US2379761A - Electric switch - Google Patents

Description

July 3, 1945. H. E.. STRANG ELECTRIC SWITCH Fileq Jul :9, 1943 7 Fig.1.

Inventor: Harold E. Strang,

by WW His Attorney.

Patented July 3, i945 2,379,761. ELECTRIC swrron Harold E. Strang, Ardmore, Pa., assignor to General Electric York Company, a corporation of New Application July 9, 1943, Serial No. 493,979

8 Claims.

My invention relates to improvements in electric switches and more particularly to improvements in disconnecting switches, and especially disconnecting switches of the angularly movable blade type. y

In the application of disconnecting switches, it is neecssary to increase the separation distance with increase in the voltage of the circuit. Consequently, high operating voltages require a relatively long movable switch conducting member, usually in the formof an angularly movable blade. Inasmuch as a relatively strong contact pressure is desired between the blade and stationary contact, a considerable force is required to release the blade member from the stationary contact member by the operating means which effects theangular movement of the blade member. This of itself involves a matter of stress distribution such that parts like'ceramic insulators, for example, will not be overstressed or subjected to stresses which they are not adapted to sustain. But when disconnecting switches are mounted outdoors, as is usual with high operating voltages, the blade member and its cooperating contact may become so coated with ice and the like adjacent their engaging parts that the difliculty of separating the blade member from its cooperating contact is greatlyincreased. Also, when the switch is open, ice may collect on the cooperating contact in such a way as to prevent switch closing engagement by the blade. To take care of all these conditions merely by strength of parts in the design of the switch would require such a massive construction as to' render the de-' sign economically unfeasible.

An object of my invention is to provide means, operable independently of the movement of the movable contact of an electric switchfor breaking away ice formations and the like adjacent the engaging portions of the movable and stationary contacts when the switch is closed and from the stationary contact when the switch is open. Another object of my invention is to provide for an electric switch an ice breaking means by which an initial opening impulse is given to V the movable contact after first breaking away ice formations from both contacts'when they are engaged. A further object of my inventionis to provide an improvedelectric switch wherein the ice clearing action and the initial operating impulse are accomplished by fluid pressure or other power operated means. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide for an electric switch an ice breaking member which is movably positioned adjacent the stationary contact of the switch and is arranged to be actuated relatively to the stationary contact so as to break away ice formations thereon and also on the movable contact when in engagement with the stationary contact. Also in accordance with my invention, the ice breaking member is arranged upon further movement in the ice breaking direction to give an initial opening impulse to the movable contact when the switch is closed. Further in accordance with the preferred embodiment of my invention, I provide fluid pressure operated means for effecting the ice breaking move ment of the ice breaking member and means in which energy is stored during such movement for embodiment of my invention applied to the dis- 7 connecting switch in Fig. 1 with the switch closed and the ice breaking means in position to start the ice breaking action; Fig. 3 is a view similar to Fig. 2 showing the ice breaking movement completed. and the disconnecting switch partly open; Fig. 4 is a sectional elevation on the line 44 of Fig. 2; and Fig.5 is-an exploded perspective of-the disconnecting switch stationary contact and the ice breaking member.

For the purpose of illustrating an application of my invention, I have shown in Fig. 1 a

single-pole unit of a double break, high voltage,

gas blast circuit breaker and disconnecting switch combination, such as is disclosed, for example, in United States Letters Patent 2,306,186, issued December 22, 1942, but it is distinctly to be understood that my invention is not limited to this particular combination or the particular type of disconnecting switch illustrated. As shown, the switch combination comprises two similar circuit breaker interrupting means mounted within and on high voltage insulating shells .I and 2,; respectively, supported on suitable insulating columns 3 and 4 which are mounted on a supporting frame 5 of suitable structural form. Each interrupting unit is provided with upper and A lower terminals 6 and I, respectively, and a muffler type exhaust opening 8. Also supported on the frame is a gas tank 9which is adapted to supply both interrupting units through conduits I0. The lower terminals of the interrupting units are provided with suitable contact means I I, illustrated as of the jaw type, for .coacting with a movable disconnecting switch contact I2 of the blade type. As shown, this contact I 2 is mounted for movement relatively to the terminals I on an insulating support I3 which is rotatably mounted on the frame 5. The disconnecting switch contact I2 when rotated counterclockwise, as viewed looking down on the switch, through a predetermined angle disconnects each interrupting unit at its terminal I to disconnect the power circuit. Any suitable means may be provided for actuating the blade I2, but, as illustrated, the insulating support I3 is' suitably journaled on the frame for rotative movement in response to the actuation of suitable operating means mounted in a housing I4 and illustrated in part by bevel gearing I5. This operating means, of itself, constitutes no part of my present invention.

In accordance with my invention, I provide means for removing ice formations and the like from the cooperating contacts I I and I2 of the disconnecting switch adjacent their engaging portions. For this purpose, I provide a member I6 which is movably mounted adjacent one of the cooperating contacts II and provided with means, suchas wedge-shaped bifurcations IT, for breaking ice away from both contacts when the disconnecting switch is closed and from the stationary contact when the disconnecting switch is open. In order to obtain maximum conductivity and also to provide the maximum of distributed shearing action on ice formations adjacent the stationary contact II, this jaw contact may take the form of a plurality of spaced pairs of resilient contact fingers I8 and I 9 in the spaces between which-the bifurcations ll of the ice breaking member I6 are slidable. The space between opposed bifurcations I1 is somewhat greater than the thickness of the blade contact when the disconnecting switch is arranged for operation from the gas supply tank 9. As illustrated, the actuating means comprises a cylinder 20 which is suitably conductively secured to the circuit breaker terminal I. Within the cylinder 20, there is slidably mounted a piston minal I, which is provided with a port 21 registering with a port 28 in the cylinder 26 so as to admit air back of the piston 2| and thereby force the member I6 outwardly between the contact fingers I8 and I9 ,and across the end of the blade I2 when it is in the switch closed position.

Further in accordance with my invention, I provide means for returning the ice breaking member I6 to the initial position. As shown, this return movement means is of the type in which energy is stored during the ice breaking movement of th'e'member under the action of the gas pressure from the tank 9. For this purpose, this return movement means may be a helical spring 29 positioned on the rod 22 between the cylinder head 3'0 and the piston 2|. For relieving the back pressure in the cylinder on theice breaking movement of the piston 2 I, this cylinder head may be provided with a suitable exhaust port 3 I. When the two-way valve operating rod 26 is pulled down a predetermined amount, air is admitted from the gas supply tank through the pipe 24 to the conduits 23 whereby to force the ice breaking member I6 at each jaw contact II in the ice breaking direction. Upon moving the rod 26 up to the exhaust position shown in Fig. l, the gas supply is shut oil and the conduits 23 are open to the air for exhaustion of the gas in the cylinder 20 so that the spring 29 may return the ice breaking member to its initial position.

Also in accordance with my invention, I may so arrange the ice breaking member I 6 that it provides an initial opening impulse to the blade I2 in order forcibly to move the blade relatively to the contacts II whereby to relieve any sticking tendency that the contacts II and I2 may have as a result of corrosion or freezing action which has not been entirely released by the prying and shearing action of the wedge-shaped elements II. For this purpose, the body I6 of the ice breaking member may be made of such width as to engage the inner edge of the blade following the major ice breaking action and push the blade relatively to the contacts I I so as forcibly to produce movement of the blade relatively to the contacts II.

Assuming the parts positioned as shown in Figs. 1, 2 and 4, and that it is desired to open the disconnecting switch while there is ice formation in and around the engaging parts of the contacts II and I2, the'valve operating rod 26 is pulled down sufficiently to admit gas from the supply tank 9 through the conduit 24 to theconduits 23 and thence back of the piston 2I at each jaw contact I I whereby forcibly to actuate the ice breaking mechanism I6 in the ice breaking direction. Under these conditions, the wedgeshapcd bifurcations II on the member I6 shear and crack the ice away from the contacts I I and I2, and subsequently the body portion of the .member I6 at each jaw contact engages the adjacent end of the blade I2 to move it forcibly relatively to the contacts II. During this movement, energy is stored in the return springs 29. When the ice has been suitably cleared from the contacts and the blade given its initial impulse, the valve actuating rod 26 may be raised upwardly to the position shown in Fig. l to permit exhaustion of the air from the cylinders 2|] and to allow the springs 29 to return the ice breaking members IE to their initial positions. The disconnecting switch operating means may then be actuated to open the switch. If the switch is open and ice has formed in and around the stationary contacts II and the fingers thereof, then prior to closure of the switch, the ice breaking members I6 may be actuated as heretofore de- .scribed so as to clear the ice away from the stationary contacts. Under extreme conditions, it is possible to leave the members I6 in the full out position shown in Fig. 3 so that as the blade I2 is operated toward the closed position, any ice accumulated on the blade ends may be sheared therefrom by the wedge-shaped elements H. In this case, the members 5 must be allowed to return to the initial position by suitably opening the valve 25 to exhaust the air behind the pistons 2| before completing the final closing movement of the'blade 12.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising relatively movable, cooperating contacts and means for removing ice and the like from said contacts adjacent their engaging portions comprising a member movably mounted adjacent one of said contacts and provided with means movable across said contacts when in the switch closed position and prior to relative movement thereof from said position for breaking ice away from said contacts upon movement of the member, and means for effecting the ice breaking movement of said memher.

2. An electric switch comprising a movably mounted contact and a cooperating stationary contact and means for removing ice and the like from said contacts adjacent their engaging portions comprising a member provided with ice breaking elements and mounted adjacent said stationary contact for movement relatively thereto with said elements movable across said movable contact when in the switch closed'position, and means for effecting the ice breaking movement of said member.

3. An electric switch comprising a movably mounted blade contact, a cooperating stationary jaw contact having a plurality of spaced pairs of opposed contact fingers, and means for breaking ice and the like away from said fingers comprising a member provided with a plurality of spaced wedge-shaped portions and mounted for movement adjacent said jaw contact with said portions slidable in the spaces between the contact fingers on each side of the jaw contact and across said blade contact when in the switch closed position, and means for effecting the movement of said member.

4. An electric switch comprising a rotatably mounted blade contact, a, cooperating stationary jaw contact having a plurality of spaced pairs of opposed contact fingers, and means for removing ice and the like from said contacts adjacent their contacting portions comprising a member movably mounted adjacent said jaw contact and contacts and provided with means for breaking ice away from the contacts upon movement of the member in one direction and for subsequently engaging the other of said contacts to give an initial opening impulse thereto, pneumatic means for eifecting movement of said member in said one direction, and means in which energy is stored during'said movement for eifecting movement of said member in the opposite direction.

6. An electric switch comprising relatively movable cooperating contacts and means for removing ice and the like from said contacts adjacent their engaging portions comprising a reciprocably movable member mounted adjacent one of said contacts and provided with means for breaking. ice way from the contacts upon movement of the member in one direction and for subsequently engaging the other of said contacts to give an initial opening impulse thereto, and means for effecting movement of said member in said one direction.

7. An electric switch comprising a movably mounted blade contact, a stationary jaw contact having a plurality of spaced pairs of opposed contact elements positioned for engagement by one end of said blade contact, and means for breaking ice and the like away from said contact e'le ments comprising a reciprocably movable mem ber mounted adjacent said jaw contact and pro vided with portions slidable in the spaces between the contact elements on each side of the jaw contact and across said blade contact when in the switch closed position upon movement of the member in one direction, pneumatic means for eiitecting movement of said member in said one direction, and resilient means in which energy is stored during said movement for eifecting movement of said member in the opposite direction.

8. An electric switch comprising a movable con- .tact, a cooperating stationary jaw contact, and

HAROLD E. STRANG.

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