US2071157A - Circuit breaker - Google Patents

Description

Feb. 16, 1937. p A E 2,071,157

CIRCUIT BREAKER Filed Aug.' 25, 1933 5 Sheets-Sheet 1 l 1 WITNESSES. INVENTOR 5 d W Be bm/h PBaAen TTOR Y Feb. 16, 1937.

Filed Aug. 25, 1933 3 Sheets-Sheet 2 7 INVENTOR Eery am/hPBQK/T 0 3 0 m 6 ay w a 7 w z a 4w a 4 w 4 4 v w x w w 4 3 w a w W WITN 7b opera f/ng mechanism.

B. P. BAKER CIRCUIT BREAKER Feb. 16, 1937.

Filed Aug. 25, 1953 5 Sheets-Sheet 3 l'nsu/afion I'nJu/af/on a INVENTOR Be bm/h PBaA er'.

WITNESSES:

Patented Feb. 16, 1937 UNITEDSTATES PATENT OFFICE CIRCUIT BREAKER Benjamin P. Baker, Turtle Creek, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 25, 1933, Serial No. 686,764

30 Claims.

connecting a load device, such as a transformer,

to a high-voltage system. This has necessitated the use ,of two individual sets of apparatus comvide for incorporating a circuit breaker structure in the lead-in bushingof a load device, such for example, as a transformer.

Another object of my invention is to provide for opening the circuit to a load device in several series sections.

Still another object of my invention is to provide for rapidly extinguishing arcs formed between several series connected contact members ,prising the circuit breaker and the transformer i Y which have required a considerable space for their occupancy. When a sub-station is located in the densely populated district where space is at a premium, such an arrangement causes the expense of the installation to be increased merely .for the purpose of providing sufficient room. to mount the necessary electrical apparatus. In addition, when separate devices are provided, it has been necessary to provide for their separate insulation which is also an important factor in the economics of operation of a power distribution system. 7 v It has been proposed to combine these two types of apparatus into a single unitary structure in order to reduce the'required space therefor, and also to utlize the insulation of the load device for the circuit breaker device. However, this has lead to considerable difliculty and it has heretofore been impractical until the provision of this'invention for extinguishing the arcs formed on openingof the circuit breaker which will-be set forth indetail hereinafter. In general, I propose to mount the which are providedwith a transformer for insulating the power conductors from the case or tank'. This form of mounting inherently provides a relatively great degree of insulation, since it is particularly designed to withstand the voltages which are to be a lied to the transformer windings. It is, the fore. unnecessary to circuit breaker within the customary insulator bushings by rotating the arcs through the agency of a radial magnetic field.

A further object of my invention is to provide for simultaneously opening several series con-- nected contact members and extinguishing the arcs drawn therebetween by rotating them between grid plates by means of a radial magnetic field.

A still further object of my invention is to provide for uniformly distributing the potential among the arc extinguishing devices surrounding a plurality of series connected contact members when the area are extinct.

Other objects of my invention will in part be obvious and in part appear hereinafter.

My invention accordingly is disclosed in the embodiment hereof shown in the accompanying drawings and comprises'the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims;

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description taken in connection with the accompanyi s drawings,

in which- Figure 1 is a view, partly in side elevation and partly in section, illustrating the application of myinventionto a transformer;

Fig. 2 is an enlarged sectional view showing, in

' part, the details of construction of my novel cirprovide additional insulation for the circuit' breaker mechanism with the result that the cost of the combined unit of circuit breaker apparatus and load device is materially reduced. It will, of course, be apparent that the space requirements for a combination constructed in accordance with my invention will also be materially reduced.

The object of my invention, generally stated, is;

to provide circuit breaker equipment for a load device which shall be simple and'efiicient in operationand which may be readily and economically constructed and installed.

The principal object of my invention is to procult breaker, certain duplicate elements being omitted for the sake of clearness;

Fig.3isasectionalvie tak alongtheline III-4'11 of Hg. 2; and

Figs. 4 through 8 illustrate certain constructional details used in the ly of the arc extinguishing device illustrated in Fig. 2.

v For the purpose of illustration. my invention hasbeen showninl'ig. lasappliedtoatransformer for a load device. .However, it will be readily understood that the application of my 111- I yention is not limited to use with a transformer and that it may be used with any other suitable type of load device. It will also be understood that my invention may be utilized in the form of a suspension insulator mounted on a transmission line tower or the like, if it is so desired.

As illustrated, in Fig. 1 of the drawings, a transformer, shown generally at iii, is provided, having a core Hand a winding i2 immersed in insulating -oil E3 in the customary and well known manner. A tank 4 is provided for the transformer it having a cover l5 on which. leadin bushings iii may be mounted. The lead-in bushings it are mounted on the cover [15 and. extend into the tank it, as shown. The winding i2 is connected by means of conductors ill tothe insulating bushings it in the usual manner. Connection with power lines it? is had by means of terminals i 9 mounted on the upper ends of the insulator bushings i6.

As will be more fully set forth hereinafter, a circuit breaker is mounted within the insulator bushing iii and an operating mechanism comprising an armature Eli and a winding 25 are provided, individual to each circuit breaker, for effecting its operation to either the open or the closed position. The movement of the armatures 23 is communicated to the circuit breakers by means of lift rods 22. It will be understood that the control of the energization of the winding 2! may be effected by any well known control means and, therefore, a detailed description of it will not be given in this specification.

Referring now particularly to Fig. 2 of the drawings, it will be observed that the circuit breaker structure, which may be mounted within the insulator bushing i8, is shown. In order to more clearly illustrate the important details of my invention, the insulator bushing i6 is en tirely omitted from this figure of the drawings and the supporting framework is shown in section. The entire mechanism illustrated in Fig. 2 may be mounted within the insulator bushing i 6, as will be readily understood, thereby taking advantage of its insulating properties without necessitating the provision of additional insulatmg bushings for the circuit breaker structure itself.

As illustrated, the frame, shown generally at 28, comprises upper and lower end plates 29 and 30, respectively, between which suitable holding members for the circuit interrupter structure are provided. These holding members comprise the insulating rods 5| which engage the notches in the edges of the plates shown in Figs. 3 to 6, inclusive, and the insulating tube 3| having a ring 6| at each end, to lugs on which the end plates 29 and 30 are bolted. The terminal I 9 is connected to an upper end cup 32 while the conductor ll may be connected to a suitable lower end cup 33, the connections to which are not shown in detail.

Between the upper and lower end cups 32 and 33, a plurality of fixed and movable contact members 34 and 35 are provided which are arranged to be connected in series circuit relation by means of flexible shunts 36. It will be readily understood that the number of sets of contact members 34 and. 35 will depend upon the voltage which is to be applied to the load device. Thus, if a relatively high voltage is to be applied it is desirable to provide a relatively large number of contact members 34 and 35 in order to provide for more readily opening the circuit with a. minimum of disturbance.

The fixed contact members 34 are secured to disks 3'! around which windings 3B are disposed,

the purpose for which will be set forth in detail hereinafter.

As illustrated, the movable contact members are mounted transversely of the lift rod 22 in suitable slotted openings 40 and are biased upwardly by means of springs 4| which are disposed between the underside of the movable contact members 35 and plugs 42 which are secured to the lift rod 22 by means of rivets 43. It will be observed that, as the lift rod 22 is moved downwardly, the movable contact members 35 will be moved downwardly when the ends of the slots 40 are encountered. However, until this engagement takes place, the contact members 34 and 35 will be maintained in engagement by means of the springs M.

The flexible shunts 36 are connected to coil plates 55 which are disposed above the windings 33 and which are more clearly illustrated in Figs. 6 and 8 of the drawings. It will then be observed that the terminal i3 is connected to the conductor i'l through a plurality of series-connected separable contact members 34 and 35. Thus, when these contact members are moved to the open positions several air gaps are provided in the circuit thereby splitting up the single arc,v which would normally be formed, into several arcs provided that all of the contact members are opened simultaneously. ,The voltage stress which is applied to any particular set of contact members is considerably reduced from that which would be applied if only a single set of contact members were used. Because of this arrangement, it is not necessary to separate the contact members 34 and 35 to the extent that would be necessary if a single equivalent set of contact members were used.

When the lift rod 22 is moved downwardly, so that arcs individual to each of the sets of contact members 34 and 35 will be drawn, it is essential that these arcs be extinguished as rapidly as possible in order to avoid damage to the circuit breaker. For this purpose, 'deionizing devices, shown generally at 41, are provided comprising a plurality of metal grid plates 48 preferably of copper and more clearly illustrated in Fig. 5 of the drawings. The metal plates 48 are provided with openings 48a having tapered portions 481) for the purpose of providing a path for the are which is formed between the contact members 34- and 35. As shown in Fig. 3 of the drawings,

.the movable contact members 35 are disposed within the openings 48a.

Only two of the deionizing devices 41 are illustrated in the drawings but it will be understood that each set of contact members 34 and 35 is provided with one of them to provide for rapidly extinguishing the arcs drawn therebetween.

In order to provide for insulating the plates 48 from each other, an outer insulating ring 43 is provided at the outer edge thereof while inner insulating segments 50 are provided around the openings 48a. These insulation pieces 49 and 5B are shown more clearly in Figs. 4. and '7 respectively of the drawings and their assembly with the grid plate 48 is shown in Fig.3. Insulating rods 5i are provided for lining up the elements of the deionizing devices 41 and securing them in position.

With a view to providing for rotating the arcs .formed between contact members 34 and 35,

until they are extinguished, the windings 38 are provided as hereinbefore set forth, which are arranged to generate a radial field between t e grid plates 48 on flow of current therethrou h.

The radial field generated by the windings 38 causes the several arcs to traverse paths which may be indicated by the dotted lines 52 or 53 and 54 in Fig. 3. It will be readily understood that the arcs may be formed at either end of the movable contact members 35 and that they mayfollow either of the paths indicated by the dotted lines 52 and 53 to intersect the paths indicated by the dotted line 54. It will be understood that the inner terminals of the windings 38 may be connected to the disks 31 which are connected in turn to the fixed contact members 34 while the outer terminals thereof may be connected to the coil plates 45' beneath the windlugs 38 or vice versa, as the case may be.

y In order to insure that the arcs formed between the contact members 34 and 35 are transferred to the plates 48, the coil plates 45 above the coils are provided with upstanding leaf portions or tabs 58 which are disposed along the paths of the arcs between these contact members and to which the arcs tend to transfer as the contact 'members 35 are moved to the open positions.

The other end of the arc transfers from the fixed contact 34 to the coil plates 45 below the coils. The are current is thus caused to quickly flow through the windings 38 thereby instantaneously establishing the desired radial field for rotating the several arcs between the grid plates 48. It will be understood that the windings 38 are normally de-energized and that load current does not flow through them except when arcs have formed between the contact members 34 and 35 and transferred to the coil plates 45 and 45' which form arc terminal members extending from the annular path to points closely adjacent the contacts 34 and 35 in order that the arc may quickly transfer from the contacts 34 and 35 to the coil plates 45 and 45'.

Since the direction of the radial field on the lower sides of the windings 38 is opposite to its direction on the upper sides, alternate deionizing devices are provided with the grid plates 48 in reversed position. Thus, on one side of the wind- 45'- ings 38, the arcs will be rotated in one direction while on the other side they will be rotated in the opposite direction. The terminals of the windings 38 are properly connected so that the direction of fields generated thereby between them will be the same.

Assuming that operating potential is applied to the power conductors l8 and load current is being supplied to the transformer II), the circuit breaker may be operated to the open position by permitting the lift rod 22 to move downwardly. when the winding 2| is de-energized. As soon as the lift rod 22 is moved downwardly, arcs will be formed between the several contact members 34 and 35 and the ends of the arc will be transferred from the contact members 34 and 35 to the coil plates 45', and to the arcing leaves 58 of the coil plates 45 as they are passed by the movable contact members 35. Current will then be caused to flow through the windings 38, thereby setting up aradial field between the grid plates 48 and causing the arcs to be split up into several series of short arcs between these plates and to travel along the paths indicated by thedotted lines 52 or 53 and 54. The rotation of these short arcs will be continued by the respective radial flelds generated by the windings 38 until they are extinguished.

When the arcs are extinguished, it willbe apparent that the potential distribution between the series connected contact members and along the plates 48 will be non-uniform due to their capacity effect. In order to prevent this nonuniform distribution oi potential, static shield layers 53 and 88 of conducting material are pro vided along the plates 48 but insulated therefrom by being embedded in the tube 3|, thereby serving to more uniformly distribute the potential along the structure.

Since certain further changes may be made in the above construction and different embodimerits of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable contact members between which a plurality of arcs may be drawn, said sets of contact members being connected in series circuit relation, and arc extinguishing means individual to each set of contact members and disposed adjacentto the arc paths therebetween, said arc extinguishing means comprising a plurality of metal plates adapted to sub-divide the arcs into a series of short arcs, said metal plates providing recurrent paths for the short arcs and said metal plates having openings therethrough, and operating means movable in said openings for actuating the movable contact members to the open position.

2. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable contact members between which a plurality of arcs may be drawn, said sets of contact members being connected in series circuit relation, operating means for actuating said contact members to ,either the open or the closed position, and are extinguishing means individual to each of a plurality of said sets of contact members comprising a plurality of metal plates each having an annular portion extending around said contact members and disposed to subdivide the arcs into a plurality of series of short arcs, and means for causing said short arcs to move about recurrent paths on said annular portions of the plates for extinguishing the short arcs.

3. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable contact members between which a plurality of arcs may be drawn, said sets of contact members being connected in series circuit relation, operating contact members for said short arcs, and means.

for creating a radial magnetic field between said plates for causing said short arcs to rotate along said recurrent paths. 3

4. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable contact members between which a plurality of arcs may be drawn, said sets of contact members being connected in series circuit relation, operating means for actuating said contact members to either the open or the closed position, a plurality of sets of metal plates each set being individual to and surrounding one set of contact members and disposed to subdivide the arcs into a plurality of series of short arcs. the configuration of said plates being such as to provide recur rent paths around said contact members for said short arcs, and generating means disposed substantially concentrically with the aids of move ment of said movable contact members for creating a radial magnetic field between said plates for causing said short arcs to rotate along said recurrent paths.

5. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable con tact members between which a plurality of arcs may be drawn, saidsets of contact members be ing connected in series circuit relation, operating means for actuating said contact members to either the open or the closed position, and a plu rality of arc extinguishing devices, each being individual to one set of contact members and each comprising a plurality of metal plates surrounding the contact -members and operating means and disposed to subdivide the are drawn therebetween into a series oi short arcs, the shape of said metal plates being such as provide recurrent paths around said contact members for said short arcs, and a winding connected in series circuit relation with said plates and adapted on flow of current therethrough to generate a radial field between said plates for causing said short arcs to rotate along said recurrent paths.

6. A circuit breaker comprising, in combination, a plurality of sets of fixed and movable contact members between which a plurality of arcs may be drawn, said sets of contact members being connected in series circuit relation, operating means for actuating said contmt members to either the open or the closed position, and a plurality of arc extinguishing devices, each being individual to one set of contact members and each comprising a plurality of metal plates surrounding the contact members and disposed to subdivide the arc drawn therebetween into a series of short arcs, the shape of said metal plates being such as to provide recurrent paths for said short arcs, a winding connected in series circuit relation with said plates and adapted on flow of current therethrough to generate a radial field betweemsaid plates for causing said short arcs to rotate along said recurrent paths, and an arc horn positioned inside of the recurrent paths provided by said plates for facilitating the transfer of the are from the movable contact member to the metal plates surrounding it.

7. A circuit breaker comprising, in combination, a. plurality of sets of fixed and movable contact members between which a plurality'of arcs may be drawn, said sets of contact members being connected in series circuit relation, operating means for actuating said contact members to either the open or the closed position, and a plurality of arc extinguishing devices, each being individual to one set of contact members and a each comprising a stack of metal plates surroundlng the contact members and disposed to subdivide the are drawn therebetween into a series of short arcs, the shape of said metal plates being such as to provide recurrent paths for said short arcs, a winding connected in series circuit relation wlth said plates and adapted on flow of current therethrough to generate a radial field between said plates for causing said short arcs to rotate alongsaid recurrent paths, and a plurality of arcing plates disposed at intervals in said stack and each being provided with an upstanding portion disposed adjacent the path of one of the movable contact members for effecting the ormer transfer of the arc to the upstanding portions to facilitate its transfer to the metal plates.

8. In a circuit breaker, in combination, a fixed and a movable contact member between which an arc may be drawn, a plurality of metal plates sur' rounding the contact members for subdividing the are drawn therebetween into a series of short arcs, and an arcing plate provided with an upstanding portion disposed adjacent the path of the movable contact member for effecting the transfer of the arc thereto for facilitating its transfer to the metal plates.

9. in a circuit breaker, in combination, a fixed and a movable contact member between which an arc may be drawn, a plurality of metal plates completely surrounding the contact members for subdividing the are drawn therebetween into a series of short arcs, the shape of said metal plates being such as to provide recurrent paths for said short arcs, a winding connected in series circuit relation with said plates and adapted on flow of current therethrough to generate a radial field between said plates for causing sm'd short arcs to rotate along said recurrent paths, and an arcing member provided with a portion extending from said recurrent path into the inside thereof adjacent to the path of the movable contact member for efiecting the transfer of the arc thereto for facilitating its transfer to the metal plates.-

10. Electrical apparatus comprising, in combination, a load device, a plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and incorporated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of fixed and movable contact members connected in series circuit relation, and operating means including a rod movable longitudinally in said insulator bushing and operatively connected to each of a plurality of said movable contact members for actuating them simultaneously to either the open or the closed position, said operating means having its moving parts enclosed within said electrical apparatus.

ll. Electrical apparatus comprising, in combination, a load device, a plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and incorporated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of sets of series-connected fixed and movable contact members between which a. plurality of arcs may be drawn, and are extinguishing means for each of a plurality of said sets of contact members and disposed adjacent to the arc paths therebetween for extinguishing said arcs, and an operating rod movable in said insulator bushing and connected'to each of said movable contacts for simultaneously actuating said contact members to either the open or the closed posltion.

12. Electrical apparatus comprising, in combination, a load device, a. plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and incorporated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of sets of series-connected fixed and movable contact members between which a plurality of arcs may be drawma plurality of sets of metal plates, each set being individual to one set of contact members for subdividing said arcs into a series of short arcs, said plates being so formed as to provide recurrent paths for said short arcs, and means for creating a radial magnetic field between said plates for causing said short arcs to rotate along said recurrent paths, and operating means connected to'each of said movable contact members for actuating said movable contact members to either the open or the closed position.

13. Electrical apparatus comprising, in combination, a load device, a plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and incorporated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of sets of series connected fixed and movable contact members between which a plurality of arcs may be drawn, a plurality of sets of metal plates, each set being individual to and surrounding one set of contact members for subdividing the arcs into a plurality of series of short arcs, the configuration of said plates being such as to provide recurrent paths for said short arcs, and a winding connected in series cir- -cuit relation with said plates and disposed on flow of current therethrough to generate a radial field between said plates for causing said short arcs to rotate along said recurrent paths, said plates having openings therethrough within the outer periphery of said recurrent paths, and operating means movable through said openings for actuating said contact members to either the open or the closed position.

14. In a circuit breaker, in combination, fixed and movable contact members between which an arc may be drawn; a plurality of spaced apart metal plates adjacent the contact members for subdividing the arc drawn therebetween into a series of short arcs, a normally deenergized winding adapted to be connected in series circuit relation with said plates for generating a radial field therebetween, a pair of arc terminal members one of which extends to a point closely adiacent'to said fixed contact and the other of which comprises an arcing horn extending to a point closely adjacent the path of the movable contact member for effecting the transfer of the arc to the arc horn, and said winding for gen-. erating a radial field being energized upon the transfer of the arc to said are terminal members.

15. In a circuit interrupter, means for establishing an arc, means for extinguishing said arc.

' ing energized upon the transfer of one end of the are from the means for establishing the arc to said are terminal member.

16. In a circuit interrupter, means for establishing an arc, means for extinguishing said arc, including conducting members providing an annular path about which the arc may be rotated,

conducting means which when energized sets up a radial magnetic field for rotating the arc about said annular path, arc terminal means extending from said annular path to a point closely adjacent the path where said are is initially established to permit the arc to immediately transfer to the arc terminal member, said are terminal means being connected to said conducting means and causing energization thereof. upon the transfer of one end of the arc to said arc terminal means, and said are terminal means being positioned within the radial magnetic field set up by said conducting means whereby the arc is moved thereon by the radial magnetic field.

1'7. In a circuit interrupter, means for establishing an arc, means for extinguishing said arc including conducting members providing an annular path about which the arc may be rotated, said means for establishing the are being positioned within said annular path, conducting means which when energized sets up a radial magnetic field for rotating the are about said annular path, arc terminal means extending from said annular path toward the center thereof to a point closely adjacent the path where said are is initially established, said are terminal means being connected to said conducting means and causing energization thereof upon the transfer of one end of the arc to said arc terminal means, and said arc terminal means being positioned within the radial magnetic field set up by said conducting means whereby the arc is moved thereon by the radial magnetic field.

18. In a circuit interrupter, a plurality of members of conducting material, each of said members of conducting material providing a recurrent path for an arc, and having an opening therethrough at one side of said recurrent path, means for setting up a radial magnetic field across said recurrent path and acrosssaid openings, means for initially establishing an arc in said opening, and said means for setting up the radial magnetic field causing it to be set up at least while said arc is still in said opening whereby said radial magnetic field moves the arc from said opening into said recurrent path and rotates it thereabout.

19. In a'circuit interrupter, a plurality of plates of conducting material, each of said plates providing an annular path for an arc and having an opening therethrough at one side of said annular path,'a plurality of said openings each having a generally V-shaped portion with the apex of the V pointing toward the annular path for the arc, means for initially causing an arc in said opening, and means for setting up a radial magnetic field across said opening and across said annular path while the arc plays in the opening for moving the arc in the opening toward the apex of the V- shaped portion and in said annular path. 20. In a circuit interrupter, a plurality of members of conducting material each providing an annular arc path, a plurality of said members each having an opening therethrough inside oi said annular path, means for causing an arc in said opening inside of said annular path, and

- means for moving said arc outwardly from said opening into said annular path and moving it thereabout.

21. In a circuit interrupter, a plurality of plates of conducting material each providing an annular path for the arc, a plurality of said plates each having an opening therethrough inside of said annular path, means for causing an are through said openings inside of said annular path, means energized at least shortly after said are is drawn and while it plays through said openings for setting upa radial magnetic field across said openings and across said annular path, said radial magnetic field moving said arc from said opening into said annular path and splitting it up into short arcs, and causing rotation of said short arcs about said annular path.

22. In a circuit interrupter, a pair of separable contacts for drawing an arc, means for extinguishing the are including a coil for causing a radial magnetic field across the arc path, said coil having an opening through the central portion thereof, and an operating rod movable in said opening through the coil for actuating said separable contacts.

23. In a circuit interrupter, a plurality of arc extinguishing structures, a plurality of pairs of separable contact members for establishing an arc in each of said structures, a plurality of coils ior moving the arcs in an arcuate path in said are extinguishing structures, and an operating rod movable through the central portion of said are extinguishing structures and through said coils for actuating said separable contact members.

' 2a. In a circuit interrupter, a staclr oi axially aligned arc extinguishing structures each including a pair of arcuate arc terminal members, a movable are drawing member for establishing an are between each pair of arcuate arc terminal members and a coil for moving the arcs around said arcuate arc terminal members, an opening extending through said stack of are extinguishing structures within said arcuate arc terminal members and within said coils, and an operating rod movable through said opening :ior actuating said movable are drawing members.

25. In a circuit interrupter, a plurality of groups of plate members, each group having a pair of arcuate are terminal members and a mov able arc drawing member for establishing an arc thereacross, an opening extending longitudinally through said plurality of groups of plate members adjacent to the center of said arcuate arc terminal members, and an operating member movable through said opening to actuate said movable are drawing members.

26, In a. circuit interrupter, a stack of plate members, a plurality of are drawing members for establishing a plurality of arcs among said plate members, an opening through said plate members adjacent the center thereof, an operating rod extending through said opening for actuating said plurality of are drawing members, and means for causing said arcs to move in an arouate path around said operating rod.

27. In a circuit interrupter, a tubular member of insulating material, a plurality of arc extinguishing means stacked in said tubular member bular member of insulating material, an operating rod movable longitudinally in said tubular member of insulating material for actuating said are establishing means, and means for causing movement of the arc in an arcuate path about an axis extending longitudinally through the tubular member of insulating material.

28. In a circuit interrupter, a tubular member of insulating material, a plurality of arc extinguishing means stacked in said tubular member of insulating material, a plurality of arc drawing members movable to establish a plurality of series-related arcs extending longitudinally of the tubular member of insulating material, an operating rod movable longitudinally in said tubidar member of insulating material for actuating said plurality of are drawing members, and means for causing movement of said arcs in an arcuate path about said operating rod.

29. Electrical apparatus comprising, in combination, a load device having a metal housing, a

plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and extending through said metal housing and thereby incorporated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of fixed and movable contact members connected in series circuit relation, and operating means including a rod movable longitudinally in said insulator bushing and operatively connected to each of a plurality of said movable contact members for actuating them simultaneously to either the open or the closed position, said operating means having its moving parts enclosed within said electrical apparatus.

80. Electrical apparatus comprising, in combination, a load device having a metal housing, a

, plurality of conductors for connecting the load device to a current source, an insulator bushing surrounding at least one of said conductors and extending through the metal housing and incor-- porated as a part of the load device, circuit breaker means mounted within said insulator bushing comprising a plurality of sets of seriesconnected fixed and movable contact members between which a plurality of arcs may be drawn, and arc-extinguishing means for each of a. plurality of said sets of contact members and disposed adjacent to the arc paths therebetween for extinguishing said arcs, and an operating rod movable in said insulator bushing and connected to each of said movable contacts for simultaneously actuating said contact members to either the open or the closed position.

BENJAMIN P. BARR.

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