US3784774A

US3784774A - Vacuum circuit breaker current transfer and actuation

Info

Publication number: US3784774A
Application number: US00282339A
Authority: US
Inventors: G Wilson
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1972-08-21
Filing date: 1972-08-21
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: CA970808A

Abstract

A vacuum circuit breaker having a movable contact carrying rod extending outside the circuit breaker through a vacuum tight seal. The rod is positioned in a pair of spaced bearings with a bushing floatingly mounted on the rod between the bearings. The contact rod is driven by the bushing through a spring connected between the bushing and a spring bearing element on the rod in order to provide for overtravel of the drive mechanism connected to the bushing after the movable contact engages a complementary contact. Additional elements may be connected to said contact rod.

Description

United States Patent I1 1 Wilson 1 1 Jan. 8, 1974 [54] VACUUM CIRCUIT BREAKER CURRENT 3,632,933 1/1972 McClain et ah: 200/153 SC TRANSFER AND ACTUATION 3,727,019 4/1973 Harvey 200/153 SC [75] Inventor: George A. Wilson, Pineville, Pa.

5191973. E Hfifi' :R 91 E -Ma9 Asslgfleei Imperial Corporatmn, Att0rneyOstrolenk, Faber, Gerb & Soffen Philadelphia, Pa. .21 ,3 3, a. ,5 5

221 Filed: Aug. 21, 1972 [57] ABSTRACT Appl. No.: 282,339

: References Cited UNITED STATES PATENTS Roxburgh et al 200/144 B Frink 200/144 B A vacuum circuit breaker having a movable contact carrying rod extending outside the circuit breaker through a vacuum tight seaL-The rod is positioned in a pair of spaced bearings with a bushing floatingly mounted on the rod between the bearings. The contact rod is driven by the bushing through a spring connected'between the bushing and a spring bearing element on the rod in order to provide for overtravel of the drive mechanism connected to the bushing after the movable contact engages a complementary .contact. Additional elements may be connected to said contact rod. v I

5 Claims, 8 Drawing Figures 52 l azzmws PATENTEDJAN 8:974 3,784,774

SHEU 3 OF 5 SP/Q/A/G A 0,4050

VACUUM CIRCUIT BREAKER CURRENT TRANSFER AND ACTUATION The present invention relates to telescoping withdrawal switchgear and circuit breakers for minimum size compartments and more particularly relates to a miniature high voltage circuit breaker for utilization in acompartment in which the interrupters and operating mechanism will completely utilize the available compartment space. For this purpose the operating mechanism and the current conducting mechanism are so arranged that when it is desired to'withdraw the current conducting mechanism from a connected toa test position the section of the unit which carries the current conducting mechanism will telescope with respect to and around the operating mechanism thereby making it possible to reduce the size of the entire switching or circuit breaker mechanism and therefore to reduce the size of the compartment and of course to reduce the size of the entire switchboard and installation.

, By the construction and novel elements hereinafter described it is possible to arrange a KV line breaker so that it may be completely housed in cubicle having dimensions 28 inches high, 37 inches deep and 36 inches wide for a three pole circuit breaker.

In addition, the present invention relates to modular switchgear which is so arranged that the various parts and elements thereof may be interconnected in a switchboard in selected arrangements and combinations.

Essentially the circuit so that it may be inserted and withdrawn from the compartment as a whole'and is therefore mounted on appropriate rolling or wheel devices. The circuit breaker structure itself is mounted on, two platforms which may telescope or slide with respect to each other. One porbreaker structure is arranged tion of the circuit breaker structure including the contact-elements. and the current carrying element are mounted on a truck which is separated from the mounting for the operating elements. The mounting for the operating elements is so arranged that the truck carrying the contact members and current carrying members may telescope with respect thereto and thereby, when disconnected, approach the operating parts closely.

Since the current carrying elements of the circuit breaker structure, on their own truck, are disconnected from the bus in the manner hereinafter described when the truck carrying the same is moved toward theoperating section and telescopes therewith, electrical clearance in this disconnected position is not necessary between the circuit breaker current carrying elements and the operating parts.

When the circuit breaker current carrying elements are fully racked into connected position, appropriate electrical clearance is provided between the circuit breaker contacts and current carrying elements on the one hand and the operating parts on the other hand so that no danger to the operator exists.

A primary object of this invention is the arrangement of a vacuum circuit breaker so that it is provided with an appropriate compression spring for the moving contact to ensure proper contact travel and proper engagement with the stationary contact, the compression spring being connected between the contact carrying rod and a floating bushing which is driven'by the operating mechanism.

Another object of the present invention includes the simplified arrangement of connections between the vacuum interrupter and the operating mechanism therefor so that this connection will maintain itsintegrity whether or not the circuit interrupter elements are telescoped with the operating mechanism and whereby current transfer between the vacuum interrupter contacts and the current conducting leads is simplified.

The foregoing and other objects of this invention will become apparent in the following description and drawings in which:

FIG. 1 is a side view partly in section and partly broken away of the novel miniature high voltage circuit breaker with the contact members and current carrying members fully racked into operative position showing the relative positioning and placement of the various parts of the entire circuit breaker mechanism.

FIG. 2 is a view corresponding to that of FIG. 1 showing the same structure in the same racked in position of FIG. 1 with certain of the details omitted so that the telescoping operation, which may more readily be seen in FIGS. 3 and 4, may be understood.

FIG. 3 is a schematic side view showing the manner in which the circuit breaker contact and current carrying elements of the miniature high voltage circuit breaker mounted on their own truck may be integrated, controlled and positioned with respect to the frame which carries the operating mechanism.

FIG. 4 is a view corresponding to that of FIG. 2 showing the racked out position of the circuit breaker contact and current carrying elements, demonstrating the manner in which the truck carrying these elements may telescope with respect to' the frame which carries the operating mechanism.

FIG. 5is a side view partly in cross-section of the mechanism for operating the circuit breaker contacts of the circuitbreaker of FIGS. 1 to 4 with the springs charged and the breaker closed. FIG. 6 is a more detailed view partly in cross-section, partly in phantom, of the interrupter of FIG. 1.

FIG. 7 is a view taken on line 77 of FIG. 6 looking in the direction of the arrows.

FIG. 8 is a view taken on line 8-8 of FIG. 7 looking in the direction of the arrows.

Referring first to FIGS. 1, 2 and 4, the circuit breaker structure is a vacuum type of circuit breaker now well known in the art in which a vacuum-tight housing 11 encloses and supports a stationary contact 12 and a moving contact 13. The connections to the interrupter 10 are specifically described in connection with FIGS. 6, 7 and 8. It is sufficient for the present to note that stationary contact 12 is electrically connected to the rigid connector 14 which in turn is connected in any suitable manner as'by the nut 12a to upper or load back disconnect contact 15. The upper back disconnect 15 is provided with suitable contact fingers 16 in a manner now well known in the art when the circuit breaker structure is in the position shown in FIG. I to electrically engage the stationary back disconnect contact 17 in the compartment the said back disconnect contact 17 being connected to a load bus.

The movable contact 13 is a plunger type contact electrically connected by the means described in connection with FIGS. 6, 7 and 8 to the lower disconnect contact 22 which is similar to the upper back disconnect contact 15; the contacts 23 of the lower back disconnect contact 22 are engageable with the lower stationary back disconnect contact 24 which is connected to the line bus. The circuit is then made from back disconnect contact 17 to the circuit breaker upper back disconnect contact 15 stationary contact 12 in the vacuum housing 11 then to the movable contact 13, the lower disconnect contact 22, the contacts 23 and the lower stationary disconnect contact 24. While in the view of FIGS. 2 and 4 a single circuit breaker is shown, it is obvious that the circuit breaker may be set up and in the present embodiment is intended to be set up as a three pole circuit breaker in which the operating mechanism carrying frame 30 will, through the connecting link 84, hereinafter described, and the jack shaft 82 which is common to and runs through all of the three poles'of the breaker structure thereby operating the threepoles simultaneously.

Each of the poles is provided with the structure thus far described including the vacuum interrupter an d the back disconnectstructures -and 22. The three pole circuit breaker arrangement including vacuum interrupters 10 are carried on the frame 40 which is truck mounted on

wheels

41, 42 at the front and back of the frame so that they may roll; thus the frame 40 as a whole may roll with respect to frame 30 which carries the operating mechanism.

The circuit breaker back disconnect contacts of the breakers 10 are racked out with the frame 40 to disconnect the upper and lower back

disconnect contacts

15 and 22, when the frame is moved to1the positionshow in FIG. 4. i I

Telescoping Withdrawal Circuit Breaker The frame 40, as may readily be seen from FIG. 4, telescopes with respect to the frame 30 of the operating mechanism. The frame 30 is fixed in position by hooks 710 engaging appropriate elements 712, 714 on the opposite side walls 44 of the compartment so that during the racking operation from the connected position of FIG. 1 to the disconnect position of FIG. 4 the operating mechanism on the frame 30 is for allpractical purposes to be regarded as integrated with the compartment and switchboard in which the compartment is located.

Since the frame 30 is thus fixed, the circuit breaker structure on the moving frame 40 moves with respect to the frame 30 and hence with respect to the compartment wall 44. It is guided in its movement by the slide arrangement which is more clearly seen in FIG. 3 but appears in FIGS. 1 to 4; that is the frame 30 carries the upper side 50 and the lower side rod 51. The frame 40 carrying the circuit breaker is provided with the slide member 53 at the upper rear portion of the frame and the slide member 54 at the upper front of the frame 40 which slides on the upper slide bar 50 carried by the operating mechanism frame 30. The lower portion of the circuit breaker frame 40 is provided with a slide 55 which slides on the lower guide bar 51 on the frame 30.

It may thus be seen that when the racking mechanism is operated the circuit breaker structure on frame 40 may be moved from the position of FIG. 1 to the position of FIG. 4 telescoping with respect to the operating mechanism ofv frame 30.

Since, in the telescoped position of FIG. 4 the circuit breaker back

disconnect contacts

15 and 22 are fully disconnected there is no need at this position ofthe circuit breaker mechanism to isolate the operating mechanism, there being no danger of any flashover to the operating mechanism. This is especially so since the

stationary back conductors

17 and 24 remain in their original position within the stationary insulated bushings and 61 on the back wall 62 of the compartment and covered by the shutter 400.

The mechanical connection for the operating mechanism on frame 30 to the truck mounted interrupter elements on frame 40 in order to operate the circuit interrupter 10 is made through the insulated operating link which engages pin 71 on the bell crank lever 7.2 on pivot 73. The bell crank lever 72 at the end opposite the pin 71 is provided with the pins 74 which engage the clevis 75 of the extension 76 of the moving contact 13 of the interrupter 10. The specific operation of the interrupter 10 by bell crank lever 72 is described in connection with FIGS. 6', 7 and 8.

Consequently the movement of the link 70 to the right with respect to FIG. 1 will rotate the bell crank lever 72 to raise the moving contact 13 into engagement with stationary contact 12 and the movement of the link 70 to the left will operate the bell crank lever 72 to open the contacts 13. The operating link 70 may be centrally located to operate the center pole or may be provided in duplicate on each side to be operated by bell crank levers 81 (hereinafter described) keyed to a single jack shaft 82 which is common to all the poles of the circuit breaker.

The end of the operating link 70 opposite its connection to the bell crank lever 72 is connected at pin 80 to bell crank lever 81 which is keyed to jack shaft 82 on frame 40. The opposite end of the bell crank lever is connected by pin 83 to the link 84 which is the driving link in the operating mechanism for operating the circuit breaker. The driving link 84 in the operating mechanism frame is connected at its upper end 85 so that it may react appropriately to the closingspring 120 (FIG. 5) and respond to the latch system as hereinafter described in connection with FIG. 5 and related figures.

The moving contact plunger 13-76 is biased toward the stationary contact 12 in the closed position by the compression spring captured between the upper portion of the clevis 75 on the external portion of the moving'contact plunger 76 and the base 91 of the moving contact plunger 13. Vacuum interrupter 10 contains a bellows 93 which is connected to the plunger 13 within the interrupter housing 11 in order to maintain the vacuumdespite the fact that the plunger 13-76 must slide in and out of the housing. This is more specifically described in connection with FIGS. 6, 7 and 8.

When, therefore, the link 84 is permitted to rise it rotates the bell crank lever 81 thereby pulling the link 70 to the right, rotating the bell crank lever 72 clockwise and moving the contact plunger 13 up to the closed po- As pointed out above, the operation of the link 84 to close the contact 13 and the release of the link 84 to permit the contact 13 to open withirespect to stationary contact 12 are more specifically described in connectionwith FIG. 5. In FIGS. 1, 2 and 4 the racking shaft 101 may be seen. The racking shaft is a through shaft in the operating mechanism frame 30. The racking shaft 101 is provided on each sidethereof with a crank 102 keyed to shaft 101 and connected by the pin 103 to the link 104 which is connected to the pin 105 on the interrupter frame 40. The crank 102 and link 104 are in togglerelationship.

The two racking positions of the swinging link 84, FIG. 1, a re symmetrically arranged so-that the closing mechanism will operate the interrupter contacts equally'when the circuit breaker is in the connected position or in the test position. This is nece's'saryso that the operation of the circuit breaker while in the test position may be checked with appropriate assurance that its subsequent operation when racked in will be the same. I

When the racking shaft is rotated counterclockwise from the position of FIG. 2 tothe position of FIG. 4, the crank'l02 and link 104 on each side move to the closed toggle positionshown in FIG. 4 thereby resulting in the racking out of the interrupter carrying frame 40. When the racking shaft 101 is rotated clockwise from the position of FIG. 4 to the test position of FIG. 2 then the interrupter carrying frame 40 is moved also from the position of FIG. 4to the position of FIGS. 1 and 2 into the fully connected position. The racking shaft is provided with a handle receiving member 110 keyed thereto, having an opening 111 therein to receive a removable handle 112. Therefore the racking shaft 101 may be rotated to move the interrupters from the position of FIGS. 1 and 2 to the position of FIG. 4 by inserting the handle 112 in the opening 111 of the handle member land lifting the handle as shown by comparison of FIGS. 2 and 4. Similarly the circuit breaker interrupter elements may be racked into connected position by a reverse operation in which the handle 112 is inserted inthe opening 111v of the handle member l l0-and the handle 112 lowered from the position of FIG. 4 to the position of FIGS. 1 and 2.

By this means therefore a full telescoping arrangement is provided for the truck elements of the circuit interrupter andback disconnectcontacts mounted on the truck 40 so that they may approach the operating mechanism and overlap and surround elements of the frame 30.

The only operative connection between the operating mechanism on frame 30 and the interrupter elements on frame 40 is the link 84 which operates the in- Telescoping Arrangement and Modular Concept I It should be borne in mind that, for this purpose, the ability of the driving link 84 on the operating mechanism to swing as shown from the position of FIGS. 1 and 2 to the position of FIG. 4 permits the telescoping arrangement to occur. By isolating this link 84, any interrupter device on frame 40 which will respond to the movement of the driving link to close may be substituted for the interrupter on frame 40, and any operating mechanism utilizing a swinging link (or a link which may shift'its position) while still being operatively con-- nected through bell crank lever 81 to an interrupter contact drive link, such as link 70, may be substituted for the operating mechanism shown. This makes possible the modular arrangement in which various types of interrupters may be used in connection with various types of operating mechanisms.

The opening spring is part of and associated directly with the frame; the closing operation as well as the latch arrangement which resists the opening spring and the controls for the latch are in the operating mechanism on the telescoping frame.- Hence, the telescoping and modular arrangements are both made possible.

Interrupter Structure and Current Transfer I FIGS. 6, 7 and 8 show the novel portions of the min-.

iature high voltage circuit breaker as it relates to the interrupter 10 itself which includes the stationary contact 12, the moving contact 13. As previously pointed out, the moving contact has a bellows 93 connected to a sealing sleeve 280 carried thereby. The bellows 93 is connected at the bottom wall 281 of the vacuum interrupter housing by a vacuum type seal therewith so that the movement of the movable contact plunger 13 through the opening 282 in the bottom wall will not result in contamination of the vacuum condition within the housing 11 of the vacuum interrupter 10. The vacuum interrupter 10 is supported by an annular insulator 283 and is secured to the rigid connector strap 284 which, in turn, is connected ,tothelower back disconnect contact 22. The moving contact plunger 13 is secured in any suitable manner as by, for

instance, screw threads 290 to an exterior plunger 29].

The strap 284 is provided with an opening'292 through which the exterior plunger 291 may pass and the periphery of this opening is provided with spring contact elements 295 arranged annularly of the contact plunger extension 291 so that effective contact can at all times bemade between the moving'contact plunger 13 and the connecting strap 284. An extension 301 of the plunger is provided with a ring 302 secured thereto and another ring 303 which together form the clevis 75 previously referred to which is slidably mounted on plunger extension 291. Plunger l3 and

extensions

291 and 301 move as a unit. Clevis 75 slides along this unit to compress spring 90. Only contacts 295 transfer current to the moving plunger extension 291; extension 291 is threaded into and hence a part of moving contact plunger 13.

The operating pin previously described in connection with FIG. 1 engages the clevis on both sides; the operating bell crank lever is basically a two piece member with the pin 74 projecting from each side thereof so that when the circuit breaker is to be closed upward movement of the pin 74 will operate the clevis 75-. Raising the clevis 75 will compress the spring 90. Aspreviously described the arm which operates the bell crank lever 72, which in turn operates the pins 74 which engage the clevis, is latched in position through its connection bell through crank lever 81 to operating link 84 which in turn is connected to elements which engage the latch (see also FIG. 8).

Consequently when the plunger 13 is raised to the position shown in FIG. 18, the circuit breaker is closed. On release of the holding force which is transmitted to the link 70 and bell crank lever 72, the opening spring 82A (FIG. 1) will now drive the plunger 13 down to the open position. The stationary contact 12 is supported in the upper wall 30 of the housing 11 ofthe interrupter and there connected to the rigid connection strap 14 which is, in turn, connected to the movable back disconnect contact 15. The garter spring 291 maintains contact pressure between contacts 295 and the plunger assembly 13-291-301. Spring 90 maintains contact pressure between

contacts

12 and 13 when the'circuit breaker is closed. By the means herein described, the minimum number of current transfer joints are'used to minimize heating. The straight line guiding of the moving contact 13 prevents damage to the bellows 93 and insures full seating of the internal contact surface in the vacuum interrupter. The contact pressurespring 90 is placed as close as possible to the gap between

contacts

12 and 13 with a minimum amount of added material between the springs and the contact gap. This spares the stationary housing 11 for the vacuum interrupter and especially the stationary contact extra abuse from the inertia of material of any kind added between the contact pressure springs and the contact gap. Such material would otherwise be brought to an abrupthalt by the stationary vacuum interrupter contact on closing. The rigidity of the mounting and actuating assembly minimizes contact bounce on closing and rebound on opening.

The vacuum housing 11 is mounted to the copper the moving plunger 13. The floating bushing with the actuation groove or clevis 75 forces the copper bushing and the moving contact 13 upward through the captive contact pressure spring 90. The floating bushing isheld assembled by the limit washer. The moving contact and spring assembly are guided by the widely spaced bearings 321 inside the housing 11 and the lower stationary bearing 322 which is secured to the frame.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclu sive privilege or property is claimed are defined as follows: v g v 1. In a vacuum circuit breaker, an evacuated housing; a contact rod carrying a movable contact in said housing; and a complementary contact in said housing; said contact rod having an extension outside said housing and being longitudinally reciprocal toward and away from said complementary contact; a vacuum tight seal at said contact rod at its entry into said housing;

a pair of spaced bearings positioning and guiding said contact rod for reciprocal movement; 7

a bushing floatingly mounted on said contact rods between said bearings; I a spring bearing surface on said contact rod;

a compression spring on said contact rod between said spring bearing surface and said floating bushmeans for operating said bushing toward said housing; i

the said movement of said bushing toward said housing driving said contact rod through said spring into engagement with said complementary contact; 7

said spring being compressible as said contact rod engages said complementary contact;

further travel of said bushing toward said housing further compressing said spring and establishing firm electrical contact between the movable contact on the contact rod and the complementary contact.

2. The circuit'breaker' of claim 1 in which said operating means for said bushing comprises:

a driving linkage;

a clevis carried by said bushing;

a connection between said driving linkage and said clevis.

3. The circuit breaker of claim 2 wherein said last mentioned connection includes a bell-crank lever;

one end of said bell-crank lever being connected to said driving linkage;

the other end of said bell-crank levcr having an ex- 5. The circuit breaker of claim 1 having an electrical connector for said contact rod; 7

additional sliding contacts carried. by said electrical connector and in engagement with said contact rod.

Claims

1. In a vacuum circuit breaker, an evacuated housing; a contact rod carrying a movable contact in said housing; and a complementary contact in said housing; said contact rod having an extension outside said housing and being longitudinally reciprocal toward and away from said complementary contact; a vacuum tight seal at said contact rod at its entry into said housing; a pair of spaced bearings positioning and guiding said contact rod for reciprocal movement; a bushing floatingly mounted on said contact rods between said bearings; a spring bearing surface on said contact rod; a compression spring on said contact rod between said spring bearing surface and said floating bushing; means for operating said bushing toward said housing; the said movement of said bushing toward said housing driving said contact rod through said spring into engagement with said complementary contact; said spring being compressible as said contact rod engages said complementary contact; further travel of said bushing toward said housing further compressing said spring and establishing firm electrical contact between the movable contact on the contact rod and the complementary contact.

2. The circuit breaker of claim 1 in which said operating means for said bushing comprises: a driving linkage; a clevis carried by said bushing; a connection between said driving linkage and said clevis.

3. The circuit breaker of claim 2 wherein said last mentioned connection includes a bell-crank lever; one end of said bell-crank lever being connected to said driving linkage; the other end of said bell-crank lever having an extension received in said clevis.

4. The circuit breaker of claim 1 having an electrical connector for said contact rod; said contact rod being movable with respect to said electrical connector; and additional sliding contacts between said electrical connector and said contact rod.

5. The circuit breaker of claim 1 having an electrical connector for said contact rod; additional sliding contacts carried by said electrical connector and in engagement with said contact rod.