US3005063A

US3005063A - Self-aligning switch

Info

Publication number: US3005063A
Application number: US796029A
Authority: US
Inventors: Carl G Zemels; Thomas B Ortwig
Original assignee: James R Kearney Corp
Current assignee: James R Kearney Corp
Priority date: 1959-02-27
Filing date: 1959-02-27
Publication date: 1961-10-17
Anticipated expiration: 1978-10-17

Description

Oct. 17, 1961 c. e. ZEMELS EI'AL 3,005,063

SELF-ALIGNING' SWITCH Filed Feb. 27, 1959 4 Sheets-Sheet 1 Oct. 17, 1961 c. G. ZEMELS ETAL 3,005,063

SELF-ALIGNING' SWITCH 4 Sheets-Sheet 2 Filed Feb. 27, 1959 NOE nvnewrwes. 6'41?! 6. ZM6Z5 filo/ 105 3, den

SM LXMJ wywu a u a Oct. 17, 1961 Filed Feb. 27, 1959 C. G. ZEMELS EI'AL SELF-ALIGNINGi SWITCH 4 Sheets-Sheet 3 United States Patent 3,005,063 SELF-ALIGNING SWITCH Carl G. Zemels, illayton, and Thomas B. Ortwrg, Florissani, l t '10., assignors to James R. Kearney Corporation, St. Louis, M0., a corporation of Delaware Filed Feb. 27, 1959, Ser. No. 796,029 8 Claims. (Cl. 200-48) This invention concerns high-voltage, high-current electrical switches, and particularly those of the type in which a rotary switch blade mounted on an insulator can swing into and out of contact with a contact structure mounted on another insulator.

it has been found that in the practical use of rotary blade type switches, the base on which the insulators are mounted often becomes bent or twisted, or both, during installation or use. This type of damage can occur either through mechanical abuse during handling or through warpage of the wood of the crossarms on which the switch is installed. The deformation is usually so slight that it is hard to detect in and of itself, but due to the lever arm formed by the insulators and the blade, it can easily result in a substantial misalignment of the blade tip with respect to the contact structure. If this misalignment is sufficiently great, the blade may engage only one of the contact jaws, or it may still engage both contact jaws, out the quality of current transfer will be substantially reduced by a change from line-contact to point-contact due to twist in the base, and/or by a considerable difference in the contact pressure due to bending of the base. With such greatly lowered quality of current transfer, the switch will overheat and eventually be destroyed.

Another difficulty in the use of ordinary rotary-blade switches is caused by the accumulation of ice between the contact jaws under severe weather conditions. Removal of the ice by a mere shearing motion of the blade between the contacts is feasible but this technique requires strength and imposes an undesirable mechanical strain on the operating linkages in three-phase banks.

The switch of our invention is designed to overcome these difiiculties by mounting the switch blade for limited omnidirectional movement, so as to automatically compensate for any misalignment, and by providing a novel contact structure, the effect of which is to break off any ice accumulated on the contacts by a hinge-like rotary motion which requires considerably less force than was previously necessary. At the same time, the hinge-like motion results in improved wiping of the switch blade against the contact jaws.

It is, therefore, an object of our invention to provide a switch which is capable of self-alignment within predeterminable limits.

It is a further object of our invention to provide a rotatable contact structure having improved ice-breaking properties and an improved contact wiping action.

It is a still further object of our invention to provide an efiicient and rugged side-break switch having only two supporting insulators.

We will now describe a preferred embodiment of our invention, reference being had to the drawings'in which:

FIGURE 1 is a side elevation of the switch, of our. invention;

FIGURE 2 is a plan view of the switch in its closed position;

FIGURE 3 is a plan view of the switch in partly open position;

FIGURE 4 is a section along line 4-4 of FIGURE 1 showing the contact structure and arcing horns;

FIGURE 5 is a vertical section through the rear insulator along line 5-5 of FIGURE 1;

FIGURE 6 is a vertical section through the contact structure along line 6-6 of FIGURE 2;

FIGURE 7 is a detail plan view of the operating mechanism;

FIGURE 8 is a horizontal section along line 8-8 of FIG. 6; and

FIGURE 9 is a perspective cut-away view of the universal bearing.

Generally our switch consists of a pair of insulators mounted on a base. One of the insulators is rotatable and carries at its top a switch blade which rotates with the insulator into and out of contact with a contact structure mounted on the second fixed insulator. The switch blade is journalled for limited motion in a universal. bearing, and the blade terminal is so mounted on the top of the rotary insulator that it does not rotate with the insulator and blade.

The contact structure consists of a pair of flared jaws which are rotatably mounted on the top of the fixed insulator, and which are spring-biased together at a point between their axis of rotation and the switch blade for a reason hereafter explained. Conventional arcing horns are provided to prevent formation of an are between the switch blade and the contact structure during the opening movement of the switch blade.

Electrical contact between the blade terminal and the blade is established through the universal hearing by highly machined circular contact surfaces which are subjected to a moderate compressive force. In the case of the bearing allowing vertical motion of the blade; this force is the result of tightening the bolts on the bearing shaft to the desired tightness; in the bearing allowing axial rotation of the switch blade, and in the hearing which connects the blade terminal assembly to the rear insulator assembly, a spring washer and a coil spring respectively, are used to urge the circular contact surfaces together. Provisions are made in the design of the parts of the universal bearing for limiting the movement of the switch blade with respect to its mounting structure, so as to prevent any over-compensation which might result in failure of the blade to engage the contacts during the closing motion.

The contact supporting plate is likewise equipped with a pair of current transfer rings against which matching surfaces of contact pieces are urged by a spring. Because of the fact that when the switch blade engages the contacts, it tends to force the contact pieces apart and thus to make them non-parallel, the spring which urges the contact pieces together is located eccentrically of the current transfer rings. Thus the pressure of the spring compensates for the spreading of the jaws by the blade and results in holding the contact pieces parallel. This arrangement assures intimate contact between the current transfer rings on the contact pieces and those on the contact supporting blade over the entire area of the current transfer rings. A tie bolt tying the contact jaw pieces together is also provided to prevent one of the contact jaws from becoming spaced from the switch blade when a sudden magnetic force, such as may be engendered by a fault current, suddenly forces the switch blade sharply against the other contact jaw.

Referring now to the drawings, switch 10 is mounted on abuse 12, which in turn may be attached to a crossarm' or other suitable mounting surface (not shown). Mounted near the rear end of base 12 (the left end in FIGURE 1') is a rotatable insulator 14 which can be turned by pulling operating handle 16. The operating handle 16 is limited in its movement by adjustable stop screws 20 threaded into brackets 18. A terminal member 22 is mounted on the top of insulator 14 in such a manner that it can rotate about shaft 24. Electrical contact is established between member 22 and the blade support 26, which is'fixedly 3 attached to insulator '14, by highly machined circular contact surfaces 25, 27 (FIG. 5) which are pressed together by a coil spring 28. The

contact surfaces

25, 27 are protected from the weather'by a fiexible'sleeve 232:. In use, the terminal member 22 is held in a' fixedposition with respect to base 12 by the line wire (not shown) attached to it.

Since the line wiremay be quite heavy in some installations, the upper contact surface is not quite flat, but very slightly convex (shown in grossly exaggerated form in FIGURE 5), so that an excessive weighthanging from terminal member 22 will cause a rocking motion of its extremity 23 resulting in a shifting of the contact line between

surfaces

25 and 27 toward the outside of the circle. At the some time,the rocking of member 22 may cause the

surfaces

25 and 27 to separate minutely at a location diametrically opposite the terminal 21. H ws,oob,oes

ever, the excess pressure resulting from the'excessive weight will compensate for the loss of contact area between

surfaces

25 and 27, so that the total current-carrying capacity of the

bearing

25, 27 will not be impaired. If it were not for the convexity of surface 25, rocking of member 22 would result in a contact only at theoutward edge of the contact circle, where not as as much clean contact area would be available.

Blade support 26 terminates in a pair of ears 36 which are traversed by a horizontal shaft 32 on which an intermediate member 38 is journalled for rotation about shaft 32 in a clockwise or counter-clockwise direction as seen in FIGURES 1 and 9. Movement of the switch blade about its own axis is permitted by a second shaft 34'forming part of blade holder 36, which is journalled in a longitudinal bore 33 of intermediate member 38. The shaft 34 has a hole 35 formed therein. The hole 35 is slightly larger than the shaft 32 which extends therethrough, so that shaft 34 can be rotated through an arc of about six degrees at either end of which an edge of he hole 35 will strike the shaft 32 to prevent further rotation of shaft 34.

Rotation of the intermediate. member 38 about shaft 32 is limited bya pin 37 mounted on an extension 39 of intermediate member 38. The pin 37 can move back and forth between cars 41 of bladesupport 26. Compressive pressure is exerted on high conductivity contact rings 31a by tightening bolt 27, and on contact rings 31b by the spring washer 29 (FIG. 9). For optimum operation of the switch, the pressure on each bearing should by the smallestpressure which will allow sufiicient current transfer through the. highly machined contact rings 31a and 31b. Blade holder 36 is equipped with a cradle 49 in which the switch blade 5-2 is firmly held by a pair of U-bolts 44 (HG. l). Rotation of blade 42 with respect to cradle is prevented by a pin 43 which extends through blade 42 and engages a slot 45 (FIG. 9) in the bottom of cradle 40. This slot is sufficiently long to permit enough longitudinal movement of blade 42 to allow proper positioning of blade 42 after installation by merely loosening U-bolts 44 and moving blade 42 forward or backward as necessary.

It will be seen from the foregoing that blade 42 is in effect universally journalled with respect to blade support 26. The blade 42 terminates at its forward end in a flat paddle-like silver-plated tip 46.-An arcing rod is attached to the blade 42 by a bracket 59, and during opening movement of the switch, the forward top portion of the arcing rod 48 engages arcing horns 52 and 54 which are mounted on supporting plate 69, and hence electrically connected to forward terminal 56, until after the main contacts have opened.

Contact terminal 56 is attached to the fixed insulator 58 mounted on the forward end of base 12, by a supporting plate 69. A contact bearing plate 62 is firmly attached to the supporting plate 6! The contact bearing plate 62 carries near its rear (i.e., right in FIG. 6) extremity a pair of highly machined high conductivity current trans- .fer. rings 61'which match corresponding rings 63 on the forward extremities of cont-act pieces 67 and 69. A

' of slot 65 limits the rotation of the contacts to about thirty degrees in our preferredembodiment. The purpose of protuberances 75 is to increase the length of the bores 73, into which bolt 71 is snugly fitted, so as to give bolt 71 greater leverage in maintaining contact pieces 67 and 69 parallel. A pair of springs 72 surround the ends of bolt 71 and the protuberances 75 for the purpose of urging the

jaws

66, 68 together with the required contact pressure which, in our preferred embodiment, is about ninety pounds. Collars 74a coacting with washers 74b are provided to prevent excessive compression of the springs 72 when nuts 74c of bolt 71 are tightened. Inasmuch as the springs 72 are eccentrically located with respect to shaft 70, their pressure compensates for the stress caused by theblade tip 46 being inserted between the

jaws

66, 68. This stress would normally tend to render contact pieces 67, 69 nonparallel, but because of the springs 72 optimum parallelism is achieved when the blade tip 46 is in position between

jaws

66, 68 so that the maximum current transfer capacity of

rings

61, 63 will be utilized.

A bolt 77 is further provided rearwardly of the bolt 71 for the purpose of preventing the

jaws

66, 68 from becoming separated any farther than necessary to admit blade tip 46. Consequently, the magnetic field set up by a sudden current surge will be unable to push tip 46 so hard against one of the. jaws that the contact with the other jaw becomesmomentarily broken, a condition which would result in a destructive are between the tip 46 and the other jaw. The contact structure is protected from the weather by a hood 64 attached to the forward end of upper contact niece 69 by a bolt 33 having a spacer portion 85 and cooperating with a

lock nut assembly

86, 87. A pin 79 engages an aperture 81 in the central portion of. contact piece 69 and causes the hood 64to rotate with thecontact structure.

In operation, when the switch 16 is opened, the blade tip 46 will draw with itthe contact structure so as to rotate it about shaft 70 in a counterclockwise direction in FIGURES 2 and 3. .When the contact structure has rotated far enough that the end of the blade tip 46 comes free of the

jaws

66, 68, the rotary movement of the contact structure will cease, while the opening motion of the blade 42 continues. The. electrical contact between the

terminals

22 and 56 will be broken as soon as'the arcing rod 48 comes free'of the arcing horns 52 and 54in the course of the opening movement of the blade 42.

During the'closing'movemcnt, the blade-tip 46 slides between the

jaws

66 and 68 and rotates them back in a clockwise direction in FIGURES 2 and 3 by means of the friction between the jaws and the blade tip. It will be readily seen that a hinge-like motion occurs between the blade tip 46 and the

jaws

66, 68 at the beginning of the opening movement. This hinge-like motion is very effective in breaking any ice which may have accumulated between the jaws and the blade tip. An improved wiping action is also provided by this type of motion. 1

The

jaws

66, 68 are flared so as to guide blade tip 46 into position regardless of any misalignment. Hooks 78 and 84 (FIG. 4) are provided on the upper jaw 68 for engagement with the

edges

76 and 82 respectively, of the blade tip 46 in the event that, due to some misadjustment, the force necessary to turn the contact structure should become greater than the frictional force between the blade tip and the jaws, so that friction alone would'be insufficient to turn the contact structure.

It will be seen that we have provided an extremely simple and effective self-aligning side-break switch for high-current and high-voltage operation, It will be readily seen that numerous embodiments of our invention are possible, and we therefore do not desire to be limited except by the scope of the following claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. An electrical switch having a plurality of insulators, one of said insulators being movable, a switch blade mounted on one of said insulators for movement into and out of contact with a contact structure mounted on another of said insulators, said switch blade being journalled for limited rotation about a pair of axes perpendicular to each other and situated substantially in the plane of said movement into and out of contact with said contact and separate pairs of relatively movable contact surfaces on each of said pair of axes to form an electrically conductive path around the journals for said switch blade.

2. An electrical switch having a plurality of insulators, a switch blade mounted on one of said insulators for movement into and out of contact with a contact structure mounted on another of said insulators, said contact structure comprising -a pair of contact members mounted for rotation and adapted to receive said switch blade between them, a pivot means for said contact members including springs mounted thereon for biasing said contact members toward one another to grip said switch blade, and means spaced from the axis of rotation of said contact members for limiting the gap opening of said contact members.

3. An electrical switch having a plurality of insulators and a base, one of said insulators being movable with respect to said base and supporting a switch blade, said switch blade being mounted on said insulator for movement therewith, and terminal means mechanically mounted on said insulator and electrically connected by said means to said switch blade, said terminal means being mounted for swinging and limited rocking movement with respect to said insulator by rotatable and rockable bearing means between said terminal means and said insulator.

4. An electrical switch having a pair of insulators, a contact on one of said insulators adapted to receive a switch blade moving in a predetermined plane, a movable switch blade adapted to be received by said contact and a mounting for said switch blade on the other insulator adapted to permit movement of said switch blade into and out of engagement with said contact and, into the predetermined plane to be received by said contact, said mounting comprising, means for swinging said switch blade toward and away from said first contact, and means including a pair of journals between said switch blade and said mounting located on axes perpendicular to each other adjacent to, and mounting said blade for, movement into said predetermined plane when received by said contact, means for limiting rotation of said blade on said journal, and means associated with at least one of said journals to predetermine the frictional resistance to movement of said blade on one of said journals independent of the other.

5. The combination as defined in claim 4, in which the last said means includes electric contact surfaces on a member associated with one of said journals.

6. An electrical switch having a pair of insulators, a contact on one of said insulators adapted to receive a switch blade moving in a predetermined plane, a movable switch blade adapted to. be received by said contact, and a mounting for said switch blade on the other insulator adapted to permit movement of said blade into and out of engagement with said contact and, into the predetermined plane to be received by said contact, said mounting comprising, means for swinging said switch blade toward and away from said first contact, means including a pair of journals between said switch blade and said mounting located on axes perpendicular to each other adjacent to, and mounting said blade for, movement into said predetermined plane when received by said contact, means for limiting rotation of said blade on said journals, and means associated with said journals to predetermine the frictional resistance to movement of said blade on said journals and including electric contact surfaces on separate members associated with said journals forming an electrically conductive path around said journals from said switch blade.

7. An electrical switch having a plurality of insulators, a switch blade swingably mounted at one end on one of said insulators for movement of its other end into and out of contact with a contact structure mounted on another of said insulators, said switch blade being journalled at its swingably mounted end for limited rotation about one of a pair of axes perpendicular to each other and situated substantially in the plane of said movement into and out of contact with said contact structure, said switch blade being journalled for swinging movement about the other of said pair of axes, independently operating contact surfaces on each of said pair of axes cooperating to form an electrically conductive path around the journals for said switch blade.

8. An electrical switch having a pair of insulators, a switch blade swingably mounted at one end on one of said insulators for movement of its opposite end into and out of contact with a contact structure mounted on another of said insulators, said switch blade being journalled at its swingably mounted end for limited rotation about one of a pair of axes perpendicular to each other and situated substantially in the plane of said swinging movement into and out of contact with said contact structure, said switch blade being journalled for swinging movement about the other of said pair of axes, independently operating contact surfaces on each of said pair of axes cooperating to form an electrically conductive path around the journals for said switch blade and means for predetermining the frictional resistance to movement about one of said journals.

References Cited in the file of this patent UNITED STATES PATENTS 2,193,122 Crabbs Mar. 12, 1940 2,303,914 Crabbs Dec. 1, 1942 2,709,739 Gilliland et al May 31, 1955 2,780,684 Brown et al. Feb. 5, 1957 2,786,121 Bridges Mar. 19, 1957 2,791,651 Ortwig May 7, 1957