US3745274A

US3745274A - Tripod-supported electric disconnect switch for high-voltage electric power systems

Info

Publication number: US3745274A
Application number: US00268476A
Authority: US
Inventors: F Cole
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-07-03
Filing date: 1972-07-03
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10

Abstract

An electric disconnect switch is disclosed having a pair of spaced terminals which include axially aligned switch blades thereon which move into and out of engagement with each other upon rotation of a pair of vertically extending insulated leg members connected to each of the terminals. A tripod support is associated with each leg member, the support including at least three spaced insluated inclined legs connected at their lower ends to a base supporting the leg member and extending to the top of the leg members.

Description

nited States Patent Cole [ 11 3,745,274 1 July 10, 1973 TRIPOD-SUPPORTED ELECTRIC DISCONNECT SWITCH FOR HIGH-VOLTAGE ELECTRIC POWER SYSTEMS Inventor: Fred H. Cole, 1028 S. Sierra Bonita Avenue, Los Angeles, Calif. 90019 Filed: July 3, 1972 Appl. No.: 268,476

US. Cl 200/48 CB, 174/150, 174/161 R Int. Cl. H01h 31/00 Field of Search 200/48 R, 48 CB;

References Cited UNITED STATES PATENTS 2/1948 Cole 174/148 X Primary Examiner-Herman J. Hohauser Attorney-Harry G. Weissenberger [5 7 ABSTRACT An electric disconnect switch is disclosed having a pair of spaced terminals which include axially aligned switch blades thereon which move into and out of engagement with each other upon rotation of a pair of vertically extending insulated leg members connected to each of the terminals. A tripod support is associated with each leg member, the support including at least three spaced insluated inclined legs connected at their lower ends to a base supporting the leg member and extending to the top of the leg members.

6 Claims, 3 Drawing Figures TRIPOD-SUPPORTED ELECTRIC DISCONNECT SWITCH FOR HIGH-VOLTAGE ELECTRIC POWER SYSTEMS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to electric disconnect switches; and, more particularly, to an insulated tripod support for a pair of spaced terminals whereby switch blades carried by the terminals may be pivoted into and out of contacting engagement.

2. Description of the Prior Art In high-current disconnect switches for electric power systems, axially aligned contacting switch blades are used to carry current therethrough. Generally, the current is supplied by a plurality of wires connected to the blades.

These blades are generally connected to terminals supported by insulators or the like mounted on singular insulated ports extending upwardly from a base. The insulated posts are rotated by suitable operating means well known in the art which thus moves the switch blades into and out of contacting engagement. One such arrangement is disclosed in my US. Pat. No. 3,634,634.

With increased voltage requirements, there has developed a need for increasingly stronger and stronger insulated posts. The insulating material, such as ceramic material, would have to be extremely long for the required insulation for such voltage needs. At the same time, it must be thick enough in cross-sectional diameter to carry such longer lengths. Such increased thickness results in an extremely unwieldy insulator. Further, earthquake requirements necessitate insulated posts of a thickness that must withstand considerable earthquake force.

It has been suggested to support such switch blades on a three-legged or tripod insulator arrangement without a central insulated post. In this arrangement, the 4 terminals are rotatably connected to the top of one of the legs. However, a plurality of bearings are required, creating cost, alignment and friction problems since the bearings must be kept both aligned and sealed. Also, the bearings necessary to carry out such rotation must be at an angle which increases the complexity of the bearing arrangement. Further, the movement of the switch blades into and out of contacting relationship is not totally in a generally horizontal plane as in the aforementioned single-legged version, thus requiring more space for such movement. Also, earthquake torsion tends to bend the top bearing in such an arrangement. It is further difficult to keep such a plurality of legs in alignment. Rings have been suggested for encircling all of the legs at spaced locations therealong. However, such rings also require bearings or the like to permit rotation of one of these legs which, in addition to increased costs, also creates more alignment problems (since the legs are inclined from the vertical). Also, dust may collect on such insulators and if dust collects more on one of the legs than others, the resistance of the insulators becomes different in different sections and flashovers will result if the electric path is less than the resistance of any one individual leg (the current selecting the path of least resistance which may be through part of one leg, part of the ring encircling this and another leg, part of a second leg, part of another ring encirclingthis leg and still another leg, etc.).

Insulated bracing is not a desirable substitute since it reduces the mechanical length and the resistances are not even along such bracing. This decreases the effective insulated distance that the current has to travel over dirt.

There thus exists a need for a support for disconnect switches for high-voltage electric power systems whereby the switch blades of such switches are readily rotated into and out of contacting engagement while the system accommodates extremely high voltages.

SUMMARY OF THE INVENTION It is an object of this invention to provide a disconnect switch for electric power systems wherein the system can accommodate extremely high voltage requirements.

It is a still further object of this invention to provide a support for such a system wherein a minimum number of bearings are required and alignment problems are eliminated.

It is another object of this invention to provide such a switch which can withstand considerable earthquake forces.

These and other objects are preferably accomplished by providing a disconnect switch having a pair of spaced terminals with axially aligned switch blades thereon which move into and out of engagement with each other upon rotation of a pair of vertically extending insulated leg members connected to each of the terminals. A tripod support is associated with each leg member, the support including at least three spaced insulated and inclined legs connected at one end to a base supporting the leg member. It has been found that such a tripod arrangement would be mechanically sufficient with the three legs connected to a point on the leg member remote from the top thereof. However, in such an arrangement, it has been found that the capacitance distribution between the switch blades and the insula- 0 tor joints on the central leg member may concentrate BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a disconnect switch in accordance with the teachings of my invention;

FIG. 2 is a view taken along the lines 2-2 of FIG. 1, parts being omitted for convenience of illustration; and

FIG. 3 is a top plan view of the switch of FIG. 1 with parts again omitted for convenience of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings, a switch assembly 10 is shown having a main base 11 in the general form of elongated spaced rails or the like. A pair of

posts

12 and 13 extend upwardly from sub-bases 15a which may be secured to each end of base 11 by any suitable means, such as bolts or the like. Of course, base 11 may be eliminated if desired. A pair of longitudinally extending vertically disposed insulator assemblies l5 and 16 are rotatably mounted on each

post

12 and 13. A pair of actuating'rods 17 and 17a are connected to

eccentric brackets

50 and 51 attached to the

insulator assemblies

15 and 16, respectively, at their junction or point of connection to

posts

12 and 13.

These actuating

rods

17 and 17a and

eccentric brackets

50 and 51 constitute conventional means for rotating insulator assemblies and 16 in opposite directions as is well known in the electric power switch art and will be discussed further hereinbelow. The free ends of

rods

17 and 17a are connected, through suitable connecting means, to a bearing member 52 or the like secured to base 11. In this manner, actuating

rods

17 and 17a may be rotated to pivotally open the disconnect switch, as will be explained more fully hereinbelow and such means are well known in the electrical art and thus no further description would appear to be necessary. Further, any suitable means may be provided for rotating rods .17 and 17a about their longitudinal axes and in opposite directions. Rail 11 may be supported above ground by insulated legs 14, if desired.

A pair of

switch blades

18 and 19 which are preferably tubular in configuration are fixedly secured to shafts 53 which are in turn secured to insulator collars 2t) and 21 at the top of each insulator assembly 15, 16 (FIG. 1). As can be seen more clearly in FIG. 2, generally annular collars or rings 54 surround each shaft 53 at the top of the

insular assemblies

15 and 16. Bearing members 55 are provided in the rings 54. Thus, the shafts 53 can rotate within rings 54 while the rings themselves remain stationary.

Blades

18 and 19 are secured to shafts 53 by any suitable means, such as by providing flanges or the like (not visible in FIG. 1) fixedly secured at one end to shafts 53 and at their other ends to

blades

18 and 19 through suitable bolt and clamp means 24 and 25, respectively. Thus, as can be seen in FIG. 3, as the insulator assemblies 15 and 16 are rotated in opposite directions,

switch blades

18 and 19 are rotated in the manner shown in the dotted lines, as will be discussed further hereinbelow.

Conventional terminals

26 and 27 are pivotally secured to the ends of

blades

18 and 19, respectively, adjacent their point of attachment to shafts 53, to receive power cables W. Pivotal connection therebetween is provided by conventional pintle mountings 28 and 29, which are coaxial with

insulator assemblies

15, 16, respectively. Electrical contact between the

blades

18 and 19 and the

terminals

26 and 27 may be made by means of contacts 30 described in U.S. Pat. No. 3,209,087. The particular configuration of

terminals

26 and 27 and their connection to switch

blades

18 and 19 forms no part of this invention, and any other conventional arrangement may be substituted.

As can be seen in FIG. 1 and in solid lines in FIG. 3, the

switch blades

18 and 19 are axially aligned when the switch is closed.

The rotation of a pair of switch blades mounted on rotating insulators into axial alignment with each other is well known in the electrical art. Briefly, the head of one blade, as for example, blade 18, may be a simple rounded nose (FIG. 3) while the other blade, as, for example, blade 19 may carry a conventional flared anticorona cap 45 (see also FIG. 1) with resilient fingers (not shown) disposed inside cap 45 and adapted to be engaged by the head of blade 18 when it is rotated into alignment with switch 19 as shown by the solid lines in FIG. 3. The circle segment of radius a indicates the path of the head end of blade 18 during closure or opening of the switch. Likewise, the circle segment of radius b indicates the path of the blade-receiving fingers inside anti-corona cap 45. Elements 44 are conventional anti-corona devices which are well known in I switches of this type and may be provided at terminals 27, 28 and

blades

18, 19 as shown.

In summary, by operating actuating rod 17, the

insulated assemblies

15 and 16 are rotated, thus moving

switch blades

18 and 19 into and out of contact. The head of switch blade 18 moves into flared spring contact in a male-female relationship with the resilient fingers on blade 19, as for example, about 3 inches into contact therewith (distance C). Any axial movement of sufficient magnitude to approach this 3-inch tolerance and thereby create the danger of formation of an electric arc to burn away a portion of the switch blade or blades before a circuit breaker can be opened may be prevented by providing a locking pin and notch arrangement thereon as disclosed in my aforementioned U.S. Pat. No. 3,634,634. It will be understood that the disconnect switch described herein is not intended to be opened while current is flowing therethrough. Any short-circuit or transient current surge in the power system in which the switch is to be used not only tends to squeeze together and thereby shorten the parallel electric cables associated with the switch, but also tends to create unpredictable mechanical stresses both within and without the switch structure. The conventional operating mechanism of the switch as described hereinabove is sufiiciently strong to resist any rotary or transverse stresses which tend to pull the switch open, but any longitudinal stress may effectively be controlled in practice by the mechanism disclosed in my patent. Of course, my invention is not limited to the particular structure described hereinabove but is adaptable to any electric disconnect switch wherein the switch blades are rotated into generally axial alignment.

The novel features of my invention will now be described. In addition to

insulator assemblies

15 and 16, a pair of tripod supports 56 and 57 are associated with each

assembly

15 and 16. Each support includes at least three spaced insulated legs 58 through 60 secured at their lower ends either directly to base 15a by any suitable means (or to extensions thereon depending upon the size of the bases 15a) and at their upper ends by any suitable means to collars or rings 54 (see FIG. 2). These legs 58 through 60 are preferably generally equally spaced about rings 54 and inclined from the vertical (legs 59 not being visible in FIG. 1). It should be noted that in such an arrangement only two bearing members are required, both on each

assembly

15 and 16 at the top and bottom thereof, and none on the legs 58 through 60. Also, the bearing members may include conventional ball bearings since such bearing members are perpendicular to

assemblies

15 and 16 and no alignment problems are created. Thus, legs 58 through 60 remain stationary as the central vertical leg member or insulating

assembly

15 or 16 rotates.

It is important that legs 58 through 60 extend to the top of the

assemblies

15 and 16. l have found that if the legs 58 through 60 terminated at some point along assemblies l5 and 16 instead of extending to the top thereof, problems would result. Although this arrangement would provide the necessary rigidity to the structure from a mechanical standpoint, the capacitance distribution of such an arrangement might be concentrated at a joint on the central insulator assembly (above the junction with the respective tripod assembly) resulting in fiashovers. My arrangement retains the stability of the tripod structure while reducing the tremendous cost and number of bearings required (more bearing members would be required at the aforementioned junction of each leg with the assembly) and increases the strength of the structure. If further bracing were found to be necessary, it could be provided on the tripod legs without touching the rotating assembly or 16. If my structure were subject to earthquake forces, the

assembly

15 or 16 might break but this would merely inactivate the switching mechanism. Further, breakage of one or more of the legs 58 through 60 would not topple my structure. In such a tripodsupported arrangement, the

central assemblies

15 and 16 may be made smaller and thinner in cross section, thus permitting the use of hearings in the bearing members up to about one-quarter the size required in non-tripod-supported arrangements. The use of

assemblies

15 and 16 without such tripod supports would not render them sufficiently earthquake proof when used with voltage requirements of around 500 kv. to l mv. Finally, this problem would not be solved by merely making the

single assemblies

15, 16 greater in cross section or length since, in addition to being unwieldy, tremendous strain would be put on the necessary bearings and the column structure itself would require materials not yet invented. v

It can be seen from the foregoing that I have described a disconnect switch whichcan be used in today's high voltage requirements, yet would not be costly, dangerous or unwieldy. Further, my switch eliminates alignment and flashover problems which would result in other types of switches.

I claim as my invention:

1. A disconnect switch for an electric power system comprising:

a pair of axially aligned contacting switch blades having non-contacting ends thereon;

a pair of generally vertically disposed elongated insulator assemblies having their lower ends connected to a supporting base member and their upper ends fixedly connected to the non-contacting ends of said switch blades;

means operatively engaging said insulator assemblies for rotating said insulator assemblies about their longitudinal axes and in opposite directions, the rotation of said insulator assemblies moving said blades carried thereby into and out of contacting engagement; and

electrically insulated bracing means operatively connected to each of said insulator assemblies for bracing said assemblies, said bracing means including at least three spaced elongated insulated legs inclined from the vertical and fixedly connected at their lower ends to the base supporting each of said insulator assemblies and having their upper ends extending to the point of connection of said assemblies to their respective switch blades, said bracing means including a bearing member at the upper end thereof having an aperture therein with the upper ends of the three legs fixedly secured to said bearing member, each of said insulator assemblies having their upper ends extending through said aperture and being freely rotatable therein and about said bearing member.

2. The switch of claim 1 including a pair of terminals pivotally connected to the non-contacting ends of each of said switch blades.

3 The switch of claim 1 wherein said insulator assemblies and said legs are electrically insulated along substantially the entire lengths thereof.

4. Apparatus forsupporting a pair of axially aligned contacting switch blades for carrying electric current therethrough comprising:

a pairof generally vertically disposed elongated insulator assemblies having their lower ends connected to a supporting base member and their upper ends fixedly connected to the non-contacting ends of said switch blades; 7.

electrically insulated bracing means operatively connected to each of said insulator assemblies for bracing said assemblies, said bracing means includ ing at least three spaced elongated insulated legs inclined from the vertical and fixedly connected at their lower ends to the base supporting each of said insulator assemblies and having their upper ends extending to the point of connection of said assemblies to their respective switch blades, said bracing means including a bearing member at the upper end thereof having an aperture therein with the upper ends of the three legs fixedly secured to said bearing member, each of said insulator assemblies having their upper ends extending through said aperture and being freely rotatable therein and about said bearing member.

5. The switch of claim 4 including-a pair of terminals pivotally connected to the non-contacting ends of each of said switch blades.

6. The switch of claim 4 wherein said insulator assemblies and said legs are electrically insulated along substantially the entire lengths thereof.

Claims

1. A disconnect switch for an electric power system comprising: a pair of axially aligned contacting switch blades having noncontacting ends thereon; a pair of generally vertically disposed elongated insulator assemblies having their lower ends connected to a supporting base member and their upper ends fixedly connected to the noncontacting ends of said switch blades; means operatively engaging said insulator assemblies for rotating said insulator assemblies about their longitudinal axes and in opposite directions, the rotation of said insulator assemblies moving said blades carried thereby into and out of contacting engagement; and electrically insulated bracing means operatively connected to each of said insulator assemblies for bracing said assemblies, said bracing means including at least three spaced elongated insulated legs inclined from the vertical and fixedly connected at their lower ends to the base supporting each of said insulator assemblies and having their upper ends extending to the point of connection of said assemblies to their respective switch blades, said bracing means including a bearing member at the upper end thereof having an aperture therein with the upper ends of the three legs fixedly secured to said bearing member, each of said insulator assemblies having their upper ends extending through said aperture and being freely rotatable therein and about said bearing member.

3. The switch of claim 1 wherein said insulator assemblies and said legs are electrically insulated along substantially the entire lengths thereof.

4. Apparatus for supporting a pair of axially aligned contacting switch blades for carrying electric current therethrough comprising: a pair of generally vertically disposed elongated insulator assemblies having their lower ends connected to a supporting base member and their upper ends fixedly connected to the non-contacting ends of said switch blades; means operatively engaging said insulator assemblies for rotating said insulator assemblies about their longitudinal axes and in opposite directions, the rotation of said insulator assemblies moving said blades carried thereby into and out of contacting engagement; and electrically insulated bracing means operatively connected to each of said insulator assemblies for bracing said assemblies, said bracing means including at least three spaced elongated insulated legs inclined from the vertical and fixedly connected at their lower ends to the base supporting each of said insulator assemblies and having their upper ends extending to the point of connection of said assemblies to their respective switch blades, said bracing means including a bearing member at the upper end thereof having an aperture therein with the upper ends of the three legs fixedly secured to said bearing member, each of said insulator assemblies having their upper ends extending through said aperture and being freely rotatable therein and about said bearing member.

5. The switch of claim 4 including a pair of terminals pivotally connected to the non-contacting ends of each of said switch blades.