US3848101A

US3848101A - Elongated jaw contact for oil circuit breaker disconnect contact

Info

Publication number: US3848101A
Application number: US00861300A
Authority: US
Inventors: E Eberhard; H Meier
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1969-09-26
Filing date: 1969-09-26
Publication date: 1974-11-12
Anticipated expiration: 1991-11-12

Abstract

The movable contact of an oil circuit breaker has an isolating contact at its lower end which engages a jaw contact on the cross-bar. The jaw contact is elongated in the plane which includes the centerlines of two series connected interrupters so that the isolating contacts are free to engage and disengage even though the interrupters move in this plane. An oil dashpot is carried below the jaw contact on the cross-bar.

Description

United States Patent' [191 Eberhard et al.

ELONGATED JAW CONTACT FOR OIL CIRCUIT BREAKER DISCONNECT CONTACT Inventors: Elmer T. Eberhard, Tahoe City;

Henry G. Meier, Glendale, both of Calif.

l-T-E Imperial Corporation, Philadelphia, Pa.

Filed: Sept. 26, 1969 Appl. No.: 861,300

Assignee:

US. Cl. 200/150 R, 200/146 R, 200/150 L, ZOO/166 H Int. Cl. H0lh 33/68 Field of Search 200/150, 150 B, 150 C, 200/166 H, 146

References Cited UNITED STATES PATENTS 12/1928 Hilliard 200/150 B Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb and Soffen 5 7 ABSTRACT The movable contact of an oil circuit breaker has an isolating contact at its lower end which engages a jaw contact on the cross-bar. The jaw contact is elongated in the plane which includes the centerlines of two series connected interrupters so that the isolating contacts are free to engage and disengage even though the interrupters move in this plane. An oil dashpot is carried below the jaw contact on the crossbar.

6 Claims, 7 Drawing Figures SHEET 2 OF 2 PATENIE mv 1 2|914 \\&

INVENTORS BY KY 5, M540 ELONGATED J AW CONTACT FOR OIL CIRCUIT BREAKER DISCONNECT CONTACT THE PRIOR ART Oil circuit breakers are well known and can consist of two series connected interrupter structures connected in series and supported within an oil-filled tank. Each of the interrupters has a stationary contact at its upper end which cooperates with a respective elongated bayonet contact which moves into and out of its respective interrupter structure. The bottoms of the elongated contacts are connected to a common conductive crossbar through respective isolating contacts formed between the cross-bar and the respective contacts. An operating mechanism connected to the cross-bar raises the cross-bar to move the elongated contacts into their respective interrupters, thereby closing the breaker and connecting the interrupters in series: To open the breaker, the cross-bar moves down and the movable contacts separate from the stationary contact in their respective interrupter to interrupt the circuit. As the cross-bar continues to move down, the movable contacts reach a stop position and continued downward movement of the cross-bar causes separation of the isolating contacts formed between the ends of the movable contact and the cross-bar, thereby forming an added and isolating gap in the circuit.

In the past, the isolating contact on the cross-bar rigidly gripped the bottom of the movable contact around its full periphery. Therefore, when the interrupter tubes were laterally deflected with respect to the cross-bar, the movable contact within the interrupter would bind within the interrupter, sometimes to a point where the interrupter would not open. Some of the forces that will cause this lateral deflection (in the plane formed by the axes of the two interrupters) are: magnetic forces due to high current in the V-shaped loop formed by the two series connected interrupters; the jet action at the interrupters which occurs during interruption; ground shock during interruption; and thermal expansion differences in the supporting structure.

BRIEF DESCRIPTION OF THE INVENTION To prevent binding of the movable contact within the interrupter due to deflection of the interrupter tubes with respect to the cross-bar, the isolating contact between the end of at least one of the elongated contacts and the cross-bar permits lateral movement of the elongated contact while still maintaining engagement of the isolating contacts and permitting the isolating contacts to engage, regardless of lateral misalignment. In particular, the isolating contact on the cross-bar is an elongated-type jaw contact such that the contacting end of the elongated movable contact can engage the jaw contact over a given maximum lateral movement between the interrupter tube axis and the cross-bar. Moreover, an oil dash-pot is formed within the crossbar to absorb closing forces when the isolating contacts are closed.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 schematically shows an oil circuit breaker which uses the present invention.

FIG. 2 shows the contacts and cross-bar of FIG. 1 with the interrupter contacts open.

FIG. 3 shows the contacts and cross-bar of FIG. 2 with the isolation or disconnect contacts open.

FIG. 4 is a detailed cross-sectional view of the isolation contacts of the invention and dashpot on the crossbar with the isolation contacts open.

FIG. 5 is a view of the isolation contact connected to the movable interrupter contact as seen from section line 5 5 in FIG. 4.

FIG. 6 is a cross-sectional view of the isolation contact of FIG. 4 taken across section line 6 6 in FIG. 4.

FIG. 7 shows one manner in which the isolator contact can be made to simplify alignment of the isolator contacts.

DETAILED DESCRIPTION OF INVENTION Referring first to FIGS. 1 to 3, there is shown an oil circuit breaker which comprises a metallic tank 10, which may be filled with oil to level 11. One phase of a circuit to be protected is connected to terminal bushings 12 and 13 which extend through tank 10 and carry

interrupters

14 and 15, respectively, at their ends.

Interrupters

14 and 15 may, typically, be formed of insulation tubes having

stationary contacts

16 and 17 at their upper ends and connected to the conductors of bushings 12 and 13, respectively.

Insulation tubes

14 and 15 will carry suitable arc splitters and discharge ports which are well known to those skilled in this art.

Each of

interrupters

14 and 15 cooperate with

elongated contacts

18 and 19, respectively, which are movable through the bottom of

tubes

14 and 15 and along the axes thereof to engage and disengage

stationary contacts

16 and 17, respectively. The bottoms of

contacts

18 and 19 are provided with

isolation contacts

20 and 21, respectively, which cooperate with

isolation contacts

22 and 23 carried at the opposite ends of conductive cross-bar 24. The cross-bar 24 is then moved up and down by the usual lift rod 25 and operating mechanism 26 which moves lift rod 25.

FIG. 1 shows the circuit breaker in its closed position To open the breaker, either manually, or automatically, operating mechanism 26 moves lift rod 25 and cross-bar 24 down to the position of FIG. 2 where contacts 16-18 and 17-19 separate to interrupt the circuit breaker current. Continued movement of lift rod and cross-bar 24 downwardly moves the

contacts

18 and 19 to engage any desired stop mechanism 27 (FIG. 2) which prevents their further downward motion. Therefore, as the cross-bar continues to move down, and as shown in FIG. 3, the

isolation contacts

22 and 23 separate from

contacts

20 and 21, thereby to form two isolation or disconnect gaps.

To close the breaker, lift rod 25 is moved up from the position of FIG. 3 to the position of FIG. 1, first closing isolation contacts 20-22 and 21-23, and then closing interrupter contacts 18-16 and 19-17.

It is necessary to have

contacts

18 and 19 accurately aligned on the axis of

tubes

14 and 15, respectively, since it is otherwise possible that

contacts

18 and 16 will bind in their respective interrupter. Many forces can act on the interrupters which cause their lateral displacement; that is, a displacement in the plane formed by the axes of

interrupters

14 and 15. Such forces may be caused by magnetic forces in the U-shaped current path defined within the breaker; due to ground shock during circuit breaker operation; due to the jet action of oil and gas jets forced out of the ports of the interrupters during operation; or, more simply, forces due to differential thermal expansion or contraction of the structural parts of the breaker. A greatly exaggerated lateral displacement of

interrupters

14 and 15 is shown in dotted lines in FIG. 1. In the past, isolation contacts on

movable contacts

18 and 19 have been built so that they are laterally fixed with relation to the cross-bar 24 when they engage

cross-bar contacts

22 and 23. This type design was used since it was also desired to obtain a dashpot-type action when the isolation contacts closed.

Isolation contact 22 (FIGS. 4 and 6) consists of a conductive body 32 having an extension 33 which is suitably mounted or clamped to cross-bar 24. Two pairs of end plates 34 and 35 extend from body 32 and receive contact fingers 36 to 38 and 39 to 42, respectively.

Contacts

37 and 40 are shown in FIG. 4 which is a cross-sectional view of FIG. 6 seen across section line 4 4 in FIG. 6. Each of contact fingers 36 to 42 are identical to one another and are loosely mounted on pivot pins 43 and 44 as shown. Each of contact fingers 36 to 42 are provided with upper and lower biasing springs, shown as upper springs and 51 and lower springs 52 and 53 in FIG. 4 for

contacts

37 and 40, respectively. By fixing the location of the bottom of

contacts

18 and 19, however, lateral deflection of

interrupters

14 and 15 can cause binding of the

contacts

18 and 19 inside

interrupters

14 and 15. The present invention provides a novel isolation contact structure in which the bottom of

contacts

18 and 19 are free to have lateral movement while still obtaining a dashpottype of action.

FIGS. 4 to 6 show the construction of one pair of isolator contacts (

contacts

20 and 22 of FIGS. 1 to 3) in accordance with the invention.

Contacts

21 and 23 may be constructed inan identical manner.

lsolator contact 20 consists of an elongated contact 30 suitably fixed to the end of contact 18. Contact 30 may be a composite of separately formed parts to simplify its manufacture. Thus, as shown in FIG. 7, the end of the contact 18 is threaded so that a lock plate 81 and contact 30, both having an internal thread, can be assembled and aligned with the isolating contact 22. A gap between the lock plate 81 and contact 30 and two screws 82 passing through contact 30 and screwing into the lockplate provide a means of clamping 81 and 30 on the thread of 18. Lower springs 52 and 53 press insulation buttons 54 and 55 against the bottom of plate 34, thereby pressing the bottom of

contacts

37 and 42, respectively, against

conductive extensions

56 and 57 of body 32. In this manner, each of contact fingers 36 to 42 are biased into engagement with one of

members

56 and 57 and thus with body 32. The upper ends of the contacts are pressed away from walls 34 and 35, as by springs 50 and 51 in FIG. 4. Thus, when contact 30 moves to the dotted line position of FIG. 4, its side surfaces, which are adjacent its bottom, are strongly engaged by contact fingers 36 to 42 so that contact 30 is connected to body 32 and thus crossbar 24.

In order to form a dashpot-type structure for cushioning the force of engagement of

contacts

20 and 22, end walls 60 and 61 (FIG. 6) are provided at the ends of

extensions

56 and 57 to form a rectangular oil-filled volume. The height of end walls is equal to the height of

extensions

56 and 57. A rectangular piston is then provided which fits closely into the rectangular volume formed by

members

56, 57, 60 and 61. Suitable vents, such as opening 71 (FIG. 6) are formed in side wall 61 to provide controlled discharge of oil from the rectangular volume beneath piston 70. A shaft 72 is connected to piston 70 and bears against compression spring 73 (FIG. 4) which seats against a plug 74 which is threaded into body 33.

In operation, when contact 30 moves into engagement with contact fingers 36 to 42, it strikes piston 70 and moves piston 70 to the right in FIG. 4 to the dotted line position. This compresses spring 73 and ejects oil from the volume beneath piston 70, thereby causing a smooth, bounce-free connection between

contacts

20 and 22. When the

contacts

20 and 22 are opened, spring 73 will drive piston 70 tothe position shown in FIG. 4, to await the next contact closing.

An important feature of the invention in that lateral movement of the interrupters 14 and 15 (FIGS. 1 to 3) will not cause binding of

movable contacts

18 and 19 since the bottom of these contacts (contact 30 of FIGS. 4 to 6) can move laterally within the elongated jaw contact 22 on the cross-bar 24. Thus, the isolation contacts will still operate properly during opening and closing operations even though there is lateral deflection of the interrupters.

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and, therefore, the scope of this invention is limited not by the specific disclosure herein, but only by the appended claims.

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

1. A contact structure for a circuit interrupter; said circuit interrupter comprising an oil circuit breaker having: first and second interrupter structures, first and second elongated movable contacts movable along the axes of said first and second interrupter structures, respectively, and between interrupter contact open and closed positions, a conductive cross-bar, first and second isolation contact means on said conductive crossbar movable between engagement and disengagement with respect to the bottom of said first and second elongated movable contacts, respectively, an oil-filled tank for receiving said first and second interrupter structures, and operating means for moving said cross-bar and said first and second elongated movable contacts along said axes of said first and second interrupter structures; the improvement which comprises the construction of at least said first isolation contact means to permit lateral movement of said bottom of said first elongated contact while maintaining contact with said first isolation contact means responsive to lateral movement of at least one of said first or second interrupter structures in the plane formed by the axes of said interrupter structures; said first isolation contact means comprising a jaw-type contact having opposing elongated contact surfaces disposed in spaced parallel planes which each extend in said lateral direction and receiving side surfaces adjacent said bottom of said first elongated contact between said opposing surfaces and in high pressure sliding contact; said bottom of said first elongated contact being laterally slidable within said jaw-type contact.

2. The contact structure of claim 1 wherein said second isolation contact means is constructed in a manner identical to said first isolation contact means.

3. The contact structure of claim 1 wherein said opposing elongated contact surfaces comprise a plurality of elongated contact fingers, and biasing means connected to said elongated contact fingers normally pressing said fingers away from said contact surfaces and toward engagement with said side surfaces adjacent said bottom of said first elongated contact.

4. The contact structure of claim 1 which includes a generally laterally elongated enclosed volume at the base of said jaw-type contact and an elongated piston contact and said first isolation contact means.

5. The contact structure of claim 4 wherein said second isolation contact means is constructed in a manner identical to said first isolation contact means.

6. The contact structure of claim 4 which includes biasing means connected to said piston for biasing said piston out of said volume.

Claims

1. A contact structure for a circuit interrupter; said circuit interrupter comprising an oil circuit breaker having: first and second interrupter structures, first and second elongated movable contacts movable along the axes of said first and second interrupter structures, respectively, and between interrupter contact open and closed positions, a conductive cross-bar, first and second isolation contact means on said conductive cross-bar movable between engagement and disengagement with respect to the bottom of said first and second elongated movable contacts, respectively, an oil-filled tank for receiving said first and second interrupter structures, and operating means for moving said cross-bar and said first and second elongated movable contacts along said axes of said first and second interrupter structures; the improvement which comprises the construction of at least said first isolation contact means to permit lateral movement of said bottom of said first elongated contact while maintaining contact with said first isolation contact means responsive to lateral movement of at least one of said first or second interrupter structures in the plane formed by the axes of said interrupter structures; said first isolation contact means comprising a jaw-type contact having opposing elongated contact surfaces disposed in spaced parallel planes which each extend in said lateral direction and receiving side surfaces adjacent said bottom of said first elongated contact between said opposing surfaces and in high pressure sliding contact; said bottom of said first elongated contact being laterally slidable within said jaw-type contact.

4. The contact structure of claim 1 which includes a generally laterally elongated enclosed volume at the base of said jaw-type contact and an elongated piston disposed within said elongated enclosed volume; said piston being engageable by said bottom of said first elongated contact when said first elongated contact engages said first isolation contact means; said elongated enclosed volume filled with oil of said oil-filled tank, whereby said piston moving in said volume absorbs the energy of engagement between said first elongated contact and said first isolation contact means.