US3235698A

US3235698A - Disconnect switch construction having reduced thrust forces

Info

Publication number: US3235698A
Application number: US312185A
Authority: US
Inventors: Joseph A Turgeon
Original assignee: ITE Circuit Breaker Co
Current assignee: ABB Inc USA; ITE Circuit Breaker Co
Priority date: 1963-09-27
Filing date: 1963-09-27
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15

Description

Feb. 15, 1966 TURGEQN 3,235,698

DISCONNEC'I' SWITCH CONSTRUCTION HAVING REDUCED THRUST FORCES Filed Sept. 2'7, 1963 2 Sheets-Sheet 1 INVENTOR. JflJEP/l 4 rmaim Feb. 15, 1966 J. A. TURGEON DISCONNECT SWITCH CONSTRUCTION HAVING REDUCED THRUST FORCES 2 Sheets-Sheet 2 Filed Sept. 27, 1963 United States Patent DISCONNECT SWITCH ,CQNSTRUCTIQN HAVING REDUCED THRUST FQRCES Joseph A. Turgeon, Toronto, Ontario, Canada, assignor,

by fnes'ne assignments, to I-T- E Circuit Breaker (Canada) Limited, Po'r't Credit, Ontario, Canada, a

limited-liability company of Qanada Filed Sept. 27, 1963, Set. No. 312,185 12 Claims. (Cl. 0-16'6) My invention relates to a center break two-insulator disconnect switch wherein the contacts are so arranged that substantial contact pressure may be achieved in the absence of significant thrust forces along the contact carrying members, which would result in a cantilever defiective force on the support insulators, and is more particularly a continuation-in-part of my copending US. patent application Serial No. 79,890 filed December 30, 1960, now abandoned. Center break two-insulator disconnect switches are well known in the art, wherein the first insulator carries a first contact arm which extends perpendicular to the axis of the insulator, while the second insulator carries a second contact arm which similarly extends perpendicular from its support insulator. Each of the contact arms are terminated with respective contacts. The first of the contacts may carry a jaw-type contact finger arrangement biased towards a contact pressure position, while the other is a solid contact extending generally transverse to the jaw contact. The solid contact then enters the contact fingers of the jaw-type contact when the elongated contact arms are rotated to a position of aligned engagement with one another.

High contact pressures must be provided when the contacts are engaged. Such high contact engagement is ef fected by making the solid contact member of a somewhat greater extent than the normal spaced apart separation of the jaw contact fingers. As the contacts engage, the jaw contact fingers are gradually spread apart to permit entry of their cooperating elongated contact, with such spreading apart being resisted by the biased construction of the jaw contact. Hence substantial frictional forces will be established during the relative movement between the contact members which frictional force transmits a substantial thrust component generally along the axis of the contact arms acting as a cantilever defiective force on the support insulator stacks.

The essence of the present invention is to suitably construct and inter-relate the cooperating contact members, such that during the generation of such substantial frictional forces, to obtain the requisite high contact pressure, a cancellation in forces occurs so as to effect a substantially zero defiective thrust condition at the insulator support stacks. More specifically, I have found that this cancellation will occur when substantially all the frictional engagement between the contact members corresponds to the opposed ends thereof straddling the centerline connecting their pivotal support stacks. That is, as the elongated contact enters the jaw contact member, frictional engagement therebetween is delayed until the leading edge of the elongated contact is substantially along the centerline joining the arm pivot points. During the further arcuate movement of the arm members, the leading end of the elongated contact crosses the centerline, such that it will continue its movement about, for example, the upper side of the centerline, while the lagging end thereof will be moving about the lower side of the centerline. The final engaged position of the contact members is reached before the lagging end crosses the centerline; hence, substantially all the spread apart movement of the contact jaws corresponds to the movement of the opposed 'ice ends of the contact member about opposed sides of the centerline joining the pivotal support stacks. During this movement the engagement of the leading end and its cooperating upper jaw finger are moving apart, tending to transmit 'an outward thrust to the insulator support stacks. Simultaneously, the engagement of the lagging end and its cooperating lower jaw finger are moving together, tending to pull the insulator stacks together. Hence, the forces will cancel, with such cancellation being most effective when the opposed ends of the elongated contacts translate equal distances along their respective cooperating jaw fingers. Thus, there is a cancellation of the frictional forces generated at the opposite surfaces of contact engagement, with such cancellation serving to effect a substantially null thrust condition at the insulator stacks in accordance with the advantageous teachings of my invention.

Various arrangements have been previously suggested for reducing "the frictional forces generated between the engaging contact members, with such arrangements, however, failing to reduce the thrust forces over other than a minor portion of their movement. That is, although such prior structures might provide the requisite cancellation of forces over some portion of their movement, they do not realize the basic importance of straddling the centerline over substantially the entire contact frictional engagement, and therefore fail to effect a substantial reduction of the defiective thrust forces at the insulator support stacks.

One such arrangement is shown in Gillilarrd U.S. Patent No. 2,709,739, wherein the spread-apart movement of the contact .jaws is initiated with the upper end of the cooperating contacts above the centerline, and the lower end below the centerline. During the ensuing movement to the final engaged position, the lower end crosses the centerline resulting in the substantial generation of fric tional forces in a non-cancelling manner and the deflective pushing apart of the support insulator stacks. Hence, by utilizing over-center movement of the engaged contact members, that patent fails to achieve a substantially zero transmission of thrust forces to the insulator stacks, as is the essential concept of my invention.

In a preferred embodiment of my invention, both the elongated contact andcontact jaw members are angularly offset from the longitudinal axis of their respective arms. Such angular disposition in con-junction with the dimensions of the cooperating contact members servesto facilitate the limiting of the spread-apart movement of the contact jaws to such portion of their travel wherein the opposed ends thereof straddle the centerline joining the pivotal insulator stack members.

Hence, it is seen that the basic concept of my invention resides in providing a switch contact construction for achieving high contact pressures in a center break two-insulator disconnect switch while effecting a substantial reduction in the defiective thrust forces transmitted to the pivotal insulator stacks.

Accordingly, a primary object of this invention is to provide a novel pair of c'ooperable contacts for a center break disconnect switch, which etfec'ts a null thrust condition at the insulator support stacks.

Another object of my invention is to provide a switch contact construction for a center break disconnect switch, wherein the high frictional engagement of the respective contact members is substantially limited to that portion of their travel wherein the opposed'ends thereof straddle the centerline connecting the pivotal insulator columns.

An additional object of my invention is to provide such a switch contact construction, wherein the leading end of the elongated contact engages the jaw contact substantially at a point on the centerline joining the pivotal insulator columns, and its final position is along one side of the centerline, while the lagging end of the elongated contact is positioned at the opposed side of the centerline.

A still further object of my invention is to provide a switch contact construction for effecting a substantial reduction in the thrust forces transmitted to the insulator support stacks of a center break disconnect switch, wherein the contacts are angularly offset from the axis of their respective switch contact arms and dimensionally inter related such that substantially all the frictional forces generated therebetween will correspond to the opposed ends of the contact members straddling the centerline joining the insulator support stack members.

These as well as other objects of my invention will become readily apparent from the following description of the accompanying drawings in which:

FIGURES 1-5 schematically illustrate the operation of the present invention as applied to a center break disconnect switch with its contacts sequentially shown in the open position; just prior to engagement; at the point of initial engagement; at a point during the engaged movement thereof; and in the closed position.

FIGURE 6 is a plan view of a two-insulator disconnect switch, which uses the contact structure of the instant invention.

FIGURE 7 is a side elevation view of FIGIURE 6.

FIGURE 8 is a side end view of FIGUURE 7.

Referring first to FIGURES 1-5, I have schematically illustrated first and second pivotally mounted

contact arms

10, 11 respectively, which are pivotally mounted on fixed

pivots

12 and 13 respectively.

Pivots

12 and 13 correspond to the elevated insulator support stacks conventionally used in the center break type of disconnect switch, as will be shown in the discussion of FIGURES 6-8. Contact arms and 11 are typically of an appreciable length, particularly in conjunction with the extrahigh voltage systems to which such center break type disconnect switches are presently being employed, such that any frictional forces generated upon engagement of the

contact arms

10 and 11 at their cooperating ends, if uncompensated for will tend to establish substantial defiective thrust forces at the

pivotal points

12, 13 respectively. Centerline 100 is shown joining the

pivotal center points

12, 13 of

arms

10, 11 respectively.

Contact arm 10 is terminated by a solid flat contact member 14, and is preferably disposed with respect to the longitudinal axis 10 of contact arm 10, such that its

opposite ends

15 and 16 lie along a line which forms an angle other than 90 with respect to said axis 10'. Contact arm 11 is terminated by a jaw member 17, which has extending

fingers

18 and 19 preferably in a nonparallel relationship with respect to longitudinal axis 11' of contact arm 11.

Fingers

18, 19 are resiliently biased to a normal position during which the

fingers

18 and 19 are spaced apart from one another by a distance shown as A. The distance between

ends

15 and 16 of contact 14 is made greater than A by some predetermined amount, and is illustrated as having a dimension A-I-B. As will be subsequently shown, engagement of contact member 14

intermediate fingers

18 and 19 necessitates spaced-apart movement of said contact fingers to accommodate the greater dimension (A-I-B) of the contact member, so as to insure high electrical contact pressure engagement therebetween.

In order to cause an electrical path to exist from contact arm 10 to contact arm 11, the arms are rotated towards one another, as is shown by the sequential operation intermediate FIGURES 1-5, whereby the contact 14 enters the jaw 17 and then forces the jaws apart. In FIGURE 2, the contacts are first coming into the entering relationship, with the leading end 15 of contact 14 not yet in engagement with finger 19 of jaw 17. FIG- URE 3 corresponds to initial engagement of the leading end 15 of contact 14 with cooperating finger 19 (at point during which time lagging end 16 will also be in engagement with opposed finger 18 of jaw contact member 17 (at point X). Hence, prior to the position shown in FIGURE 2, there will be substantially no frictional engagement intermediate contact members 14 and 17, with there being no thrust correspondingly transmitted to the support stacks located at

pivots

12, 13 respectively.

The angle of contact members 14, 15 and their dimensions are carefully selected such that the engagement point of FIGURE 3 corresponds to the leading end 15 of elongated contact 14 being substantially along the centerline joining the

pivotal centers

12, 13 respectively. FIG- URE 4 corresponds to an intermediate position of the switch during the closing cycle, wherein leading end 15 is seen to have moved about to one side of the centerline 1130 joining the pivotal centers, while the lagging end 16 is moved about the opposed end of the centerline.

The rotational translation of

arms

10, 11 then continues to the finally engaged position of FIGURE 5, wherein ends 15, 16 are at jaw contact points y, x, respectively, and the axes 1t), 11' of

arms

10, 11 respectively are seen to be in colinear relationship with respect to the centerline 100 of the support stack pivotal points. Intermediate the positions shown in FIGURES 2-5, the entry of elongated contact member 14 within jaw contact member 17 will be spreading apart

jaws

18, 19 to generate substantial frictional forces along the respective engagement points of

ends

15, 16. However, I have found that by causing these respective ends to straddle the centerline 100 during the generation of such substantial frictional forces there will be an appreciable cancellation thereof, such that substantially little if any thrust forces will be transmitted to the pivotal support stacks 12, 1 3.

To further facilitate the degree to which the frictional forces are cancelled, the translation of the respective

elongated contact ends

15, 16 along cooperating

fingers

19, 18 are preferably equal between the positions shown in FIGURES 3 and 5; That is, the distance between initial and final engagement points x-x' corresponds to the distance between y-y'. It is to be noted, however, that a substantial reduction of the thrust forces will still be effected should these distances differ somewhat.

It will be apparent that when the switch is opened and it is necessary to defeat the contact pressure between contacts 14 and 17, the operation above described will be repeated in the reverse sequence, whereby the frictional forces on either side of the contact jaw will still cancel, by virtue of the straddling of the centerline 100.

Hence, in accordance with my invention, there will be a substantial decrease in the reactive force transmitted back to the pivotal mounting structure of the

main contact arms

10 and 11, in both the opening and closing cycles, although substantial contact pressure will still be achieved between the cooperating contacts 14, 17 to provide firm electrical engagement therebetween.

An illustrative embodiment of the invention is shown in FIGURES 6-8. Referring to these figures, I have shown a center break switch which includes a mounting channel or base 30 which permits the switch to be mounted to any desired mounting structure, and which supports rotatable insulator stacks 31 and 32 which are pivotally mounted to support 30. The upper end of stack 31 carries a tubular contact arm 33 which is electrically connected to a terminal 34 in the usual manner.

In a similar manner, insulator stack 32 carries a tubular contact arm 35 which is electrically connected to a terminal 36, as is typical of the prior art.

The contact structures which terminate

tubular contact arms

33 and 35 are preferably formed in accordance with the present invention wherein a solid contact plate member 37 is secured to contact arm 33 as by brazing or any other typical securing means so that the plate forms an angle with respect to the axis of tubular contact arm 33, as shown in FIGURE 6. It should be likewise understood that the basic concept of my invention may be likewise obtainable by suitably dimensioning the contact jaw and elongated contact members, such that the straddling of the centerline will be effected without angularly offsetting the operating contact members from their respective contact arm axes.

The cooperating jaw for contact 37 is shown as jaw 38, which is secured to tubular contact arm 35 again as by brazing or any other method well known in the art.

Contact jaw 38 is more specifically comprised of a plurality of contact fingers shown as

contact fingers

39 and 40 in FIGURE 7 (which correspond to contact finger 19 of FIGURES 1-5), and a pair of opposing contact fingers including contact finger 41 which opposes contact finger 39 in FIGURE 6 and which correspond to contact finger 18 of FIGURES 1-5.

The contact fingers such as fingers 39 and 4.0 are so arranged that they are relatively flexible and are normally biased toward one another to a final resting place at which they are spaced by a distance which is less than the width of contact member 37.

In order to operate the switch of FIGURES 6-8 to an open position, the insulator stack 31 is provided with an operating crank arm 42 which is movable to the dotted and open position shown in FIGURE 6 as position 42'. Conversely, to move from the switch open position to the final engaged switch closed position (as between FIGS. 1 and 5 of the schematic representation), the crank arm is moved from the dotted position 42' to the solid position 42. Such movement is limited between the extremes shown in these positions, as by the provision of an appropriate stop, to provide a means for limiting substantially all the movement into high pressure engagement between the elongated contact member (37 or '14) and the contact fingers (39, 41 or 18, 19;) into the switch closed position (FIGS. 6 or 5) to occur when the opposed ends of the elongated contact are engaging their respective contact fingers at the opposite sides of the centerline joining the insulators 31, 32 (or 12, 13). Such movement is sequentially shown by FIGS. 35, discussed above.

Crank arm 42 is rigidly connected to arm 43 which projects from and is secured to stack 31. Arm 43 is pivotally connected to a connecting link 44 which, in turn, is pivotally connected at its opposite end to crank arm 45 fastened to stack 32.

Accordingly, when crank arm 42 is rotated toward the position 43, stack 31 will rotate in a clockwise direction in FIGURE 5, and because of connecting link 44, stack 32 will rotate in a counterclockwise direction so that

contact arms

33 and 35 and their contacts 37 and 38 respectively are moved toward a disengaged position similar to that shown in FIGURE 1.

In accordance with the present invention, during both the engaging and disengaging operation of the switch contact, the force in directions C and D (FIGURE 6) along

contact arms

33 and 35 respectively when the axes of

tubular members

33 and 35 fall along the dot-dash line of FIGURE 6 is either decreased to zero or to a substantially smaller value than is normally required to achieve contact pressure between their respective contact elements.

More specifically, and as was indicated above with regard to FIGURES 1-5, force for achieving contact pressure during switch opening conditions, is achieved by requiring a rotational motion of contact member 37 within the contact fingers such as fingers 39 and 4t} and contact fingers 41 and another (not shown) of the contact jaw 38, while the centerline 100 of the pivotal support stack is straddled. In view of this rotational motion, the reactive forces transmitted back to

insulator stacks

31 and 32 will be the vectorial sum of the forces applied on opposite sides of the contact jaw which can be made negligible or zero by appropriately forming the angular relationship and/ or dimensional relationship between contact 37 and the fingers such as fingers 39, 4t? and 41.

Because of this substantial decrease in thrust on the insulator stacks 31 and 32, it will be apparent that the design of these stacks can be more economical and the stacks can be lighter than those previously used where a substantial cantilever force was applied to the top of the stacks when high contact pressure is achieved and defeated during switch closing and switch opening conditions.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclos- =ure 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 center break two-insulator switch; said switch including a first and second contact arm and a first and second insulator; a pivot end of each of said first and; second contact arms pivotally carried by said first and second insulators respectively; a contact end of said first and second contact arms respectively being rotatable toward and away from one another; said contact end of said first contact arm having an elongated cont-act member thereon including opposed first and, second ends; said contact end of said second contact arm having a contact jaw member thereon, including first and second opposing contact fingers; said elongated contact member being movable into said opposing contact fingers of said jaw contact member when said first and second contact arms are rotated toward one another for separating movement of said opposing contact fingers; said separating movement providing substantial contact pressure between said elongated contact and said opposing contact fingers, and generating substantial frictional forces; said first end of said elongated contact having a point of initial engagement with said first contact finger substantially along the centerline joining said first and second insulators, and said second end of said elongated contact having a point of initial engagement with said second contact finger on a first side of said centerline; the rotational movement of said contact arms being stopped at a switch closed position where said elongated contact has fully entered said contact jaw, and said contact fingers are fully separated to provide high pressure engagement between said elongated and jaw contact members; said switch closed position occurring when said first end of said elongated contact is in engagement with said first contact finger at a point on a second side of said centerline, and said, second end of said elongated contact is in engagement with said second contact finger at a point on said first side of said centerline; means for limiting substantially all of the movement, into high pressure engagement between said elongated contact member and said contact fingers into said switch closed position to occur when said first and second ends of said elongated contact are engaging their respective contact fingers at said opposite first and second sides of the centerline, thereby substantially cancelling the frictional forces generated between said opposed first and second ends and contact fingers respectively which are transmitted to said first and second insulators.

2. A center break two-insulator switch as set forth in claim 1; said first end of said elongated contact initially engaging said first contact finger at said centerline joining said insulator supports.

3. A center break two-insulator switch as set forth in claim 1; said switch closed position corresponding to said centerline passing through an intermediate region of said elongated contact.

4. A center break two-insulator switch as set forth in claim 1, said first end of said elongated contact moving in a first direction intermediate its respective points of initial engagement and switch closed positions, along said contact finger towards one of said insulators, while on said second side of said centerline; and said second end of said elongated contact moving in a second direction intermediate its respective points of intial engagement and switch closed positions, along said second contact finger towards the other of said insulators, while on said first side of said centerline.

A center break insulator switch, as set forth in claim 4, wherein the extent of said respective movements are substantially equal.

6. A center break two-insulator switch as set forth in claim 1, said switch closed position corresponding to said centerline passing through an intermediate region of said elongated contact, and the longitudinal axis of said first and second contact arms respectively being in colinear alignment along said centerline.

7. A center break two-insulator switch as set forth in claim 1; a line drawn between said first and second ends of said elongated contact being at a first angle greater than 90 and less than 180 with respect to the longitudinal axis of said first contact arm; said first and second contact fingers extending in a direction which is in nonparallel relationship with respect to the longitudinal axis of said second contact arm.

8. A center break two-insulator switch; said switch including a first and second contact arm and a first and second insulator; a pivot end of each of said first and second contact arms being carried by said first and second insulators respectively; a contact end of said first and second contact arms respectively being rotatable toward and away from one another; said contact end of said first contact arm having an elongated contact thereon; said contact end of said second contact arm having a contact jaw thereon including a first and second opposing contact finger; said elongated contact being movable into said contact jaw when said first and second contact arms are rotated toward one another for separating movement of said contact fingers; said separating movement providing substantial contact pressure between said elongated contact and said contact fingers; said elongated contact and said first and second opposing contact fingers having a first and second contact position with respect to one another; said first contact position corresponding to initial engagement of said elongated contact and said contact jaw, and said second cont-act position corresponding to final high pressure engagement of said elongated contact and said contact jaw, with said opposing contact fingers being fully separated; a first end of said elongated contact engaging said first contact finger at first and second locations, corresponding to said first and second contact positions respectively; a second end of said elongated contact engaging said second contact finger at third and fourth locations, corresponding to said first and second contact positions respectively; substantially all the movement of said elongated contact first end intermediate said first and second locations occurring to one side of the centerline joining said first and second insulators, and substantially all the movement of said elongated contact second end intermediate said third and fourth locations occurring at the opposite side of said centerline; means for limiting substantially all the movement into high pressure engagement between said elongated contact and said contact jaw to occur between said first and second contact positions, whereby the net frictional forces created during such engagement of said elongated contact and said contact jaw during movement from one to the other of said contact positions oppose one another during substantially all of said movement and only the net difference in said frictional forces are transmitted to said first and second insulators,

9. A center break two-insulator switch as set forth in claim 8; said first contact location positioned substantially along said centerline joining said first and second insulators.

19. A center break two-insulator switch as set forth in claim 8; a line drawn between said first and second ends of said elongated contact being at a first angle greater than and'less than with respect to the longitudinal axis of said first contact arm; said first and second contact arms extending in a direction which is in nonparallel relationship with respect to the longitudinal axis of said second contact arm.

11. A center break two-insulator switch as set forth in claim 8; said second switch contact position corresponding to said centerline passing through an intermediate region of said elongated contact; and the longitudinal axis of said first and second contact arms respectively in colinear alignment along said centerline.

12. A center break two-insulator switch as set forth in claim 8; said first end of said elongated contact moving in a first direction towards one of said insulators, intermediate said first and second locations, and said second end of said elongated contact moving in a second direction towards the other of said insulators intermediate said third and fourth locations.

References Cited by the Examiner UNITED STATES PATENTS 1,835,696 12/1931 Croft 20048 1,949,019 2/1934 Koppitz 20048 2,709,739 5/1955 Gilliland et al. 200-l70 KATHLEEN H. CLAFFY, Primary Examiner. ROBERT K. SCI-IAEFER, Examiner,

Claims

1. A CENTER BREAK TWO-INSULATOR SWITCH; SAID SWITCH INCLUDING A FIRST AND SECOND CONTACT ARM AND A FIRST AND SECOND INSULATOR; A PIVOT END OF EACH OF SAID FIRST AND SECOND CONTACT ARMS PIVOTALLY CARRIED BY SAID FIRST AND SECOND INSULATORS RESPECTIVELY; A CONTACT END OF SAID FIRST AND SECOND CONTACT ARMS RESPECTIVELY BEING ROTATABLE TOWARD AND AWAY FROM ONE ANOTHER; SAID CONTACT END OF SAID FIRST CONTACT ARM HAVING AN ELONGATED CONTACT MEMBER THEREON INCLUDING OPPOSED FIRST AND SECOND ENDS; SAID CONTACT END OF SAID SECOND CONTACT ARM HAVING A CONTACT JAW, MEMBER THEREON, INCLUDING FIRST AND SECOND OPPOSING CONTACT FINGERS; SAID ELONGATED CONTACT MEMBER BEING MOVABLE INTO SAID OPPOSING CONTACT FINGERS OF SAID JAW CONTACT MEMBER WHEN SAID FIRST AND SECOND CONTACT ARMS ARE ROTATED TOWARD ONE ANOTHER FOR SEPARATING MOVEMENT OF SAID OPPOSING CONTACT FINGERS; SAID SEPARATING MOVEMENT PROVIDING SUBSTANTIAL CONTACT PRESSURE BETWEEN SAID ELONGATED CONTACT AND SAID OPPOSING CONTACT FINGERS, AND GENERATING SUBSTANTIAL FRICTIONAL FORCES; SAID FIRST END OF SAID ELONGATED CONTACT HAVING A POINT OF INITIAL ENGAGEMENT WITH SAID FIRST CONTACT FINGER SUBSTANTAIALLY ALONG THE CENTERLINE JOINING SAID FIRST AND SECOND INSULATORS, AND SAID SECOND END OF SAID ELONGATED CONTACT HAVING A POINT OF INITIAL ENGAGEMENT WITH SAID SECOND CONTACT FINGER ON OF FIRST SIDE OF SAID CENTERLINE; THE ROTATIONAL MOVEMENT OF SAID CONTACT ARMS BEING STOPPED AT A SWITCH CLOSED POSITION WHERE SAID ELONGATED CONTACT HAS FULLY ENTERED SAID