US3671696A

US3671696A - Vacuum interrupter shunted with mechanical switch

Info

Publication number: US3671696A
Application number: US89893A
Authority: US
Inventors: Richard G Brunner
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1970-11-16
Filing date: 1970-11-16
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20
Also published as: CA934796A

Abstract

An electric circuit breaker for switching capacitive loads, such as capacitor banks or long electric power transmission lines, comprises a metallic housing having a pair of spaced apart terminal bushings extending through the wall thereof. Each bushing comprises a conductor and an insulator. A vacuum interrupter comprising an evacuated envelope and a stationary and a movable contact therein is mounted in the housing between the bushings and each contact is connected to the conductor in a respective bushing. A shunting switch for parallel connection with the vacuum interrupter is mounted in the housing between the bushings. The shunting switch has less current interrupting capacity but greater current carrying capacity than the vacuum interrupter. The shunting switch comprises a stationary contact which is mounted on one bushing and electrically connected to the conductor therein. The shunting switch further comprises a pivotable blade type contact which is mounted on the other bushing and electrically connected to the conductor therein. Operating means are located in the housing and comprises a first and second insulated contact rods which are connected to the movable contact of the vacuum interrupter and the blade of the shunting switch, respectively. In operation, the operating means causes the vacuum interrupter to close before and open after the closing and opening, respectively, of the shunting switch.

Description

United States Patent Brunner 1 June 20, 1972 [54] VACUUM INTERRUPTER SHUNTED WITH MECHANICAL SWITCH [7 21 Inventor: Richard G. Brunncr, Dedham, Mass.

[73] Assignee: Allis-Chalmers Manufacturing Company,

Milwaukee, Wis.

22 Filed: Nov. 16,1970

211 Appl.No.: 89,893

[56] References Cited UNITED STATES PATENTS 1,783,279 12/1930 Burnham ..200/l44 B 2,480,622 8/1949 Wamock 3.560,682 2/197] Kohler et a] ..200/l44 B Primary Examiner-Robert S. Macon Attorney-Thomas F. Kirby, Robert B. Benson and Lee H. Kaiser [57] ABSTRACT An electric circuit breaker for switching capacitive loads, such as capacitor banks or long electric power transmission lines, comprises a metallic housing having a pair of spaced apart terminal bushings extending through the wall thereof. Each bushing comprises a conductor and an insulator. A vacuum interrupter comprising an evacuated envelope and a stationary and a movable contact therein is mounted in the housing between the bushings and each contact is connected to the conductor in a respective bushing. A shunting switch for parallel connection with the vacuum interrupter is mounted in the housing between the bushings. The shunting switch has less current interrupting capacity but greater current carrying capacity than the vacuum interrupter. The shunting switch comprises a stationary contact which is mounted on one bushing and electrically connected to the conductor therein. The shunting switch further comprises a pivotable blade type contact which is mounted on the other bushing and electrically connected to the conductor therein. Operating means are located in the housing and comprises a first and second insulated contact rods which are connected to the movable contact of the vacuum interrupter and the blade of the shunting switch, respectively. In operation, the operating means causes the vacuum interrupter to close before and open after the closing and opening, respectively, of the shunting switch.

1 Claim, 2 Drawing Figures BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates generally to electric circuit breakers and particularly to those which comprise vacuum type interrupters or switches.

2. Description of the Prior Art Vacuum interrupters and switches are inherently wellsuited for duty in switching capacitive loads, such as capacitor banks or long transmission lines. However, vacuum interrupters and switches have extremely high momentaryarc current interrupting capabilities which very often exceed their continuous current carrying capabilities. It was the practice, therefore, to rely on vacuum interrupters and switches for switching capacitive loads and to rely on other types of circuit breakers for carrying and interrupting high current loads, such as metal-clad breakers using magnetic blow-out principles or oil type circuit interrupters. However, these other types of circuit breakers require more maintenance and more space-than vacuum interrupters and, frequently, need to be used in addition to vacuum interrupters and switches. It is desirable, therefore, to provide new and improved circuit breakers which provide the inherent I advantages of vacuum interrupter and switches and the current carrying capabilities of other types of circuit breakers but which are smaller, less costly and simpler than installations which merely combine both types of switches.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a new and improved electric circuit breaker which comprises a vacuum type circuit interrupter or switch having a sealed envelope and a pair of relatively movable interrupter contacts therewithin. An air-break shunting switch comprising relatively movable shunting contactsis connectedin parallel with the vacuum interrupter. The shunting switch has less interrupting capacity but greater current carrying capacity than the vacuum interrupter. Operating means connected to the vacuum interrupter and to the shunting switch effect closure of the interrupter contacts prior to closure of the shunting contacts and opening of the interrupter contacts after opening of the shunting contacts.

In a preferred embodiment of the invention, a metallic housingis provided which has at least one pair of spaced apart terminal bushings extending through thewall thereof. Each terminal bushing comprises an insulator with a conductor extending therethrough. The vacuum interrupter and theshunting switch are supported inside the housing between the bushings. An operating means is mounted inside the housing and comprises insulating rods which are connected to the movable contacts of the vacuum interrupter and the shunting switch.

OBJECTS It is an object of the present invention to provide improved electric circuit breakers which afford the arc interrupting advantages of vacuum interrupters and the greater current carrying capabilities of other types of switches but which are more compact, more economical, more reliable, and longer-lived than conventional installations which merely combine various types of switches and interrupters.

Another object is to provide circuit breakers of the aforesaid character which are well-adapted for use in a wide variety of specific applications in electrical power transmission and distribution systems.

Another object is to provide such circuit breakers which include commercially available components and a minimum number of custom-made parts.

Other objects and advantages of the invention hereinafter appear.

will

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustrates a preferred embodiment of the invention but it is to be understood that the embodiment illustrated is susceptible of modification with respect to details thereof without departing from the scope of the appended claims.

In the drawing:

FIG. 1 is a side elevational view of the=interior of a circuit breaker in accordance with the present invention; and

FIG. 2 is an end elevational view in reduced scale of one end of the exterior of the circuit breaker shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 of .the drawing, the numeral 10 designates a circuit breaker in accordance with the present invention. Circuit breaker 10 is a multipole device comprising a metallic housing or enclosure. 12 containing three pole units 14,716 and 18 and is understood, for example, to be adapted for use in a three phase a.c. high voltage, high current electriapart terminal bushings 20 and 22 which extend through wall 24 of housing. 12.

Bushings

20 and 22 comprise

conductors

26 and 28, respectively, which extend through insulated

portions

30 and 32, respectively, of the bushings.

Ari-electric circuit interrupter 34, such as a vacuum type circuit interrupter or vacuum switch, is disposed between the

bushings

20 and 22 inside housing 12. Interrupter 34 comprises a sealed envelope36 in which a vacuum is maintained and further comprises a pair of relatively movable contacts within the envelope, such as a stationary contact 38 and a movable contact 40. interrupter '34 is shown in circuit open position in FIG.'1.

Means are provided for mounting interrupter 34 between the bushings 20 and 122 and comprise a metallic bracket or support 42 which is rigidly mounted on the inner end of bushing 22. Interrupter 34 is rigidly secured at one end to bracket 42 as by bolts 44.In this manner, interrupter 34 is insulated from housing 12.

Means are provided for electrically connecting the

contacts

38 and 40, respectively, of interrupters 34 to the

conductors

26 and 28, respectively, of the

terminal bushings

20 and 22, respectively. Thus, a first electrically conductive terminal block 46 ismounted on conductor 26 and is connected by a ry contact 56 which is mounted on and electrically connected to inner end conductor 26 of bushing 20 by suitable means, such as terminal block 46. Shunting switch 54 further comprises a movable contact 58 in the form of an electrically conductive switch blade which is pivotably mounted on a pin 59 carriedon bracket 42.

Means are provided for electrically connecting blade contact 58 to conductor 28 of bushing .22 and comprise a flexible conductor 60 which is connected to blade contact 58 and to second terminal block 50.

Operating means 64 are provided to operate interrupter 34 and shunting switch 54 of circuit breaker 10 in accordance with the invention and, preferably, are mounted on and enclosed in housing I2. Operating means 64 comprise an enclosure '66 in which an operating linkage 68 is housed. Reciprocably movable insulated operating rods 70 and 72 extend into enclosure 66 and are connected at their one end to linkage 68 of operating means 64. The operating rods 70 and 72 are mechanically connected at their other end to the movable contact 40 of interrupter 34 and to the movable contact 58 of shunting switch 54, respectively. In the preferred embodiment, operating means 64 effects simultaneous operation of the pole units l4, l6 and 18.

It is to be understood that linkage 68 of operating means 64 is operated, when desired, by suitable mechanical or electrical control means 74 which are connected thereto and located, for example, exteriorly of housing 12.

Circuit breaker 10 operates as follows. Assume that circuit breaker 10 is in open condition as shown in FIG. 1 and that it is desired to close it. Further assume that all directions of movement hereinafter referred to are with respect to FIG. 1. A closing signal from control means 74 is transmitted to operating linkage 68 of operating means 64. In response to this signal, linkage 68 effects upward movement of operating rod 70 and closure of

contacts

38 and 40 in interrupter 34. Any arcing that occurs as the

contacts

38 and 40 close is confined within envelope 36 of interrupter 34. Subsequent to closure of interrupter 34, linkage 68 of operating means 64 effects upward movement of operating rod 72 and clockwise pivotal movement of movable blade contact 58 of shunting switch 54. Since the circuit between the

bushing

20 and 22 is already closed by interrupter 34, no arcing occurs between contacts 56 and 58 of shunting switch 54 as they close. However, since the contacts 56 and 58 are larger than the contacts in interrupter 34, switch 54 has greater current carrying capacity than interrupter 34.

Assume now that circuit breaker 10 is in closed condition and that it is desired to open it. An opening signal from control means 74 is transmitted to operating linkage 68 of operating means 64. In response to this signal, linkage 68 effects downward movement of operating rod 72, counter-clockwise movement of contact 58 and separation of contacts 56 and 58 of shunting switch 54. Since interrupter 34 is still closed, no arcing occurs between the contacts 56 and 58 of switch 54 as they part. Subsequent to opening of shunting switch 54, linkage 68 of operating means 64 effects downward movement of operating rod 70 and separation of

contacts

38 and 40 of interrupter 34. Arcing that occurs is confined within envelope 36 of interrupter 34.

It will be apparent that circuit breaker 10 has greater current carrying capacity than interrupter 34 alone and greater interrupting capability than shunting switch 54 alone. However, switch 54 requires no arc chute or are quenching means, as do comparable prior art air-break switches, which require maintenance or service. Furthermore, enclosure of interrupter 34, shunting switch 54 and operating means 64 within housing 12 eliminates problems associated with icing and contamination and reduces the possibility of damage to components. All live components are electrically insulated from housing 12 by the

insulators

30 and 32 of the

bushings

20 and 22, respectively, and by the insulated operating rods 70 and 72, yet no complicated structure is required.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An electric circuit breaker comprising:

a metallic housing,

a first terminal bushing comprising an insulator constructed and arranged to extend through a wall of said housing and having a conductor extending through said insulator into the interior of said housing;

a second terminal bushing comprising an insulator constructed and arranged to extend through the wall of said housing in spaced relationship to said first bushing and having a conductor extending through said insulator thereof into the interior of said housing;

a bracket secured to the inner end of said first bushing and the conductor associated therewith;

an electric circuit interrupter of the vacuum type comprising a sealed envelope mounted on said bracket; a movable contact extending rnto sard envelope in movable sealed relationship therewith;

a flexible conductor operably connected to the conductor associated with said first bushing and to said movable contact of said interrupter switch;

a stationary contact extending into said envelope in sealed relationship therewith;

a conductor operably connected to the conductor associated with said second bushing and to said stationary contact of said circuit interrupter;

a shunting switch having a greater current carrying capacity but less interrupting capacity than said circuit interrupter, said shunting switch comprising a fixed shunting contact secured in operative position to said conductor of said second bushing, and a movable shunting contact pivotally carried on said bracket for movement into and out of engagement with said fixed shunting contact;

a flexible conductor electrically connecting said movable shunting contact to the conductor associated with said first bushing;

operating means located within said housing, said operating means comprising a first insulated rod connected to the movable contact of said circuit interrupter, a second insulated rod connected to said movable shunting contact, and operating linkage operably interconnecting said first and second insulated rods in a manner that actuation of said operating means in one direction effects the movement of said movable contact of said circuit interrupter to closed position prior to effecting the pivotal movement of said movable shunt contact to closed position, and actuation of said operafing means in the opposite direction effects the pivotal movement of said movable shunting contact to open position prior to moving the movable contact of said circuit interrupter to open position;

whereby the greater interrupting capacity of said circuit interrupter is always in circuit prior to the closing and subsequent to the opening of said shunting switch which serves as the main current carrier, and any arcing occurs between the contacts of said circuit interrupter and is confined within the sealed envelope thereof.

III III II II!

Claims

1. An electric circuit breaker comprising: a metallic housing, a first terminal bushing comprising an insulator constructed and arranged to extend through a wall of said housing and having a conductor extending through said insulator into the interior of said housing; a second terminal bushing comprising an insulator constructed and arranged to extend through the wall of said housing in spaced relationship to said first bushing and having a conductor extending through said insulator thereof into the interior of said housing; a bracket secured to the inner end of said first bushing and the conductor associated therewith; an electric circuit interrupter of the vacuum type comprising a sealed envelope mounted on said bracket; a movable contact extending into said envelope in movable sealed relationship therewith; a flexible conductor operably connected to the conductor associated with said first bushing and to said movable contact of said interrupter switch; a stationary contact extending into said envelope in sealed relationship therewith; a conductor operably connected to the conductor associated with said second bushing and to said stationary contact of said circuit interrupter; a shunting switch having a greater current carrying capacity but less interrupting capacity than said circuit interrupter, said shunting switch comprising a fixed shunting contact secured in operative position to said conductor of said second bushing, and a movable shunting contact pivotally carried on said bracket for movement into and out of engagement with said fixed shunting contact; a flexible conductor electrically connecting said movable shunting contact to the conductor associated with said first bushing; operating means located within said housing, said operating means comprising a first insulated rod connected to the movable contact of said circuit interrupter, a second insulated rod connected to said movable shunting contact, and operating linkage operably interconnecting said first and second insulated rods in a manner that actuation of said operating means in one direction effects the movement of said movable contact of said circuit interrupter to closed position prior to effecting the pivotal movement of said movable shunt contact to closed position, and actuation of said operating means in the opposite direction effects the pivotal movement of said movable shunting contact to open position prior to moving the movable contact of said circuit interrupter to open position; whereby the greater interrupting capacity of said circuit interrupter is always in circuit prior to the closing and subsequent to the opening of said shunting switch which serves as the main current carrier, and any arcing occurs between the contacts of said circuit interrupter and is confined within the sealed envelope thereof.