US1973265A - Electric switch - Google Patents

Description

l 1934- c. .1. B. OLSEN El AL 1,973,265

ELECTRIC SWITCH Filed Oct. 6, 1933 fi ji Inventor's: Z9 45 Ooreg JBDISeYL George F Lin 5, bu v I Their Attorney Patented Sept. 11, 1934 ELECTRIC SWITCH Corey J. B. Olsen and George F. Lincks, Pittsfleld, Mass., assignors to General Electric Company, a corporation of New York Application October 6, 1933, Serial No. 692,448

4 Claims. (Cl. 260-116) Our invention relates to electric switches and more particularly to switches combined with fuses which are released from engagement with the switch terminals upon operation of the fuse.

In the protection of overhead outdoor transmission lines, it has become a common practice to combine a fuse with a line switch. For economy and safety, it is desirable to locate the switch and the fuse combined with it near the top of the pole adjacent the transmission line. The manual opening and closing of the switch may be accomplished by a long switch stick with a hook adapted to engage the switch handle. However, examination of the fuse to determine whether or not it has operated, and replacement of the fusible element is hazardous, due to the close proximity of the live switch contact and transmission line. Combined switches and fuses have been provided with an arrangement for automatically opening the switch when the fuse operates. In this manner, the operation of the fuse is clearly indicated without the necessity of a close examination. The automatic opening of the switch has the additional advantage of removing the voltage stress from the fuse holder after the operation of the fuse. While the fuse is intact, there is no voltage stress on the fuse holder. When the fuse has completed its operation before the switch begins to open no arc is drawn between the switch and contact. On the other hand, if the switch does begin to open before the fuse has completed its operation, an arc may be drawn between the switch and contact which will do serious damage to the fuse holder and may require its replacement.

An object of our invention is to provide an improved switch and fuse in which the movable switch member will be securely carried on the lower switch contact during the automatic opening of the switch on operation of the fuse.

What we consider to be novel and our invention will be better understood by reference to the following specification and appended claims when considered in connection with the accompanying drawing in which Fig. 1 is a perspective view of our improved combined switch and fuse; Fig. 2 is a side elevation of the switch with parts broken away to expose the parts beneath; Fig. 3 is a side view of the switch immediately after its automatic operation; and Fig. 4 is a side view of the switch in the open position.

Referring to the drawing, indicates a crossarm secured to a pole, not shown, on which the transmission lines are carried. An insulator 11 is mounted on cross-arm 10 by means of a strap 12 and a-two-part clamp 13. Strap 12 surrounds a reduced central portion of insulator 11 and is secured to one part of clamp 13. Strap 12 is held in engagement with insulator 11 by a bolt 14. The two parts of clamp 13 are bolted together tightly on opposite sides of cross-arm 10 which may vary in thickness, by means of bolts 15. The upper switch contact 16 consists of a copper rod which extends about the upper end of insulator 11 and seats in an annular groove 17. The switch is guided to the contact surface of contact 16 by two flared. ends 18 which form a V between them. Contact 16 is held in engagement with groove 17 by a combined clamp and connector 19. Contact 16 is clamped between two parts 20 and 21 of connector 19 by a stud 22. Stud 22 is provided with a longitudinal slot 23 in which a supply conductor 24 is adapted to be secured by means of a nut 25. Conductor 24 serves to connect switch contact 16 to one of the overhead transmission lines. Lower switch contact 26 is formed of a copper rod which surrounds the lower end of insulator l1 and seats in a groove 27. Contact 26 is held in position on insulator 11 by means of a combined connector and clamp 28 which is similar to connector 19 previously described. The rod forming lower switch contact 26 has its free ends turned inwardly and extending into a sleeve 29 forming a pivot for switch 30. A load conductor 31 is connected to contact 26 by means of connector 28. The formation of the switch contacts and support is not our invention but is the subject of another application Serial No. 692.469, filed concurrently herewith in the name of R. S. Bennett and assigned to the same assignee to which this application is assigned.

Switch is provided with a fuse holder 32 in which a fuse is carried. The upper end of fuse holder-32 is closed by a contact cap 33. Cap 33 has a conical projection 34 which is adapted to be inserted between the two parts of contact 16. The shape of projection 34 is important because when it is wedged between the two parts of contact 16, it opposes rotation of fuse holder 32 and delays the opening of switch 30 upon the operation of the fuse to permit the extinction of the arc in a manner that will be described later. Switch 36 is pivotally mounted on lower switch contact 26 by means of a toggle lever 35 and fuse holder support 36. Lever 35 and support 36 are connected by a pivot pin 37. A fuse link 38 is located in fuse holder 32 and extends through the lower open end of fuse holder 32. Fuse link 38 is connected to lever 35 by means of thumbscrew 39. When the fuse is intact, lever 35 is held in the position indicated in Figs. 1 and 2 by fuse link 38 being tightly drawn and held by thumbscrew 39. In this position, lever 35 is stopped by projection 40 which engages support 36. The upper end of fuse link 38 is connected to a contact button 38' which rests on the top of fuse holder 32 and is secured in position by contact cap 33 as indicated in Fig. 2. While the fuse link 38 is intact, switch 30 be manually opened or closed in the usual manner by a switch stick provided with a hook which is adapted to engage operating handle 41; As switch 30 is moved to the closed position projection 34 engages the flared ends 18 and separates the two parts ofcontact 16 as it moves to the contact surface. Contact 16 is also moved upwardly by engagement with the top of contact cap 33 producing a-spring tension tending to move switch 30 downwardly. Rotation of switch 30 'to the open position is opposed by abutting surfaces adjacent to flared ends 18 and in the path of movement of projection 34. Operating handle 41 is secured to fuse holder 32 adjacent cap 33 by means of a screw 42. To prevent radio interference by static electric discharges between cap 33 and operating handle 41, when switch 30 is in the closed position, a spring wire connector 43 is provided which engages operating handle 41 and cap 33.

Upon the operation of'the fuse, the fuse link 38 is expelled out of the lower end of fuse holder 32 by the gas pressure generated by the arcing in fuse holder 32. In this manner the support for lever 35 is removed. Lever 35 then rotates about sleeve 29 as a pivot. Lateral movement of lever 35 is prevented by two side plates 44 and 45 which are secured to sleeve 29 and switch contact 26. The rotation of lever 35 is stopped by engagement between projections 46 from the sides of lever 35 and end plates 44 and 45. Switch 30 does not immediately open following the operation of the fuse and movement of lever 35 due to the reaction produced by the rapid expulsion of the arc gases from the lower end of the fuse holder 32. Shortly after the movement of lever 35, fuse holder 32 begins longitudinal movement produced by the spring tension of contact 16 in engagement with the top of contact cap 33 and the two parts of contact 16 engaging the conical projection 34, pivoting about pin 3'? which connects lever 35 to support 36. The

longitudinal movement of fuse holder 32 is still opposed by the reaction to the gases being expelled from the lower end of fuse holder 32 but this reaction diminishes rapidly as the arc is extinguished and the expulsion of gases ceases. The position of fuse holder 32 shortly after its initial movement is indicated in Fig. 3. Lever 35 is provided with an opening 4'7 for its removal from switch contact 26. The recoil action of fuse holder 32 while the lever 35 is rotating to the open position tends to lift the lever from sleeve 29 and switch contact 26. The support for switch 30 would then be removed and it would fall to the ground. To prevent the lever from being thus moved out of engagement with sleeve 29, a latch 48 is provided and pivotally connected to fuse holder support 36. Guides 49 and 50 are provided between the two parts of lever 35 between which the latch 48 is adapted 'to pass. Upon the operation of the fuse, the relative movement of lever 35 and fuse holder 36 moves the latch 48 between the guides 49 and 50 tothe position indicated in Fig; 3, latch 48 being held in engagement between guide 49 and sleeve 29. In this position, latch 48 completely closes the opening 47 of lever 35 and thus switch may then be lifted from the switch contact 26 by engagement between the hook of a switch stick and operating handle 41 for replacement of the blown fuse link 38 in fuse holder 32. A strap connecting the two parts of operating handle 41 is indicated in dotted lines in Figs. 2, 3 and 4 by'means of which the hook of the switch stick is adapted to engage switch 30 for its re-v moval, as described above. The provision of operating handle 41 and its arrangement for the manual operation of switch 30 and removal upon automatic operation of the fuse, as well as conical projection cap 33 are not our invention, but are the subject of another application Serial No. 692,414, filed concurrently herewith in the name of B. R. Hermann, and assigned to the same as- ,signee to which this application is assigned.

From the foregoing it will be seen that damage to the fuse holder 32 by jumping of the lever 35 from switch contact 26 as it isautomatically opened is prevented by latch 48. This arrangement is important because it is necessary to provide means'for easy removal of switch 30 after the operation of the fuse for replacement of the fuse and in the provision of this means for easy removal it is highly important to prevent damage to the fuse holder switch by the jumping of the lever 35 from switch contact 26 upon the recoil to the expulsion action of the fuse.

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

1. An electric switch comprising stationary switchcontacts, a fuse holder, a fuse link located in said fuse holder, a fuse holder support, a lever pivoted on one of said switch contacts and having an opening for removal from saidswitch contact, and a latch connected to said fuse holder and adapted to pass over the opening of said lever upon. movement of the lever with respect to the fuse holder support.

2. An electric switch comprising stationary switch contacts, a fuse holder, a fuse link located in said fuse holder, a fuse holder support, a lever mounted on one of said switch contacts and having an opening for removal from said switch contact, and a latch pivotally connected to said fuse holder support and adapted to pass over the opening of said lever upon movement of the lever with respect to the fuse holder support.

3. An electric switch comprising stationary switch contacts, a fuse holder, a fuse link located in said fuse holder, a lever mounted on one of said switch contacts and having an opening for removal from said switch contact, a fuse holder support pivotally connected to said lever, means to connect said fuse link to said lever, and a latch pivotally connected to said fuse holder and adapted to pass over the opening of said lever upon release of the lever by said fuse'link.

4. An electric switch comprising stationary switch contacts, a fuse holder, a fuse link located in said fuse holder, a lever mounted on one of said switch contacts and having an opening for removal from the switch contact, a fuse holder support pivotally connected to said lever, means to hold said lever in the closed position by connection to said fuse link, a latch pivotally con-.

nected to said fuse holder support, and a guide secured to said lever to cause the latch to pass over the opening of the lever on the release of the lever by the fuse link.

COREY J. B. ofsim. GEORGE F. LINCKS.

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