US3823288A

US3823288A - Vacuum interrupter capacitance discharge and contact grounding system

Info

Publication number: US3823288A
Application number: US00302792A
Authority: US
Inventors: G Wilson
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1972-11-01
Filing date: 1972-11-01
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09

Abstract

A vacuum interrupter capacitance discharge and contact grounding system for a withdrawal type telescoping circuit breaker mechanism wherein the interrupter is racked toward the frame of the structure to disconnect it and racked away from the frame to connect it in circuit; the frame carrying a plurality of flexible contact probes electrically connected to the frame which, in turn, has contacts engaging a grounding bus in the compartment. The flexible contact probes are individual to and aligned with a ring on the interrupter through which any capacitance may be discharged and with the respective terminals of the interrupter to discharge the capacitance and ground the terminals of the interrupter when the interrupter is racked to disconnect position and toward the frame.

Description

United StatesPatent 1. Wilson I Y VACUUM INTERRUPTER CAPACITANCE DISCHARGE AND CONTACT GROUNDING SYSTEM [75] Inventor: George A. Wilson, Pineville, Pa.

'[73] Assignee: I-T-Elmperial Corporation, Spring House, Pa. [22] Filed: Nov. 1, 1972 [21] Appl. No.: 302,792

[52] US. Cl 200/144 B, 200/50 AA M/JUL A TfD M02 o/Nq: 430

. [4s]v July 9,1974

Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb & Soffen [5 7] ABSTRACT A vacuum interrupter capacitance discharge and contact grounding system for a withdrawal type telescoping circuit breaker mechanism wherein the interrupter is racked toward the frame of the structure to disconnect it and racked away from the frame to connect it in circuit; the frame carrying a plurality of flexible contact probes electrically connected to the frame which, in turn, has contacts engaging a grounding bus in the compartment. The flexible contact probes are individual to and aligned with a ring on the interrupter through which any capacitance maybe discharged and with the respective terminals of the interrupter to discharge the capacitance and ground the terminals of the interrupter when the interrupter is racked to disconnect position and toward the frame.

4 Claims, 8 Drawing Figures AIEMEDJUL 91924 $82,288

SHEET 2 (IF 4 PAIENIED JUL 91914 3, 2 0288 saw u 0? 4 VACUUM INTERRUPTER CAPACITANCE DISCHARGE AND CONTACT GROUNDING SYSTEM The present invention relates to a grounding system including grounding contacts for telescoping withdrawal switchgear and circuit breakers of the type shown and describedin applications, Ser. No. 282,319; 282,597; 282,358; 282,325; 282,330 and 282,339, all filed Aug. 21, 1972 by the present applicant and all assigned to the same assignee.

In the said switchgear, one of the primary elements is that the interrupters and operating mechanism will completely utilize the available compartment space so that a KV line breaker may be completely housed in a cubicle having dimensions 28 inches high, 37 inches deep and 36 inches wide. 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 to a test position, the section of the unit which carries the current conducting mechanism will telescope with respect to and around the operating mechanism.

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 the operating 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 element on the one hand and the operating parts on the other hand, so that no danger to the operator exists.

. In the embodiment here described, the circuit breaker interrupter elements are vacuum interrupters.

The primary object of this invention is to provide a means of automatically and simply discharging such capacitance as voltage built up in a vacuum interrupter, when the circuit breaker which includes a plurality of such vacuum interrupters is withdrawn to the test position.

A further object is the provision of similar means for connecting the terminals of each interrupter to ground when the circuitbreaker is withdrawn to test position.

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

FIG. l 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. I 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. 5 is a more detailed view partly in cross-section, partly in phantom, of an interrupter of FIG. 1.

FIG. 6 is a view taken on line 66 of FIG. 5 looking in the direction of the arrows.

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

FIG. 8 is a schematic top view of the circuit breaker of FIGS. 1 to 4, taken from line 8-8 of FIG. 2 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 vacuumtight 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. 5, 6 and 7. 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 ll2a 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. 5, 6 and 7 to the lower disconnect contact 22 which is similar to the upper back disconnect contact 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 ill, 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 (see FIG. 8) 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 operate the three poles simultaneously.

Each of the poles is provided with the structure thus far described, including the vacuum interrupter 10 and the

back disconnect structures

15 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 are racked out with the frame 40 to disconnect the upper and lower back disconnect contacts and 22, when the frame is moved to the position shown in FIG. 4.

Telescoping Withdrawal Circuit Breaker The frame 40, as mayreadily be seen from FIG. 4, telescopes with respect to the frame 30 of the operating mechanism. The frame 30 is releasably fixed in position as described in the aforesaid applications for patent 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 all practical 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 slide 50 and the lower slide 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 of 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 of the 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

60 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 10is made through the insulated operating link 70 which engages pin 71 on the bell crank lever 72 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 interrupterlt) by bell crank lever 72 is described in connection with FIGS. 5, 6 and 7.

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 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 closing spring 120 (FIG. 1) and respond to the latch system.

Themoving contact plunger l376 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 113. Vacuum interrupter 10 contains a bellows 93 which is connected to the plunger 13 within the interrupter housing 11 in order tomaintain the vacuum despite the fact that the plunger 13-76 must slide in and out of the housing. This is more specifically described in connection with FIGS. '5, 6 and 7.

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 position where it engages the stationary inter- I rupter contact 12. When the link 84 is released so that Racking Into and Out of Telescoping Position to Disconnect and Connect the Back Contacts The racking shaft 101 is a through shaft in the operating mechanism frame 30. The racking shaft 101 is provided on each side thereof 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 of the interrupter frame 40. The crank 102 and link 104 are in toggle relationship.

The two racking positions of the swinging link 84, FIG. I, are 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 necessary so 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.

When the racking shaft is rotated counterclockwise from the position of FIG. 2 to the position of FIG. 4, the crank 102 and link 104 on each side move to the closed toggle position shown 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 connected position of FIG. 2 then the interrupter carrying frame 40 is moved also from the position of FIG. 4 to the position of FIGS. 1 and 2 into the fully connected position. The racking shaft is provided with a handle receiving member keyed interrupter 10 itself which includes the thereto, having an opening Ml 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. 41 by inserting the handle 112 in the opening 111 of the handle member 110 and lifting the handle as shown by comparison of FIGS. 2 and 4. Similarly the circuit breaker interrupter elements may be racked into connected po- 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 interrupter elements. The link 84 in turn operates as previously described on the three links 70 which are housed in the interrupter mechanism frame 40.

As will be seen from a comparison of FIGS. l. and 2 on one hand and F [G d on the other hand, the link 84 is free to swing alongside the operating mechanism. Thus, the interrupter on frame 40 may cooperate with any type of operating mechanism on frame 39 and vice versa in accordance with the modular concept above disclosed.

Telescoping Arrangement and Modular Concept It should be borne in mind that, for this purpose, the' ability of the driving link 54 on the operating mechanism to swing as shown from the position of FIGS. 11 and 2 to the position of H6. 4 permits the telescoping arrangement to occur. By isolating this link M, 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 419, and any operating mechanism utilizing a swinging link (or a link which may shift its position) while still being operatively connected 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.

The specific operating system which achieves all of the foregoing functions is described in the aforesaid applications for patent.

interrupter Structure and Current Transfer H65. 5, 6 and 7 show the novel portions of the miniature high voltage circuit breaker as it relates to the stationary contact 12, the moving contact 113. 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 2811 of the vaciii}: uum 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 ill of the vacuum interrupter lltl. The vacuum interrupter 10 is supported by an annular insulator 25.9 and is secured to the rigid connector strap 254 which, in turn, is connected to the lower 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 291. The strap 254i 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 2911, so that effective contact can at all times be made between the moving contact plunger 113 and the connecting strap 2541. An extension 3011 of the plunger is provided with a ring 302 secured thereto and another ring 303 which together form the clevis previously referred to which is slidably mounted on plunger extension 2911. Plunger l3 and extensions 2911 and 3% 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 2911 is threaded into and hence a part of moving contact plunger 113.

The operating pin previously described in connection with FlG. l engages the clevis on both sides; the operating bell crank lever is basically a two piece member with the pin 74l 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. As previously described the arm 70 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 51 to operating link 54 which in turn is connected to elements which engage the latch (see also FIG. 7-).

Consequently when the plunger 113 is raised to the position shown in FIG. 5, 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 52A (lFlG. ll) will now drive the plunger 13 down to the open position. The stationary contact 12 is supported in the upper wall lllla of the housing ill, of the interrupter and there connected to the rigid connection strap M which is, in turn, connected to the movable back disconnect contact 15. The garter spring 2911 maintains contact pressure between contacts 295 and the plunger assembly 132911-301. Spring maintains contact pressure between contacts 112 and 113 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 pressure spring 90 is placed as close as possible to the gap between

contacts

12 and 13 otherwise be brought to an abrupt halt 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 conductor 284 which, in turn, is bolted to the incoming lower disconnect 22. The stationary contact 12 is bolted to the outgoing copper conductor 14 which is connected to the upper disconnect 15. The moving contact plunger 13 has a threaded external end on which is mounted the copper bushing 291 which is then clamped by the washer, the long bushing, and the long bolt which enters a tapped hole in the external end of 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 is held assembled by a limit washer. The moving contact and spring assembly are guided by the widely spaced bearings 321 inside the housing 11 and the lowerstationary bearing 322 which is secured to the frame.

The vacuuminterrupter may be a vacuum bottle type of interrupter such as that shown in US. Pat. No. 2,892,91 l and be provided with a shield 906 of the general type therein shown for the purposes there shown.

The shield 906 is connected electrically to the external ring 905 on the exterior of the interrupter l0, approximately mid-way between the terminals of the interrupter.

Grounding Contacts The grounding contact arrangement is shown in FIGS. 1, 2, 4 and 8.

A means must be provided for automatically and simply discharging the capacitance voltage built up in a vacuum interrupter when the circuit breaker is withdrawn to the test position of F IG. 4. This capacitance voltage may exist between the shield 906 and the contacts and their supports or with other parts of the interrupter. This residual charge may surprise the oper-- ator and possibly lead to injury, if it were not discharged to ground,

The circuit breaker frame 30 carries at its forward surface a set of flexible metallic contact probes 901, 902, 903, one set for each of the vacuum interrupters Flexible contact probe 901 is aligned with the upper terminal wall 907 of the interrupter 10. Flexible contact probe 903 is aligned with the lower terminal wall 908 of the interrupter 10.

When, therefore, the interrupter carrying frame is racked from the fully operative position of FIGS. 1 and 2 to the test position of FIG. 4, the contacts 902,901 and 903 engage, respectively, the external ring 905 and the

terminal walls

907 and 908 of the interrupter 10.

Thus, in the test position, any capacitance voltage which may appear at ring 905 and both terminals of the interrupter are grounded to frame 30. This supplies to each of the interrupters 10 (see FIG. 8).

Since the frame 30 is a removable truck operable on wheels 42 into and out of the compartment, the frame 30 must be grounded to the compartment, which itself is fully grounded.

The compartment is provided with a grounding bus 915 (FIGS. 1 and 8) extending the length of the compartment. The frame 30 carries at its inner end a pair of

contacts

917, 918 pivotally mounted on

pins

919, 920 and urged toward each other by biasing

springs

921, 922. The inner surface of each

contact

917, 918 is cammed at 923, 924 so that they may slide readily over the end 925 of the grounding bus 915 when the frame 30 isinserted in the compartment, receiving the grounding bus 915 between them and making a good sliding contact with the grounding bus 915.

Thus, when the circuit breaker is racked to the test position of FIG. 4, the flexible grounding probes 901, 902, 903 engage the

interrupter elements

905, 907, 908 connecting them to ground through frame '30, grounding

contacts

917, 918 and grounding bus 915. In

this manner, any capacitance voltage built up in the interrupter is discharged to ground and the circuit breaker contacts are grounded for safety.

- Although there has been described a preferred embodiment of this 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 embodiment of the invention in which an exclusive priviledge or property is claimed are defined as follows:

1. In a withdrawal type of interrupter having a main frame and an interrupter carrying frame with the main frame mountable in a compartment, the interrupter carrying frame being movable with respect to the main frame from a connected position of the interrupter remote from the main frame to the disconnected position of the interrupter adjacent the main frame;

said interrupter having a pair of spaced terminal elements,

a contact member on said main frame individual to each of said terminal elements,

said terminal elements of said interrupter engaging their respective contact members when the interrupter carrying frame is moved to disconnect position with respect to said main frame,

an electrical grounding connection between said contact members and said main frame;

an additional grounding contact means carried by said main frame and a grounding bus in said compartment; said additional grounding contact means engaging said grounding bus when the main frame is in said compartment;

said interrupter being capable of developing a capacitance charge,

electrically conductive means external of the interrupter and participating in said capacitance charge;

an additional contact member on said main frame substantially aligned with said first mentioned contact members and electrically connected to said main frame,

' said last mentioned electrically conductive means extemal of said interrupter being aligned with said additional contact member,

and engaging said additional contact member when the interrupter carrying frame is moved to disconnect position with respect to said main frame.

2. The withdrawal type of interrupter of claim l in which said contact members and said additional contact member are flexible resilient members projecting from the main frame toward the interrupter carrying frame.

3. The withdrawal type of interrupter of claim 2 in which said additional grounding contact means on said main frame includes a pair of grounding contacts biased toward each other; said grounding contacts being located at and engaging opposite surfaces of the grounding bus.

4. The withdrawal type of interrupter of claim 3 in which the main frame supports the interrupter carrying frame;

the main frame being movable into and out of said compartment,

the compartment having a wall parallel to the path of frame is moved in the compartment.

Claims

1. In a withdrawal type of interrupter having a main frame and an interrupter carrying frame with the main frame mountable in a compartment, the interrupter carrying frame being movable with respect to the main frame from a connected position of the interrupter remote from the main frame to the disconnected position of the interrupter adjacent the main frame; said interrupter having a pair of spaced terminal elements, a contact member on said main frame individual to each of said terminal elements, said terminal elements of said interrupter engaging their respective contact members when the interrupter carrying frame is moved to disconnect position with respect to said main frame, an electrical grounding connection between said contact members and said main frame; an additional grounding contact means carried by said main frame and a grounding bus in said compartment; said additional grounding contact means engaging said grounding bus when the main frame is in said compartment; said interrupter being capable of developing a capacitance charge, electrically conductive means external of the interrupter and participating in said capacitance charge; an additional contact member on said main frame substantially aligned with said first mentioned contact members and electrically connected to said main frame, said last mentioned electrically conductive means external of said interrupter being aligned with said additional contact member, and engaging said additional contact member when the interrupter carrying frame is moved to disconnect position with respect to said main frame.

2. The withdrawal type of interrupter of claim 1 in which said contact members and said additional contact member are flexible resilient members projecting from the main frame toward the interrupter carrying frame.

4. The withdrawal type of interrupter of claim 3 in which the main frame supports the interrupter carrying frame; the main frame being movable into and out of said compartment, the compartment having a wall parallel to the path of movement of the main frame into and out of said compartment, said grounding bus being supported on said last mentioned wall, said grounding contacts being located on a portion of the main frame which initially enters said compartment when the withdrawal type of interrupter is inserted therein; said grounding contacts having cammed surfaces to receive the end of the grounding bus between them as the withdrawal type of interrupter is inserted therein; said grounding contacts maintaining a sliding electrical connection with said grounding bus as said withdrawal type of interrupter including its main frame is moved in the compartment.