US1696572A - Electric switch - Google Patents

Description

'Dec. 25, 1928.

J. D. HILLIARD ELECTRIC SWITCH Filed Jan. 2, 1924 Inv-er1 t ov Jahn D.Hi||ia1^d) His Attorneg.

Patented Dec. 25, 1928.

UNITED STATES JOHND. HILLIARD, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC I COMPANY, A CORPORATION OF NEW YORK.

PATENT OFFICE.

ELECTRIC SWITCH.

Application tiled January 2, 1924. Serial No. 684,003.

My invention relates to electric switches, particularly those for controlling high potential currents of large capacity. i

For the control of high potential power circuits, switches of the oil break type heretofore have been almost universally employed and as to the development of the art \under a heavy load, the switch contacts and oil have been enclosed in strong steel tanks capable of withstanding the `high pressures generated in order to avoid the loss of oil and the risk of fire and personal injury. Not only is the cost of manufacture of such apparatus excessive but because of its size serious transportation ldiliculties often arise in placingv the apparatus after it is manufactured.

It is an object of my present invention to provide a construction of switch for con` trolling high voltage circuits which shall avoid vtheY above mentioned dangers, shall comprise parts of moderate dimensions facilitating transportation, shall be manufacturablc at a relatively low cost and beI efficient in operation.

My invention willlbe better understood by reference to the accompariyin specification and drawing andt'its scope will be pointed out in the appended claims,

In the drawing, Figure 1 isla simple diagrammatic sketch showing 'the 'gist of the invention and Fig. 2 is a more complete diagrammaticV showing of -one manner of carrying out the invention. y v

Before proceeding with the detailed description, I desireto point out that in illustrating my invention, I have made no attempt to show' the various parts in their relative proportions but, in a diagrammatic manner only.

Referring `first to Fig. 1 of the drawing where I have shown diagrammatically the more essential features ofmy invention, the main break in the circuit to be controlled is between contacts 1 and 2 of which the 'line in Fig.` 1.

former is shown as a stationary socket and the latter a downwardly movable rod. The stationary contact l` is located above an open v essel 3 of comparatively. small diameter and of insulation containing a liquid 4 of fairly high dielectric strength through which the movable contact 2 projects and is adapted to be moved vertically into and out of contact with the stationary contact. For moving contact member 2, it is shown provided with a piston head 5 which is adapted to slide in a cylinder 6, the cylinder being connected at a point above the piston by a pipe 7 leading to a pressure device. .Pressure for operating the piston is obtained by a preliminary interruption of the circuit at a point other than at the main contacts and in a medium which will be vaporized or disassociated to form a gas Orvgases. According to Fig. l this may be accomplished by providing a lswitch having a movable contact 9 and a stationary contact l0 mounted on an insulator 11 in the bottom of the closed vessel 12 which is filled with al liquid which will produce a gas when sub- ]ected to the vaction of an are and which is connected wth the cylinder 6 by the pipe 7. This pipe should be of sutlicient size to freely transmit pressure to vessel 6. The movable member 9 of the switch is shown attached to the plunger 13 of the series solenoid 14 vof which' one terminal connects with the line to be controlled while-the other terminal connects with stationary contact l0. The movable contact 9 is in elec` trical connection with the main contact 2, such connection being indicated by a dotted Supposing both sets of contacts to be in closed circuit position and contact 1 to be connected to the line, an overload current of a predetermined value will actuate the solenoid 14 to separate contacts 9 and 10 and draw an arc in the closed vessel 12. The resulting vapor or gas produced being communicated to the cylinder 6 causes a rapid downward movement of the piston 5 and attached contact rod 2. Thus the circuit is opened between contacts 1 and 2 which constitutes the main break and an arc is quickl drawn first through the air aloneand nally into the insulating liquid contained in the vessel 3. Because of the small diameter of the vessel 3, the sudden formation of gas therein Causes a stream of cool liquid to be thrown directly into the arc. The-break produced by the operation of switch 9 is intended to effect only a partial interruption of the line circuit and while it thus assists in the final interruption of the circuit its principal object is the production of-an arc ina liquid which will be vaporized or disassociated for the purpose of generating sui-table pressure to actuate the main Switch rod 2.

Having thus briefly explained the chief characteristics which constitute the gist of one feature of my invention by means of the diagram comprising Fig. 1 of thedrawing, I shall now proceed to describe in greater detail, by the aid of the diagram 4comprising Fig. 2, apparatus which might be used to carry out my invention.

The switch being adapted for the. control' of a high potential circuit obviously must be supported in such a mannerl as to be thoroughly insulated from the ground. The operating mechanism of the switch being actuated as a result-of the sudden generation of gas pressure," in the nature of an explosion, the insulating supports will be subjected to severe shocks and vibrations which, as is well known to those skilled in the art, are not adapted tobe successfully withstood by rigid insulator supports such for example asv porcelain. In Fig. 2 I have shown theA entire switch mechanism suspended from anV overhead frame work by flexible insulators ofthe sus ension t e'whereby the shocks and vibrations inci ent to the operation ot' the mechanism may be absorbed or dissipated without injury to the .insulating means. v

A truss 16 is shown resting at its ends on cross channels 17 which in turn are supported on standards 18. Near each end of the truss hangs an insulator string 20 whose lower end carries a cross member 21. Intermediate the ends of the insulator string, a cross member 22 is secured, at one end of which a connection is made to the line as at 23 and at the midpoint of which the covered stationary contact is attached. This contact may be of any suitable form to frictionally engage the rod 2 as for example the contact shown in the patent to E. W. Rice #812,880. Suspended from the member 21 is the cylindrical metal vessel 6, secured into the top of which is the small vessel 3 ofinsulating material. The piston 5 fits the vessel 6 and has secured tof it the contact rod 2 which extends up through the vessel 3 to en age the stationar contact 1. Contacts 25 attached to a partition 26 'in -vessel 6 serve to provide a good lelectrical connection between that member and the Contact rod 2. The vessel 6 is closed at its lower end by a cap 27 and near that end is provided with a series of longitudinal slots 28, In the region of the slots 28, the vessel 6 is shown surrounded forming therewithA a closed receptacle which communicates through a plurallty of pipes, diagrammatically Villustrated by a single pipe 30, with a reservoir 31 situated on the cross bar 21. The vessels, the pipe and the reservoir thus far described may .be filled to the level indicated with a suitable liquid such for example'as water, a mixture of water and glycerine or other liquid having a fairly high dielectric strength. Withthe piston and rod in 'the position illustratedvit will be readily apparent if pressure is'admitted to the vessel 6 below the partition therein the piston and rod will beM forced down thereby breaking connection with the stationary contact'l and coming to rest slow' to the atmosp ere anda small tube 34 ,leads to a reservoir` 35, the same liquid being used in the closedvessel 12 and reservoir 35 as in the vessels 6 and 3. The switch 9 is Velectrically connected with the chamber l 12 through brushes 37 while the stationary, cooperating contact 10 is insulated therefrom by insulator bushing 11. `The contact 9 is connected to core` 13 and adapted to be moved to open circuit position by the solenoid 14. The solenoid 14 is shown normally shunted by a switch 38 which is adapted to bev opened by 'a solenoid A39 Whenever the current in the line reaches a predetermined value. The line to be controlled may be connected by lead 23 to -the cross member 22- and from the solenoid 1 a wire 40 may lead to a disconnecting switch shown diagrammatically at 41 and from thence to the line by wire 42. The contact rod 2 is held frictionally in its upper or circuit closing position and inorder that it may be returned to that position after havin been actuated to open the line circuit, sui able means, vas

.for example, a rod 44 may be provided which passes up through a stufiingy box 45 in the cover 27. Rod 44 has an insulation section 46 therein and a handle 47 at its lower end.

To enable the main switch tobe'ope'ned manually, the piston 5 is shown 'carrying .a

vcollar 49 having a bayonet slot therein in which a small cross rod 50 at the upper end of rod 44 is adapted to engage,

Although I have shown and described apparatus for interrupting the circuit through a single conductor o r phase it will by a second casing 29 of larger diameter be understoodthat I contemplateproviding duplicate apparatus to be suspended from a truss similar to that shown at 21 and supported in arallel relation therewith for the control o a metallic circuit single phase transmission line. Likewise for the control of a three phaseline I may use the same apparatus in triplicate. In either case'the standards or towers 23 would be suitablyv positioned so as not Ito interfere with the mechanism.

The' operation of the more complete mechanism which I have. illustrated by way of example in Fig. 2 is as follows: Assuming the parts tol be in' the. -relative positions shown by the drawing, the line current may be considered to enter at the connection 23, pass through the member 22 to contact'l, to rod 2, through contacts 25 to member 6 through supporting member 21 and pipe 7 to vessel 12 to switch rod 9. From t tionary. switch contact 11 it passes to the solenoid 39, through .switch 38 to wire 40 to disconnecting switch 41 to the lineby wire 42. Normal values of line current are 'insufficient to operate the solenoid 39 but upon the occurrence of a predetermined overload th solenoid 39 will-open the switch 38 thereby causing the operation of solenoid 14 and 'an opening of the switch 9. Thearc drawn by the opening df this switch suddenly generates a considerable Aquantity of gas-in thechamber 12 and since the vent tube 33 and the reservoir tube 34 provide only restricted outl ts for the escape of gas vand liquidfthe resu ting pressure in the chamber 12 is releved principally4 by the pipe 7 leading to the vessel 6. Piston 5 is immediately vforced down, the rod 2 breaking connection with contact 1 and opening the main circuit. The arc of the main break is thus drawn first through air and then as the end of the rod 2 becomes submerged upon continued downward movement, the arc is also drawn through the liquid in the cylinder-3. As

vthe piston moves downwardly the li uid beneath it is forced out through the s ots 28, through pipe 30 into reservoir 31. After the piston reaches the upperv ends'of the slots 28 the escape of liquid. becomes ,more and more restricted until, and when the piston reaches 'its lower limit,`the slots 28 are entirely closed. A gradual checking of the movement of the iston and contact rod is thereby effected. After the main circuit has been broken as described above the. disconnect switch may be opened. It will be noted that the switch 9 in the chamber 12 is free to close by gravity when the line circuit is finally opened.

The main contact rod 2 may be raised to closed circuit position by pushing up on the rod 44, the rod 2 being frictionally held in closed circuit position. Likewise the rod 2 may be lowered by hand to open the switch manually by first raising the rod 44 and e sta- Vandv movab e cooperating contacts, fluid pressure actuated operating means therefor, fiexible insulating means connected at its lower end with the movable contact and the operating means for freely suspending the same from said structure and means secured to the yflexible insulating means at a point intermediate its ends for supporting the stationary contact.

2. A high' potential switch comprising a stationary contact, a vessel containing in- 'sulat-ing liquid below said stationary contact, a movable contact vadapted to -extend up through' saidA liquid to engage said stationary Contact, means for drawing an arc in aninsulating fluid, to produce a fluid pressure, and means actuated by said fluid pressure for withdrawing said movable contact'from said stationary contact to a position below the level of said liquid.

3. A high potential switch mechanism comprising a main switch, an auxiliary switch having contacts separable in a liquid convertible into gas by the arc` formed upon the separation of its contacts, and means whereby the gas pressure produced by the opening of said auxiliary switch moves the main switch to open circuit position.

4. An electric switch comprising a stationary contact, a narrow open receptacle spaced below the stationary contact and containing insulating liquid, a contact rod mounted centrally iu said receptacle and movable through the bottom thereof, and means for quickly withdrawing the contact rod from the stationary contact, through the intervening space to a position below the surface of the liquid in the receptacle.

5. An electric switch mechanism comprising a pair of relatively movable contacts, a closed vessel containing a liquid, a second pair of relatively movable contacts in said liquid adapted to draw an arc when separated and means responsive to the pressure in said vessel produced by said are for separating said first contacts.

Y 6. An electric switch mechanism comprisinga pair of relatively movable contacts. pressure actuated means for separating said contacts. a closed vessel containing liquid, a second pair of contacts immersed iu said liquid adapted when opened to draw an arc in the liquid and create a pressure in the vessel, and means for communicating said pressure to said pressure actuated means.

7. An electric switch mechanism comprising a stationary contact, a narrow open vessel Containing insulating liquid spaced bcneath said contact, a 'cooperating movable contact rod mounted to extend up centrally through the liquid in said vessel, a fluid pressure operated' member on said rod adapted to withdraw the rod from the stationary contact to a position beneath the surface of the liquid and load responsive means for subjecting said member to fluid pressure.

Inwitness whereof, have hereunto set my hand this 31st day of December, 1923.

A JOHN D. HILLIARD.

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