US3530264A - Vertical reach disconnect switch - Google Patents

Description

VERTICAL REACH DISGONNECT SWITCH Filed May 9, 1969 4 Sheets-Sheet 1 I N VEN TORS 51/56/14? qme/A/ W1. 75/? 52 #514) BY flax/4.40 a Muf /PW:

Sept. 22, 1970 GQRIN ETAL VERTICAL REACH DISCONNECT SWITCH 4 Sheets-Sheet 2 Filed May 9, 1969 Sept. 22, 1970 GQRIN ETAL 3,530,264

VERTICAL REACH DISCONNECT SWITCH Filed May 9, 1969 4 Sheets-Sheet 5 ay/740 c. Muff/F414 E. GORIN ET AL VERTICAL REACH DISCONNECT SWITCH Sept. 22, 1970 Filed May 9, 1969 4 Sheets-Sheet 4 \vw MW dm lllfi United States Patent Ofifice 3,530,264 VERTICAL REACH DISCONNECT SWITCH Eugene Gorin, Walter B. Kelly, and Donald C. Musgrave,

Greensburg, Pa., assignors to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed May 9, 1969, Ser. No. 823,428

I Int. Cl. H01h 31/00 US. Cl. 200-48 Claims ABSTRACT OF THE DISCLOSURE A vertical reach disconnect switch having an operating mechanism for moving the switch blade from the open (horizontal) position to the closed (vertical) position. Approximately fifty percent of the motion experienced by the operating mechanism (during both opening and closing operations) is devoted to the twisting of the blade providing a high magnitude moment for engaging contact between the blade and the jaw structure to provide excellent wiping engagement and assure good electrical contact even in cases of heavy ice loading. Corona shielding is vastly improved over conventional techniques while, at the same time, the weight, overall length and possible ice loading are significantly diminished. Unique beaver-tail structure in the form of a bolted casting provides excellent metal-to-metal contact.

The present invention relates to power distribution and power transmission networks, and more particularly, to a novel disconnect switch of the vertical reac type specifically adapted for economizing in space requirements for switches employed in systems having extra high voltage (EHV) ratings.

In power distribution and power transmission networks, there are frequent applications, especially in the field of outdoor-type power switching equipment having ratings in the EHV range, in which it is advantageous to employ electrical disconnect switches. A preferred design of such switches is one in which the switch blade is aligned vertically when closed to bridge the vertical distance between a lower elevation bus run and an overhead, higher elevation bus run. In industry terminology, such switches are generally referred to as vertical reach switches. Switches of this design oifer several advantages over conventional switch-types such as reduction in the land area required for the outdoor substation, decrease in the overall bus insulation and supporting system requirements and simplification of substation equipment arrangements. In order to achieve all of the above advantages, a disconnect switch must be provided which is fully capable of maintaining the integrity of the station insulation system, of carrying full rated current from upper to lower bus levels, of withstanding magnetic forces and heating resulting from system short circuits, and further must be so arranged with proper linkages and operating mechanisms such that reliable closing and opening functions are capable of being controlled with ease from ground level, even under the most adverse atmospheric conditions of high wind and heavy ice loading.

The present invention is characterized by providing a disconnect switch of the vertical reach type which offers a reasonable and economic solution to the simplification of substation design and operation.

The vertical reach disconnect switch of the present invention combines the economy of a switch operating linkage and switch blade hinge assembly mounted on two columns of porcelain insulators. In order to attain reliable performance, the switch is provided with a rigid main blade which, upon closing, twists its contact surfaces into the high pressure contact members of an upper level jaw assembly which is electrically and mechanically 3,530,264 Patented Sept. 22, 1970 joined to an upper level rigid station bus system, and as such eliminates the need for additional columns of porcelain insulators for its support.

A single rotatable insulator column rotated through an attached lever or crank and a system of planetary linkages operates to raise the switch blade to a vertical position and then twist the contact surfaces into the high pressure con tacts of an overhead jaw. The opening operation completely reverses the order of the above-mentioned closing operations. In both the opening and closing operations, nearly fifty percent of the drive linkage movement is devoted to blade rotation, yielding a very significant mechanical advantage especially for switches provided with long blades.

The elongated blade member is provided with a beavertail casting which is bolted to the main blade portion providing excellent metal-to-metal contact and yielding a blade having a high conductivity beaver-tail member to provide superior electrical contact between the blade and jaw structures. A corona ball of variable radius is further bolted to the beaver-tail, which ball is of such design as to provide superior corona shielding as compared with conventional corona shields while, at the same time, being of significantly smaller surface area and lighter in design to reduce the blade moment required during opening and closing operations, and further to reduce the amount of potential ice loading experienced by the corona ball.

The disconnect switch operating mechanism is provided with a pair of counter-balancing springs arranged equidistant from the operating spring center line, thereby enabling the pair of springs to be significantly longer than prior art counter-balancing springs without conflicting with the operating mechanism arrangement and/ or movement while, at the same time, providing a more economical design from the viewpoint of overall cost.

The orientation of a jaw structure arranged in an overhead fashion eliminates the need for any insulator support for the jaw, and is further designed so as to provide ad justment over a wide range to compensate for any minor or significant variations in the terrain upon which the substation is installed.

It is, therefore, one object of the present invention to provide a novel disconnect switch of the vertical reach type having an operating mechanism whose significant portion of mechanical movement is entirely devoted to twisting of the blade to provide an extremely large mechanical advantage during opening and closing operations to assure good electrical contact between blade and jaw structures even in cases of extreme ice loading.

Still another object of the present invention is to provide a novel corona shield assembly for use in disconnect switches, and the like, wherein the cone of protection provided by the shield is significantly greater than that afforded in the prior art, while the shield itself is of significantly smaller size, weight and surface area to reduce the total amount of potential ice loading which may occur as well as reducing the blade moment which results in a significant reduction in the operating force required to move the blade between open and closed positions.

Yet another object of the present invention is to provide a novel beaver-tail design for use in disconnect switches, and the like, providing an excellent metal-tometal electrical joint to assure extremely high currentcarrying capability, as well as superior corona shielding of that joint.

These as well as other objects of the present invention will become apparent when reading the accompanying description and drawings in which:

FIG. 1 is an ele-vational view showing a vertical reach disconnect switch embodying the principles of the present invention.

FIGS. 2a and 2b are elevational and top views, respectively, showing the operating mechanism of FIG. 1 in greater detail.

FIG. 2c is an isometric view of the operating mechanism of FIG. 1 showing the mechanism in the closed position.

FIGS. 3a and 3b are side and end views, respectively, of the beaver-tail and blade corona ball of FIG. 1, showing these elements in greater detail.

FIGS. 4a and 4b are side and top views, respectively, showing the jaw structure of FIG. 1 in greater detail.

FIG. 1 shows the entire switch blade structure comprised of a switch base structure 11 supporting a pair of insulators 12 and 13, one of which, namely insulator 12, is mounted to rotate about its longitudinal axis, while insulator 13 is mounted in a stationary fashion. A tie casting 14 is secured to the tops of porcelain insulator columns 12 and 13. A hinge casting 15 is pivoted upon tie casting 14 by means of hinge and bearing pins 16, 16 (note also FIGS. and 2b). The switch blade member 17 is attached to a trunnion 18 which is rotatably mounted upon a cylindrical projection 15a which forms part of the hinge casting 15. The blade member 17 and trunnion 18 are adapted to rotate about their longitudinal axes with respect to the hinge casting projection 15a.

The top of rotatable insulator 12 is rigidly secured to main crank 19' whose center of rotation lies along phantom line 20 which is colinear with the longitudinal axis of blade member 17 when viewed from the top, as shown in FIG. 2b. The shaft (not shown) coupling main crank 19 to rotatable insulator 12 passes through a suitable opening 14a in tie casting 14.

The free end of main crank 19 is pivotally connected to an intermediate portion of connecting link 21 by means of a coupling pin 22. One free end of connecting link 21 is mechanically linked to auxiliary crank 23 which rotates about the central axis of a pin 24 rotatably coupled within a suitable opening (not'shown) within the casting 14. A similar coupling pin 25 pivotally couples connecting link 21 to auxiliary crank 23.

The opposite end of connecting link 21 is piovtally coupled through a clevis pin 26 to fork link swivel 20. In actuality, pin 26 (as shown best in FIG. 2a) permits the rotation of the clevis portion about its longitudinal axis which member, in turn, is provided with a slot for receiving the left-hand end of fork link swivel 29 which is provided with an eyelet (not shown) for receiving a pin 30 pivotally coupling the eyelet to the clevis portion of pin 26, thereby enabling fork link swivel 29 to experience rotational motion about longitudinal axis of pin 26 and pivotal motion about connecting pin 30.

The right-hand end of fork link swivel 29 is threaded into a fork link 27 whose pair of arms 27a and 27b are pivotally connected by pin means 28, thereby mechanically coupling the fork link 27 with trunnion casting 18.

FIG. 20 shows the position of the operating mechanism 31 when the blade 17 is in the closed (vertical) position. As insulator 12 rotates in the counterclockwise direction (relative to FIGS. 2b and 20) this motion is directly imparted to main crank 19 which likewise rotates from the solid line position of FIG. 20 in the counterclockwise direction, causing the clevis-pin member 26 (see FIGS. 2b and 2c) to describe a trajectory 32, one portion, 32a of which is perfectly circular and concentric with the axis of the hinge projection 15a and blade member 17 when both are in the vertically aligned (closed) position, as shown in FIG. 20. This circular movement is imparted to trunnion 18 by means of fork link 27a, 27b to cause a twisting action of the blade contact surfaces within the cooperating jaw assembly (which structures are to be more fully described), thus initially relieving contact pressure between blade and jaw assemblies.

The second or remaining portion 32a of trajectory 32 4 makes a significant departure from concentric motion relative to the hinge projection and blade member, causing :both elements to pivot about hinge pins 16, 16 (see FIG. 2b) and thereby move the blade from the vertical (closed) position to the horizontal (open) position, shown best in FIG. 2a.

Operating in reverse order, the rotatable insulator 12 imparts clockwise motion to main crank 19 (relative to FIG. 2b), initially causing the blade to pivot about hinge pins 16, 16 lifting the blade from the open (horizontal) position to the vertical position wherein the beaver-tail portion of the blade lies between the cooperating jaw contactsof the blade assembly (to be more fully described), but has yet to make good contact pressure therewith. The remaining portion of the trajectory (32a), which is concentric with rotation of trunnion 18 and fork link 27, then rotates the blade 17 about its longitudinal axis 17a to twist the substantially oval-shaped beaver-tail portion within the jaw contacts and thereby wipingly engage the exposed contact surfaces before moving to the fully closed position. This wiping action serves to wipe any contaminants both from the surface of the beavertail contact portions and the exposed contact surfaces of the jaw assembly. In addition thereto, the wiping action is highly effective in removing any ice which may form upon the contact surfaces of the jaw structure prior to the moment at which the beaver-tail portion of the blade fully locks into the closed position. The concentric portion 32a of the trajectory constitutes approximately 50% of the overall trajectory experienced by member 26, thereby providing an extremely advantageous mechanical advantage to provide excellent wiping action and removal of any ice from both the beaver-tail and jaw structures. The distinct advantage of this arrangement results in the fact that the vertical reach disconnect switches employed in substations designed for EHV ratings usually employ blades which are greater than 20 feet in length. The employment of a single unitary blade member 17 and a large angular rotation of the blade about its longitudinal axis assures excellent wiping action.

FIGS. 3a and 3b show the beaver-tail portion and corona shield components provided at the free end of blade 17. As shown in these figures, the blade 17 which is a single unitary member, is formed of a light-weight metal such as aluminum. The choice of a light-weight metal is significant since the weight of the blade contributes appreciably to the necessary operating forces which must be employed in moving the blade between open and closed positions.

Another important requirement is to provide a highly conductive path between the contact surfaces of the jaw assembly and the free end of the blade, which surfaces have excellent conductivity and do not wear easily as a result of the repeated wiping action.

For the above reasons, the blade free end is rigidly mechanically linked to a beaver-tail portion 33 which is formed of a metal having high conductivity as compared with aluminum. Preferably, beaver-tail portion 33 is formed of bronze and has a cross-section configuration as shown best in FIG. 3b wherein the major diameter D is significantly greater than the minor diameter D to provide adequate clearance for blade entry before initiation of the twisting action.

The left-hand end of beaver-tail portion 33 is provided with a flange 34 having a plurality of openings 35 arranged at spaced intervals about flange 34. The right-hand end of blade 17 is fitted with a corona ring 36 preferably formed of aluminum. The corona ring 36 is provided with a sleeve portion 37 which telescopes within the right-hand end of blade 17, as shown best in FIG. 3a. The ring is preferably welded to the blade at 38 to rigidly secure these two elements to one another. The corona ring 36 is provided with a flat surface portion 36a which engages the left-hand surface 34a of flange 34 and is belted thereto by means of stainless steel fasteners 39 which threadedly engage corona ring 36.

The beaver-tail portion is provided with a short cylindrical projection 33a which telescopes into the hollow interior of corona ring 36 so as to center beaver-tail portion 33 relative to corona ring 36 and hence relative to blade member 17.

The right-hand end of beaver-tail 33 is provided with a continuous conical flange 40 which acts as a bearing surface for the blade corona ball 41. The interior portion of beaver-tail 33 is provided with a rib 42 (see FIG. 3b) adapted to threadedly engage a fastening member 43 for securing the hollow blade corona ball 41 to beavertail 33.

The blade corona ball 41 is provided with a centrally located flat portion 44 having a threaded boss for receiving fastening means 43. Surrounding the flat portion 44 is a conical portion 45 whose exterior region bears against the conical flange 40 and extends well beyond the periphery of flange 40 to a point 46. In fabrication, the blade corona ball 41 is formed of a first section comprised of the portions 44, 45 and 50 and a second nearly hemispheric-shaped portion 47 which is welded to portion 50 after the threaded boss is secured to flat portion 44. The weld is at location 48, shown best in FIG. 3a.

The generally hemispherical top portion 47 of corona ball 41 is comprised of only one portion having a large radius of curvature R, which extends over an angle 0 on both halves of center line 17a.

The bottom dish-shaped portion of the corona ball 41 is comprised of a centrally located flat portion 44 which includes the threaded fastening boss, a conical portion 45 and a curved portion 50 having a small radius R extending over angle 0 and which is tangent to conical portion 45 and to the large radius R of the top hemispherical section 47.

The extremity of the bottom-shaped portion 50 is joined through a weld seal 48 to the top hemispherical section 47 of the corona ball.

The cone of protection afforded by corona ball 41 is represented by the dotted lines 51, 51 shown in FIG. 3a which represents the corona protection afforded to beavertail portion 33. The corona ring 36 provides two cones of protection represented by the dotted lines 52, 52 and 53, 53, of which the cone of protection 53, 53 overlaps with the cone of protection 51, 51 to aflford excellent corona protection for the beaver-tail portion especially. A corona ball of the type shown in FIG. 3a is of significantly reduced surface area and overall length L, as shown in FIG. 311, while at the same time providing a larger cone of protection as compared with corona balls presently being employed.

FIG. 1 and FIGS. 4a and 4b show the jaw assembly 60 of the present invention which is comprised of a T-connector 61 provided with a cylindrical opening 62 for receiving an overhead bus 63. T-connector 61 is further provided with a vertically aligned opening 64 for receiving a vertical tube support 65 which extends downwardly from T-connector 61 for coupling with jaw support casting 66. Casting 66 is provided with a circularshaped opening 67 for receiving the lower end of vertical tube support 65. Casting 66 is provided with a plurality of openings 68 (note especially FIG. 4b) for receiving set-screws 49, 49 (only two of which are shown in FIG. 4a) for temporarily adjusting casting 66 to vertical tube support 65 at any desired position to allow suflicient compensation for the variation of terrain and bus elevations as between the main portion of the switch and its jaw assembly 60. After adjusting, casting 66 is welded to tube support 65.

The jaw casting 66 has integrally formed therewith a pair of spaced parallel projections 69, 69 joined near their centers by a supporting rib 70. The free ends of arms 69, 69 have secured thereto first and second pluralities of contact fingers 71 and 72. The outer surfaces of contact fingers 71 and 72 are bolted by means of fastening members 73 to lower projection 69 (relative to FIG. 4b). The inner ends of contact finger 72 are urged toward the center line 74 of jaw assembly 65 (as shown in FIG. 4b) by means of pressure springs 75 mounted upon fastening members 73. Contact fingers 71 are similarly secured to upper projection 69 (relative to FIG. 4b) by fastening means 76 secured to the outer ends of the contact fingers, while the inner ends of contact fingers 71 are caused to be urged in the direction of center line 74 by pressure springs 77. Fastening members 73 and 76 further secure to projections 69, 69 a pair of jaw guides 78 and 79 which act to guide the blade into the region between the contacts as the blade moves from the open (horizontal) position toward the closed (vertical) position. Since the blade of greater than 20 foot length may deviate slightly from movement totally Within a vertically aligned plane, guide members 78 and 79 act to align the blade and guide it into the region between the jaw contacts and thereby compensate for any deviation in movement of the blade from such an imaginary vertically aligned plane.

The amount of movement which the inner surfaces of jaw contacts 71 and 72 may experience is limited by means of the finger retainer members 81 and 82 which are rigidly fastened to upright projections 83 and 84 ex tending from center rib 70. Spring retaining members 81 and 82 are secured to these upright projections by fastening means 85 and 86, respectively.

The design of the jaw assembly and connecting components is such that the jaw casting 66 may be arranged at any point along the length of vertical tube support 65 and further the jaw casting 66 may be oriented at any angle over a 360 range relative to overhead bus 63, thereby providing great latitude in the manner in which the disconnect switch may be integrated into the overall design of an outdoor substation. The projecting arms 69, 69, together with the closely arranged jaw contacts 71 and 72 provide an ice shield which substantially diminishes the amount of ice loading which may be experienced by the surfaces of the jaw contact which engage the beavertail portion. In addition thereto, a thin ice shield member 85, 85 is provided in the region of each jaw contact for further reducing potential ice loading. Each of the ice shields is formed from a thin metallic sheet bent to form an S-shaped configuration where in one leg 85b is attached to the jaw assembly by means of fastening members 73 which are associated with securing of jaw guides 78 and 79. The remainder of the S-shaped shields 85a is positioned above pressure springs 75 and 77 and constitute a rain trough immediately above jaw contacts 71 and 72, as well as pressure springs 75 and 77 so as to protect them from accumulated ice build-up.

FIG. 4b shows the jaw assembly prior to the entrv of the beaver-tail portion. As the blade moves from the open (horizontal) position toward the closed (vertical) position, the beaver-tail portion 33 enters into the region between the jaw contacts 71 and 72 so as to be diagonally aligned relative to center line 74. The beaver-tail portion continues to enter into the jaw contact region in this diagonal alignment until its forwardmost edge bears against resilient stop member 86 secured to center rib 70 by means of fastening members 87 which further secure a metallic plate 88 upon resilient member 86 to sandwich member 86 between plate 88 and rib 70.

At this time, the pivotal movement of the blade is terminated and the rotational movement of the blade about its longitudinal axis is initiated, rotating the beaver-tail from the orientation 33' to the final orientation 33". In one preferred embodiment, prior to entry and twisting of beaver-tail portion 33, the finger retaining members 81 and 82 restrain the contact fingers 71 and 72, respectively, to provide a clearance of the order of 6 /2 inches between the opposing faces of the contact fingers. In one preferred embodiment, the beaver-tail is provided with a major diameter (D of the order of 7 inches and a minor diame ter (D of the order of 4 inches. When the beaver-tail is diagonally oriented, as shown at 33 and 33 in FIG. 4b, more than adequate clearance is provided for entry of the beaver-tail into the region between the jaw contact fingers. Upon rotation of the beaver-tail from the orientation 33' to the orientation 33", the major diameter being greater than the clearance between the jaw contact fingers causes the contact fingers to be urged against the pressure springs 77 and 75, thereby urging the jaw contact fingers into firm electrical contact with the engaging contact surfaces of the beaver-tail (in the region of the major diameter).

In moving from the orientation 33' to 33", the beavertail makes wiping engagement with the surfaces of the contact fingers so as to wipe olf any contaminants on either of the engaging surfaces prior to reaching the final angular orientation 33". In addition thereto, this wiping engaging is highly effective for the removal of any ice which may form upon the contact surfaces of the jaw contact fingers and is found to be effective in removing ice of greater than 4 thickness on each jaw contact surface and still nevertheless providing good electrical contact between beaver-tail and jaw assembly. In addition thereto, this structure has proven to provide good electrical contact through the wiping action, necessitating only a single closing operation, whereas conventional devices have proven to require repeated opening and closing operations before the ice accumulated upon the contact surfaces is cleaned oif sufficiently to provide good electrical contact between jaw assembly and beaver-tail.

When disconnect switches of the type herein described are utilized in regions having climatic conditions which potentially expose the disconnect switch to a high degree of ice loading, the overall length and surface area of the blade structure becomes quite significant, since the blade structure is exposed to ice loading over its entire length. Such ice loading may add rather appreciable weight to the blade and thereby significantly increase the required force for operating the blade between its open and closed positions. Thus any reduction in blade length and surface area acts to reduce the blade moment. The utilization of the corona ball of the present invention significantly reduces the surface area and overall length of the blade as compared with conventional techniques, thereby significantly reducing the potential ice loading which may be experienced by the blade structure.

The operating mechanism of the present invention is further provided with a pair of counterbalancing spring assemblies 99 and 100, shown best in FIGS. 2a and 2b of the present application. These assemblies are mounted in a symmetrical fashion on opposite sides of the switch center line 20 shown in FIG. 2b. Only one of these assemblies, namely assembly 100, will be described herein in detail, it being understood that the remaining assembly is substantially identical in design and configuration. As shown best in FIG. 2a, spring assembly 100 is comprised of a housing 101 whose left-hand end is provided with an opening 102 for receiving a pin 103 having a T-shaped configuration whose projecting arm 104 passes through an opening 105 in tie casting 14 and is threadedly fastened thereto by fastening means 106. Housing 101 has mounted therein a helical spring 107 having a first end which bears upon the end cap 108 and having a second end thereof which bears upon a plate 109 which, in turn, is secured to an elongated rod 110 projecting through an opening in end cap 108 and being provided with an eyelet 111 for receiving a pin 112 which pivotally links arm 110 to hinge casting 15. As shown in FIG. 2a, spring 107 is substantially fully charged when compressed, as shown in the figure, acting to urge rod 110 generally toward the left-hand direction, as shown by arrow 113, which thereby acts to urge blade 17 toward rotation substantially in the counterclockwise rotation about its hinge bearings 16 (relative to FIG. 2a). Thus, the counterbalancing spring assemblies 99 and 100 act in unison to counterbalance the effect of the weight of blade 17 upon the operating mechanism, thereby maintaining the blade in the horizontal position or, for that matter, in any other position to which the blade is moved by the operating mechanism.

As the blade is moved from the open (horizontal) position toward the closed (vertical) position, rod moves in the direction shown by arrow 113 to reduce the charging of spring 107 to the point where the charging of spring 107 is substantially at a minimum at the time that the blade 17 reaches the vertical position. Since the blade is substantially vertically oriented at this time, it, in effect, supports its own weight, thereby reducing the importance of the functions performed by the counterbalancing springs at this time. Since the blade is substantially cantilevered when in the open (horizontal) position, the counterbalancing springs are most effective at this time to counterbalance the effect of the weight of the cantilever blade upon the operating mechanism. The pair of springs shown arranged symmetrically about center line 20 are positioned in such a manner as to avoid any conflict with the operation or movement of the switch operating mechanism. This provides a decided advantage over conventional devices employing only a single counterbalancing spring arranged so as to be coaxial with the switch center line 20, and thereby severely limited as to its overall size and requiring an increasing distance between the end connecting points in order to provide sufiicient room for a counterbalancing spring of adequate operating characteristics. In the present arrangement, the counterbalancing springs provide more than twice the effectiveness of conventional techniques since, in addition to the duality of functions, their positioning off-center relative to the switch center line enables larger individual springs to be provided as compared with conventional techniques.

It can be seen from the foregoing disclosure that the present invention provides a novel disconnect switch design of the vertical reach type which are adaptable for use in outdoor substations having severely limited space requirements wherein an improved operating mechanism is provided to provide great mechanical advantage during switch opening and closure which is capable of supporting blades of extremely long length in cantilevered fashion for indefinite periods of time due to the novel counter- Ibalancing spring arrangement, having a universal-type jaw assembly capable of providing any orientation as between upper and lower level buses connected by the disconnect switch, having a beaver-tail design which enables optimum weight reduction for an extremely long blade, while at the same time providing good metal-to-metal electrical contact, and further having a novel blade corona ball which provides a larger cone of protection than that provided for through the use of conventional techniques, while at the same time reducing overall blade length and surface area and contributing to a reduction in the amount of potential ice loading experienced by such a blade structure.

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and, therefore, the scope of this invention is limited not by the specific disclosure herein, but only by the appended claims.

We claim:

1. A disconnect switch of the vertical reach type comprising:

an operating mechanism;

a jaw assembly mounted at an elevated position above said mechanism;

a switch blade secured at a first end to said operating mechanism and having a second end movable from a horizontal (open) position toward a vertical (closed) position in electrical contact with said assembly;

said mechanism comprising a main crank rotatable about a first point located at a first end thereof;

said first point lying on the longitudinal axis of said blade;

a connecting link pivotally connected, at a point intermediate its ends, to the free end of said main crank;

an auxiliary crank mounted to pivot about a first end thereof;

said auxiliary crank first end being positioned a spaced distance from said main crank first end and lying to one side of said blade longitudinal axis;

a first end of said connecting link being pivotally connected to the free end of said auxiliary crank;

a swivel assembly having a first end pivotally coupled to the second end of said connecting link;

the opposite end of said swivel assembly being bifurcated, said bifurcated end being pivotally linked to said blade first end.

2. The switch of claim 1 wherein said main crank is adapted to pivot through an angle to pivot said blade between the open (horizontal) position and the closed (vertical) position and to rotate said blade about its longitudinal axis to make wiping engagement with the contact surface of said jaw assembly.

3. The disconnect switch of claim 2 wherein said nearly one-half /z) of the angle of said pivotal movement of said main crank causes the rotation of said blade and the remainder of said main crank pivotal movement causes the pivoting of said blade.

4. The disconnect switch of claim 1 further comprising a support;

a first insulator rigidly mounted upon said support;

a second insulator being rotatably mounted upon said support;

means for rotating said insulator positioned near the lower end thereof;

said operating mechanism being mounted upon said first and second insulators;

the first point of said main crank being coaxial with the longitudinal axis of said second insulator;

means coupling said main crank first end to said second insulator for rotating said main crank in unison with rotation of said second insulator.

5. A blade assembly for use in disconnect switches and the like comprising an elongated tubular member of light-weight conductive material;

an annular shaped conductive member having a central opening;

a tubular sleeve extending outwardly from said opening and being telescoped within a first end of said tubular member;

the annular region surrounding said central opening on the opposite side of said sleeve being a substantially flat ring-shaped surface;

a beaver-tail portion having a substantially oval-shaped cross-section and being formed of a metal having a greater conductivity than said tubular member;

a first end of said beaver-tail being provided with a ring-shaped flange, a first surface of said flange being flat and adapted to engage the surface of said annularshaped conductive member;

said flange and said annular-shaped member each being provided with a plurality of openings arranged at spaced intervals about an imaginary circle, each opening in said flange being aligned with an associated opening in said annular-shaped member;

substantial fastening means associated with each of said aligned openings for securing said beaver-tail to said blade.

6. The assembly of claim 5 wherein said fastening means are threaded bolts of a metal resulting in a flanged connection having greater conductivity than said beavertail.

7. The assembly of claim 6 wherein said blade is formed of aluminum.

"8. The assembly of claim 7 wherein said beaver-tail is formed of bronze.

9. The assembly of claim 8 wherein said fastening means are formed of steel.

10. The assembly of claim 5 wherein said annularshaped member is provided with a substantially C-shaped corona ring surrounding said central opening.

11. The assembly of claim 5 wherein said beaver-tail is further provided with a circular-shaped projection within the interior periphery of said flange, said projection being telescoped within the central opening of said annular shaped member for facilitating concentrically alignment therebetween.

12. A blade assembly for use in disconnect switches of claim 1 comprising:

an elongated tubular member of light-weight conductive material;

an annular-shaped conductive member having a central opening;

a tubular sleeve extending outwardly from said opening and being telescoped within first end of said tubular member;

the annular region surrounding said central opening on the opposite side of said sleeve being a substantially flat ring shaped surface;

a beavertail portion having a substantially oval shaped cross-section and being formed of a metal having a greater conductivity than said tubular member;

a first end of said beavertail being provided with a ring shaped flange, a first surface of said flange being flat and adapted to engage the surface of said annular shped conductive member;

said flange and said annular shaped member each being provided with a plurality of openings arranged at spaced intervals about an imaginary circle, each opening in said flange being aligned with an associated opening in said annular shaped member;

substantial fastening means associated with each of said aligned openings for securing said beavertail to said blade.

13. A disconnect switch assembly blade for use in disconnect switches and the like having a blade operating mechanism and a jaw assembly, said blade comprising:

an elonlgated tubular member formed of a light-weight meta means coupled to a first end of said member for pivotally coupling said blade assembly to said operating mechanism;

a beavertail shaped conductive member coupled to the second end of said tubular member for making conductive engagement with said jaw assembly when in the closed position;

a substantially ball-shaped corona shield secured to the free end of said beavertail member, said shield being comprised of a truncated conical-shaped section;

the central portion of said section being secured to said beavertail portion;

a hollow substantially hemispheric shaped section having its outer periphery secured to the outer periphery of said conical-shaped section.

14. The assembly of claim 13 wherein said hemispheric shaped section is comprised of a hollow metallic shell having a first radius of curvature surrounded by and joined to one edge of an annular-shaped section having a second radius of curvature transverse to the curvature of the annular section which is substantially less than said first radius of curvature.

15. The assembly of claim 14 wherein the opposite edge of said annular shaped section is integrally joined with the outer periphery of said conical shaped section; said first edge having a diameter greater than the diameter of said second edge.

(References on following page) 6 6 12 References Cited ROBERT K. SCHAEFER, Primary Examiner UNITED STATES PATENTS H. J. HOHAUSER, Assistant Examiner 3,009,995 11/1961 Turgeon. 3,243,561 3/1966 Foti.

3,299,230 1/ 1967 Myers. 5 174144

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