US3909573A

US3909573A - Squeeze coil primary disconnect contacts

Info

Publication number: US3909573A
Application number: US463727A
Authority: US
Inventors: George A Wilson
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1974-04-24
Filing date: 1974-04-24
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30
Also published as: CA1032209A

Abstract

Self-aligning primary disconnect contacts having a helical coil spring helically wound on the conductor of the disconnect; the coil spring is received in a recess of the terminal of switchgear and is compressed between the conductor and the recess. This permits limited omni-directional movement of the disconnect conductor at the terminal for alignment with the stationary disconnect. The conductor may have similar contacts at the outer end to engage the stationary disconnect contact which, in this case, is then a cylindrical recess. The long arm of the conductor permits relatively stressless alignment as compared with a rigidly mounted conductor in which latter case alignment can occur only at the contacts.

Description

United States Patent Wilson Sept. 30, 1975 [54] SQUEEZE COIL PRIMARY DISCONNECT 3,559,056 l/l97l Eusi 339/64 M X CONTACTS 3,571,547 3/l97l Boersma et a1.. 200/258 [75] Inventor: George A. Wilson, P neville, Pa. Primary Examiner Roben K. schaefer [73] Assignee: l-T-E imperial Corporation, Spring Assistant Examiner-William J. Smith House, Pa. Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb 221 Filed: Apr. 24, 1974 Safe" [2i] Appl. No.: 463,727 [57] ABSTRACT Self-aligning primary disconnect contacts having a hefi fig isfigg lical coil spring helically wound on the conductor of [S8] F id 2 163' the disconnect; the coil springis received in a recess l o 4 R 64 2 5 of the terminal of switchgear and is compressed between the conductor and the recess. This permits lim- 56 R f d ited 'omni-directional movement of the disconnect l e eirences I e conductor at the terminal for alignment with the sta- UNITED STATES PATENTS tionary disconnect. The conductor may have similar 903,927 1111908 Wendler 339/64 M contacts at the outer end to engagethe stationary dis- 1.531. 1 5 French connect contact which, in this case, is then a cylindri- 1966334 7/1934 cal recess. The long arm of the conductor permits rel- 5' 13 3 2- i f atively stressless alignment as compared with a rigidly ;g; ec mg mounted conductor in which latter case alignment can /l96l Cole, 1 th t 3,074,046 1/1963 Sullivan y at e acts 3.094.364 6/1963 Lingg 3,363,220 H1968 Redd et al. 339/64 M x 4 4 D'awmg F'gures O O O O Jd/a J I? J/O .720

O C O US. Patent Sept. 30,1975 Sheet 1 of 2 3,909,573

US. Patent Sept. 30,1975 Sheet 2 of2 3,909,573

Wr &

30/4 339 33 3/2 2644/ Y W "E W/////////// SQUEEZE COIL PRIMARY DISCONNECT CONTACTS The present invention relates to switchgear and more specifically to a primary disconnect contact structure wherein the contacts have a simplified form and where exact alignment of the movable disconnect elements with the stationary disconnect elements is not essential for full operation, the contacts being capable of adjusting readily to any reasonable misalignment.

A basic structure in which the novel disconnect elements of the present switchgear may be utilized is shown in US. Pat. No. 3,728,508 assigned to the assignee of the present invention.

The particular type of contact used in order to pro vide for simplified adjustment to any possible misalignment is shown in US. Pat. No. 3,793,606 also assigned to the assignee of the present invention.

In drawout switchgear one of the problems which arises is the possibility of misalignment between the disconnect contacts of the drawout switchgear and the stationary disconnect elements. The ordinary tulip-type of contact may adjust somewhat to such misalignment but provides specific problems in seeking to obtain such an adjustment.

The primary object of the present invention is the provision of a back disconnect contact for drawout switchgear in which the disconnect contact structure is in effect hingedly or flexibly connected at the switchgear end thereof by appropriate contacts hereinafter described; and wherein the outer or free end of the dis connect contact which is to engage the stationary disconnect contact in the switchboard is provided with similar contact members.

The present invention contemplates specifically the utilization of squeeze-type coil contacts of the type shown in prior US. Pat. No. 3,793,606 in a disconnect contact of the type shown in prior U.S. Pat. No. 3,728,508 both of which are assigned to the assignee of the present invention.

Where there is any misalignment between the disconnect contact on the drawout switchgear and the stationary disconnect contact the short tulip-type of contacts previously known and shown in prior US. Pat. No. 3,728,508 can accommodate itself only minimally to such misalignments as hereinafter described. Where however the disconnect structure is itself connected by contacts to the switchgear structure at one end and is provided with appropriate contact elements at its outer end (the end which will engage the stationary disconnect contact in the switchboard) then the misalignment may readily be accommodated by reason of the length of the lever arm which is thus created.

The foregoing and many other objects of the present invention will become apparent in the following description and drawings in which FIG. 1 is a view of a vacuum circuit breaker operating mechanism having back disconnect contacts for a drawout structure of the type to which the present invention is to be applied and corresponds substantially except for the disconnect contact structures to the structure shown in US. Pat. No. 3,728,508.

FIG. 2 is a schematic view showing the manner in which the known tulip-type of contact structure indicated generally in prior US. Pat. No. 3,728,508 will accommodate itself to a limited extent to any possible misalignment.

FIG. 3 is a longitudinal sectional view of the disconnect contacts showing the manner in which the novel contact arrangement at each end of the back disconnect contact of the switchgear will permit accomodation to any misalignment without straining the contacts or bringing undue pressure to bear on any portions of the contact structure.

FIG. 4 is a fragmentary view of a modified form of the structure of FIGS. 1 and 3 in which the switchgear unit (in this case a vacuum bottle) is mounted in a different orientation from that shown in FIGS. 1 and 3.

Referring first to FIG. 1, this figure corresponds sub- I stantially to FIG. 5 of prior US. Pat. No. 3,728,508. The overall breaker comprises support molding structures and 101, which serve to support

vacuum interrupter bottles

102 and 103 respectively. A terminal bushing 104, having a primary disconnect contact 105 at the end thereof, is connected to the fixed contact terminal of vacuum bottle 102.

An electrical conductor bar 106 is connected to the fixed contact terminal of vacuum bottle 103, and the conductor bar 106 is appropriately connected to a suitably supported bushing 107, having the second primary disconnect contact 108 at the end thereof. Note that the

primary disconnect contacts

105 and 108 are not disposed above one another, but are staggered in positioned in order to permit a low profile for the breaker. That is, a given dielectric spacing is obtained between

terminals

105 and 108, where this spacing is not a complete vertical spacing, as was the case in the prior art. Consequently, the breaker can be mounted in an outdoor cubicle having a height less than about 6 feet, which can conveniently be shielded or hidden by common shrubbery to produce an unimposing appearance for the substation using the switchgear.

Thus, the overall breaker will have a shorter profile than it would have had if the breaker terminals were disposed above one another in a conventional manner. This is the subject matter of the invention claimed in US. Pat. No. 3,735,065.

FIG. 1 also shows the operating shaft 110 where the operating shaft 1 10 moves in the direction of arrow 1 l l to open the contact of

vacuum interrupters

102 and 103, and moves in the direction of arrow 112 to close the interrupter contacts.

The operating mechanism for operating the

interrupters

102 and 103 is driven from shaft 110 and is generally supported and sub-assembled on the conductive block 120. The block is, in turn, secured on a top cover plate 121 by

bolts

122 and 123 which tread into the top of conductive member 120. The cover plate is not shown fully in detail, but is made sufficiently wide to cover the top of the operating mechanism.

The top cover 121 is then connected to

suitable side plates

124 and 125, which are, in turn, connected to the

support moldings

100 and 101, and are disposed adjacent the

vacuum interrupter bottles

102 and 103.

A generally L-shaped slide guide plate 126 has a flange at its upper end bolted to the top cover 121 by the

bolts

127 and 128. Guide plate 126 then has an elongated guide opening 129 therein which opening receives and guides the motion of pivot shaft 130.

The upper end of a shaft portion 131 which is adjustably connected to the main operating shaft 112, has a cylindrical bushing 132 connected to the end thereof which slidably receives the pivot pin or shaft 130. The pivot pin is then connected to the toggle link pairs 133-134 and 135-136 respectively. These toggles link pairs correspond generally to the toggle links 31 and 30 respectively in FIG. 1. Note that these links are separated from one another by the bushing 132 on the pin 130; that these links may be bent to accommodate themselves to a relatively small volume.

The opposite edns of links 133 and 134 are then pivotally connected to toggle links 137 and 138 through the pin 139, while the outer ends of links 135 and 136 are similarly connected to toggle links 140 and'141, which are carried on pin 142. The upper end of the pairs of links 137 and 138 are pivotally connected to the conductive support 120 by the pin 143 while the upper ends of links 140 and 141 are pivotally connected to support 120 by the pin 144.

Each of pins 139 and 142 are surrounded by bushing members which have extensions 150-151 and 152-153 extending therefrom. These extensions are spring guide pins which respectively receive contact pressure spring 154 to 157 respectively. The opposite ends of contact pressure springs 154 and 155 then bear against a spring carrier plate 158 and, similarly, springs 156 and 157 press against a spring carrier plate 159. The spring carrier plates 158 and 159 then receive contact clamps 160 and 161 which clamp onto the

movable contact terminals

162 and 163 respectively of

vacuum interrupters

103 and 102 respectively. Note that the clamps 160 and 161 are conventional split member clamps which are tightened on the

cylindrical contact terminals

162 and 163 respectively by tightening the clamping bolts. The spring carriers 158 and 159 are then firmly secured to the

terminals

162 and 163 respectively, by the bolts 170 and 171 respectively, which extend through the center of the spring carriers 158 and 159 respectively, and into the ends of

terminals

162 and 163 respectively.

The upper ends of clamp members 160 and 161 then have extending

tongues

175 and 176, which tongues contain openings which receive suitable pins such as

pins

180 and 181, which are used to form an electrical connection permitting mechanical rotation between the clamps 160 and 161 and the electrical connecting links 190-191 and 192-193. The upper ends of links 190 to 193 are also in rotatable pressure contact with the main conductive support body 120 by a suitable pressure connection which includes shafts 194 and 195 respectively. Thus, the links 190 and 191 form an electrical connection from the terminal 162 of vacuum interrupter 103 to the conductive support 120. The links 192 and 193 then continue this electrical connection from the body 120 to the terminal 163 of interrupter 102.

It should be noted that links 190-193 take all of the electrical conducting duty involved in the series connection of

interrupters

102 and 103, and remove the need for electrical conduction through portions of the main operating mechanism. It will further be noted that these links also act to force movement of

members

162 and 163 of

interrupters

103 and 102 respectively to be constrained to a straight line so that pure butt contacting action is obtained within the vacuum interrupter units.

It will finally be observed that there is intentional free play between the end cap nuts 200-201 and 202-203, which are secured to the ends of posts 150-153 respectively, and serve as a stop for the movement of the spring brackets 158 and 159. As will be seen more fully hereinafter. this intentional free-play improves-the operation of the unit during opening, since it permits the application of an impact force to the closed contacts.

The operating mechanism is shown with the interrupter contacts in their closed position. It will be noted that the forces of springs 154 through 157 press the spring carriers 158 and 159 outwardly and aqay from i one another, thereby to press the

movable contact terminals

162 and 163 of

interrupters

103 and 102 respectively toward their contact engaged position. Note further that the contact biasing force is axially directed in the same direction in which the contacts would normally move. It will also be seen that the breaker can be held in its closed position through the toggle mechanism with the application of relatively small forces to the shaft 110. v

The operating mechanism is so adjusted that when the toggle is in its fully extended position, as shown in the force on the contacts is about 112.5 percent of the rated force. Thus, when the contacts erode due to interruption, so that the spring carriers 158 and 159 will be further apart when the breaker contacts are closed, the reduction in spring force will be to the percent figure after the contacts have eroded by their half-life, which would conventionally be about 0.0625 inch. This force can then be easily adjusted by the location of shims in the toggle mechanism. Thus, there are shown shims 210 and 211 disposed between spring carriers 158 and 159 and the

terminal members

162 and 163 respectively.

It is important to note that the use of these shims does not affect the stroke of the operating mechanism, but merely change the end position of the movable contacts.

in order to open the interrupter, shaft moves upwardly in the direction of arrow 111, with the shaft being guided for linear movement by the guide slot 129, which receives pin 130. The upward movement of pin causes toggle links 133-134 and -136 to move inwardly. Once they have reached a given position, the nuts 200 and 203 on the spring guide pins -153 respectively, strike their respective spring carriers 158 and 159. This impact force is then applied to the contacts of

interrupters

102 and 103 in order to break any welds that may have been formed between these contacts, and the continued movement of pin 130 upwardly causes the continued relative inward movement of the interrupter contacts, moving them to their disengaged positions.

During this movement, guide links 137 and 138, and 140-141 move respectively clockwise and counterclockwise and similarly, the links 190-191 and 192-193 execute the same movement. Thus, these various pairs of links form two parallelograms causing the brackets.

and 161 to move gencrallylinearly, without rotation. Thus, good straight-line action is obtained for the contacts touch, the contact loading springs are preloaded to about '75 percent of the required force for full momentary rating. As the toggle is further operated, this force on the contacts builds up to its predescribed maximum of 112.5 percent when the toggle has been fully extended.

It will be noted that when the disconnect contact arm 104 of FIG. 2 are in the form shown in FIG. 2 with a rigid connection to support 311, using a tulip-type contact 300 of the type shown in FIG. 2 and in theprior U.S. Pat. No. 3,728,508 any misalignment of either of the disconnect contact arm 104 with the stationary contact stud 301 will cause the elements of the tulip contact 300 to assume a severe angularly displaced condition as shown in FIG. 2.

Where, however, the disconnect contact arms 304, 307 of FIGS. 1 and 3 are mounted so that they are hingedly connected by

contact elements

310, 310 to the support 311 for vacuum bottle the length of the arm over which accommodation to misalignment takes place is such that a sharp angular displacement at the contacts is avoided In FIG. 3 the lower disconnect contact arm 307 encased in the insulating housing 341 is shown hingedly connected at 310 to the connector 311 for the vacuum bottle 102. The lower rear disconnect contact arm 307 of the switchgear is provided at the contact 310 with a series of concentric ring contacts 312 of the type shown in the aforesaid prior U.S. Pat. No. 3,793,606 wherein the concentric rings 312 are individual coiled springs which are curved around the recessed portion 320 of the hingedly mounted end of the disconnect contact arm 307. These are positioned also by the recess 321 in the connector member 311 and held in position in any suitable manner as for instance by the retaining rings 322 which may be held in place in the recess as shown in FIG. 3.

It will thus be seen that the disconnect contact arm 307, being connected to the terminal member 311 of the switchgear by the series of squeezible or compressible annularly arranged springs 312 may rock slightly with respect to the relatively rigid terminal 31 1; and the free end 330 of the back connection stud 307 may thus readily be adjusted to accommodate to variations in the back connection stud member 301a. Thus with the ,same type of misalignment shown in FIG. 2 (producing a violent disarrangement of the tulip contacts 300 as used in the prior art) only a minor variation in the contact elements occurs by reason of the use of the plurality of annular springs of the type shown in prior U.S. Pat. No. 3,793,606 and the location of these contact elements.

Contact is made between the disconnect contact arm 307 and the stationary, disconnect contact stud by another plurality of coiled springs 330 secured in the annular recesses 331 at the free or disconnect end of the disconnect contact arm 307.

Thus despite any misalignment of the disconnect contact arm 307 and the stationary contact member 301a the fact that the contact springs 312 and the contact springs 330 may be squeezed and compressed provide for simplified pivoting of the disconnect contact arm 307 in order to accommodate for such misalignment and for entry of the contact element 330 of the rear end of the disconnect contact arm 307 into the stationary Contact stud 301a which now may be utilized in the form of a receptacle to receive the said disconnect contact arm 307.

In addition and for further protection against flashover, stationary disconnect contact stud 301a may be recessed in an insulating member 340 into which the switchgear mounted contact back disconnect member 307 may enter, and the switchgear mounted back disconnect contact arm 307 may itself be protected by an insulating bushing 341.

It will thus be seen that since the disconnect contact arm 307 may now pivot around its point of connection with the switchgear, it may thus accommodate itself more readily (because of the longer lever arm thus created) to any possible misalignment.

Essentially as previously described the operation here now permits a simplified alignment structure wherein the squeeze contacts particularly of the type shown in FIGS. 9 and 12 of the prior U.S. Pat. No.

3,793,606 may be used for the purpose of arranging the disconnect contacts so that they may readily be aligned with the stationary disconnect contacts in the switchboard without requiring the violent distortion which might occur as described in connection with FIG. 2.

While in the foregoing particular attention has been paid to the description of the back disconnect contact arm 307 it will be obvious that disconnect contact arm 304 is structured and supported in the identical manner and operates in the identical manner and requires no further specific description here.

In the foregoing the present invention has been described solely in connection with preferred illustrative embodiments thereof. Since many variations and modifications to the present invention will now be obvious to those skilled in the art it is preferred it be bound, not by the specific disclosure herein contained but by the appended claims.

I claim:

1. In drawout switchgear, comprising a device for opening and closing a circuit; said device having a pair of terminals;

disconnect contact assemblies each comprising a stationary disconnect contact; I and a movable disconnect contact arm connected to one of said terminals;

said movable disconnect contact arm comprising:

resilient contact members mechanically and electri-' cally connecting one end of said conductor to one of said terminals;

said conductor having limited omnidirectional movement at said connected end thereof;

and additional contact elements on the end of the its connection to said terminal permitting the additional contacts at the opposite end to be aligned with said stationary disconnect contact, the said first mentioned resilient contact members comprise:

a plurality of helical spring turns; each of said helical spring turns being wound as a helical spring around an end of said conductor;

said terminal having a cylindrical recess receiving said end of said conductor; said cylindrical recess and said end of said conductor being spaced so that the helical spring members are compressed between them transverse to the main axis of the spring members;

said alignment and universal movement of said conductor compressing said springs further on one side and correspondingly reducing the degree of compression on the opposite side while maintaining the electrical and mechanical connection between said conductor and said terminal.

2. The drawout switchgear of claim 1 in which said spring members comprise a plurality of circular helical springs parallel to eac.h other and surrounding said end of said conductor at said terminal.

3. The drawout switchgear of claim 1 in which said contacts comprise a single helical spring helically wound on said end of said conductor.

4. The drawout switchgear of claim 1 in which said additional contacts on the end of the conductor opposite the connections thereof to the terminal also comprise:

a plurality of turns of a helical spring; each turn of helical spring being wound as a helical spring around an end of said conductor;

said stationary disconnect contact having a cylindrical recess receiving said opposite end of said conductor with the springs mounted thereon, the spacing between said last mentioned cylindrical recess and said last mentioned springs being such as to compress said springs transverse to their axis to effect electrical contact.

Claims

1. In drawout switchgear, comprising a device for opening and closing a circuit; said device having a pair of terminals; disconnect contact assemblies each comprising a stationary disconnect contact; and a movable disconnect contact arm connected to one of said terminals; said movable disconnect contact arm comprising: resilient contact members mechanically and electrically connecting one end of said conductor to one of said terminals; said conductor having limited omnidirectional movement at said connected end thereof; and additional contact elements on the end of the conductor opposite the end thereof connected to said terminal; said additional contact elements being engageable with said stationary disconnect contact; said omnidirectional movement of said conductor at its connection to said terminal permitting the additional contacts at the opposite end to be aligned with said stationary disconnect contact, the said first mentioned resilient contact members comprise: a plurality of helical spring turns; each of said helical spring turns being wound as a helical spring around an end of said conductor; said terminal having a cylindrical recess receiving said end of said conductor; said cylindrical recess and said end of said conductor being spaced so that the helical spring members are compressed between them transverse to the main axis of the spring members; said alignment and universal movement of said conductor compressing said springs further on one side and correspondingly reducing the degree of compression on the opposite side while maintaining the electrical and mechanical connection between said conductor and said terminal.

2. The drawout switchgear of claim 1 in which said spring members comprise a plurality of circular helical springs parallel to each other and surrounding said end of said conductor at said terminal.

4. The drawout switchgear of claim 1 in which said additional contacts on the end of the conductor opposite the connections thereof to the terminal also comprise: a plurality of turns of a helical spring; each turn of helical spring being wound as a helical spring around an end of said conductor; said stationary disconnect contact having a cylindrical recess receiving said opposite end of said conductor with the springs mounted thereon, the spacing between said last mentioned cylindrical recess and said last mentioned springs being such as to compress said springs transverse to their axis to effect electrical contact.