US1628405A - Electric switch - Google Patents

Description

1 192 May 0 7 J. D. HILLIARD ELECTRIC SWITCH Filed June 23, 1922 Il w `n i IllIlIIllIlll/IlllrllIllllll/llll/lllIllll/llllllllllllllllll/lllllllllll/11111 Inventor: John D, Hllial'r` b5 MMP? d? OQQQIJ Hls Attorneg.

Patented May 10, 1927.

UNITED STATES PATENT OFFICE.

JOHN D. HILLIARD, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

:ELECTRIC SWITCH.

.Application led June 23, 1922. Serial No. 570,394.

My invention relates to electric switches and in particular to means for preventing burning at the contacts when the switch is closed under load.

In systems of electrical distribution of power and particularly in circuits normally carrying great amounts of power at high pressure, automatic means are often cmployed to cut out of the system a branch or feeder upon the occurrence of t-he fault therein. If the fault is of considerable mag-A nitude it often happens that the burden is removed from the system near the point of generation.. In such systems automatic means are usually employed t-o restore pressure to the line after a definite time in which the faulty feeder should be isolated by the opening of the feeder circuit breaker. If the means provided for the opening of the faulty feeder circuit breaker have failed and the fault persist-s in the feeder, the reclosing of the main circuit breaker will instantly permit a flow of current through the contacts of the circuit breaker which is largely limited merely by the capacity ot the generator and the nature of the fault.-

This initial rush of current is often greatly in excess of the current flowing when the circuit breaker opens upon the occurrence of the fault.

Many switches heretofore designed for this service have operated satisfactorily in the matter of carrying and rupturing such circuits but have failed when called upon to close the circuit upon low resistance short circuits because of the severe burning of the contacts at such closure the current densities often becoming high enough to cause welding of the contacts. In such switches thc circuit is made and finally rupturedat secondary contacts which for several reasons are not capable of continuously carrying the rated load of the switch.

One of the objects of my invention has therefore been to provide in a switch of this character a means for preventing excessive burning of the contacts upon closure of the switch.

Another object of my invention is to provide inI a switch of this character a 'set of auxiliary contacts which will make the circuit upon closing the switch, such contacts having .suflicient capacity to handle short circuit currents upon closing but said contacts not being required to make th^eJ final break in the circuit when the switch is opened.

A further object of my invent-ion is to provide in a switch of this character auxiliary contacts for making the circuitl when the switch is being closed, said contacts having renewable burning tips which may be readily applied thereby prolonging the life of the switch, reducing to a minimum the time required to make renewals and consequently increasing the continuity ot service.

Otherobjects and advantages of my invention will appear from the following description taken in connection with the accompanying drawings, wherein Fig. 1 is an external view partly in elevation and partly broken away of the fluid tank and contact mechanism of a single pole switch embodying the preferred form of my invention, and Fig. 2 is a view taken on the line y2--2 in Fig. 1.

In the drawing will be seen a fluid tank or receptacle with an insulated lining 11 adaptedv to contain an insulating fluid 12, the normal level of which is indicated by the shading. A cover 15 for the fluid tank is provided with apertures to receive insulating bushings 16 for the stationary electrodes 17 of the switch, the bushings beingheld in place by clamping rings 18. An aperture is also provided in the tank cover 15 to allow the passage of a contact supporting rod 2O through the packed bushing 21. A metallic explosion chamber casing in which the circuit is ruptured upon opening of the switch is attached to the stationary electrode 17 and is in electrical connection therewith. This explosion chamber is adapted to contain a movable secondary contact 26 having a renewable burning tip 27. Electrical connection between the secondary contact 26 and the explosion chamber casing 25 is maintained by the lead 28. Movement of the secondary contact 26 is limited by a support 30 and contact with a secondary contact stud 40 is maintained within this limit by the compression spring 29. Tertiary contact levers 31 are pivoted to lugs 32 on the out-side of each of the eX- plosion chamber /casings 25 and are provided with renewable burning tips 33. Dash pots 35 are formed on the outside of each of' the explosion chamber casings 25, the plungers 36 of lwhich are connected to the leversA 31 by the pins 37. The dash pot Sti plunger 36 is provided with valved openings so that its speed may he regulated by the resistance which the plunger offers to passage ot' fluid through these openings. Electrical connection heween the tertiary contact lever 31 and the explosion chamber casing 25 is maintained by the lead 34.

The secondaryv contact stud 40 is provided with av renewable burning tip 41 and is attached to a bridging member 45 and enters the explosion chamber through an insulating bushing 46. A lead 47 forms the electrical connections between the secondary contact studs.

A substantially stationary contact brush 50 is attached to the explosion chamber cas ing 25 and together with the tertiary contact lever 31 makes contact with a main bridging member 51 which is attached to the rod 20.

The sequence of operation from the closed position of the switch is as follows: Manual or automatic tripping` of operating means (not shown, but which may be similar to that shown in patent to Emmet and Hewlett, 942,491. December 7, 1909) will cause the rod 20 to move downwardly and to separate the main bridging member 5l from the stationary contact brushy 50. Further movement of the contact rod 20 will cause separation ot the main bridging member 51 from the tertiary contact tip 33, movement l`of which to follow the main bridging member is impeded by action of the dash pot plunger 36. In the meantime the secondary contact 26 has followed the downward movement of the secondary Contact stud 40 by the action of the spring 29 and with further movement ot the contact rod 20 will reach its limit of travel against they support 30 after which the circuit will be finally opened upon parting of the burning tips 27 and 41. The circuit will be ruptured in the explosion chamber by the quenching of the arc formed upon the separation of the burning tips 27 and 41 in the usual manner employed in this type of switch structure.

As the pressure created in the explosion chamber by the arc formed by the separation of the contact tips 27 and 41 is released and as the fluid passes through the valved openings in the piston 36 the tertiary Contact lever 31 will fall to its lower position indicated by the dotted lines.

In closing. the operating means will cause the contact rod 2O to rise` first making contact between the main bridging member 51 and the burning tips 3? of the tertiary con` tact lever 31, after which contact will be made between the secondary contact tips 27 and 41, and finally between the main bridging member 51 and the stationary contact brush 50. i

From the above it will be seen that the embodiment of my invention provides a switch closing the circuit, the circuit being closed at the tips of the tertiary contact lever. As

the closing contacts are not used in ruptur-l ing the circuit they may be made suiliciently rugged to withstand the severe burning which will take place when the switch is closed ou short-circuit 'and being made renewable. the life of the switch is great ly increased.

lVhilc the preferred embodiment otl my ine vcntion is substantially as shown in Figs. 1 and 2, that is, applied to switches ol' tht` fluid break type, the same principles may as readily be, applied to air break switches and to other forms of electrical apparatus. l therefore do not wish to be limited to the particular structure shown.

This application is a continuation in parl of my prior application, Serial No. 548,155. filed March 30, 1922.

What I claim as new and desire to secure by Letters Patent of the United States` is 1. In a switch, .a receptacle adapted to contain an insulating liquid, means forming an explosion chamber within said receptacle. a pair of contacts located within said explosion chamber adapted to break a circuit and a .second pair of contacts connected in Htl shunt with said first contacts and adapted to make said circuit within said liquid.

2. In a switch, a. receptacle adapted to contain a liquid. means forming an explosion chamber within said receptacle. a pair of contacts adapted to break a circuit within said explosion chamber, a second pair of contacts within said receptacle connected in shunt with sai-d first contacts and adapted to make said circuit and a single means for operating bot-h pairs of contacts.

3. A switch having a pair of contacts adapted to break a circuit, a second pair of contacts in shunt. relation with said first contacts adapted to makesaid circuit and a single means for operating both pairs of contacts.

4. A switch having a pair of contacts adapted to break a circuit and a second pair of contacts adapted to make said circuit. one contact of one of the pairs of contacts being rigidly connected to a Contact ot the other of said pairs.

5. A switch having a pair ot contacts adapted to break a circuit and asecond pair of contacts adapted to make said circuit` one Contact of one of the pairs ot contacts being rigidly connected `to a contact of the other of said pairs and movable therewith.

6. A switch having a primary set of contacts arranged to carry continuously a full load current flowing through a circuit, a secondary setl of contacts, a tertiary set of ltltl lill ltr

contacts and means whereby said circuit is broken at said secondary contact and made at said tertiary set of contacts.

7. In a switch, the combination of a receptacle adapted to contain an insulating 'liquid, a primary set o't contacts arranged to carry continuously a full load current flowing through a. circuit, a secondary set of contacts, a tertiary set of contacts within said liquid and means whereby said circuit is broken at said secondary set of contacts and made ail said tertiary set of contacts.

8. In a switch, amovable Contact and a substantially stationary contact adapted to cooperate'therewith,4 a second movable contact, and a contact adapted to cooperate therewith and mounted to follow and to maintain engagement with said second movable contact for a limited distance when the same is moved to break the circuit, a third movable contact, and a contact ada ted to cooperate therewith to follow sai third movable contact for a limiteddistance after said third movable contact is separated therefrom, whereby a circuit may be broken at said second movable contact Iand made at said third movable contact.

able contact for a limited distance after said third movable contact is. separated therel from, all constructed and' arranged whereby a circuit is broken beneath Athe surface of said liquid vat said second movable contact and made beneaththe surface of said liquid at said third movable contact.

10. In a switch, a receptacle adapted to contain an insulating fluid', a movable contact and a substantially stationary contact. adapte-d to cooperate therewith', a second movable contact a contact adapted to cooperate therewith and mounted to follow and to maintain engagement with said second movable'contact for a limited distance when the same is moved to break the circuit, a third movable contact and a ,Contact adapted to cooperate therewith to follow said movable contact for a limited distance after said third movable contact is separated therefrom, all constructed and arranged whereby a circuitvis broken beneath the surface of said liquid at said second movable contact and made beneath the surface of said liquid at said third movable contact, and arc cx- 'tingiiishingmeans operative to extinguish the arc formed upon the separation of said second movable contact and its cooperating Contact.

11. In a switch, a rece tacle adapted to contain an insulating fluid); tact and a substantially stationary contact adapted to cooperate therewith, a second movable contact, a contact ada )ted to cooperate therewith and mounte to follow and to maintain engagement with said socond movable contact` for a limited distance when the same is moved to `break-fthe cir,- cuit, a third movable contact anda contact adapted to cooperate therewith to follow said movable contact for a limited distance after said third movable contact is separated therefrom, all constructed and arranged whereby a circuit is broken beneath the surface of said liquid at said second movable contact and made beneath'vthe surface of said liquid at said third movablecontact, and means forming an explosion chamber Isurrounding said second movable contact and its cooperating contact.

- 12. A switch comprising main current carrying contacts, secondary arcing contacts in shunt therewith, means comprising other contacts in shunt with the main contacts for a movable conpreventing burning of said secondary con tacts when said switch fis being` closed, and means for rendering said means inoperative when the switch is being opened),

13. A circuit controlling switch having vmain current carrying contacts, secondary contacts adapted to produce the final break in the circuit and means operable upon the closing movement of said switch to shunt said secondary contacts. i

14. A switch comprising main current carrying contacts, an explosion chamber, secondary arcing contacts therein connected in shunt with said main contacts and arranged to produce the final break in Ithe circuit, and means for preventing burning of said secondary 'contacts when said switch is closed, said means being Vlocated external of said eX- Vplosion chamber'- and being connected in xshunt with wthe secondary contact.

In witness whereof, I have hereunto set my hand this 22nd kday of June, 1922.

JoHND. HILLiARD.

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