US2480622A

US2480622A - Electric switch

Info

Publication number: US2480622A
Application number: US632734A
Authority: US
Inventors: Frank E Warnock
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1945-12-04
Filing date: 1945-12-04
Publication date: 1949-08-30
Anticipated expiration: 1966-08-30

Description

F. E. WARNOCK ELECTRIC SWITCH Aug. 30, 1949;

Filed Dec. 4, 1945 lr'xventcr Frank E. Wan mock,

by 4? h Hi8 Attorney Patented Aug. 30, 1949 ELECTRIC SWITCH Frank E. Warnock, Merwood, Pa., assignor to General Electric Company, a corporation of New York Application December 4, 1945, Serial No. 632,734 3 Claims. (01. 200-146) My invention relates to electric circuit disconnecting switches, and more particularly to those of the load break switch type wherein auxiliary arcing contacts are provided to interrupt currents such as transformer magnetizing currents and the like, in addition to the main switch members for carrying the normal load current and disconnecting the circuit.

Such load break disconnecting switches, in a relatively inexpensive yet fully insulated and readily mounted and interconnected form, can be used with advantage for both interrupting and disconnecting a high voltage power circuit at points where conventional power circuit breakers are impractical or uneconomical. Also it is desirable that electric switches for interrupting the magnetizing current of power transformers be of a form adapted to be immersed in a relatively small space in the same liquid insulating dielectric such as oil or a halogenated hydrocarbon as the transformer. Thus when arcs are drawn in oil there is always the hazard of fire. On the other hand, when arcs are drawn in a non-inflammable dielectric, there is always the possibility of some decomposition of the halogenated hydrocarbons and the consequent formation of corrosive decomposition products that are injurious to transformer insulation as well as other parts.

Accordingly it is an object of my invention; to provide a new and improved form ofload break switch that is capable of efficiently interrupting moderate load currents of high voltage power circuits within a relatively small hermeticallysealed and evacuated enclosure in addition to externally carrying the load currents and disconnecting the power circuits.

It is another object of my invention to provide a switch of the type described above which may be immersed in any form of liquid insulating dielectric without fire hazard or deleterious effect on the liquid dielectric when operating to interrupt moderate load currents.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawing in which Fig. 1 is an elevational view, partly in section, of an electric switch embodying my invention with the switch shown in the closed position, and Fig. 2 is a view similar to Fig. 1

' electric switch shown in the drawing is illus- McCarty application Serial trated as being mounted in air, it should be understood that it is particularly well adapted for being immersed in a liquid insulating dielectric, in which case it may be mounted in a relatively small housing integral with a transformer, as is disclosed for example, in copending Palme and No. 632,735, now Patent No. 2,469,203, May 3, 1949, filed concurrently with the present application, and assigned to the same assighee as the present application.

Circuit terminals! and 2 are arranged to be electrically interconnected by a pair of relatively movable. knife switch members illustrated as a stationary switchmember or contact 5, electrically connected and supported from circuit terminal I, and a movable blade or contact 6 pivotally mounted as indicated at 'l to circuit terminal 2 and having load current-carrying overlapping engagement with the switch member 5 when the pivotally mounted rotatable blade 6 is in a predeterm ned angular position as shown in Fig. 1. For the purpose of interrupting moderate load power currents when the electric switch of my invention is to be opened there is provided a relatively small auxiliary circuit interrupter. generally indicated at 8, which can be carried directly by one of the relatively movable switch members without requiring any additional insulating support. As illustrated, circuit interrupter 8 is associated with stationary contact or 1 switch member 5, and circuit terminal I by means of Z-shaped conducting supporting member 9. It should be understood that circuit interrupter 8 might be carried by movable blade 6 if desired. Circuit interrupter 8 comprises an hermetically sealedenclosure 10 formed or insulating material such as glass, or the like, which is essentially an evacuated envelope for housing a pair of relatively movable arcing or interrupting contacts II and I2. Interrupting contact II is illustrated as a stationary contact electrically connected to stationary current carrying contact 5 by means of Z-shaped bracket or support 9. Movable arcing contact 12, on the other hand,

is a rod-shaped contact having a portion thereof extending outside of evacuated envelope l through a flexible member or diaphragm 13. The portion of rod contact l2 extending outside of housing I0 -is in efiect a contact actuating member and includes at the outer extremity thereof an auxiliary terminal 14 which is positioned outside of housing or enclosure l0. Relatively movable arcing or interrupting contacts II and I2 are preferably biased to the open position by suitable means such as the flexible diaphragm l3 or if desired, by additional spring means such as I5.

Supported on movable blade 6 is an auxiliary contact surface in the form of a conducting lever or transfer switch l6. Lever I6 is pivotally mounted as indicated at IT and is normally biased in a counter-clockwise direction, as viewed in Fig. 1, by resilientmeans, such as a spring l8, such counter-clockwise movement being limited by a stop [9 on blade 6 adapted to engage with an extension 20 of lever I6.

The auxiliary contact surface in the form of lever I6, the auxiliary terminal l4, together with interrupting contacts II' and I2, provide a shunt electrical connection across the relatively movable switch members and 6. An important feature of my invention is the arrangement of the current carrying contacts and arcing contacts whereby the current carrying contacts are first opened thereby shunting all of the power current through circuit interrupter 8. As illustrated in the drawings, a portion of the current is normally shunted through the circuit interrupter 8 but it will be understood that the circuit through interrupting contacts H and I2 may normally be open until just prior to disengagement of the current carrying contacts. Such an arrangement is disclosed and claimed in the above-mentioned copending application of Palme and McCarty.

As illustrated by dotted lines in Fig. 2, arcing contacts H and i2 remain in current carrying engagement until after current carrying contacts 5 and 6 have been disengaged and all of the current has been transferred to the shunt circuit comprising interrupting or arcing contacts II and I2. Furthermore, contacts 5 and 6 must have separated a suflicient distance before contacts Ill and H separate so that arcing will not occur at contacts 5 and 6. Spring l8, which is a stronger spring than spring 15, maintains arcing contacts I I and l 2 in a closed position during the opening movement of blade 6 and until extension of lever [B engages stop l9. Thereafter, arcing contacts II and I2 are separated under the influence of spring l5 and in view of the high vacuum'in envelope ill the interrupting operation even with very high voltages is readily accomplished. It will be observed that the auxiliary contact surface in the form of lever I6 is separated from auxiliary terminal [4 thereby providing an additional insulating gap in the shunt circuit including interrupting contacts II and I2. The other gap is provided by contacts II and [2 which, during the opening operation of the switch, are opened and remain open.

During the circuit closing operation the circuit is first completed through the shunt circuit includin arcing contacts H and I2 after which the main current carrying contacts 5 and 6 are closed to complete the circuit.

It will be understood that the insulating evacuated envelope It prevents any are which is drawn from, in any way, deleteriously affecting the surrounding medium whether it be air or oil or other liquid insulating dielectric.

It should be understood that my invention is not limited to the specific details of construction and arrangement thereof herein illustrated and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a load break disconnecting switch, a first insulating support for a first circuit terminal, a second insulating support for a second circuit terminal, a pair of relatively movable cooperating switch members which when brought into face carried by said blade, means including said auxiliary contact surface, said auxiliary terminal and said interrupting contacts for providing a shunt electrical connection between said switch members before the members are moved out of electrical engagement, a spring mounted on said blade to maintain said shunt connection during a portion of the opening movement of said switch members, a stop for limiting the effective operation of said spring, sprin means for separating said interrupting contacts to draw an arc and extinguish the same within said envelope upon continued opening movement of said switch members and to provide a gap in said shunt circuit, and means including said stop for subsequently providing an additional insulating gap in said shunt circuit between said auxiliary terminal and said auxiliary contact surface.

2. In a load break disconnecting switch, a pair of switch members integrally mounted for load current carrying, overlapping engagement and including a pivotally mounted rotatable blade, a relatively small current interrupter having a hermetically sealed and evacuated enclosure fixedly mounted on one of the switch members and provided with a first interrupting contact fixedly extendin through the enclosure and electrically connected to the one switch member, and a second interrupting contact extending through and having a flexible seal with the enclosure through the movement of which the second interrupting contact engages or disengages the first interrupting contact, an auxiliary movable terminal external to the enclosure mechanically connected to operate the second interrupting contact and electrically connected therewith, an auxiliary contact surface carried by and electrically connected to the other switch member for engaging the external terminal to interconnect the interrupter contacts in shunt with the pair of switch members during current-carrying engagement thereof, resilient biasing means for maintaining engagement between the auxiliary contact surface and the auxiliary terminal upon disengagement of the switch members, and means including the auxiliary terminal and the auxiliary contact sur- 5 face for disengaging the interrupting contacts draw an arc and extinguish the same within the enclosure upon further opening of the switch members.

3. In a load break disconnecting switch, a pair of knife switch members having load current carrying overlapping engagement and each having a spaced apart insulating support, a relatively small current interrupter having an evacuated envelope supported on one of the switch members substantially in the space between the insulating supports when the switch members are in engagement and provided with a first interrupting contact extending through the envelope and electrically connected to the one switch member, and a second interrupting contact extending through and having a flexible seal with the envelope through the movement of which the movable interrupting contact engages or disengages the first interruptin contact, an auxiliary movable terminal external to the envelope mechanically connected to operate the second interrupting contact and electrically connected therewith, an auxiliary contact surface extending from and electrically connected to the other of said switch members for engaging said movable auxiliary terminal to interconnect the interrupter contacts in shunt with the switch members during current-carrying engagement thereof, resilient means for maintaining engagement between the auxiliary contact surface and the auxiliary terminal to maintain the 6 shunt electrical circuit including the interrupting contacts between the current-carrying switch members after the disengagement thereof, means including the auxiliary terminal and the auxiliary contact surface for separatin the interrupting contacts to draw an arc in the shunt circuit and extinguish the same within the envelope after the disengagement of the switch members, and means including the auxiliary terminal and the auxiliary contact surface for providing an insulating gap in the shunt circuit upon continued opening of the switch members after the disengagement of the interrupting contacts.

FRANK E. WARNOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 532,594 Scott et al Jan. 15, 1895 589,582 Smith et a1 Sept. 7, 1897 594,656 Schwedtmann Nov. 30, 1897 1,783,279 Burnham Dec. 2, 1930 1,963,418 Pittman et al June 19, 1934 2,121,180 Vatter June 21, 1938 FOREIGN PATENTS Number Country Date 400,716 Great Britain Nov. 2, 1933