US2832859A - Center break disconnect switch hinge contacts and switch structures employing same - Google Patents

Description

Apnl 29, 1958 w. H. GILLILAND 2,832,859

CENTER BREAK DISCONNECT swrrcu HINGE CONTACTS AND SWITCH STRUCTURES EMPLOYING SAME Filed Feb. 15, 1956 4 Sheets-Sheet 1 INVENTOR WILL/AM H GILL/LA N0 FY w ATTORNEYS Aprll 29, 1958 w, GlLLlLAND 2,832,859

CENTER BREAK DISCONNECT SWITCH HINGE CONTACTS AND SWITCH STRUCTURES EMPLOYING SAME Filed Feb. 15, 1956 4 Sheets-Sheet 2 INVENTOR WALL/AM H. 0/ LL ILA N0 ATTORNEYS April 29, 1958 w. H. GILLILAND CENTER BREAK DISCONNECT swncn HINGE CONTACTS AND SWITCH STRUCTURES; EMPLOYING SAME 4 Sheets-Sheet 3 Filed Feb. 15, 1956 INVENTOR WILL/AM H. GILL/LA N0 ATTORNEYS .GILLILAND April 29, 1958 w, 2,832,859

CENTER BREAK DISCONNECT SWITCH HINGE CONTACTS AND SWITCH STRUCTURES EMPLOYING SAME 4 Sheets-Sheet 4 Filed Feb. 15, 1956 Un-U ilbl INVENTOR WILL/AM hi GILL/LAND BY JM, mm

ATTORNEY United States Patent O CENTER BREAK DISCONNECT SWITCH HINGE CONTACTS AND SWITCH STRUCTURES EM- PLOYING SAL IE William H. Gilliland, Birmingham, Ala., assignor to USCO Power Equipment Corporation, Birmingham, Ala., a corporation of Alabama Application February 15, 1956, Serial No. 565,649

7 Claims. (Cl. 200-48) This invention relates to improved center break disconnect switches having shuntless hinge end contact assemblies and more particularly to improved shuntless hinge end contacts therefor.

While shuntless center break disconnect switches have been previously proposed as will appear from a consideration of United States Letters Patent 2,227,925, issued January 7, 1941, to E. S. Cornell et al., 2,359,055, issued September 26, 1954, to A. C. Schwagger et al., and 2,660,631, issued November 24, 1953, to H. R. Harrison, these prior art structures have not been entirely satisfactory because of their limited current carrying capacity, lack of flexibility in meeting field conditions rcquin'ng varying contact pressures, their relatively high cost and failure to provide rugged, long life current carrying contacts.

It, accordingly, is a primary object of this invention to provide a new and novel shuntless center break disconnect switch structure for maintaining a good electrical connection between the opposed stationary line terminals and their respective relatively horizontally swingable, center break switch blades.

Another object of this invention is to provide a center break disconnect switch with a new and novel shuntless hinge connection which is extremely simple yet rugged and inexpensive to manufacture.

Still another object of the present invention resides in the provision of a shuntless, hinge end center break disconnect switch contact structure comprising a rotatably mounted insulator stack rigidly supporting the hinge end of a horizontally swingable blade having opposed laterally spaced contact shoes straddling the hinge axis and a relatively stationary line terminal having a generally cylindrical hub coaxially related to the hinge axis and disposed between and in electrical contact with the laterally spaced shoes along diametrically opposed contact areas.

A further object of the present invention resides in providing the generally cylindrical hub of the preceding object with peripherally spaced, axially extending grooves the opposed edges of which scrapingly cooperate with i the contact areas of the laterally opposed shoes during opening and closing movement of the swingable blade to remove foreign matter and oxide from the contact surfaces of the shoes.

Another object of the present invention resides in providing a center break disconnect switch having a swingable blade with laterally opposed, hinge end contact shoes with a relatively stationaiily mounted line terminal conhector in the form of a generally cylindrical hub having an integrally formed, radially extending connector arm at one end and a centered axially extending bore adapting the line terminal connector for invertible mounting between the laterally opposed, hinge end contact shoes.

A further object of the present invention resides in providing a rotatable insulator stack having an upwardly protruding shaft portion for relatively rotatably supportng inwardly of its upper end a normally stationary line 2,832,859 Patented Apr. 29, 1958 terminal connector with a stack supported switch blade and an upwardly extending brace arm rigidly connected at one end to the switch blade and apertured at its other end to receive the upper end of the protruding shaft and resist the cantilever forces acting on the switch blade.

Further objects will appear from the following description and appended claims when read in conjunction with the attached drawings wherein:

Figure 1 is a view in side elevation of a switch containing the contact assembly of this invention;

Figure 2 is a side view in elevation of the hinge assembly with parts broken away;

Figure 3 is a plan view of the assembly, with par-ts broken away;

Figure 4 is a side view of a modified form of the hinge assembly with parts in section and parts broken away;

Figure 5 is a plan view of the modification of Figure 4 with parts broken away;

Figure 6 is a top sectional view of the surface of the cylinder of Figure 4 taken on line 6-6 of Figure 4;

Figure 7 is an end view of the assembly of Figure 4;

Figure 8 is a side view of a further modified form of the assembly and with parts broken away;

Figure 9 is a sectional view of the cylinder taken on line 9-9 of Figure 8, and;

Figure 10 is a view in elevation of a switch including the assembly of Figure 8.

Referring to the drawings whercinlike reference numerals are used throughout to indicate the same parts and in particular for the moment to Figures 1-3, a high voltage disconnect switch comprising a pair of, sidewise swinging switch blades 10 mounted on respective brackets 11 which are suitably fixedly secured to the caps 12 of respective base supported rotatable insulator 13 is illustrated. As best shown in Figures 2 and 3, the blades 10 are each clamped to their respective brackets 11 by a clamping plate 14, and bolts 15 which extend through the blade end, the clamping plate and the bracket. Upstanding lugs 16 on the bracket provide clamp faces 16 offset outwardly from'the body of bracket 11 which carry on each side of the bracket a fabricated jaw assembly made up of respective pairs of contact shoes 1'7 of bus bar copper which are secured at their forward ends to the lugs 16 by bolts The shoes are vertically spaced above the base of plate 14 as indicated at 19 and near their free ends are recessed as indicated at 2% to receive a bolt 21 of a pressure assembly including washers 22, caps 23, and pressure springs 2 5 which act between caps 23 and the free contact shoe ends to resiliently bias the shoe ends inwardly. This fabricated jaw assembly makes it possible to secure the advantage of low price bus bar copper as compared to the higher cost of castings as exemplified in the further embodiments hereinafter described. The clearance provides an important advantage in that it increases the flexibility of the shoes and allows the shoes to bend in or out with respect to the clamp faces 16 under the inherent magnetic forces induced by current fiow to maintain the most cfi cacious contact pressure at all times. The bracket tlthas an upstanding boss 25 mounting a vertically extending rod 26 entered in a bore in the boss and secured therein by a rivet 27. e

A stationary line terminal connector 23 having an integrally formed cylinderv portion 29 is relatively rotatably disposed about the rod26. The upper end of the boss 25 cooperates with an inwardly directed annular recess 30 of cylinder 29 and with rod 26 to define a raceway for bronze antifriction balls 31 which support the lower end of connector 28. At the upper end of the cylinder 29 a similar recess 32 is formed to cooperate with rod 26 and with a spring cap member 33 to form a raceway for bronze balls 34 which support the uppeilend of connector 28. The cap member 33 is fixed on the upper end of the rod 26, and is suitably anchored thereto to assure turning of cap member 33 with rod 26. The racewaysare identically formed at the opposite ends of cylinder 29 so that terminal connector 28 may be inverted if desired so that the line connect on arm may extend outwardly from the upper end of rod 26.

The exterior face of cylinder 29 is provided with four vertically extending annularly spaced ribs 35 and 36 interconnected in a plane containing the center lines of the respective upper and lower pairs of contact shoes by annularly extending webs forming vertically spaced horizontally disposed rings 37. As best shown in Figures 1 and 3, the contact shoes 17 are in contact with the heavier ribs 36 only when the switch is in its closed or current carrying position. This assures a minimum drag during opening and closing movement through shoe contact with the vertically spaced and horizontally extending rings 37 which respectively separate ribs 35 and 36 into sharp edged rib segments the edges of which are designed upon relative rotational movement of shoes 17 to scrapingly cooperate with the contact faces of the shoes and remove foreign matter and any oxide layer that may have formed on the contact faces of the shoes. This. scraping function takes place each time the switch blade is swung from an open to a closed position or vice versa and only at the beginning and end of the movement. Thus, these novel hinge contacts will function equally well whether a heavy pipe bus type line or a small, tight main wire type line is connected to the connector 28.

The cylinder 29 is resiliently urged downwardly at all times by the spring cap member 33 engaging the balls 34 which ride in the recess 32 of the cylinder 29. 7

Assuming a copper bus or the like from the transmission line is connected to the line terminal connector 28, the position of the cylinder 29 is such that the contact shoes bear on the heavy ribs 36 when the switch is closed assuring a maximum contact area between the shoes and the cylinder 29. The shoes, however, bear on the horizontal rings 37 at all other times and these can be made deep enough to carry the normal current and with the additional area of the ribs 36 give a large margin of safety.

All of the contact making areas are preferably suitably plated for high conductivity.

Normally, current flow is from the line terminal 28, through the cylinder 29, through the contact shoes 17 and to the switch blade when the switch is in its closed position. There may be small leakage current flow from the cylinder 29 through the balls 31 and 34 to the rod 26 and then through the bracket 11 to the switch blade 10. This flow is insignificant magnetically during normal line conditions when the switch is to be operated. However, when the switch is closed and has to carry the excessive current of a short-circuit condition on the transmission line, a maximum contact area is provided and the increased current flow through the normal path and through the balls to the bracket becomes appreciable. Since this leakage path through the balls to the rod and through the bracket is in parallel with the normal current path, the magnetic effect of this leakage current is additive to the increased magnetic efiect produced by the main current flow and both act to pull the contact shoes 17 into closer contact with the cylinder 29 as current flow rises and particularly during a short-circuit condition.

In the modification shown in Figures 4 to 7, a swinging switch blade 40 is clamped to a bracket 41 through a clamping plate 42 having upstanding lugs 43 and clamp bolt threaded into suitably tapped opening in the bracket. The bracket 41 is fixedly mounted on a tumable insulator (not shown) for turning therewith as in the preferred modification just discussed.

A rod 44 is fixedly mounted at one end in a :bore of a boss 45 formed on the bracket by a rivet 46 or other suitable means. A line terminal connector 47 formed integrally with a cylindrical mounting hub 48 disposed about the rod 44. The boss cooperates with an inwardly directed recess or outer ball bearing raceway 49 of hub 48, and with the rod 44 to define an inner ball bearing raceway for bronze mounting balls 50. The upper end of the hub 48 is similarly recessed at 51 to form with rod 44 a raceway for balls 52. If desired, the connector 47 may be inverted as in the previous embodiment so that the line connector arm extends outwardly from its base rather than from its top as shown.

A bracing arm 53 provided by this embodiment is secured to the upper face of clamp plate 42 by bolt 15 which secures blade 40 and clamp plate 42 to bracket 41. The upper end 55 of bracing arm 53 is provided with a bore to fit about the upper end of the rod 44 and so brace it. The lower face 56 of arm 53 is in the form of a reduced diameter boss which cooperates with rod 44 to form an inner raceway for the bearing balls 52 seated in the outer raceway provided by upper hub recess 49. A headed bolt 57 is threaded into the upper end of rod 44 with its head engaging a spring washer 58 which bears against the upper face of end 55 of bracing member 53 to resiliently clamp hub 48 and bearing balls and 52 between boss 45 and end of arm 53. It will be appreciated, therefore, that arm 53 has a dual function, namely, to support the upper end of rod 44 and to provide a pressure member for reloading the bearings supporting connector 47 and thus eliminate all clearances in the journal arrangement provided between connector 47 and bracket 41.

Contact shoes 59 are bolted to the upstanding lugs 43 which in this form of the invention provide offset clamp faces similar in all respects to clamp faces 16 of the previously described embodiment. Shoes 59 extend rearwardly to engage the exterior surface of cylindrical hub 48 and are urged inwardly against the hub by a pressure assembly made up of a. bolt 60' passed through the shoes, and provided at its opposite ends with spring washers 61. The exterior surface of hub 48 is provided with a plurality of vertically extending wiping grooves 62 to provide means for scraping foreign matter and oxide from the contact faces of contact shoes 59. The portions 80 of the surface of hub 48 between the grooves are silver plated and it isagainst these silver portions that the shoes hear when the switch is closed to transmit current.

From the foregoing description, it will be clear that this form of the invention provides the same magnetic forces and contact scraping functions described in connection with the previous embodiment. However, because of its uniform diameter cylindrical shape there is no lessening of the drag forces in operation. As a consequence, it is not as etfective in use on light wire main lines.

In the further modification shown in Figures 8, 9 and 10, a sidewise swinging switch blade 63 is suitably clamped to a bracket 64 which is secured to the cap 65 of a turntable insulator 81 for turning therewith. A rod 66 is fixedly mounted in a bore of a boss 67 of bracket 64 by a rivet 68, or the like.

A line terminal connector 69 having an integral cylindrical hub 70 is disposed about the rod 66. The lower end of hub 70 has an inwardly directed bored partition 71 which fits the rod 66 and which also provides a bearing surface for the hub as it bears against the upper face of boss 67. The upper end of hub 70 has an inwardly projecting bored partition 72 which also fits the rod 66 to provide a bearing against it. The construction of hub 70 is such that it may be inverted on the rod 66 so that its line connection arm projects out from the base of the cylinder.

A nut 73 is threaded on the upper end of the re 66 and bears against a compression washer 74 which is seated on the upper face of the partition 72 to urge the hub into good electrical contact with boss 67. A suitable rivet 74 fixes nut 73 against accidental loosening.

The exterior surface of hub 70 has a plurality of peripherally spaced and vertically extending grooves 75 thereon to provide wiping means as heretofore described. The ungrooved portions indicated at 79 of the exterior surface of the hub are silver plated and it is against these plated portions that the contact shoes hear when the switch is in its closed position.

Contact shoes 76 are secured to narrow upstanding lugs 77 on the bracket 64 by bolts 78 and extend rearwardly to engage the exterior surface of hub 70 between their free ends. A bolt 81 is passed through the contact shoes adjacent their free ends and is fitted with spring washers 82 hearing against the shoes to urge them into good contact with the cylinder.

As in the previously described embodiments of the invention, the magnetic forces through this hinge end contact are such as to increase the contact pressure upon an effective increase in current fiow. It will also be appreciated that this form of the invention, like that of Figures 4 to 7, provides a uniform contact pressure during opening and closing of the switch and as a consequence involves a high drag force making its use more desirable with the heavy pipe bus type line than the small wire type of main line.

To better understand the action or" the magnetic forces in these several switches, reference should be made to Figures 4 and 5 wherein the primary path of current flow is shown by a series of solid arrows and the leakage path by a series of dotted arrows. As will be apparent from these arrows, the current flow through both paths, irrespective of the direction of flow, respectively divides opposite the ends of the contact shoes to flow in parallel paths through the shoes and passes through the bearing connection for the line connectors to the pivot rod thence the support bracket to the swingable blade in a third parallel path. It follows, therefore, that the primary flow sets up attractive magnetic forces between the free ends of the opposed shoes and between the respective free shoe ends and the hub of the connector and that these magnetic forces are augmented by the magnetic forces induced by leakage current and acting between the respective free shoe ends and the connector hub. It is apparent, therefore, that relatively movable contact hinge contacts made in accord with the application teachings will not only provide an ample contact area to assure eificient current transmission without unduly high'temperatures of the parts but assure erficient high contact pressures under all current transmission conditions to maintain proper functioning or" the switch. it is further apparent that the preferred embodiment of Figures 1 to 3, additionally assures a material reduction in contact area during opening and closing movement of the switch blade which reduces the drag forces to be resisted by the connected line and overcome by the operator or operating mechanism in mechanically operated switches which is a decided advantage over previously proposed hinge contacts of a similar nature and most, if not all, shunt type hinge end connections.

While the hinge end contacts just described perform efiiciently with any suitable type swing end connections, the swing end connections preferably employed are of the general type disclosed and claimed in United States Letters Patent 2,709,739 issued May 31, 1955, to William H. Gilliland and Fitzhugh H. Turnham. These swing end contacts, as more fully illustrated and described in Patent 2,709,739, comprise a rigid, loop-like male contact and a mating, double jawed, flexible fem-ale contact 91 respectively rigidly bolted to the respective. swing ends of the cooperating blades 10, 49 or 63 by bolts 93. The female contact is made up of an opposed pair of spaced single (Figure or double (Figure l) jaw arms interconnected near their free ends by a compression spring assembly 94. The primary advantage of the utilization of these swing end contacts is that the current flow therethrough irrespective of its direction divides at the ends of the flexible female jaw contacts and traverses the parallel paths provided by the spaced arms setting up a magnetic attraction between the arms which augments the spring induced contact pressure, particularly during a short circuit or other overcharge conditions, to maintain contact at the swing ends.

In addition to this desirable feature, which together with the similar pressure increasing magnetic eflects of the hinge end contacts assures a switch structure having highly efficient contact pressures at all contact points in proportion to the current value, these swing end and hinge end contacts together also assure a relatively smooth swinging, easily opening and closing switch structure in use.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A hinge end contact assembly for a center break disconnect switch of the spaced rotatable insulator type comprising a mounting bracket fixedly connected to the upper end of said rotatable insulator and providing a blade support arm and an a-ngularly related support rod coaxially disposed with respect to said insulator; a line connector having a longitudinally elongated hub portion axially bored to encircle said support rod in relative radially spaced relation, an exterior surface providing longitudinally continuous, transversely opposed contact surfaces, and an arm adapted for connection to an electrical transmission line; ball bearing means at each end of said hub portion to journal said rod and bracket for relative rotation with respect to said line connector hub portion and form a high resistance current path and low friction journal bearing engagement between said rod and said hub portion; a pair of contact shoes of a width substantially equal to the length of said hub portion adapted in closed switch position to engage said hub along areas extending the full length of said longitudinally elongated hub portion to thereby form a large area of contact between said shoes and said hub portion, said shoes being supported at one end from said blade support arm and extending therefrom in laterally spaced relation toward and part-way past said hub portion to dispose their respective free ends at opposite sides of said hub portion; resilient means interconnecting said contact shoes adjacent their free ends and arranged to bias said shoes toward each other to assure a positive high contact pressure, low resistance current path between each of said shoes and opposed areas of said hub portion of said line connector, and means surrounding only the free end of and secured against axial movement oft of said rod to cooperate through said ball bearing means and said hub portion of said line connector to retain said line connector in spaced, journalled, assembled relation on said support rod and said mounting bracket.

2. The hinge end contact of claim 1 wherein said hub portion at opposite ends of its base is coaxially annularly recessed to form outer ball bearing raceways, a plurality of bearing balls are disposed in said outer raceways and opposed annular recess is formed in said mounting bracket and said means surrounding the free end of said rod to provide respective inner raceways directly receiving said ball bearings and retaining them in antifriction bearing relation between said support rod, said mounting bracket and said line connector.

3. A hinge end contact assembly for a center break disconnect switch of the spaced rotatable insulator type comprising a mounting bracket fixedly connected to the upper end of said rotatable insulator and providing a blade support arm and an angularly related support rod coaxially disposed with respect to said insulator; a line connector having a hub portion axially bored to receive said support rod in relative journalled relation, a peripheral surface in the form of at least one pair of axially extending, diametrically opposed contact ribs extending from end to end interconnected between their ends by annularly related rib means proportioned and positioned to engage contact shoes over a substantially smaller area during opening and closing movement of said switch whereby the frictional drag on said line connector is held to a minimum during such movement, and an arm adapted for connection to an electrical transmission line; a pair of contact shoes supported at one end from said blade support arm and extending therefrom in laterally spaced relation toward and to dispose their respective free ends at opposite sides of said hub portion; resilient means interconnecting said contact shoes adjacent their free ends and arranged to bias said shoes toward each other to assure a positive Contact pressure between each of said shoes and said hub portion of said line connector; and means mounted on the upper end of said rod and cooperating with said hub portion of said line connector to retain said line connector in assembled relation to said support rod, said contact shoes and said mounting bracket.

4. The hinge end contact of claim 1 wherein said exterior surface of said hub portion of saidline connector is in the form of a cylindrical peripheral surface interrupted at spaced intervals by a plurality of shallow, axially extending grooves the axially extending corners of which serve as scraper elements to scrape or wipe the contact surfaces of said shoes to free them of foreign matter. a

5. A rotatable insulating support; a bracket secured on said support for turning therewith; a vertically extending rod secured to said bracket; 8. cylinder disposed about said rod and having means thereon defining a line terminal, a first pair of outstanding and peripherally spaced vertically extending ribs on its exterior surface, a second pair of peripherally spaced and relatively thin vertically extending ribs on its exterior surface, and a pair of outstanding and vertically spaced horizontal rings on its exterior surface; bearing means supporting said cylinder so that said rod and insulating support may be rotated while said cylinder remains stationary; a switch blade secured to said bracket for sidewise swinging when said support is 8 rotated; and contact shoes secured to said bracket and in engagement with the exterior surface of said cylinder. 6. The hinge end contact of claim 1 wherein said arm is disposed at right angles to the transverse plane bisecting said opposed contact surfaces and is ofiset toward one end of said hub portion and said hub portion has a concentric longitudinally directed through bore the opposite ends of which intersect identical, concentric, enlarged annular recesses providing similar ball bearing raceways at the opposite ends whereby said line connector is adapted for end for end reversal on said support rod to dispose said arm in either of two axially spaced planes normal to the axis of said support rod. 7. A device for connecting a stationary line terminal to a switch blade having sidewise swinging movement, said device comprising a bracket secured to a rotatable insulating support; a boss on said bracket; a vertical rod having one end entered in said boss and secured thereto; an openended cylinder disposed about said rod and having a plurality of peripherally spaced and vertically extending outstanding ribs on its exterior surface and horizontal rings on its exterior surface connected to said vertical ribs; a first inwardly projecting recess in one end of said cylinder, a first set of balls on said boss and enclosed by said first recess to non-rotatably support said cylinder as said bracket is turned, a second inwardly projecting recess at the other end of said cylinder, 21 second set of balls seated in said recess, a spring urged arm secured at one end to said bracket with its free end surrounding said rod and seated on said second set of balls to load said bearings, a line terminal connector arm integral with said cylinder and disposed near one end of said cylinder, said cylinder being invertible on said rod to dispose said line terminal connector arm at a selected one of two levels when desired, a switch blade secured to said bracket for swinging movement as said bracket is turned, and contacting shoes secured at one-end to said bracket and having their free ends in engagement with diametrical opposed areas of the exterior surface of said cylinder.

References Cited in the file of this patent UNlTED STATES PATENTS 2,610,276 Bayer Sept. 9, 1952 2,660,631 Harrison Nov. 24, 1953 2,707,732 Ortwig May 3, 1955 2,709,739 Gilliland et al May 31, 1955

Images