US3042766A - Vacuum load-break switch - Google Patents

Description

July 3, 1962 H. c. Ross 3,042,766

' VACUUM LOAD-BREAK SWITCH Filed Oct. 28, 1958 s Sheets-Sheet 1 I INVENTOR.

HUGH 6. R055 Inf: 477021149 July 3, 1962 H. (3. R085 VACUUM LOAD-BREAK swrrcu 3 Sheets-Sheet 2 Filed Oct. 28, 1958 INVENTOR. HUGH C. ROSS July 3, 1962 H. c. Ross 7 3,042,766

VACUUM LOAD-BREAK SWITCH Filed Oct. 28, 1958 3 Sheets-Sheet 3 INVENTOR. HUGH C. ROSS United States Patent 3,042,766 VACUUM LOAD-BREAK SWITCH Hugh C. Ross, San Jose, Calif., assignor, by mesne assignments, to Jennings Radio Manufacturing Corporation, San Jose, Calif., a corporation of Delaware Filed Oct. 28, 1958, Ser. No. 770,156 Claims. (Cl. 200-62) My invention relates to load-break power switches, and particularly to a vacuum load-break switch.

One ,of the objects of my invention is the provision of a load-break switch in which the circuit is broken within an evacuated chamber.

Another object of the invention is the provision of a load-break switch incorporating relatively low and high impedance elements sequentially operable to open or close the circuit under load conditions.

Still another object or" the invention is the provision of a load-break switch which will prevent the formation of an exposed or air are.

A still further object of the invention is the provision of a vacuum load break switch in which maintenance is substantially eliminated.

Another object of the invention is the provision of a vacuum load-break switch in which the interrupting capacity may be easily modified to increase or decrease the voltage and current carrying capacities.

Still another object of the invention is the provision of a load-break switch having rapid interrupting characteristics.

Another object of the invention is the provision of a load-break switch which is compact and capable of being safely operated in confined spaces.

Another object of the invention is the provision of a load-break switch which lends itself to visual inspection from a distance to determine whether the switch is in open or closed circuit position.

The invention possesses other objects and features of value, some of which with the foregoing will be brought out in the following description of the invention. I do not limit myself to the showing made by the said description and the drawings, since I may adopt variant form of the invention within the scope of the appended claims.

Referring to the drawings:

FIG. 1 is a side elevation of the switch shown in closed circuit position. One of the switch arms is shown in open circuit position in dash lines. Portions of the switch are broken away to disclose underlying structure and to reduce the size of the view.

FIG. 2 is a front elevation of the switch shown in FIG. 1.

' FIG. 3 is a side elevation showing the switch in open circuit position. Movement of some of the parts is indicated in dash lines, and portions of the device are broken away to disclose underlying structure and to reduce the size of the view.

FIG. 4 is a fragmentary elevational view of the trip mechanism for the second switch arm.

All of the views are drawn in reduced scale. I

In the power transmisison field, it frequently becomes necessary to disconnect power lines under load conditions for repair, maintenance and replacement. In most power lines air break or air gap switches are utilized, which indacte upon visual inspection, whether the line is open or closed. When it is desired to open a closed switch of the conventional air gap type, the lineman uses a hot stick approximately eight feet long or longer, especially treated to make it moisture proof and capable of insulating the operator from up to 60,000 volts on the power line.

One difiiculty encountered in this procedure is that when high current at high voltages are interrupted in air,

a large are forms between the switch contacts. Unless extinguished promptly, this are can do considerable damage to elements of the switch in the immediate proximity of the arc. Another danger is that the arc will ignite associated combustible materials and thus be the cause of a conflag-ration.

To obviate these difiiculties, the load-break switch of my invention combines the advantages of a low impedance air gap switch with the advantages of a high power vacuum switch. Broadly considered, my load-break switch comprises a pair of spaced switch terminals adapted to be connected and disconnected to close or open a circuit between them. A movable switch arm mounted on one of the terminals is proportioned to span the distance between the terminals to provide a low impedance conductor capable of being connected and disconnected to close and open a circuit therebetween. Also mounted on one of the terminals, and in closed position being'in electrical parallelism with the low impedance switch arm, is a second switch arm which includes a vacuum switch assembly. The first and second switch arms are cooperatively related so that movement of the low impedance arm from a closed circuit position to an open circuit position effects transfer of the current load through the vacuumized portion of the second switch arm. No arc will form between the receding low impedance or first switch arm and the terminal from which it has been disconnected.

Further opening movement of the first switch arm now efliects opening of the vacuum switch contacts within the vacuumized chamber provided, thus interrupting the current flow under load within.

Means are interposed between the first and second switch arms, operative upon movement of the first switch arm, to eiiect a break in the conductive path provided by the second switch arm. The parts are proportioned and arranged so that'the break occurs within the vacuumized chamber provided by the vacuum switch assembly. In point of time, the break in the second switch arm occurs after the first or low impedance arm has moved out of contact with the disconnected terminal. With the load current thus interrupted, means are provided operatively interposed between the first and second switch arms whereby further opening movement of the first switch arm eifects a subsequent mechanical disengagement of the second s'm'tch arm from one of the terminals so that visual inspection will readily indicate whether the switch' is open or closed.

In more specific detail, the vacuum load-break switch of my invention comprises a pair of upper and lower spaced terminal plates 2 and 3 rigidly fixed as by cap screws 4 on the outer ends of standoff insulators 6. The, insulators are in turn fixed in the conventional way to a convenient base structure (not shown).

'The upper. terminal plate 2 is provided with an integral upwardly extending apertured connector portion 7 to which a power line may be bolted. Integral with th terminal plate and extending forwardly therefrom is a bifurcated terminal lug 8 providing spaced side arms 9 which flare outwardly at their outer ends to provide spaced but inwardlyconverging guides into the space between. Detachably fixed to each opposite side of the lug by bolts 12 is a contact plate '13 having an integral resilient contact tongue 14 extending forwardly and inward-1y toward each other through apertures 16 formed in the side arms 9. On its outer free end, each resilient tongue is provided with a conductive contact shoe 17. past which anything inserted into the space between the arms 9 must pass in sliding engagement.

The lower terminal plate 3 is also provided with a forwardly extending integral lug 18 lying substantially in the same vertical plane as the lug 8. The lug 18 serves as a support for a movably mounted switch arm comprised of spaced parallel bars or blades 19, pivotally mounted at their lower ends on opposite sides of the 1113 18 by bolt 21. The switch arm or blades extend upwardly and are joined at their upper ends by a bolt 22 which serves to clamp a plate 23 therebetween. The plate is provided with an aperture 24 through which the hook of a hot stick may be inserted for manipulation of the switch arm between open and closed circuit positions. An extension 26 on the plate provides a stop to limit movement of the switch arm in a circuit closing direction. As shown best in FIG. 1, the low impedance switch arm 19 completes the circuit between the upper and lower terminals by being pivoted into engagement with the spring arms 14 attached to the upper terminal. In. this position the switch arm carries substantially the full current load.

Clamped under the terminal plate 3 and extending to one side thereof is a lower auxiliary terminal plate 27 which in effect forms a transverse extension of the terminal plate 3. Movably supported on this auxiliary terminal plate 27, and selectively engageable with a similar upper auxiliary terminal plate 28, is a second switch arm forming a parallel circuit with the first switch arm. The second switch arm includes a conductive hinge plate 31 provided adjacent its lower edge with a forwardly extending anchor plate 32 fixed at right angles thereto and having fixed thereon a pair of spaced hinge blocks 33 pivoted as at 34 on hinge block 36 fixed adjacent the lower edge portion of the lower auxiliary terminal plate 27.

Fixed to the top edge of the hinge plate 31 is a forwardly extending conductive base plate 37. A vertical strut or brace 38 extends between the forward edges of anchor plate 32 and base plate 37 to lend stability to the structure. Detachably secured on the base plate 37 in conductive relation is the metallic end cap 39 hermetically closing one end of a vacuumized envelope which includes a dielectric shell 41 shown in FIG. 2. The other end of the shell is hermetically closed by a second metal lic end cap 42, which in turn is detachalbly and conductively fixed to a conductive contact plate 43. The contact plate is provided with an integral contact lug 44.

arranged to resiliently engage in conductive relation with a plurality of resilient conductive contact fingers 46 fixed on the upper auxiliary terminal plate 28. A dielectric back plate 47 and dielectric side plates 48 interposed between the conductive base and contact plates confine the dielectric envelope to protect the shell 41, and also electrically insulate the contact plate from the base plate.

To form a conductive path through the vacuumized envelope, the end cap 42 is provided with an integral inwardly extending fixed contact rod 49 which terminates approximately midway of the glass shell. Aligned with the fixed rod 49 and adapted to selectively abut therewith within the vacuumized envelope is amovable contact rod 51 integrally connected to and supported by an expansible conductive bellows 52 on the end cap 39. Within the envelope the normally abutting but separable inner ends of the contact rods 49 and 51 are shielded by a concentric dielectric shield 53 fixed on the envelope.

The contact rod 51 extends downwardly through the end cap 39 and the base plate 37, and terminates in a threaded portion 54 engaged in the upper end of a shaft 56 slidably journaled in a slide bearing 57 fixed to a bearing support plate 58. The bearing support plate 58 is rigidly suspended from the base plate 37 by posts 59 interposed therebetween and secured by screws 61. Securing the bearing support plate to the brace 38 at the front by means of a screw 62 and to the hinge plate 31 at the rear insures rigidity in the construction. The shaft 56 passes through the slide bearing 57 and terminates below the bearing plate in a slotted end portion 63.

Means are provided for elfecting axial. displacement of the shaft 56 and the attached movable contact rod 51 to interrupt the continuity of the conductive path links 68, the remote ends of which are pivoted by a bolt 69 to a fixed lug 71 brazed or otherwise fixed to the anchor plate 32. As shown best in FIGS. 2 and 3, a pair of coil springs 72, each attached at one end to the pivot pin 64 and at the other end attached to adjustable anchor posts 73 fixed on the plate 32, provide a force tending to buckle the toggle joint. The tendency to buckle is normally resisted by atmospheric pressure exerted inwardly against the bellows, and by arranging the toggle links so that in the closed circuit position shown in FIGS. 1, 2 and 4, the toggle links are extended and no lateral pressure is applied tending to buckle the toggle. An adjustable toggle stop 76 fixed on the brace 38 limits lateral movement of the toggle knee in one direction, while a similar adjustable toggle stop 77 fixed on the hinge plate 31, limits movement of the toggle in the opposite direction. Buckling of the toggle will of course effect a downward pull on the shaft 56 and contact rod 51, thus separating the contact points within the evacuated shell.

Means are provided fixed to the toggle links 68 to selectively effect extension or buckling of the toggle to open and close the conductive path between contact rods 49 and 51. Welded or otherwise fixed to the rear edges of links 68 adjacent the pivot pin 67 and extending laterally toward the terminal plate 3 is a cantilever toggle operating rod 78. On its outer free end the toggle rod is provided with a freely rotatable wheel or roller bearing 79. The roller bearing is arranged between bifurcated thrust lugs 81 and 82 formed on the lower end of operating bar or lever 83, pivoted on the bearing support plate 58 by a screw 84. Pivoted movement of the operating bar will thus eifect displacement of the thrust lugs, either forwardly or backwardly, resulting in a corresponding displacement of the roller bearing 79. From the position shown in FIGS. 1 and 2 displacement of the roller bearing rearwardly or to the right, will cause the toggle to buckle and the contact rods 49 and 51 to separate. Movement in this direction need only be initiated by the thrust lug 81, whereupon the springs 72 resiliently pull the toggle into a pivoted position limited by the toggle stop 77.

Movement of the operating bar 83 thus controls operation of the toggle. Fro-m its pivot 84 the operating bar extends upwardly closely adjacent the side wall 48 and switch arm blades 19, terminating adjacent the upper terminal assembly. Interposed between the switch blades 19 and the operating bar 83 is a trip bar 86. The trip bar is slidably arranged on the right side wall 48 by headed pins 87 working in a longitudinal slot 88 in the trip bar adjacent one end thereof. A roller bearing 89 rotatably mounted on the end of the trip bar adjacent the slot is arranged to be rollably engaged by the leading or forward edge of one of the switch blades 19 when the latter is pulled into open circuit position by means of a hot stick. At its other end, the trip bar is narrowed to provide a neck portion 91 terminating in a hook 92. A trip pin 93 fixed in the side wall 48 slidably impinges on the neck portion and is positioned so that longitudinal sliding.

movement of the trip barwill effect engagement of the hook 92 against the pin 93. A coil spring '94, interposed between the trip bar and the base plate 37 normally resiliently urges the trip bar into the position shown in FIGS. 1 and 2. In FIG. 3, the trip bar is shown pulled downwardly by action of the switch blades 19 against the roller bearing 89.

In the position of the parts illustrated in full lines in FIG. 3, sliding movement of the trip bar has brought the hook 92 against the pin 93, and continued movement of the switch blades has eifected a counterclockwise rotary displacement of the operating bar about its pivot 64, cansing the roller bearing 79 to be displaced rearwardly, thus causing the toggle to buckle and the switch contact rods 49 and 51 to separate, thus breaking the continuity of the conductive path through the second switch arm. Since the load current has been broken within the evacuated shell 41, there is little if any are, and restrikes are virtually eliminated by the rapidity with which the contact rods are separated. Interruption within the first half cycle of most power frequencies is not uncommon.

In the position of the parts illustrated in dash lines in FIG. 3, the first switch arm has been pivoted still farther, resulting in the trip bar hook 92 pulling forwardly on the operating bar 83. Since the lower end of the bar is now impinging on the hinge plate 31, this forward drag causes the hinge plate and related assembly to pivot about pintle pin 34, and the contact lug 44 of the second switch arm is thus pulled from its resilient contact with the fingers 46. This releases the second switch arm, whereupon both switch arms swing downwardly 180 and depend in an open circuit position easily visible from a distance. Because of the limitation in space, this position of the parts is not shown in the drawings.

To reconnect the open circuited switch arms, the hot stick is engaged in the aperture 24 on the first switch arm, and the arm swung upwardly. As the arm swings upwardly, a roller 96 rotatably fixed on one 'of the switch blades 19 of the switch arm, impinges against the leading edge 97 of the operating bar 83. This causes the operating bar to pivot clockwise, thus straightening the toggle links and bringing the contact rods 49 and 51 into tight abutment to form an uninterrupted conductor through the evacuated shell.

With movement of the toggle knee beyond its extended position restricted by toggle stop 76, continued upward movement of the first switch arm causes the second switch arm to pivot about the pin 34, and to be swung upwardly with the first switch arm. The parts are proportioned so that the first switch arm conductively contacts the upper terminal before the second switch arm is inserted in the circuit. This insures that fault currents, if present, will be carried by the low impedance first switch arm until fuses or circuitbreakers come into operation to relieve the switch gear of the load.

From the foregoing it will be clear that in the operation of this switch from a closed circuit position to an open circuit position, and back again to a closed circuit position, the operator and surrounding structure is protected by a mode and with a certainty not found in conventional switch gear. The necessity of maintenance is almost nonexistent, since the device lends itself to being wholly encased as a protection against the elements when installed out doors. Because the actual interruption of the load current takes place inside a vacuum chamber, considerable higher interrupting ratings are possible, with no increase in the space required for installation. Several of these devices are also capable of being installed in series to further increase the interrupting maximums of both voltage and current.

I claim:

1. A load-break switch for high power transmission lines, comprising a pair of fixed terminals spaced apart, a first conductive switch arm movably mounted on one of the terminals and movable into or out of contact with the other terminal to open or close a circuit therebetween, a second switch arm mounted on one of the terminals and normally conductively connecting with the other terminal to complete a circuit therebetween independently of said first switch arm, means operatively interposed between said first and second switch arms to effect sequential opening thereof in the circuit, and means operatively interposed between said first and second switch aims to eifect sequential closing thereof in an order reversed to the order of said sequential opening.

2. The combination according to claim 1, in which said first switch arm is freely movable from a closed circuit position to a predetermined open circuit position while said second switch arm remains in a closed circuit position to complete a circuit between said terminals independently of said first switch arm, said means for effecting sequential opening of the switch arms efiects opening of said second switch arm when said first switch arm is moved beyond said predetermined open circuit position, and said means for effecting sequential closing of the switch arms efiects closing of said second switch arm after said first switch arm has moved into closed circuit position.

3. A load-break switchfor high power transmission lines, comprising a pair of fixed terminals spaced apart, a first conductive switch arm movably mounted on one of the terminals and movable into or out of contact with the other terminal to open or close a circuit therebetween, -a second switch arm including axially aligned fixed and movable contacts movably mounted on one of the terminals and movable into or out of conductive engagement with the other terminal to open or close a circuit therebetween, and means operatively interposed between said first and second switch arms to effect reverse order sequential opening and closing of said fixed and movable contacts and disengagement or engagement of said second switch arm with said other terminal upon predetermined movement of the first switch arm.

4. The combination according to claim 3, in which said first switch arm is movable from a closed circuit position to a predetermined open circuit position while said second switch arm remains in a closed circuit position, and said means for efiecting reverse order sequential operation of the switch arms includes a toggle pivotally mounted on the second switch arm and movable between fixed limits thereon to effect opening movement of the movable contact of said second switch arm to open the circuit therethrough when said first switch arm is moved beyond said predetermined open circuit position and while said-second switch arm remains interposed between said spaced terminals.

5. A load break switch for high power transmission lines, comprising a pair of fixed terminals spaced apart, a first switch arm movably mounted on one of the terminals and movable into or out of conductive contact with the other terminal to open or close a circuit therebetween, a second switch arm openatively interposed between said terminals independently of said first arm to selectively open or close a circuit and comprising a mobile contact movably mounted conductively on one terminal and a fixed contact detachably engageable with the other ter-.

minal and normally conductively engaging said mobile contact, a vacuumized envelope hermetically interposed between said fixed and mobile contacts, and means operatively interposed between said first and second switch arms to effect reverse order sequential opening or closing thereof to open or close a circuit between said fixed and mobile contacts and between said fixed contact and the associated other terminal.

6. The combination according to claim 5, in which said first switch arm is movable from a closed circuit position to a predetermined open circuit position while said vacuum switch remains in a closed circuit condition, and said means for effecting sequential opening or closing of said first and second switch arms efiects opening of said vacuum switch upon movement of the first switch arm beyond said predetermined open circuit position and subsequent disengagement of said fixed contact from its associated terminal upon. continued movement of the first switch arm toward open circuit position.

7. A load break switch for high power transmission lines, comprising a pair of fixed terminals spaced apart, a first conductive switch arm pivotally mounted on one of the terminals and movable into or out of contact with the other terminal to open or close a circuit therebetween, a normally conductive second switch arm pivotally mounted on one of the terminals and normally detachably connecting conductively with the other terminal to complete a circuit therebetween, fixed and movable contact points interposed in said second switch arm and operable to selectively interrupt the conductive continuity of said second switch arm, a lever pivotally mounted on the second switch arm and operatively connected to said movable contact point thereon to effect opening and closing thereof, and a trip bar movably mounted on the second switch arm and operatively interposed between the first switch arm and said lever to effect pivotal movement of said lever after a predetermined pivotal movement of said first switch arm and disengagement of said second switch arm from said other terminal upon continued pivotal movement of the lever by the first switch arm.

8. A loadbreak switch for high power transmission lines, comprising -a pair of fixed terminals spaced apart, a first conductive switch arm pivotally mounted. on one of the terminals and movable into or out of engagement with the other terminal, a second switch arm including a switch assembly having fixed and movable contact points, said second switch arm being pivotally mounted on one of the terminals and movable into or out of engagement with the other terminal, a lever mo vably mounted on the second switch arm, means operatively interposed between the lever and said movable contact on the second switch arm to open or close said fixed and movable contacts upon movement of the lever, and a trip bar movably mounted on the second switch arm and movable by said first switch arm to engage said lever to effect sequential opening of said fixed and movable contacts and disengagement of the second switch arm from said other terminal to break a circuit therebetween.

9. A load-break switch for high power transmission lines, comprising a pair of fixed terminals spaced apart, a first conductive switch arm pivotally mounted on one of the terminals and movable into or out of engagement with the other terminal, a second switch arm including a switch assembly having fixed and movable contact points, said second switch arm being pivotally mounted on one of the terminals and movable into or out of engagement with the other terminal, a lever pivotally mounted on the second switch arm, means on said second switch arm including a toggle link operatively interposed between the lever and said movable contact on the second switch arm and responsive to movement of said lever to move said movable contact to open or close said fixed and movable contacts upon movement of the lever, and means operatively interposed between the first switch arm and the lever to effect movement of the lever to sequentially open or close said fixed and movable contacts and disengage or engage said second switch arm from said other terminal.

10. A load-break switch for high power transmission lines, comprising a pair of fixed terminals spaced apart, a first conductive switch arm pivotally mounted on one of the terminals and movable into or out of engagement with the-other terminal, a second switch arm including a switch assembly having fixed and movable contact points,

said second switch arm being pivotally mounted on one of the terminals and movable into or out of engagement with the other terminal, -a lever pivotally mounted on the second switch arm, means on said second switch arm operatively interposed between the lever and said movable contact on the second switch arm to open or close said fixed and movable contacts upon movement of the lever, and means operatively interposed between the first switch arm and the lever to effect movement of the lever to sequentially open or close said fixed and movable contacts and disengage or engage said second switch arm from said other terminal, said last mentioned means including means on the first switch arm engageable by movement thereof in a closing direction with said lever to move said lever to efiiect sequential closing of said fixed and movable contacts and subsequent engagement of the second switch arm with said other terminal to sequentially complete parallel circuits therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 2,469,203 Palme et a1. May 3, 1949 2,480,622 Warnock Aug. 30, 1949 2,626,332 Earle et al. Jan. 20, 1953 2,761,040 Ulrich Aug. 28, 1956 2,872,550 Schwager Feb. 3 1959 2,883,493 Stoelting Apr. 21, 1959

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