US2185719A - Circuit breaker - Google Patents

Description

Jan. 2, 1940.

- Filed Jun! 5. 1956 3 Sheets-Sheet 1 9, I INVENTOR [L52 [Benjamin Baker.

Jan. 2, 1940. B. P. BAKER 2,185,719

CIRCUIT BREAKER Filed June 3, 1936 3 Sheets-Sheet 2 6p 6/ Q III III 66 4/ f3 2 3/ 45 as 37 I a Q 619 45 a; I

wmv 30 OR W 61% fie/y'am/n PBakex 'Jan. 2, 1940. BAKER 2,185,719

cmcun' BREAKER Filed June 3, 1936 3 Sheets-Sheet 3- .5; 4-. [mu/07mm x INVENTOR fiery arm?! P Bake/1 Patented Jan. 2, 1940 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Pennsylvania Application June 3, 1936, Serial No. 83,260

13 Claims.

My invention relates, generally, to electrical circuit breakers and it has particular relation to arc extinguishing apparatus therefor. This application is a continuation in part of my copending application Serial No. 686,764, filed August 25, 1935, now Patent 2,071,157, issued February 16, 1937.

In the past, it has been customary to provide an individual circuit breaker and mechanism for connecting a load device, such as a transilormer, to a high-voltage system. necessitated the use of two individual sets of apparatus comprising the circuit breaker and the transformer which have required a considerable space for their occupancy. When a substation 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 suificient 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.

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 utilize the insulation of the load device for the circuit breaker device. However, this has led to considerable difficulty and it has heretofore been impractical until the provision of this invention for extinguishing the arcs formed on opening of the circuit breaker which will be set forth in detail hereinafter.

In general, I propose to mount the circuit breaker within the customary insulator bushings which are provided with 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 applied to the transformer windings. It is, therefore, unnecessary to provide 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 efi'icient in oper- This has ation and which may be readily and economically constructed and installed.

The principal object of my invention is to provide for incorporating a circuit breaker structure in the lead-in bushing of 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 be tween several series connected contact members 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 connected 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 arcs are extinct.

An additional object of my invention is to provide for controlling the distribution of potential among the series connected contact members by means of an electrostatic shield in the form of a tubular member of insulating materiaLhaving conducting sheets embedded therein, and enclosing the series connected contact members and the arc extinguishing devices therefor,v with an operating rod for the contact members extending up the length of the tubular member.

It is also an object of my invention to provide an electrostatic shield which, forms a minimum of corona at high voltages, due to the layers of conducting foil being in cylindrical form.

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 accompanying drawings, in which Figure l is a view, partly in side elevation and partly in section, illustrating the application of my invention to a transformer;

Fig. 2 is an enlarged sectional view showing, in the details of construction of my novel circuit breaker, certain duplicate elements being 0 ted for the sake of clearness;

Fig. is a sectional view taken through one of the arc extinguishing structures along the line I1l-lll of Fig. 2;

Figs. i through 8 illustrate certain constructional details used in the assembly or the are extinguishing device illustrated in Fig. 2;

Fig. 9 is a view in elevation of the electrostatic shield with one quarter cut away and shown in section on the line IXIX of Fig. 10; and

Fig. 1G is a sectional view of the electrostatic shield taken on the line XX of Fig. 9.

For the purpose of illustration, my invention has been shown in Fig. l as applied to a transformer for a load device. However, it will be readily understood that the application of my invention is not limited to use with a transformer and that it may be used with any other suitable type oi 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. l of the drawings, a transformer, shown generally at iii, is provided, having a core ii and a winding l2 immersed in insulating oil it in the customary and well known manner. A tank M is provided for the transi'ormer it having a cover i5 on which lead-in bushings it may be mounted. The lead-in bushings in? are mounted on the cover 15 and extend into the tank M as shown. The winding i2 is connected by means of conductors ll to the insulating bushings it in the usual manner. Connection with power lines i8 is had by means of terminals i9 mounted on the upper ends of the insulator bushings "5.

As will be more fully set forth hereinafter, a circuit breaker is mounted within the insulator bushing i6 and an operating mechanism comprising an armature Eli and a winding 2i are provided, individual to each circuit breaker, for effecting its operation to either the open or the closed position. The movement of the armatures 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 2i 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 IE, is shown. In order to more clearly illustrate the important details of my invention, the insulator bushing it is entirely 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 it, as will be readily understood, thereby taking advantage of its insulating properties without necessitating the provision of additional insulating bushings for the circuit breaker structure itself.

As illustrated, the frame, shown generally at comprises upper and lower end plates 29 and 38, respectively, between which suitable holding members for the circuit interrupter structure are provided. These holding members comprise the insulating rods 5i which engage the notches in the edges of the plates shown in Figs. 3 to 6 inclusive, and the insulating tube 3i having a ring '62 at each end, to lugs on which the end plates 29 and 30 are bolted. The terminal i9 is connected to an upper end cup 32 while the conductor l'l 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 a plurality of fixed and movable contact members 3 3 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 3d and 35 will depend upon the voltage which is to be applied to the load device. Thus, ii 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 38 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 28 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 122 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 all are encountered. However, until this engagement takes place, the contact members 34 and 35 will be maintained in engagement by means of the springs 4|.

The flexible shunts 36 are connected to coil plates 35 which are disposed above the windings 3B and which are more clearly illustrated in Figs. 6 and 8 of the drawings. It will then be observed that the terminal !9 is connected to the conductor l7 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, 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 M 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 and 35 will be drawn, it is essential that these arcs be extinguished as rapas possible in order to avoid damage to the circuit breaker. For this purpose, deionizing devices, shown generally at M, are provided comrising a plurality of metal grid plates 48 preferably or copper and more clearly illustrated in Fig. 5 of the drawings. The metal plates 48 are provided with openings 48a having tapered portions 4% for the purpose of providing a path for the are which is formed between the contact members 3i! and 35. As shown in Fig. 30f the drawings, the movable contact members 35 are disposed within the openings 48a.

Only two of the deionizing devices 47 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 63 from each other, an outer insulating ring 49 is provided at the outer edge thereof while inner insulating segments 58 are provided around the openings ite. These insulation pieces 39 and d are shown more clearly in Figs. 4 and 7 respectively of the drawings and their assembly with the grid plate to is shown in Fig. 3. Insulating rods 51 are provided for lining up the elements of the deionizing devices, 4? and securing them in position.

With a vi w to providing for rotating the arcs formed between contact members 34 and t5, until they are extinguished, the windings 38 are provided as h reinbefore set forth, which are arranged to generate a radial field between the grid plates ii? on how of current therethrough. The radial field generated by the. windings 38 causes the. several arcs to traverse paths which may be indicated by the dotted lines $2 or 53 and 5 K in Fig. 3. It will be readly understood that the arcs may be formed at either end of the movable contact members 35 and that they may follow either of the paths indicated by the dotted line 52 and 53 to intersect the paths indicated by the dotted line E i. It will be understood that the inner terminals of the windings 38 may be connected to the disks 3? which are connected in turn to the fixed contact members while the outer terminals thereof may be connected to the coil plates 45 beneath the windings 38 or vice versa, as the case may be.

Assuming that operating potential is applied to the power conductors l3 and load current is being supplied to the transformer ill, the circuit ore r may be operated to the open position by per g the lift rod 22 to move downwardiy when the winding 25 is deenergized. As soon as the lift rod 22 is moved downwardly, arcs will formed between the several contact memand 35 and the ends of the arc will be transferred from the contact members 34 and 35 to the coil plates it, and to the arcing leaves iiB 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 a, radial field between the grid plates 38 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 the dotted lines 52 or 53- and 54. The rotation of these short arcs will be continued by the respective radial fields generated by the windings 38 until they are extinguished.

The arcs playing between the plates 48 are short in contradistinction to the arcs initially drawn between the several pairs of contacts 34 and Eli which are generally designated as long. The terms short and long are herein used to define two types of arcs that distinguish from each other not only in the ordinary physical sense but in an electrical sense as well. An arc is short in the electrical sense if immediately after the transient rise to open circuit voltage of the external circuit, practically all the dielectric strength resides in the cathode layer and an are tacts. is due to the capacity effect of the structure. The contacts and 35, the conductshunts the plates 18, and other parts of the are extinguishing structure are at high potential, whereas the tank Hi, It of the load device or other supporting structure for the circuit breaker and the ground itself are at ground potential. This great difierence in potential and the capacitance between the conducting parts and the grounded parts cause leakage or charging currents to iicw to ground and cause the non-uniform distribution of potential.

In order to prevent this non-uniform distribution of potential, the insulating tube Si is constructed to form an electrostatic shield'by having sheets of conducting material 53 embedded therein. Each of the con-ducting sheets E59 is a strip extending around the tube so as to be cylindrical in shape. The end sheets Gil are each electrically connected by a conductor 62 to one of the end plates 2% and 353, so as to be electrically at the potential of the two terminals of the circuit interrupter structure.

In order to insure that the arcs formed between the contact members 36: 555 are transierred to the plates the coil plates 35 above the coils are provided with upstanding leaf portions or tabs fit 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 transfers from the fixed contact to the coil plates below the coils. The are current is thus caused to ,quickly flow through the windings 3% thereby when arcs have formed between the contactmernbers 3d and and transferred to the coil plates (is and it which forn'i arc terminal members extending from the annular paths to points closely adjacent the contacts and in order that the arc may quickly transfer from the con-- tacts t and 35 to the coil plates it and Since the direction of the racial 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 43 in reversed position. Thus, on one side of the Wind 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 wind-- lugs 38 are properly connected so that the direction of fields generated thereby between them will be the same.

The cylindrical conducting sheets form the plates of a series of condensers and surround the contact elements and are extinguishing elements with conducting'cylinders at substantially the same potential as the respective elements. By having the contact elements entirely sur rounded by the cylindrical sheets, leakage currents from the contact elements to ground are prevented and the voltage across the plurality of sets of contacts is more nearly equalized. The

cylindrical form of the electrostatic shield is advantageous in that it reduces the amount of corona formed to a minimum.

The tubular electrostatic shield 3| has a metal ring 8| at each end carrying lugs E3 to which the end plates 29 and 3d are bolted making the whole contact and are extinguishing a unit which may be placed in the porcelain insulator bushing 56 and which may be readily removed therefrom as a unit for maintenance or inspection.

Since certain further changes may be made in the above construction and diiierent embodiments 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 lim iting sense.

I claim as my invention:

1. In a multi-brealr circuit interrupter, a plurality of arc establishing means including a plurality of sets of cooperating contacts relatively movable for drawing a plurality of long arcs, a tubular member of insulating material entirely surrounding said are establishing means, a metallic closure member disposed at each end of said tubular member, a plurality of cylindrical members of conducting material positioned circumferentially of and within the wall of said tubular member of insulating material, means connecting the cylindrical member of conducting material adjacent each end of said tubular member to its respective closure member, said plurality of cylindrical members of conducting ma terial being disposed in partially overlapping and spaced relation with respect to each other to provide a series capacitance, said capacitance cooperating with said closure members for controlling the voltage distribution across said plurality of arc establishing means and to completely shield said are establishing means from capacity to ground.

2. In a multi-break circuit interrupter, a plurality of sets of series connected cooperating contacts relatively movable a considerable distance apart for drawing a plurality of long arcs, a tubular member of insulating material entirely surrounding said plurality of sets of relatively movable contacts, one or more coils positioned within said tubular member of insulating material and connected in circuit with said contacts for causing a rotary motion of said plurality of arcs with in said tubular member of insulating material, and a plurality of sheets of conducting material embedded in the wall of said tubular member of insulating material, said tubular member having embedded therein at least as many sheets of conducting material as there are sets of relatively movable contacts, said sheets of conducting material being displaced axially along said tubular member in spaced partially overlapping relation with respect to each other to provide a series capacitance having a predetermined voltage gradient, and means connecting the end sheets of conducting material to the respective end contacts of said sets of series connected contac-ts for shielding said contacts and their connected coils from capacity to ground to control the voltage distribution between said plurality of sets of contacts in accordance with the voltage gradient of said series capacitance.

3. In a circuit interrupter, an outer casing of weatherproof insulating material. a tubular inner casing of insulating material removably disposed within said outer casing, a plurality of sets of series connected cooperating contacts disposed within and supported by said inner casing, means carried by said inner casing for actuating said sets of cooperating contacts to establish a plurality of serially related long arcs, means for extinguishing said arcs, and shield means disposed Within the wall of said tubular inner casing completely surrounding said plurality of sets of contacts, said shield means having a predetermined voltage gradient for controlling the voltage distribution across said plurality of sets of contacts in accordance with said gradient, said inner casing, contacts, actuating means and are extingushing means being removable as a unit from said outer casing.

In a circuit interrupter, an outer casing of Weatherproof insulating material, a tubular inner casing of insulating material removably disposed within said outer casing, a plurality of sets of series connected cooperating contacts disposed within and supported by said inner casing, means carried by said inner casing for actuating said sets of cooperating contacts to establish a plurality of serially related long arcs, means for extinguishing said arcs, a plurality of sheets of conducting material embedded within the wall of said tubular inner casing, said sheets extending circumfercntially of said inner tubular casing and being disposed in spaced and partially overlapping relation with respect to each other to provide a series capacitance having a predetermined voltage gradient and means connecting the end sheets of conducting material to the respective and contacts of said plurality of sets or" contacts for controlling the distribution of potential across said pairs of contacts, said inner casing, contacts, actuating means and are extinguishing means being removable as a unit from said outer casing.

5. In a circuit interrupter, a plurality of arc extinguishing structures, a plurality of pairs of separable contact members for establishing a long are in each of said structures, means connecting said contacts in series, a plurality of coils in circuit with said contacts for moving the arcs in an arcuate path in said are extinguishing structures, an operating rod movable through the central portion of said arc extinguishing structures and through said coils for actuating said separable contact members, a tubular memof insulating material surrounding said plurality of arc extinguishing structures and said plurality of coils, and a plurality of conducting sheets embedded in said tubular member of insulating material, said sheets being disposed in spaced and partially overlapping relation with respect to each other to provide a series capacitance and with respect to said separable contacts that each connected pair of contacts is under the capacitive influence of a difierent conducting sheet for controlling the division of potential between said plurality of pairs of separable contact members.

6. In a circuit interrupter, a stack of axially aligned arc extinguishing structures each including a pair of arcuate arc terminal members, a movable are drawing member for establishing a long are between each pair of arcuate are terminal members and a coil for moving the arcs around said arcuate arc terminal members, said are terminal members and said coil being connected in circuit with said are drawing member, an opening extending through said stack of arc extinguishing structures within said arcuate arc terminal members and Within said coils, an operbedded inv said tubular member of insulating material, said conducting members being disposed in spaced and partially overlap-ping relation with each other to produce a series capacitance for shielding said are terminal members, coils and am drawing members from capacity to ground and for controlling the distribution of potential. between the arc terminal members of each arc extinguishing structure.

'7. In a multi-brcak circuit interrupter, a tubu lar member of insulating material, a plurality of cylindrical sheets of conducting material embedded within said tubular member, said sheets extending circumferentially of said tubular mernher and being disposed in spaced andpartially overlapping relation with respect to each other her and being disposed in spaced and partially to provide a series capacitance having a predetermincd voltage gradient, a plurality of sets of cooperating contacts disposed within said tubular member, means connecting said plurality of sets of contacts in series, actuating means for operating said sets of contacts to open circuit position to establish a plurality of long arcs,

meansfor extinguishing said arcs and means connecting the end cylindrical sheets of corn ducting material to the respective end contacts,

the sheets of conducting material intermediate said end sheets being so disposed that connected pairs of contacts intermediate said end contacts are capacitatively influenced by a different intermediate sheet of said sets of contacts for controlling the distribution of potential across said sets of contacts in accordance with said voltage gradient.

8. In a circuit breaker, an arc extinguishing structure comprising a plurality of arc. extinguishing units disposed in spaced superimposed relation with respect to each other, each of said units including a separable pair of contacts, means for connecting said contacts in series, means for simultaneously opening said pairs of contacts to produce a plurality of serially related long arcs, and a cylindrical shield member mounted in surrounding spaced relation with respect to said arc extinguishing structure, said shield member comprising alternate layers of insulating and conducting material, each of said conducting layers being displaced axially with respect to the next adjacent layer to provide a predetermined overlap between adjacent layers for producing a series capacitance having a predetermined voltage gradient, means for connecting the two end conducting layers to the respective end contacts of said are extinguishing struc ture, each connected pair of contacts intermediate the two end contacts being subjected to the capacitive influence of a different conducting layer for maintaining said pairs of connected contacts at predetermined potentials with respect to the said shield member.

9. In a multi-break circuit interrupter, a plurality of sheets of conducting material embedded material, said sheets extending circumferentially of said tubular member and being disposed in spaced and partially overlapping relation with respect to each other to provide a series capacitance having a predetermined voltage gradient, and means for electrically connecting the end sheets of conducting material across the outer-- most contacts of said plurality of pairs of contacts, each of connected intermediate contacts being subjected to the capacitive influence a different intermediate sheet of conducting nrzaterial for maintaining said connected pairs of contacts at a predetermined potential with respect to said intermediate sheets of conducting material.

iii. In a multibrealr circuit interrupter, a tubular of material, a plurality of cylindrical sheets of conducting material embedded within said tubular member, said sheets extending circumierentially of said tubular memoverlapping relation. with respect to each other to provide a series capacitance having a predetermined voltage gradient, a plurality of arc extinguishing structures disposed end to end axially within said tubular member, a pair of separable contacts Within each arc extinguishing structure, means connecting said pairs of contacts in series, at least one contact of each pair being movable axially of said tubular member to establish a long are within each arc extinguishing structure, an operating rod movable axially within said tubular member for simultaneously actuating said pairs of contacts, and means connecting the end cylindrical sheets of conducting material to the respective end contacts of said pairs of contacts, said cylindrical sheets of conducting material being so disposed with respect to said contacts that each pair of connected contacts of said plurality of pairs of contacts is under the capacitive influence of a different sheet of conducting material for controlling the distribution of potential across said pairs of contacts.

11. In a multi-break circuit interrupter, a plurality of pairs of sepable contacts, means for connecting said contacts in series, a capacitance shield comprising a plurality of conducting plates separated. by a dielectric and disposed along said pairs of contacts for controlling the distribution of potential across said contacts, said conducting plates being so positioned with respect to said contacts that each pair of connected contacts of said plurality of pairs of contacts is under the capacitive influence of a difierent plate, and means connecting the outermost plates of said shield'to the outermost contacts of said pairs of contacts.

12 In a multi-breah circuit interrupter, a plurality of pairs of separable contacts, means for connecting said. contacts in series, a shield for said contacts comprising at least one pair of "-in the wall of said tubular member of insulating conducting plates separated by a dielectric for each pair of connected contacts of said plurality of pairs of contacts, said conducting plates providing a series capacitance having a predetermined voltage gradient and means for connecting the outermost conducting plates of said shield to the respective outermost contacts of said pairs of contacts, the intermediate connected pairs of contacts of said pairs of contacts assuming a voltage gradient different than said shield in accordance with the capacitive coupling between said pairs of connected contacts and their corresponding conducting plates.

tacts of said plurality of pairs of contacts to the capacitive influence of a difierent sheet of conducting material, and means for connecting the outermost sheets of conducting material to the outermost contacts of said pairs of contacts, the intermediate pairs of connected contacts assuming a voltage gradient different than said shield in accordance with the capacitive influence of said conducting sheets upon said pairs of connected contacts.

BENJAMIN P. BAKER.

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