US3746819A

US3746819A - Contact assembly for switches

Info

Publication number: US3746819A
Application number: US00279850A
Authority: US
Inventors: L Linde
Original assignee: Gulton Industries Inc
Current assignee: Gulton Industries Inc
Priority date: 1972-08-11
Filing date: 1972-08-11
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17

Abstract

In a high voltage disconnect electric switch, a rotatable switchblade is provided with a contact portion at one end having an edge which is adapted to remain coincident with the axis of rotation of the switchblade throughout the blades rotation. A stationary terminal is maintained in continuous electrical contact with this blade edge. A rotatable contact assembly is also provided receivable of the switchblade and includes a contact portion having an edge adapted to remain coincident with the assembly''s axis of rotation. Another stationary terminal is maintained in continuous electrical contact with this contact edge. Both the blade and the contact assembly remain in static contact with respective terminals throughout the rotation of the various members thereby reducing wear and other associated problems.

Description

Linde CONTACT ASSEMBLY FOR SWITCHES [451 July 17, 1973 Primary ExaminerDavid Smith, Jr.

75 Inventor: Leonard J. Linde, Brookfield, Wis. Mmiime [73] Assignee: Gulton Industries Inc., Metuchen,

NJ. [57] ABSTRACT [22] Filed: Aug. 11, 1972 in a high voltage disconnect electric switch, a rotatable I L N 279 50 Switchblade is provided with a contact portion at one [2 1 App ,8 end having an edge which is adapted to remain coincident with the axis of rotation of the switchblade US. Cl 00/170 A, 200/48 K 200/l46 R, throughout the blades rotation. A stationary terminal is O /1 ZOO/166 BF maintained in continuous electrical contact with this [51] Int. Cl. H0lh 1/50, HOlh 9/60 bl d d A rotatable contact assembly is also prol Fifild 0f Search 200/48 48 KB, vided receivable of the Switchblade and includes a con- 200/l7O 166 146 R tact portion having an edge adapted to remain coincident with the assemblys axis of rotation. Another stal l Referenctis Cited tionary terminal is maintained in continuous electrical UNITED STATES PATENTS Contact with this contact edge. Both the blade and the 1 238 597 8/1917 Terzich 200/162 assembly remain in Static with respec- 2I239I224 4/1941 Goldmer 200/146 R tive terminals throughout the rotation of the various 2,241,810 5/1941 Dickinson 200/162 members thereby reducing wear and other associated 2,714,646 8/1955 Jamison 200/48 KB problems. 3,671,689 6/l972 Falvo 200/170 A Claims, 6 Drawing Figures I 0 I l '24 ,4- .4 22 27 48 (Pao 40 II II 26 Pat ented July 17, 1973 I 3,746,819

3 Sheets-Sheet 1 Pa te'nted July 17, 1973 3 Sheets-Sheet 2 FIG. 4

r Patented July 17 1973 Sheets-Sheet :5

FIG. 6 l

CONTACT ASSEMBLY FOR SWITCHES BACKGROUND OF THE INVENTION This invention relates generally to high voltage electric switches, and more particularly to contact assemblies for reducing contact wear and operating effort required to operate high voltage switches employing members rotating in a single plane.

High voltage disconnect-type electric switches often comprise a pair of spaced stationary terminals mounted on the top of insulator stacks with a pivotally mounted switchblade which electrically interconnects the two terminals when the switch is closed. The switchblade is pivoted out of mutual electrical engagement with the terminals when the switch is open.

In many of these switches, the pivotal switchblade is continuously electrically connected to one of the terminals whether the switch is open or closed. This feature has proven to be convenient since the switchblade need only be moved into and out of engagement with the second terminal to close and open the switch.

In the past, however, problems have arisen from attempts to provide both a reliable mechanical pivotal connection and continuous electrical engagement between the movable switchblade and the terminals. For example, flexible electrical conductors have been used to continuously electrically connect a terminal to the adjacent end of the pivotable switchblade, These flexible connectors, however, have been found to be subject to wear and, when repeatedly flexed over a period of time, have often failed. A second arrangement finding common use includes pivotally mounting the switchblade directly to the terminal on an electrically conductive shaft. In these arrangements, the switchblade surface continuously rubs against the terminal contact surface during the opening and closing of the switch mechanism, producing wear which makes electrical contact unreliable. These arrangements have also proven susceptible to corrosion and pitting along the electrically conductive surfaces over extended periods of time and have proven unreliable for this reason also. Further, high voltage switches occasionally conduct high fault currents which are generated due to inadvertent short circuits and other circuit malfunctions. These fault currents have caused deformation of the electrically con- SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide new and improved contact assemblies for electrical switches.

Another object of the invention is the provision of a new and improved contact assembly which will not become unduly worn after extended periods of use.

A further object of the invention is to provide a new and improved contact assembly which will continue to operate despite high fault currents;

A still further object of this invention is the provision of a new and improved switch mechanism which has increased icebreaking capability.

Another still further object of the instant invention is the provision of a new and improved continuous contact assembly which will reduce the operating effort in opening a switch.

Briefly, in accordance with a preferred embodiment of the invention, these and other objects are attained by providing an electric switch in which the pivotally mounted switchblade is provided with a contact portion having an edge coincident with the axis of rotation of the switchblade. A stationary terminal is in continuous electrical engagement with this contact edge during the rotation of the switchblade. A rotatable contact assembly is provided for engagement with the free end of the rotating switchblade and includes a contact portion which has an edge coincident with the axis of rotation of this contact assembly. A second stationary terminal is in continuous electrical engagement with this contact edge during rotation of thecontact assembly. As the switchblade rotates into and out of engagement with the contact assembly, the contact assembly is caused to rotate along with the blade to reduce the operating forces which would otherwise be necessary to operate the switch. The free end of the switchblade has a wiping effect on the contact assembly during the opening and closing of the switch which tends to clean the contact surfaces and improve deicing capabilities.

DESCRIPTION OF THE DRAWINGS A more complete appreciation of theinvention will be had by reference to the following detailed description when considered with the accompanying drawings wherein:

FIG. 1 is a partial plan view of the stationary terminal and pivoted end of the switchblade;

FIG. 2 is a side view of the stationary terminal and switchblade of FIG. 1 in a pivoted position;

FIG. 3 is a side view taken in section along line 33 in FIG. 1; r

FIG. 4 is a plan view of the pivotal contact assembly of the present invention; a a

FIG. 5 is a side view of the pivotal contact assembly of the present invention; and

FIG. 6 is a view in section taken along line 6- 6 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings where like reference characters designate identical or corresponding parts throughout the several views and, in particular to FIGS. 13, a switchblade I0 is illustrated as pivotally mounted on the upper end of an insulator stack 12. As best seen in FIG. 1, switchblade I0 is bifurcated at its end to form a pair of legs 14 having a respective pair. of aligned bores 16 formed therein. EAch bore 16 is also aligned with a bore 18 (FIG. 1) formed in a pair of arms 19 extending from a cap 20 fixed to the upper end of the insulatorstack 12. A pivot 22 is passed through each set of aligned bores and, in the present embodiment, each pivot has a threaded shankportion which is received by internally threaded bore 18 which thereby retains the pivot 22 in position. The mounting structure is only representative of one of a number of configurations possible within the scope of the present invention.

A contact portion 26 is fixed to the switchblade end 24 by conventional means such, for example, as by bolts 28 (FIG. 3). Contact portion 26 comprises an elongate bar formed of an electrically conductive material which is suitably treated to insure high surface conductivity and has a substantially rectangular cross section with its lower surface substantially coplanar with the lower surface of switchblade 10. As best seen in FIG. 3, the upper surface 27 of the contact portion 26 extends from the approximate midway point of the height of switchblade end 24 and intersects the rear surface 29 of the contact portion at edge 30. In the present embodiment, the

surfaces

27 and 29 meet at the edge 30 at an angle of slightly less than 90 so that rotation of the switchblade can be accomplished as described below without danger of interference between contact portion 26 and various contacts. As best seen in FIG. 2, the axis of rotation of the switchblade (which is merely the axes of the pivots 22), is precisely colinear with the edge 30 of contact portion 26. Thus, when switchblade 10 is rotated about the pivots 22, the edge 30 of contact portion 26 virtually remains static along the axis of rotation of the switchblade, with at most a slight wiping action.

One means by which the switchblade may be rotated is shown in FIG. 1 and includes a push-pull rod 32 connected to an extension 33 of switchblade 10 through a universal joint 34. A pair of compression springs 36 (only one shown) are provided on associated shafts 37 which shafts are pivotally mounted at their ends to extension 33 biasing the switchblade towards its closed position as shown in FIG. 1. Thus, should it be desired to open the switch, push-pull rod 32 is moved towards the right thereby pivoting the switchblade 10 around its axis of rotation (defined by pivots 22) against the force of springs 36. As described above, as this rotation progresses, the edge 30 of the contact portion 26 remains substantially stationary coincident with the axis of rotation. Other means for actuating the switchblade are known in the art and may be employed in lieu of the structure described above.

A plurality of U-shaped or loop contact members 38 comprising a stationary terminal are fastened to cap 20 by conventional fasteners such, for example, as by bolts 40. The cap 20 is provided with a horizontal ledge 42 upon which rests the end of a bus bar 44 which carries current to the loop contacts 38. One of the legs of each terminal contact 38 is bent at right angles to itself and is sandwiched between a cover plate 47 and the upper surface of the end of the bus bar 44 thereby electrically engaging the bus bar.

Referring to FIG. 3, the free leg 45 of each terminal contact 38 is urged against the edge 30 of the contact portion 26 by a compression spring 46 which is interposed between the two legs of each contact member. Thus, the plane of the contact surface of each terminal contact contains the axis of rotation of the switchblade ID at the line of contact with edge 30. Since springs 46 are normally compressed, a high contact pressure is maintained between the free leg of each loop terminal contact and the contact portion edge 30 so that when the switchblade 10 is rotated from its closed to its open position by suitable actuation of rod 32. Electrical connection is maintained between the terminal contact 38 and the contact portion 26 of the switchblade.

The extent of rotation of the switchblade I0 is limited by a stop surface 48 formed on either or both of the legs 14. As shown in FIG. 3, the stop surface 48 is vertically oriented (when the switch is closed) so that upon rotating the switchblade 90 from the position shown in FIG. 3, the surface 48 will engage the cover plate 47 thereby preventing any further rotation.

Thus, the electrical connection between the terminal contacts 38 and the switchblade 10 is continuously maintained by virtue of the coincident relationship of the edge 30 and the axis of rotation of the switchblade with the free leg of each fixed terminal loop contact 38 bearing against the blade edge 30. The disadvantages of the continually bending, flexible, electrical connectors and those due to rubbing contact between electrically conductive surfaces are eliminated. Further, by using the terminal loop contacts 38, a constant magnetic field is produced by the current passing through the loop contacts 38 when the switch is closed. Such a magnetic field serves to increase contact pressure with contact portion 26 in a manner well-known in the art. This is especially true during operation under high fault currents.

Turning now to FIGS. 4, 5 and 6, a contact assembly 50 is illustrated which receives the free end 52 of a pivotal switchblade when the switchblade is moved to' close the switch mechanism. It should be understood that, although this contact assembly 50 may be used in conjunction with the contact structure disclosed relative to FIGS. 1-3, such conjoint use is not necessary. That is, the contact assembly 50 described below' may be used in conjunction with other prior art switches within the scope of the present invention.

The contact assembly 50 is mounted on a cap 56 fastened by bolts 57 to the upper end of an insulator stack 54.

The contact assembly 50 comprises a generally U- shaped frame defined by a pair of parallel extending

arms

58 and 60 connected by a bridging member 62 which is formed of an electrically conductive material. A plurality of loop contacts 64 are fastened to the inwardly facing surfaces of the

arms

58 and 60. In the preferred embodiment, the loop contacts are fastened to the frame by elongating one leg of each loop contact and fixing these legs between the bridging member 62 and the respective

parallel arms

58 and 60 by bolts 66. Thus, there is constant electrical connection between the bridging member 62 and the loop contacts 64.

In a manner similar to cap 20, cap 56 is formed with a pair of upwardly extending arms 68, each having a bore (FIG. 4) formed therein aligned along the same axis. The lower arm 60 is formed with a pair of upwardly projecting legs 72 which include bores 74 alignable with bores 70 when the legs 72 are suitably positioned between arms 68 as best seen in FIG. 4. The contactassembly 50 is pivotally mounted on cap 56 by a pair of bolts 76 having partially threaded shanks passing through the pair of

bores

74 and 70. Bores 70 are interiorly threaded while the inner portion of the shanks of bolts 76 are similarly threaded so that bolts 76 may be fixedly maintained within the aligned bores. This mounting structure is only one of a number of possible structures which may be employed.

The bridging member 62 of the contact assembly 50 is formed with a rearwardly protruding portion 78 terminating at a horizontally extending edge 80 (FIG. 6). Tl-Ie protruding portion 78 is formed in a manner that the edge 80 is made coincident with the axis of rotation of the contact assembly, i.e., the edge 80 lies along the axis of the aligned bores 70 and 74 and bolts 76. Thus, as the contact assembly is rotated, the edge 80 of the protruding portion 78 remains virtually stationary on the axis of rotation of the contact assembly.

A horizontally extending ledge 82 (FIG. 6) is formed on cap 56 and traverses the width of the cap. This ledge supports a bus bar 84 which will conduct current when the switch is closed. A plurality of terminal loop contacts 86 are fixed to the upper surface of the bus bar 84 by conventional means, such as, for example, bolts 88 which fix a bent portion of one leg of each loop contact 86 onto the upper surface of the bus bar 84.

The free leg 87 of each terminal contact is maintained in continuous engagement with the edge 80 of the protruding portion 78' of the bridging member 62 under the force-of a compression spring 90 which urges the legs of the terminal contacts apart thereby maintaining high contact pressure between the free leg 87 of terminal contact 86 and edge 80.

Thus, in operation as described below, as the contact assembly 50 rotates, continuous contact is maintained between edge 80 of the bridging member 62 andthe terminal contacts 86. Further, such contact is virtually static, i.e., the edge 80 and the surface of the terminal contacts with which it is in contact essentially do not move relative to each other during rotation of the contact assembly except for a slight rolling action. By virtueof this fact, similar advantages to those discussed above relative to the switchblade connection assembly are attained.

In operation, referring to FIGS. 5 and 6, a switchblade, pivoted at a remote end (not shown, but which may be as described relative to FIGS. 1-3) which had been in a previously open position, is caused to pivot downwardly with its end 52 approaching the contact assembly 50. Asshown in FIG. 5, switchblade end 52 is moving downwardly in the direction of arrow 92. A compression spring 94 positioned over a rod 96 having one end pivotally connected to leg 72 at apoint 98 and the other end slidably connected to cap 56 at point 100 normally maintains the contact assembly in the position shown in FIG. 5, i.e., in an upwardly pivoted position. When the end 52 of the switchblade moves into engagement with the contact assembly, it urges the assembly 50 downwardly against the force of spring 94. As shown in FIG. 5, the loop contacts -64 disposed on the lower plate 60may extend slightly further than those disposed on the upper plate 58. In the present embodiment the switchblade 52 is shown as comprising a pair of parallel blades 102 and 104 (FIG. 4) connected by bridgingbar 106 at the end. By virtue of this arrangement, the bridging bar 106 at the end of switchblade 52 will engagecontactassembly 50 along the loop contacts provided on lower arm 60 without interfering with the loop contacts disposed on upper arm 58.

'As the switchblade 52 moves downwardly, ultimately reaching its horizontal position as shown in FIG. 6, the contact assembly 50 pivots in a clockwise direction denoted by arrow 108 in FIG. 5, and until

arms

58, 60 are horizontal. As explained above, continuous electrical engagement is maintained between the edge 80 of bridging plate 62 and the terminal contact members 86 during the rotation of the contact assembly. The bridging bar 106 is in electrical connection with loop contacts 64 at its upper and lower edges and, therefore, the

electrical connection between switchblade 52 and bus bar 84 is made.

The rotatability of contact assembly 50 facilitates the disconnect orswitch opening operation of the end of switchblade 52 from the contact assembly 50. Further, the scraping action of the end of the switchblade 52 along the inner surfaces of the loop contacts 64 serves to break up any ice which may have formed on the contacts 64 while the switch was in its open position. The center-of-rotation contact feature provides a reliable electrical connection between the contact assembly 50 and the bus bar 84 with all of the attendant advantages described with regard to the assembly disclosed in FIGS. 1-3.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made-without departing from the invention in its broader aspects, and it is therefore intended that the appended claims cover all such changes and modifications as fall within the scope of the invention.

What is claimed is:

1. An electric switch comprising, a movable electrical member mounted for rotation around an axis of rotation, at least one stationary terminal contact mountedso that a segment thereof lies substantially along the axis of rotation of said movable member, said member having a contact portion formed on one end with an edge substantially coincident with the axis of rotationv of said member said edge electrically engaging said stationary terminal contact segment.

2. The switch recited in claim 1, wherein the stationary terminal contact includes a U-shaped contact comprisinga pair of contact legs, one of said legs in a plane passing through the axis of rotation of the switchblade.

3. The switch described in claim 1, wherein the movable member contact portion includes an edge coincident with the axis of rotation of the member and continuously in contact with the segment of the terminal contactwhich passes through said axis of rotation.

4. The switch recited in claim 1, wherein the stationary terminal contact includes a U-shaped contact which includes a pair of contact legs having a spring disposed therebetween normally urging the legs apart so that one of the legs is urged against said contact portion edge which is substantially coincident with the axis of rotation of the movable member.

5. The switch as recited in claim 1, wherein the stationary terminal contact includes a plurality of U- shaped terminal contacts, each contact member having a leg which substantially passes through the center of rotation of the'movable member.

- 6. The switch as recited in claim 1, wherein the contact portion is formed of an electrically conductive material rigidly connected to the member having an edge defined by a pair of surfaces meeting at an angle of or less, the edge being substantially coincident with the axis of rotation of the member.

7. The switch of claim 1, wherein one end of the movable member is bifurcated to form a pair of spaced legs and the contact portion of the movable member includes an electrically conductive block rigidly connected to the member, the block extending within the space between the legs substantially from one leg to the other.

8. A switch terminal contact assembly comprising a contact assembly mounted for rotation about an axis of rotation, a contact portion formed on the contact assembly having an edge adapted to remain substantially coincident with the axis of rotation of the contact assembly during rotation thereof, and at least one stationary terminal contact member mounted so that a segment thereof passes through the axis of rotation of the contact assembly.

9. The terminal assembly recited in claim 8, wherein the terminal contact member includes a U-shaped contact comprising a pair of contact legs, one of said legs passing through the axis of rotation of the contact assembly.

10. The terminal assembly recited in claim 8, wherein the contact assembly contact portion includes a projection having an edge coincident with the assembly axis of rotation and continuously inelectrical engagement with the segment of the stationary contact member which passes through the assembly axis of rotation.

11. The terminal assembly recited in claim 8, wherein the stationary terminal contact member includes a U- shaped contact formed of a pair of contact legs having a spring disposed therebetween normally urging the legs apart so that one of the legs is urged against said edge of the contact assembly contact portion which is substantially coincident with the axis of rotation of the switchblade.

12. The terminal assembly defined in claim 8, wherein the contact assembly has a substantially U- shaped frame and includes a pair of spaced parallel arms connected by an electrically conductive bridging member, the parallel arms having mutually opposed electrical contacts fixed thereon and the bridging member having a rearwardly extending projection formed thereon terminating in said edge which is substantially coincident with the center of rotation of the contact assembly.

13. The terminal assembly as defined in claim 8, wherein a pair of spaced arms are provided on the contact assembly and the contact assembly contact portion extends within the space between the arms substantially from one arm to the other.

14. An electric switch comprising a switchblade mounted for rotation around an axis of rotation, first contact means mounted so that a portion thereof substantially passes through the axis of rotation of the switchblade, a contact portion formed on one end of the switchblade having an edge substantially coincident with the axis of rotation of the switchblade, and second contact means displaced from the first contact means adapted to electrically communicate with a second contact portion formed on the other end of the switchblade.

15. A switch as defined in claim 14, wherein the second contact means comprises a contact assembly mounted for rotation about an axis of rotation having a projecting contact edge formed thereon adapted to remain substantially coincident with the axis of rotation of the contact assembly, and stationary contact mem ber mounted so that a segment thereof passes through the axis of rotation of the contact assembly.

Claims

1. An electric switch comprising, a movable electrical member mounted for rotation around an axis of rotation, at least one stationary terminal contact mounted so that a segment thereof lies substantially along the axis of rotation of said movable member, said member having a contact portion formed on one end with an edge substantially coincident with the axis of rotation of said member said edge electrically engaging said stationary terminal contact segment.

2. The switch recited in claim 1, wherein the stationary terminal contact includes a U-shaped contact comprising a pair of contact legs, one of said legs in a plane passing through the axis of rotation of the switchblade.

3. The switch described in claim 1, wherein the movable member contact portion includes an edge coincident with the axis of rotation of the member and continuously in contact with the segment of the terminal contact which passes through said axis of rotation.

5. The switch as recited in claim 1, wherein the stationary terminal contact includes a plurality of U-shaped terminal contacts, each contact member having a leg which substantially passes through the center of rotation of the movable member.

6. The switch as recited in claim 1, wherein the contact portion is formed of an electrically conductive material rigidly connected to the member having an edge defined by a pair of surfaces meeting at an angle of 90* or less, the edge being substantially coincident with the axis of rotation of the member.

10. The terminal assembly recited in claim 8, wherein the contact assembly contact portion includes a projection having an edge coincident with the assembly axis of rotation and continuously in electrical engagement with the segment of the stationary contact member which passes through the assembly axis of rotation.

11. The terminal assembly recited in claim 8, wherein the stationary terminal contact member includes a U-shaped contact formed of a pair of contact legs having a spring disposed therebetween normally urging the legs apart so that one of the legs is urged against said edge of the contact assembly contact portion which is substantially coincident with the axis of rotation of the switchblade.

12. The terminal assembly defined in claim 8, wherein the contact assembly has a substantially U-shaped frame and includes a pair of spaced parallel arms connected by an electrically conductive bridging member, the parallel arms having mutually opposed electrical contacts fixed thereon and the bridging member having a rearwardly extending projection formed thereon terminating in said edge which is substantially coincident with the center of rotation of the contact assembly.

15. A switch as defined in claim 14, wherein the second contact means comprises a contact assembly mounted for rotation about an axis of rotation having a projecting contact edge formed thereon adapted to remain substantially coincident with the axis of rotation of the contact assembly, and stationary contact member mounted so that a segment thereof passes through the axis of rotation of the contact assembly.