through the deionizing plates on the line H-I[ of Fig. 3,

Fig, 3 is a sectional view through the deionizing plates, taken on the line III-III of Fig. 2,

Figs. 4, 5, 6 and '7 are side elevational views of the metal plates which are assembled to form the deionizing structure, and

' Figs. 8 and 9 are elevational views of the sheets of insulating material which are employed to space apart the metal plates.

Referring to Fig. 1, my circuit interrupter ll comprises main contacts l3 and 15, which complete a circuit between conductors l1 and I9, and a pair of arcing contacts 2| and 23 which are connected in parallel with the main contacts l3 and I5. Main contacts I! and I5 and arcing contacts 2| and 23 are actuated by any suitable operating mechanism so that the main contacts l3 and I5 are opened first, with practically no are, and the arcing contacts 2| and 23 are-opened later, drawing an are which is transferred to a pair of stationary arc horns 25 and 21 by means of the moving arc horn 29 which is attached to the moving arcing contact 23. Stationary arc horns 25 and 21 and the moving arc horn 29 are each made of magnetic material, such as iron, to cause a more rapid transfer oi the are due to the attraction thereof to the iron members caused by the local fields set up in the iron by the arc current.

The arcing horns 25 and 21 have arc-terminal portions 3| and 33 and current-conducting portions 35 and 31. The are horns are each connected in parallel with the main contacts l3 and I5 through conductors 39 and 4| which are connected to the outer ends of the current-carrying portions 35 and 31. This causes the current to flow in such, direction in each of the are horns that the magnetic reaction between the fields, due to the current in the arc horns and due to the current in the are, is such as to cause the arc to be moved upwardly on the horns into the deionizing structure.

The deionizing structure comprises a plurality of groups 43 of main deionizing plates having coil sections 45 therebetween. The deionizing plates and coils are assembled between end plates 41 and 49 which are electrically connected to the upper ends of the arc horns 25 and 21. The plates are secured together by means of a through bolt 5| in an insulating tube 53 of a fibrous material impregnated with a condensation resin extending through the deionizing structure. The lower portion of the structure is secured together by a pair of tie rods 55 which may be of wood impregnated with a condensation resin having end pieces 51 and which support the lower outer edges of the deionizing plates, as shown in Fig. 2.

As shown in Figs. 2 and 3, each of the groups 43 of deionizing plates comprises a plurality of copper plates 59, each ofwhich is surrounded by an iron plate 6|, which is placed in the same plane in edge-to-edge relation with the plate 59, as shown in Figs. 2 and 7. By having the copper plates 59 in edge-to-edge relation with the iron plates 6|, heat may be conducted from each of the copper plates to one of the iron plates, thus adding the heat capacity of one of the iron plates to the heat capacity of each of the copper plates and making it possible to use smaller copper plates than would otherwise be possible for a structure of the same interrupting ability. Each of the conducting plates 59 has a narrow extension 63 extending from the lower end thereof and provided with a narrow converging slot 65. The slot 65 is symmetrical with the main portion of the plate 59 and has a converging tip 61 which curves away from the axis of the plate. Each of the magnetic plates 6| has a wide portion 69 surrounding the body portion of the plates 59 and a narrow portion beside the extensions 63 of the copper plates 59.

In order to prevent warping or buckling of the narrow extension 63, such as would close the slot 65 when subjected to the heat of the are, each of the copper plates has a projection 13 which extends into a cutout portion 16 in each of the iron plates 6|. This interlocks the lower ends of the two plates and prevents movement of the narrow extensions 93 out of proper alignment. Each of the copper plates 39 is provided with a slot 15 extending from the center thereoi to the outer edge to prevent the flow of eddy currents, thereby reducing the magnetic losses.

The composite plates formed by the iron plates 9| and copper plates 59 are assembled in groups the individual plates of which are spaced apart by the insulating members 11 and 19 shown in Figs. 2 and 9 and insulating washers 3| around the opening 94 in the center of each of the copper plates 59. Copper plates 59 are so assembled that all or the plates in each group have the curved portion 91 of the converging slot curved to the same side of. the axis of the plates. The slots I5 are positioned on opposite sides of adjacent plates throughout each group, thus eliminating the continuous opening through the stack in which the arc could play, which would result it the slots 15 were on the same side of all of the plates.

The insulating sheets 11 and 19 may be of fish paper and so shaped as to provide an annular path'93 in which the arc is rotated. The insulating spacers l1 and 19 have depending portions and 89 which define a narrow arc path 9| along the slot 65, and a curved portion 93 which leads the are into the annular path 93 along a tangent thereto. Insulating spacers II have projections 34 which extend overthe tips of the slots 61 and prevent the arc irom striking back through the slots on each revolution 01' the are, as it rotates across the tops of the slots. As shown in Fig. 2, the insulating spacers I1 and 19 are made of such width that they overlap the joint between the conducting plates 59 and the magnetic plates 5| adjacent to the path over I which the arc is moved. This prevents the possibility of the are playing in the joints between the plates. Each insulating sheet 19 has a projection 91 defining the upper portion of the annular path and leaving a ventilating opening 99 leading from one side thereof.

Above the extension 91, is provided a rapidly diverging ventilating passage |0| in which the are gases may expand and come into contact with large surfaces of both the iron and copper plates, whereby the gas is rapidly cooled and ions are removed therefrom.

The are horns 25 and 21 are formed of spaced sheets of iron having ventilating passages I03 therebetween. The ventilating passages I93 permit the flow of gas out of the end of the stack ahead of the arc, as it is moved upwardly on the arc horns and also permit upward ventilation through the stack after the arc has been moved into the spaces between the deionizing plates. It is thus seen that a continuous ventilating passage is provided irom the lower end of the arc chamber through the whole deionizing stack. This allows a through flow of gas to rapidly cool the arc and the plates 59 and 6| so that the heat of the arc is rapidly dissipated which allows the circuit interrupter to be used for interrupting heavy currents with a duty cycle, which calls for a large number of successive interruptions of the circuit.

The insulating plates 11 and I9 are assembled in such relation to the copper plates 59 that the curved tips 61 of the slots 65 are aligned, and

the direction of rotation of the are around the annular path 83 is such that the motion of the are adjacent to the ventilating opening 99 is in the opposite direction to the flow of gases out of the passage. This prevents the are from being blown out of the annular path int the ventilating passage by reason of the flow of gas through the stack.

- The are is rotated around the annular path 83 by the action of a radial magnetic field set up by radial field coils I which are spaced between adjacent groups 43 of deionizing plates.

As shown in Fig. 1, the directions of the fields, as indicated by the arrows I01, are opposite in alternate groups 43 of deioniz ing plates. The are is, therefore, rotated in opposite directions in alternate groups of deionizing plates. The positioning of the conducting plates 59 and the insulating spacers 11 and 19 is, therefore, reversed in alternate groups, as is indicated by the broken lines in Fig. 2.

Each of the magnetizing-coil sections 45 comprise a radial field coil I05 which is placed between a pair of coil-end plates I09, as shown in Fig. 5. Each end of each coil I05 is electrically connected to one of the coil-end plates I09. At the lower end of each coil-end plate I09 is positioned a coil-end transfer plate III which is spaced from the coil-end plate I09 by a gap II3.

Each coil-end transfer plate III has a converging slot II5 therein which extends to a point slightly below the gap H3. Each plate I09 has a hole II1, through which the bolt for securing the plates together is passed, and a slot II9 for reducing eddy currents.

A number of transfer plates I2I are positioned between the coll-end transfer plates III below each of the radial field coils I05. Each of the transfer plates I2I has a converging slot I23 similar to the slots I I5 in coil-end transfer plates III. The transfer plates are spaced apart by insulating spacers I25 of fish paper which have a narrow portion I21 to form a path in which the arc is moved and an enlarged circular portion I29 at the upper end of the passage I21.

At each end of the stack of plates and radial field coils is an end plate I3I which is electrically connected in the circuit to be interrupted. Plate I3I has an opening I33 for the through bolt 5|, and a converging slot I35 similar to the slots I23 and H5, as shown in Fig. 4.

As shown in Fig. 2, slots I I5, which are aligned with slots I23 and I35, are shorter and inwardly tapered at a more rapid rate than slots 65 in plates 59. .As the arc is moved up into the aligned slots in all of the plates, the arc is first constricted in the tips of the slots II5, I23 and I35 while still in a relatively wide portion of the slots 65. The are is then transferred to the coil-end transfer plates III and transfer plates I2I, splitting the are into a plurality of short arcs between transfer plates I2I and a plurality of arc sections between plates III. Each of the arc sections may be freely moved into the stack because of the width of the slots 65. As the plurality of sections of the are are moved upwardly, they cross the gap II3 between the coilend plates I39 and coil-end transfer plates III. The voltage drop through the radial coils I05, connected between the plates I 09, is smaller than thatnecessary to maintain the series of arcs between the transfer plates I2I so that the arcs therebetween are extinguished, and the current flows through the radial field coils I05. Since the arc is moving in relatively wide portions of the slots 65 at the time that it crosses the gap II3, there is not much resistance to its movement, so that it crosses the gap II3 without serious burning of the coil-end plates I09.

As the arc is moved farther, the slot 65 gradually converges so that each of the arc sections is concentrated into an arc of high current density and small cross section. The arc is then above the narrow extensions H on the magnetizing plates 6| so that it is no longer acted upon by the blow-in field but is within the much stronger field set up by the radial coils I05 which provide a field of such strength that the arc may be rapidly moved along the tips 61 of-the slots 65 and split between the plates 6|. This use of the radial field for splitting each section of the are into a plurality of short arcs is advantageous in that it is not necessary to provide a blow-in field of such strength ,as to provide the force necessary to split the are into a plurality of short arcs. The arc then enters tangentially into the annular path 83 and is rapidly rotated until the occurrence of the zero point on the alternating-current wave, when it is extinguished.

As shown in Figs. 1 and. 2, a plurality of iron laminations I31 are provided to form extensions of the iron plates GI beside the arc-drawing contacts and arc horns. The iron laminations I31 are spaced apart by sheets of fish pamr I39, shaped similar to the iron plates I31. The lengths of the laminations I31 are varied in different sections of the deionizing structure. The end sections II are made of such length as to extend to the arc horns and 21. The section I43 adjacent to the arcing contacts 2| and 23 and main contacts I3 and I5 are made longer than the other sections so as to extend to a point adjacent to the contacts to blow the are into the deionizing structure. The intermediate section I45 is of a length between those of the other 1 'sections so as to extend beside the moving arc horn 29. The provision of iron laminations I31 provides an iron path for the flux set up by the arc current as soon as the arc is drawn, in order to move the are into the deionizing structure in cooperation with the flux set up by the current fiowing in the arc-terminal portions 3| and 33 of arc horns 25 and 21. The edges of laminated members I31 are protected from the arc by fibre plates I41 having arc-resisting inserts I49 of asbestos or other suitable material. An insulating sheet of fish paper I50 is placed in the joint between the la wer edges of the deionizing plaes and the iron laminations I31 and also extends between the laminations I31 and fibre plates I41. The iron laminations I31 and fish paper spacers are secured in the structure by being clamped between wood blocks I5I and the fibre plate I41.

A static shield is provided in the form of a pair of sheets I53 of insulating material, such as a fibrous material impregnated with a condensation resin and having sheets of tinfoil I55 embedded therein.

From the above description, it is seen that my invention provides an air circuit breaker which is capable of interrupting large currents at high voltages in a most effective manner.

While I have described a specific embodiment of the invention, it should be understood that the various novel features thereof may be used in various combina ions. and I am not to be limited by the specific description except as indicated by the scope of the following claims.

I claim as my invention:

1. In an arc-extinguishing structure, a plurality of sheets of conducting material having slots therebetween.

3. In an arc-extinguishing structure, a plurality of non-magnetic conducting plates having V-shaped slots therein, and a magnetic plate having a portion in engagement with, and surrounding, each one of said non-magnetic conducting plates, but insulated from each of the other of said magnetic and non-magnetic conducting plates.

4. In an arc-extinguishing structure, a plurality of sheets of conducting material having slots therein, and means for moving the arc in said slots comprising a plurality of sheets of magnetic material positioned in planes parallel to said sheets of conducting material and having narrowed portions for providing a magnetic, field of increased strength adjacent to said slots.

5. In an arc-extinguishing structure, a plurality of non-magnetic conducting plates each having a narrow extension, and a plurality of magnetic plates in edge-to-edge engagement with said non-magnetic conducting plates and their extensions.

6. In an arc-extinguishing structure, means for deionizing the arc, and means for moving the arc into said deionizing means comprising a pluraliy of spaced magnetic plates having wide portions surrounding said deionizing means and narrow portions adjacent to the point where the arc is moved into said deionizing means.

7. In an arc-extinguishing structure, a plurality oi. spaced sheets of conducting material, means for rotating the are between said sheets, and

I in a continuous curve among said deionizing members, and means for moving the arc to a position where it is acted upon by said first mentioned moving means comprisinga plurality of magnetic members surrounding said deionizing members and having ventilating passages therebetween continuous with said ventilating passages between the deionizing members.

9. In an arc-extinguishing structure, a plurality of composite plates, each of said plates having a portion of magnetic material and a portion of non-magnetic niaterial which closely fit into each other, and a slot in which the arc is moved in said portion of non-magnetic material.

10. In an arc-extinguishing structure, a plurality of composite plates, each of said plates having a portion of magnetic material and a portion of non-magnetic material which closely fit into each other, and means for giving the are a rotary motion on said portion of non-magnetic material.

11. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of conducting plates and a plurality of magnetic plates positioned in edge-to-edge relation, and means for preventing the are from playing between the abutting edges of said plates, said means overlapping said abutting edges.

12. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality oi conducting plates and a plurality of magnetic plates positioned in edge-to-edge relation, and insulating members overlapping portions oi the abutting edges of said plates.

13. In an arc-extinguishing structure, a plurality of conducting plates and a plurality of magnetic plates assembled in pairs with one of the plates of conducting material and the other of magnetic material, and insulating sheets between both said conducting and said magnetic plates separating each pair 01' said plates from the adjacent pairs.

14. In an arc-extinguishing structure, a plurality of conducting plates and a plurality of magnetic plates, and insulating sheets extending from between said conducting plates to between said magnetic plates, said insulating sheets defining a passage in which the arc may be moved between said plates of conducting material.

15. In an arc-extinguishing structure, a plurality of conducting plates and a plurality oi magnetic plates, and insulating sheets extending from between said conducting plates to between said magnetic plates, said insulating sheets defining a passage in which the arc may be moved between said plates and permitting a through flow of gas between said plates.

16. InXan arc-extinguishing structure, means for deionizing the arc comprising a plurality of composite plates having central portions of nonmagnetic material and edge portions of magnetic material in engagement with said central portions, said composite plates being spaced apart by insulating members defining an annular path for the arc.

17. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of composite plates having a central portion of nonmagnetic material and edge portions of magnetic material, said composite plates being spaced apart by insulating members defining an annular path for the arc and continuous ventilating passages between both portions of said plates leading from said annular path for the are.

18. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of composite plates having a central portion of nonmagnetic material and edge portions of magnetic material, said composite plates being spaced apart by insulating members defining an annular path for the are, said insulating members extending across the joints between said central and edge portions adjacent to said are path.

19. In an arc-extinguishing structure, a plurality of sheets of non-magnetic material and a plurality of sheets of magnetic material spaced apart by a plurality of sheets oif insulating material and means providing a through ventilating passage between both said sheets of nonmagnetic and said sheets of magnetic material.

20. In an arc-extinguishing structure, a plurality of spaced conducting members providing an arc path having a looped portion and a straight portion symmetrically disposed relative thereto and having a curved portion connecting said straight and looped portions substantially tangent to said looped portion.

21. In an arc-extinguishing structure, a plurality of spaced conducting members providing an arc path having a looped portion and a straight portion symmetrically disposed relative thereto and having a curved portion connecting said straight and looped portions substantially tangent to said loopedportion, and means for producing a radial magnetic field adjacent to said looped and curved connecting portions of said arc path.

22. In an arc-extinguishing structure, a plurality of spaced conducting members having a plurality of insulating sheets therebetween defining an arc path having a looped portion and a straight portion symmetrically disposed relative thereto and having a curved portion connecting said straight and looped portions substantially tangent to said looped portion;

23. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of spaced conducting sheets, each of said sheets having a slot therein having a straight portion and a curved tip.

24. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of spaced conducting sheets, means for causing a radial magnetic field between said sheets, each of said sheets having a slot therein having a straight portion and a curved tip, the end of which is substantially normal to said radial field.

25. In an arc-extinguishing structure, means for deionizing the arc comprising a plurality of spaced conducting sheets, each of which has a body portion and an extension, means for causing a radial magnetic field adjacent to the body portion of said sheets, each of said sheets having a slot in said extension and extending into said body with the tip thereof substantially normal to said radial field, and means for causing a lateral magnetic field across the slot in said extension.

26. In an arc-extinguishing structure, a plurality of spaced plates of conducting material, each of said plates having a slot therein in which the arc moves, the slots in some of said plates being of less length than those in other of said plates, and means for setting up a radial magnetic field before the arc reaches the ends of the longer slots.

27. In an arc-extinguishing structure, a plurality of spaced plates of conducting material, each of said plates having a tapered slot therein in which the arc moves, the slots in some of said plates having a greater taper than the slots in other of said plates, and a radial field coil energized before the arc reaches the ends of the slots having the smaller taper.

28. In an arc-extinguishing structure, means for splitting the are into a plurality of sections, means for energizing a magnetizing coil at an interval of time after the arc is split up into said sections, and means for later splitting each of said sections into a plurality of short arcs.

29. In an arc-extinguishing structure, a plurality of plates of conducting material, some of said plates having portions extending beyond the corresponding portions of other of said plates, means for moving the are into said longer plates to split the are into a, plurality of sections and energizing means for causing a radial field, said radial field further moving the arc into said other plates to split said sections into a plurality of short arcs.

30. In an arc-extinguishing structure, a plurality of plates of conducting material, means for splitting the arc into a plurality of sections between certain of said plates, and means con to be split into a plurality of short arcs.

31. In an arc-extinguishing structure, a plurality of spaced plates of conducting material,

each of said plates having a slot therein, the slots in some of said plates being of less length than in other of said plates, and means for setting up a magnetic field connected between plates forming a continuation of said plates having slots of less length than those of said other plates.

82; In an arc-extinguishing structure, a plurality of spaced plates of conducting material, each of said plates having a tapered slot therein, the slots in some of said plates having a greater taper than the slots in other of said plates, and a magnetizing coil for setting up a magnetic field adjacent to the tips of said slots having the smaller taper connected between a pair of plates forming a continuation of said plates having slots with the greater taper.

33. In an arc-extinguishing structure, a plurality of spaced plates of conducting material, each of said plates having a slot therein, the slots in some of said plates being of less length than those in other of said plates, the slots of greater length in said other plates having curved tips, and a magnetizing coil for setting up a radial field adjacent to said curved tips, said coil being connected between a pair of plates in the same plane as said plates having slots of less length.

34. In an arc-extinguishing structure, a plurality of plates of conducting material/some of said plates having portions extending beyond the corresponding portions of other of said plates for splitting the are into a plurality of sections and means for rotating the arc connected between said are sections.

35. In an arc-extinguishing structure, means for splitting. the arc into a plurality of sections comprising a pair of plates having slots therein, means for connecting a magnetizing coil in series with said are sections, and means for further splitting said sections into a plurality of short arcs comprising a plurality of plates having slots extending beyond the slots in said first-mentioned plates.

36. In an arc-extinguishing structure, a plurality of spaced plates of conducting material, each of said plates having a slot therein, the slots in some of said plates being of less length than those in other of said plates, some of said plates having the shorter slots having their top edges below the tops of said longer slots and a plate having a magnetizing coil connected thereto and extending below the top of said longer slots.

' 3'7. In an arc-extinguishing structure, means for splitting the are into a plurality of sections comprising conducting plates having slots therein, means for moving the ends of said arc sections over coil-end plates having a magnetizing coil connected therebetween, and means for thereafter parallel therewith, and separate members 01' magnetic material insulated from said plates 01 magnetic material extending from the lower ends of said plates of magnetic material to a point ad- Jacent to said arc-drawing means.

39. In an arc-extinguishing structure, a plurality of conducting plates and a; plurality oi magnetic plates co-planar therewith, and means for interlocking said conducting and said magnetic plates comprising a projection on one of said plates and a recess in the other of said plates.

40. In an arc'extinguishing structure, a plurality oi non-magnetic conducting plates and a plurality of magnetic plates, said magnetic plates being positioned with one edge portion engaging one of said conducting plates and being insulated from the other of said non-magnetic conducting plates and the other of said magnetic plates by insulating plates, and some 01' said plates having overlapping edge portions preventing the arc from playing between the adjacent edges of the plates of non-magnetic conducting material and the plates of magnetic material 41. In an arc extinguishing structure, a plurality of non-magnetic conducting plates and a plurality of magnetic plates, said magnetic plates being positioned with one edge portion engaging one of said conducting plates and being insulated from the other of said non-magnetic conducting plates and the other of said magnetic plates by insulating plates, and some of said plates having overlapping edge portions preventing the are from playing between the adjacent edges of the plates of non-magnetic conducting material and the plates of magnetic material, and continuous open es extending from between said nonmagnetic conducting plates to between said magnetic plates and to the outside of said structure.

42. In an arc extinguishing structure, a plurality 01" plates of conducting material each providing an annular path for the are, each 01' said plates having a slot therein, and the tips of said slots in semen! the plates leading into one side oi said annular path and the tips of the slots in other of said plates leading into the other side or said annular path. I

43. In a circuit interrupter, means for causing an arc, and an arc extinguishing structure including a plurality of means of conducting material each providing a path for movement of the arc thereon, each of said means of conducting material having a slot therein extending from adjacent said means for causing the arc to a point adjacent said path for movement of the are on said plates, the portions 01' said slots adjacent said means for causing the are being aligned forming a groove, and the other ends of said slots in some of said plates diverging from the corresponding ends 01' said slots in other of said plates.

44. In a circuit interrupter, means for causing an arc, and an arc extinguishing structure including a plurality oi. meansof conducting material each having an annular path for the arc thereon, means for causing a radial magnetic field for rotating the are about said annular paths, the sense of said field being opposite in adjacent sections of said means of conducting material for rotating adjacent sections of the arc in opposite directions, each of said means of conducting material having a slot therein, all of said slots being aligned at one end adjacent said means for causing the arc, and the other end of said slots in one section extending toward said one side of said annular path normal to said radial field and the corresponding end oi the slots in the other section extending toward the other side of said annular path normal to said radial field.

45. In an electric switch or circuit breaker, the combination of a fixed and a movable contact piece, a plurality oi spaced plates arranged at right angles to the direction of movement of the movable contact, apertures in the plates through which the are drawn by the movable contact can play, means for providing a magnetic field having its central longitudinal axis passing through the plates and situated at one side of the said apertures in the plates, said means including a magnet winding situated at one end of a plurality of said plates, and said winding being energized while the arc plays in saidapertures so as to move and break up the arc incident to the opening of a circuit and to simultaneously whirl the arc portions through circular paths between the plates.

' 46. In an arc extinguisher, a plurality of spaced plates of conducting material each providing an annular path for the are, a coil for setting up a radial magnetic field across said annular arc paths, an opening through a plurality of said plates of conducting material, said opening having a portion within said radial magnetic field, means for causing an arc to play in said opening, and said coil being energized while the arc plays in said opening in a plurality of said plates whereby the radial magnetic field set up by the coil moves the are from the opening into the plates and splits it up into shorter arcs.

47. In an arc extinguisher, a plurality of spaced plates of conducting material each providing an annular path for .the are, a coil for setting up a radial magnetic field across said annular arc paths, an opening through a plurality of said plates of conducting material, said opening having a portion within said radial magnetic field, means for causing an arc to play in said opening, said coil being connected to one or more .of said plates and said arc playing on said plate or plates to which the coil is connected while it plays in the openings through the other plates to energize the coil whereby the radial magnetic field set up by the coil moves the are from the openings into the plates where it is split up into shorter arcs.

48. In an arc extinguisher, a plurality of members of conducting material between which the arc may be split up into shorter arcs, said conducting members each providing a recurrent path about which the short arcs may be rotated, a coil for causing a magnetic field for rotating the arcs, an opening through a. plurality of said members of conducting material, means for causing an arc to play in said opening, said opening having a portion within the magnetic field for rotating the arc, and said coil being energized while the arc plays in said opening through a plurality of said members of conducting material whereby said magnetic field caused by the coil for rotating the arc is effective for moving the are from said opening and causing it to be split up into shorter arcs between said members of conducting material.

FREDERICK B. JOHNSON.