US3240887A - Hinge mechanism for high voltage switch - Google Patents

Description

March 15, 1966 o. c. MELBYE HINGE MECHANISM FOR HIGH VOLTAGE SWITCH 3 Sheets-Sheet 1 Filed Nov. 19, 1963 INVENTOR.

Mmh 15, 1966 I o. C. MELBYE 3,240,887

HINGE MECHANISM FOR HIGH VOLTAGEA SWITCH Filed Nov. 19, 1965 3 Sheets-Shea?l 2 I NVEN TOR.

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March 15, 196e o. C. MELBYE 3,240,887

HINGE MECHANSM FOR HIGH VOLTAGE 4SNll'J'C'l- Filed Nov. 19, 1963 3 Sheets-Sheet 3 M 44 A "l .3f 40 74 l EE L 45 5 l L V f2 76' 25 I NVENTOR.

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Irotation relative to one another.

United States Patent() 3,240,887 HINGE MECHANISM FOR HIGH VOLTAGE SWITCH Oswald C. Melbye, Bellwood, lll., assigner to H. K. Porter Company, Inc., Chicago, Ill., a corporation of Delaware Filed Nov. 19, 1963, Ser. No. 324,648 8 Claims. (Cl. 200-48) The present invention relates to high tension electric switch gear, and particularly, to an improved construction for electrical switches.

High tension electric switches customarily have been constructed of `bronze and copper, both of which are relatively high-priced materials particularly when fabricated or forged into switch components. In recent years, utilities have insisted upon more economical, i.e., lowerpriced, switches satisfying their requirements, which has led some manufacturers to cheapen their switch structures or to convert their production to more economical but generally less reliable designs.

It has been suggested that economy could be attained without substantial reduction in reliability by simply constructing switches of tried and true design from aluminum rather than copper and bronze. However, this suggestion has not been carried int-o significant commercial practice because of the difficulty and expense involved in satisfactorily mounting live components of the switches for Specifically, it has been customary to journal relatively rotatable live parts for rotation with respect to one another by bronze or stainless steel 4ball bearings operating in bronze or stainless steel races. Such ball bearings, particularly in outdoor switches subject to atmospheric conditons, e.g., dust, flyash, icing, etc., would dig into and destroy races formed in aluminum parts and in addition would cause excessive corrosion, thereby resulting in early bearing failure. The alternative of installing a complete assembly of stainless steel balls and races at each of the several bearing points in the switch, due to the cost of such assemblies, tends to defeat the initial purpose of the proposal, i.e., cost reduction.

The object of the present invention is to provide an improved and economical construction for electric switches characterized by the combination of relatively rotatable aluminum switch parts, and bearing balls between the parts that are formed of plastic materials which generally are no harder than aluminum and have a low coefficient of friction, such as Delrin.

Tests conducted on the above combination of elements establish that the same is an excellent bearing for both indoor and outdoor use on switches, neither the balls nor the aluminum races are subject to any more Vthan normal wear, the balls tend to digest foreign particles (dust and flyash) falling int-o the bearings whereby the bearings are neither frozen nor rapidly deteriorated by foreign particles, and there is no corrosive or other action 'that would hasten bearing wear. At the same time, the defined combination is completely compatible with economical formation of switch structures from aluminum since the combination is itself economical, facilitates formation of bearing races directly in the aluminum parts, and has a long service life.

However, in actual use, problems are presented relative to appropriate shielding yof the bearings from excessive exposure t-o the elements, corona discharge when the switch is closed and ability to sustain short-circuiting, particularly in the higher capacity switches.

An object of the present invention is to overcome and eliminate these problems by provision of means, suitably in the form of simple annuli, in combination with the described bearing elements.

3,240,887 Patented Mar. 15, 1966 rice A further object of the invention is to utilize the abovedefined bearing means in such manner as to eliminate alternate current paths through the switch and restrict current tiow to the intended or preascertained path or paths.

Other objects and advantages of the invention will become apparent in the following detailed description.

Now, in order to acquaint those skilled in the art with the manner of making and using my improved switch construction, I shall describe, in connection with the accompanying drawings, a conventional switch design in which I have incorporated preferred embodiments of the present invention.

It the drawings:

FIGURE 1 is a side elevation of a known disconnect switch to which the present invention is applicable;

FIGURE 2 is an enlarged side View, partly in section and partly in elevation, of the blade operating mechanism of the switch in its closed position;

FIGURE 3 is a plan View of the blade operating mechanism in switch closed position; and' FIGURES 4, 5 and 6 are end views of said mechanism, taken substantially from the right side of FIGURE 2, and showing the same successively in closed, partially open and full open positions.

The switch illustrated in the drawings is of Well-known commercial design, the same constituting the subject of U.S. Patent 2,527,924 and having been marketed for many years by the assignee of this application and its predecessors. Referring particularly to FIGURE 1, the reference character 10 designates a channel base that is shown for illustrative purposes as mounted horizontally. It will be understood that the vbase 10 can also be mounted vertically and in Van inverted position. Accordingly, the words horizontal and vertica as used in the specication and claims with respect to axes of certain elements of the switch are to be considered to express certain relative positions of the axes with respect to each other since, while the words accurately define the axes which are illustrated in the drawing, the vertica `and horizontal positions might change if the switch were mounted in other than a horizontal position.

The base 10 carries insulators 11, 12 and 13 which are of conventional construction. The insulators 11 and 13 at lthe ends of the base 10 are stationary, while the intermediate insulator 12 is rotatable. For this purpose, a bearing 16 is mounted on the base 10 and constitutes the sole bearing support for the insulator 12. A shank v17 projects below the base 10 and is arranged to receive suitable crank means for rotating they insulator 12.

The insulator 11 'at its upper end carries a terminal `bracket 18 that has a terminal pad 19 formed integrally therewith .to which a terminal connector may be secured. Mounted on the terminal bracket 18 is a generally U- shaped stationary contact assembly 21 providing small area high pressure contact engaging surfaces.

At its upper end, the insulator 13 carries a frame support 25 that has a terminal pad 26 for -receiving a terminal connector. The support 25 carries a U-shaped contact assembly '28 (FIGURES 26) which like the contact 21 provides small area high pressure contact surfaces.

The two U-shaped contacts 21 and 28 are interconnected in the switch closed position by a tubular switch blade 31, the ends of which are deformed to define beaver tail or oblong end portions 32 which at their sides provides small area surfaces that cooperate with the corresponding contact surfaces of the legs of the contacts 21 and 28.

The switch blade 31 is carried by a blade carriage 40 Athat is rotatably mounted in a blade hinge 44 which in turn is mounted by Ibolts 45 on the frame support 25 to rotate about a horizontal axis through the longitudinal axes of the bolts.

In order .to rotate the blade 31 about its longitudinal 'axis in the blade hinge 44 and also to swing the switch blade 31 to a vertical switch open position, the blade carriage 40 -is provided with an arm or shaft 46 that extends angularly away from the longitudinal axis of the switch blade 31. As illustrated more clearly in FIGURE 2, the arm or shaft 46 extends at an angle from the blade carriage 40 and is journalled in a sleeve or bearing 48 of a crank pin 49 that is secured to the rotatable insulator 12 and rotates therewith when the same is turned.

When the insulator 12 is rotated from the position shown in FIGURES 1-4 to the position shown in FIG- URE 5, the switch blade 31 will initially be rotated about its longitudinal axis to relieve the pressure between the blade surfaces 32 and the stationary contacts 21 and 23. Substantially simultaneously, rotation of the insulator 12 and crank pin 49 causes the switch blade 31 in swing about `the horizontal axis through the bolts 45. As the insulator 12 continues to rotate through a total arc of about 105 degrees, the blade hinge 44 guides the switch blade in its arcuate swinging movement from the switch closed position shown in FIGURES 1-4 to a vertical switch open position shown in FIGURE 6.

Since the blade carriage 40 is fastened to the blade 31 and its arm or shaft 46 is rotatably mounted in the bearing or sleeve portion 4S of the crank 49, rotation of the insulator 12 about its vertical axis causes the crank 49 to rotate about this vertical axis and, initially, switch blade 31 to rotate principally about its longitudinal axis and thereafter principally about the horizontal axis defined by the bolts 45.

When the insulator 12 is rotated in the reverse direction, the switch blade 31 is swung to the switch closed position. At the same time, the switch blade 31 is rotated about its longitudinal axis, its final rotation about this axis taking place as it approaches the horizontal position so that the nal movement thereof into high pressure engagement with the contacts 21 and 28 takes place while there is only a small amount of arcuate movement. This permits the necessary torque to be transmitted through the switch 'blade 31 for rotating it into the switch closed position with the contact surfaces under high pressure.

According to the present invention, the principal components of said switch may be fabricated of aluminum and/or of aluminum alloys, especially ythe switch blade 31, the blade carriage 40, the blade hinge 44 and the crank 49; the blade suitably being7 standard tubular stock and the carriage, hinge and crank comprising castings. The carriage 40 includes a forwardly projecting hollow horizontal shaft 50 within which the blade 31 is secured, said shaft portion in turn extending axially through a sleeve portion 52 of the :blade hinge 44. At the rearward end of the sleeve 52, the shaft 50 includes a peripheral wall and an adjacent radial shoulder which define an inner bearing race 54 directly on the aluminum material of the blade carriage. The sleeve portion 52 includes a rearwardly and outwardly inclined surface S6 opposed to said race 54- and comprising a cooperative outer bearing race, which is formed directly on the aluminum material of the blade hinge. Defined between the races 54 and 56 to serve the dual function of thrust and journal bearings is an annular series of bearing -balls 58. In accordance with the present invention, said balls are formed of a suitable plastic material, one of which s Delrin. Delrin is a trademark owned and used by E. I. du Pont de Nemours & Co., Inc. to identify an acetal resin of its Imanufacture of composition (-OCH2--)n derived by polymerization of formaldehyde. The material has a low coeicient of friction and appears to be softer, or at least no harder, than aluminum. In combination with the aluminum races 54 and 56, it provides a very eiicient bearing of low cost and long service life.

Adjacent the front of the shaft 56 a similar bearing is provided by a forwardly and outwardly inclined race surface 66 on the sleeve 52, `an annular series of plastic bearing balls 68 and an inner race 64 defined 'by a peripheral surface on the shaft 50 and the inner radial end surface of a retainer ring 69 threaded on the shaft 50 and confining the bearing assemblies.

The bearing balls 58 and 68 are effective insulators and therefore insulate the hinge 44 from .the carriage 40 and the switch blade 31. However, in the absence of preventative means, arcing or a corona discharge would normally occur under load between opposing sharp edges of the hinge and carriage. To mitigate arcing, I further insulate the hinge from the carriage 'by means of an insulating annulus 70 bridging between the shaft and the sleeve at each end of the sleeve. Each annulus is suitably a thin annular disc of material having insulating and non-moisture absorbing characteristics, such as Bakelite or a similar phenolic resin. Each disc 70 is loosely confined against a shoulder on the shaft 50 (or a shoulder on the ring 69) and bears on and overlaps the adjacent end of the sleeve 52, and thus serves as a corona shield between the two without interfering with normal bearing action. In addition, the annuli thus also enclose the bearings and thereby shield the same against entry of large particles of foreign matter. The bearings consequently are subject to only very small particles of dust and flyash, which are readily digested by the balls SS and 63, especially when formed of Delrin, and cause no deleterious effect on the bearings. Also, due to the materials of construction employed, the bearing surfaces are not subject to excessive corrosion even though water may gain entry to the space 'between the shaft and sleeve and freeze therein.

Further in accord with the present invention, the diagonal shaft or arm 46 of the carriage 40 and the bearing sleeve 48 of the crank 49 are rotatively connected together by a pair of bearings identical to those described above (as in manifest from FIGURE 2) with the single exception that conductive annuli 70a are provided in place of the insulating annuli 70.

The reasons for employing conductive annuli 70a at this location are that the members 40 and 49 do not constitute an alternate current path between the blade 31 and contact 28, the annuli thus are not required to sustain short-circuiting loads, a conductive path is established thereby to prevent isolation of the crank 49 between the stack 12 and the insulating balls of the bearing assembly, and the conductive annuli prevent corona discharge between the members 40 and 49. For these reasons, and to shield the bearings from excessive exposure to the elements, the annuli 70a are preferably thin aluminum discs.

In addition, I prefer to construct the bearing 16 in essentially the same manner as above described. Since this bearing is disposed vertically, only the upper end need be shielded, preferably by a conductive annulus.

In view of the foregoing description, it is to be appreciated that the insulating bearing balls 58 and 68 and the insulating annuli 70 effectively insulate the blade hinge 44 from the blade 31 and the blade carriage 40, whereby the only available path of current fiow between the frame 25 and the blade 31 is directly through the points of small area high pressure engagement of the legs of the contact 28 with the adjacent beaver tail end 32 of the blade. This is a highly advantageous result.

In smaller switches which do not incorporate blade counterbalancing means, isolation of the blade hinge 44 (and existence of corona problems inherent in isolation) are prevented by electrically connecting the hinge to the frame 2S, suitably by means of conductive hinge pins or bolts 45. In larger switches incorporating counterbalance means, the counterbalance is conventionally connected, physically and conductively, between the frame 25 and the hinge 44 so that the latter is not isolated, and in such case extraneous current paths are preferably eliminated by insulating the hinge pins from one or both of members 25 and 44, as by means of insulating bushing sleeves between the bolts 45 and the hinge 44. This further mitigatesA alternate current paths between the blade and the frame, pre-establishes only desired electrically conductive connections, and restricts current ow to the high pressure small area transfer points defined by the contact 28.

If desired, insulating means such as the above-described hinge pins bushings can be utilized between hinge 44 and all of the mechanical operating or supporting components connected thereto, provided a conductive path is defined between the hinge and the frame. A contact connected to the frame and riding on or connected to the hinge would provide such path and aord the advantage of pre-establishmen-t of the conductive connection in a desired size at a desired location for attainment of specific results.

Consequently, in the closed position of the switch as shown in FIGURES l-4, none of the switch elements are isolated yet there is only a single path of current flow possible through the switch, namely, from terminal pad 26 through frame 25, contact assembly 28, blade 31, contact assembly 21 and bracket 18 to terminal pad 19. In normal use, and particularly in outdoor installations wherein the switch is fully exposed to the elements, e.g., sleet and icing, the switch is completely reliable and satisfies all requirements for mitigation of corona discharge and radio interference. Under short-circuit testing, the switch fully satisfies all industry requirements. Specifically, a 400 ampere switch has a momentary cycle) current rating of 20,000 amperes R.M.S. (root means square) and a four second rating of 12,500 amps R.M.S. A 1200 ampere switch has a momentary rating of 61,000 amps R.M.S., and a four second rating of 38,500 amps R.M.S. Even under the severe short-circuiting load of the 1200 ampere switch, the present invention has provided an economical all-aluminum switch fully satisfying all industrial requirements without any damage to the switch or its components. It is thus apparent that this invention renders aluminum switch gear commercially practical and highly advantageous.

However, there is one further consideration required, particularly in the illustrated switch structure, and that concerns the fact that when the switch is open, the blade 31 is separated from both sets `of contacts 21 and 28 leaving the blade 31 and carriage 40isolated. To eliminate this disadvantage, and yet obtain the objectives above stated, I have provided cooperative cam and spring contact means for electrically connecting the carriage 40 and blade 31 to the frame 25 when, but only when, the blade is separated from contact assembly 28.

As shown particularly in FIGURES 3-6, the carriage 40 is provided immediately to the rear of the annular bearing portion 52 of the hinge 44 with a radial ange 72, which pursuant to this invention is aligned with and centered on the pivot axis of the hinge 44 as defined by the bolts 45. Further in accord with this invention, the periphery of said flange is formed to dene a radially projecting cam surface 74 of somewhat more than 180 degrees in arcuate extent. For cooperation with the cam, I provide a simple leaf spring contact 76 which is bolted to the frame 25 and projects horizontally inward therefrom to adjacent the cam 74, the end portion of the contact intersecting the pivot axis of the hinge.

In the closed position of the switch, the rotational position of the cam 74 is such that the same is spaced circumferentially from the contact 76 as shown in FIG- URES 3 and 4. Upon switch opening movement of the insulator stack 12 and the crank arm 49, the initial movement of the carriage 44 and blade 31 is predominantly rotary movement about the blade axis, whereupon the beaver tail 32 is rotated or twisted out of engagement with the contact 28 and the cam 74 is substantially simultaneously engaged with the contact 76, as shown in FIG- URE 5.

As described in said Patent 2,527,924, the axis of the blade 31, the pivot axis formed by the bolts 45 and the axis of the carriage arm 46 all preferably intersect substantially in a point. By making this point also the center of the arc -of the cam 74, the cam will always be positioned in the plane of the hinge axis, as is the contact 76, irrespective of the position of the blade. Thus, the contact 76 remains in engagement with the cam 74 throughout the full extent of arcuate movement of the blade and engages said cam in the vertical full open position of the blade, as shown in FIGURE 6. Consequently, the blade and its carriage are never isolated from the frame 25 and terminal pad 26.

Upon closing of the switch, a reverse sequence of movements takes place, and just as the beaver tail 32 is twisted into the contact 28 the cam 74 leaves the contact 76 to again restrict current flow to the single intended path.

In the closed position of the switch, the spring contact 76 preferably engages the portion 52 of the hinge 44, whereby to prevent isolation of the hinge.

From the foregoing, vit will be appreciated that the present invention provides an extremely economical and practical switch construction facilitating economical fabrication -of proven switch designs from aluminum without dctracting from the reliability of the switch. Consequently, the objects and advantages of this invention have been shown herein to be attained in a convenient, economical and practical manner.

While I have shown and described what I regard to be the preferred embodiments of my improved switch construction, it is to be appreciated that various changes, rearrangements, and modifications may be made therein without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. In electric switch gear, the combination of relatively rotatable aluminum parts comprising a shaft and a sleeve, an annular series of plastic Ibear-ing'balls between said parts journalling one on the other, and an -annulus extending between said parts physically shieldingsaid balls and electrically shielding said part-s from corona discharge therebetween.

2. In electric switch gear having a shaft member and a relatively rotatable sleeve member encircling the shaft member and spaced radially therefrom, the improvement characterized in that the two members are electric conductors and are rotatably mounted relative to one another by insulating bearing means disposed between said members, and that an insulating aunulus extends between said membersin shielding relation to bearing means.

3. In electric switch gear, an aluminum sleeve, an aluminum shaft extending freely through said sleeve and rotatable relative thereto, an annular series of Delrin bearing balls between said shaft and said sleeve adjacent each end of said sleeve for journalling said shaft in said sleeve, and an insulating annulus bridging between said shaft and said sleeve at each end of said sleeve in enclosing and shielding relation to said balls.

4. In electric switch gear having a pair of spaced contacts and a blade mounted adjacent one of said cont-acts and movable toward and away from said contacts between switch closed and switch open positions, a hinge mechanism for said blade including a frame, said one contact being mounted on and electrically connected to said frame and the other contact being spaced from said frame, hinge means mounting said blade on said frame for movement into and out of engagement with said contacts, means insulating said blade from said hinge means for restricting current ilow between said blade and said frame to the path deined by said one Contact when the blade engages said contacts, an auxiliary cont-act mounted on and electrically connected to said frame, said auxiliary contact extending from said frame toward said blade and being spaced therefrom when the Iblade engages said one contact and means on said blade movable into engagement with said auxiliary contact when said blade is moved out of engagement with said one contact for electrically connecting said blade to said frame to prevent electrical isolation of said blade and maintain the same at the potential of said frame and said one contact.

5. In electric switch gear having rotatable and swingable switch blade means, a frame for supporting the blade means, contact means on said frame, and means mounting the blade means n the frame for rotary movement into and out of high pressure engagement with the contact means and for swinging movement toward and away from the contact means; the improvement comprising means insulating the blade means from its mounting means for restricting current ow to the blade means to the path defined by the contact means when the blade means engages the contact means, cam means on the blade means rotatable and swingable therewith, and an auxiliary contact on the frame extending toward said cam means, said cam means being spaced from said auxiliary contact when the blade means engages the contact means and being rotated into and being retained in engagement with said auxiliary contact when the blade means is disengaged from the contact means.

6. In electric switch gear having a conductive frame, a conductive blade hinge pivoted on said frame, a conductive blade carriage journalled in said hinge, a conductive blade secured in said carriage, a contact on said frame for enga-gement by said blade, and means connected to said carriage for rotating and swinging said blade into and out of engagement with said contact; the improvement comprising insulating bearing means between said carriage and said hinge restricting the current path between the blade and the frame to the path of the contact when the blade engages the contact, a cam on said carriage adjacent said frame, and an a-uxiliary cont-act extending from said frame toward said sam and spaced from said cam when the blade engages the contact, said cam being rotated into engagement and being retained in engagement with said auxiliary contact when the blade is disengaged from the contact to prevent isolation of the blade and carriage.

7. In electric switch gear having a conductive frame, a conductive blade hinge pivoted on said frame, a conductive blade carriage journalled in said hinge, a conductive blade secured in said carriage, a contact on said frame for engagement by said blade, and a crank journalled on said carriage for rotating and swinging the blade into and out of engagement with said contact; the improvement comprising insulating bearing means between said carriage and said hinge, insulating shields for said bearing means extending between said carriage and said hinge, means electrically connecting said frame and said hinge, a cam on said carriage rotatable therewith, an auxiliary contact on said frame extending to adjacent said cam and spaced therefrom when the blade engages the Contact, said cam being rotated into and retained in engagement with said auxiliary contact when said blade is disengaged from the contact, insulating bearing means between said carriage and said crank, and conductive shields for the latter bearing means extending between said carriage and said crank.

8. An electric switch comprising an aluminum frame, an aluminum blade hinge pivoted on said frame, means electrically connected said frame and said hinge, an aluminum blade carriage, plastic bearing balls journalling said carriage on said hinge and insulating the carriage from the hinge, insulating shields for said bearing balls extending between said carriage and said hinge, an aluminum blade secured in said carriage, a contact on said frame for engagement by said blade, means for rotating and swinging said carriage to move said blade into and out of engagement with said contact, a 4cam on said carriage rotatable therewith, and an auxiliary contact on said frame extending to adjacent said ycam and spaced therefrom when the blade engages the first-named contact, said cam being rotated into and retained in engagement with said auxiliary contact when said blade is disengaged from the rst-named contact.

References Cited by the Examiner UNITED STATES PATENTS l/1963 Field 200-48 1/1965 Gorman et al 20G-148

Claims (1)

1. 3. IN ELECTRIC SWITCH GEAR, AN ALUMINUM SLEEVE, AN ALUMINUM SHAFT EXTENDING FREELY THROUGH SAID SLEEVE AND ROTATABLE RELATIVE THERETO, AN ANNULAR SERIES OF DELRIN BEARING BALLS BETWEEN SAID SHAFT AND SAID SLEEVE ADJACENT EACH END OF SAID SLEEVE FOR JOURNALLING SAID SHAFT IN SAID SLEEVE, AND AN INSULATING ANNULUS BRIDGING BETWEEN SAID SHAFT AND SAID SLEEVE AT EACH END OF SAID SLEEVE IN ENCLOSING AND SHIELDING RELATION TO SAID BALLS.

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