US3671907A

US3671907A - Vacuum switch with power fuse

Info

Publication number: US3671907A
Application number: US92030A
Authority: US
Inventors: Richard G Brunner
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1970-11-23
Filing date: 1970-11-23
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20
Also published as: DE7144074U

Abstract

A vacuum switch used for switching high voltage capacitive loads comprises a support chassis on which a hollow support insulator is mounted. One or more vacuum interrupters, each comprising an insulated envelope and relatively movable contacts, are mounted on the hollow support insulator. Operating means are mounted on the support chassis and comprises an insulated operating rod which extends through the hollow support insulator for operating the vacuum interrupter(s). A replaceable power fuse is provided. Means, including a stand-off insulator and fuse connectors are provided to mount the switch in parallel physical relationship with the hollow support insulator and to electrically connect the fuse in series circuit with the vacuum interrupter(s). In one embodiment, a single vacuum interrupter is provided and it is disposed in parallel physical relationship with the hollow support insulator. In other embodiments, a plurality of vacuum interrupters are provided which are transversely disposed with respect to the hollow support insulator. In one of the other embodiments, one of the vacuum interrupters is physically located within the stand-off insulator.

Description

O Unlted States Patent 5] 3,671,907 Brunner 1 June 20, 1972 [54] VACUUM SWITCH WITH POWER FUSE K y g 'g y sistant .vaminerwltt organ Inventor: Richard Brunnel't Dedham Mass- AttorneyThomas F. Kirby, Lee H. Kaiser and Robert B. Ben- [73] Assignee: Allis-Chalmers Manufacturing Company, 9?

Milwaukee, Wis.

[22] Filed: Nov. 23, 1970 5 ABSTRACT PP .2 92,030 A vacuum switch used for switching high voltage capacitive loads comprises a support chassis on which a hollow support [52] U S 337/4 200/144 B insulator is mounted, One or more vacuum interrupters, each comprising an insulated envelope and relatively movable com 2; tacts, are mounted on the hollow support insulator. Operating 1 e o m 9 l 0 l i l 2 means are mounted on the support chassis and comprises an f insulated operating rod which extends through the hollow support insulator for operating the vacuum interrupter(s). A [56] Re'mnm Cited replaceable power fuse is provided. Means, including a standoff insulator and fuse connectors are provided to mount the UNITED STATES PATENTS switch in parallel physical relationship with the hollow support 3,280,282 10/1966 Rodeseike et al ..337/6 insulator and to electrically connect the fuse in series circuit 2,914,627 1 1/1959 Eichelberger et al ..337/4 X with the vacuum interrupteflsl In one embodiment. a single 3,567,887 3 1971 Maloney ..200 144 8 vacuum interrupter is P and it is p e in Parallel 3,418,439 12/1968 Casey et aL Nico/144B physical relationship with the hollow support insulator. in 3,176,100 3/1965 Hana X other embodiments, a plurality of vacuum lnterrupters are 2,862,080 11/1958 Yonkers. ..337 179 x P j transversely P the hollow support insulator. In one of the other embodiments, FOREIGN PATENTS 0R PL ONS one of the vacuum interrupters is physically located within the stand-off insulator. l,095,74l 12/1967 Great Britain ..200/l44 B 1,080,198 8/1967 Great Britain ..200/ 144 B 6 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to electrical circuit interruption and switching apparatus. More particularly, it relates to vacuum switches used for switching'high voltage capacitive loads.

2. Description of the Prior Art Vacuum switches are used for switching high voltage capacitive loads, such as capacitor banks in high voltage electrical transmission and distribution systems. One type of vacuum switch comprises a hollow support insulator which is mounted on a chassis and on which one or more vacuum interrupters are mounted. Operating means including an insulated rod extending through the hollow support insulator effects operation of the vacuum interrupters. The vacuum interrupters used are to be distinguished from vacuum type circuit breakers in that the former do not have a substantial capability for interrupting high currents. Therefore, since the vacuum interrupters are exposed to high overcurrent conditions caused by overloads and fault conditions, it has been necessary for safety reasons to provide protective devices such as fuses or circuit breakers in series with the vacuum switches. Heretofore, these protective devices were mounted on a separate structure or mounting pad. This approach required numerous costly components which occupied much space, particularly since electrical clearance and insulation factors had to be taken into account. Therefore, a new approach is desirable with overcomes these and other problems and has additional advantages.

SUMMARY OF THE INVENTION In accordance with the present invention, there are provided new and improved vacuum switches which comprise a supporting chassis for location in a low potential region. Hollow support insulator means are mounted on the chassis and at least one vacuum interrupter is supported in a high potential region by the hollow support insulator means. Operating means are provided on the chassis and comprise an insulating operating rod extending through the hollow support insulator means to effect operation of the vacuum interrupter. A replaceable cartridge type power fuse is provided and means are provided for supporting the fuse in the high potential region in series with the vacuum interrupter in a manner which requires minimum space usage and affords maximum accessibility for replacement. Such means comprise stand-oil insulator means transversely disposed with respect to the hollow support insulator means; first fuse connector means on the stand-off insulator means; and second fuse connector means supported by one end of the vacuum interrupter. The fuse is disposed in generally parallel relationship with the hollow support insulator to provide compactness and accessibility. In accordance with one aspect of the invention a single interrupter is provided and it is in axial alignment with respect to the hollow support insulator. In accordance with another aspect of the invention one or more interrupters are provided which are transversely disposed with respect to the hollow support insulator whereas the fuse remains in parallel relationship with the latter. In accordance with still another aspect of the invention the stand-off insulator means is hollow and one of a plurality of vacuum interrupters is disposed therein.

OBJECTS It is an object of the invention to provide new and improved vacuum switches and, particularly, those of a type which comprise one or more series connected vacuum interrupters and replaceable fuses.

Another object is to provide switches of the aforesaid character which are well-suited for application in a wide range of voltage and current ratings.

Another object is to provide such switches which are extremely compact and require no more space and only a few more components than vacuum switches which do not comprise replaceable fuses.

Another object is to provide such switches in which the fuse is easily accessible from the ground level for removal and replacement by a hook-stick device.

Another object is to provide such switches which pose no new or additional electrical clearance problems in a system wherein they are installed.

Another object is to provide such switches which are easily and economically manufactured, which use relatively low cost standardized hardware and components, which are easily serviced and maintained, and which are reliable in use.

Other objects and advantages of the invention will hereinafier appear.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustrates several preferred embodiments of the invention, but it is to be understood that the embodiments illustrated are susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawing:

FIG. 1 is a side elevational view of a first embodiment of a vacuum switch in accordance with the invention which employs a single vacuum interrupter and a single fuse;

FIG. 2 is a side elevational view of a second embodiment which employs two vacuum interrupters and a single fuse; and

FIG. 3 is a side elevational view of a third embodiment which employs four vacuum interrupters and a single fuse.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Referring to FIG. 1 of the drawing, the numeral 10 designates a first embodiment of a vacuum switch in accordance with the invention which is rated, for example, at 15.5 KV. Switch 10 comprises support chassis means such as a metal housing 12 which is understood to be adapted for disposition in a region of low potential, normallyground potential. Hollow support insulator means comprising a skirted hollow ceramic insulator 14 is mounted with its first or lower end 16 adjacent and secured to housing 12. An electrically conductive member or bracket 18 is secured to the second or upper end 20 of insulator l4 and is provided with first or line terminal means 19. Stand-off insulator means comprising a skirted solid ceramic insulator 22 is mounted in transverse relationship with respect to insulator 14 with its first or inner end 24 adjacent and secured to upper end 20 of insulator 14 by means of bracket 18. An electrically conductive member or bracket 26 is secured to the second or outer end 28 of insulator 22. Bracket 26 is provided with second or load terminal means 27 and with a first fuse connector means 29. A vacuum interrupter 30 is mounted in a region of high potential with its first or lower end 32 adjacent and secured to upper end 20 of insulator 14 by means of bracket 18. Interrupter 30 is axially aligned with the axis of insulator l4. Interrupter 30 comprises an evacuated insulating envelope 34 in which a stationary contact 36 and a movable contact 38 are mounted. Envelope 34 is disposed in and protected by an insulated housing 40, preferably of transparent material such as Plexiglass. An electrically conductive bracket 42 has one end 46 supported by the second or upper end 48 of interrupter 30 and is electrically connected to stationary contact 36. The other end 50 of bracket 42 is provided with a second fuse connector means 52. Fuse 44 is a cartridge type or elongated tubular type power fuse of suitable rating having an insulated housing 54 and electrically conductive first and second end members or ferrules S6 and 58 which engage the fuse connector means 29 and 52, respectively. The first end ferrule 56 of fuse 44 is mounted adjacent the second end 28 of stand-off insulator 22 and the second end ferrule 58 of the fuse is mounted adjacent or in line with the second end 48 of vacuum interrupter 30 so that the fuse is parallel to the axis of hollow support insulator 14 and in a vertical disposition with respect to the ground so as to be accessible. Fuse 44 is understood to be removable or replaceable from the ground by means of a hook-stick and is provided with a hook-stick ring 60 on ferrule 58. Stationary contact 36 of interrupter 34 is electrically connected to bracket 42 and movable contact 38 of interrupter 34 is electrically connected to bracket 18. Switch operating means comprising a linkage 64 disposed in housing 12 are provided and the linkage is connected to a reciprocably movable insulated operating rod 66 which extends from housing 12, through hollow insulator l4 and is mechanically connected to movable contact 38 of interrupter 30. Linkage 64 is adapted to move to open and closed position in response to suitable electrical, mechanical, or electromechanical control. means, not shown. Downward movement of rod 66 effected by linkage 64 effects separation of

contacts

38 and 36 of interrupter 30 and opening of switch 10. Upward movement of rod 66 effects closing of

contacts

38 and 36 of interrupter 30 and closing of switch 10. When switch is closed, a current path exists from line terminal 19, through movable contact 38, stationary contact 36, conductor 42, fuse connector 52, fuse 44 and fuse connector 29, to load terminal 27. Fuse 44 is appropriately rated to protect against overcurrent conditions to which switch 10 may be subjected. Since fuse 44 is in series circuit with interrupter 30, if the fuse flows, switch 10 is opened automatically. When this occurs, interrupter 30 is opened in response to actuation of the operating means by operating personnel, fuse 44 is then removed by means of a hook-stick and a new one installed in its place, and interrupter 30 is then reclosed to reestablish the circuit.

Second Embodiment Referring to FIG. 2 of the drawing, the numeral 110 designates a second embodiment of a vacuum switch in accordance with the invention which is rated, for example, at 34.5 KV. Switch 1 10 comprises support chassis means such as a metal housing 112 which is attached to a channel iron beam 113 and understood to be adapted for disposition in a region of low potential, normally ground potential. Hollow support insulator means comprising a skirted hollow ceramic insulator 114 is mounted with its first or lower end 116 adjacent and secured to housing 112. A housing 118 is secured to the second or upper end 120 of insulator 114 and supports a first vacuum interrupter 130 and a second vacuum interrupter 131.

Second interrupter 131 is provided with first or line terminal means 119 which is connected to a stationary contact 117 of interrupter 131. Stand-off insulator means comprising a skirted solid ceramic insulator 122 is mounted in transverse relationship with respect to insulator 1 14 with its first or inner end 124 adjacent lower end 1 16 of insulator 114 and secured to housing 1 12. An electrically conductive member or bracket 126 is secured to the second or outer end 128 of insulator 122. Bracket 126 is provided with second or load terminal means 127 and with a first fuse connector means 129. First vacuum interrupter 130, which is understood to be identical to interrupter 131 is mounted in a region of high potential with its first or inner end 132 adjacent and secured to upper end 120 of insulator 114 by means of a housing 118 in which motion translating means 137 are located. interrupters 130 and 131 are transversely disposed with respect to the axis of insulator 114. lnterrupter 130, which is similar to interrupter 131, comprises an evacuated insulating envelope 134 in which a stationary contact 136 and a movable contact 138 are mounted. Envelope 134 is disposed in and protected by an insulated housing 140, preferably of transparent material such as Plexiglass. An electrically conductive second fuse connector means 152 is supported by the second or outer end 148 of interrupter 130 and is electrically connected to stationary contact 136 thereof. A cartridge type or elongated tubular type power fuse 144 of suitable rating and having an insulated housing 154 and electrically conductive first and second end members or ferrules 156 and 158 engages the fuse connector means 129 and 152, respectively. The first end ferrule 156 of fuse 144 is mounted adjacent the second end 128 of stand-off insulator 122 and the second end ferrule 158 of the fuse is mounted adjacent the second end 148 of vacuum interrupter 130 so that the fuse is parallel to the axis of hollow support insulator 14 but transverse to interrupter 130. Fuse 144 is understood to be removable or replaceable from the ground by means of a hook-stick and is provided with a hook-stick ring 160 on ferrule 158. Movable contact 138 of interrupter 134 is electrically connected to a movable contact 135 of interrupter 131 by a flexible conductor 139. Switch operating means comprising a linkage 164 disposed in housing 112 are provided and the linkage is connected to a reciprocably movable insulated operating rod l66 which extends from housing 112, through hollow insulator l 14 and into housing 118 wherein it connects to motion translating means 137 which comprises a cam plate 141. Cam plate 141 engages the movable contacts 138 and 135 of interrupter 130 and 131, respectively. Linkage 164 is adapted to move to open and closed position in response to suitable electrical, mechanical, or electromechanical control means, not shown. Downward movement of rod 166 effected by linkage 164 elTects separation of contacts 138 and 135 of interrupters 130 and 131, respectively, and opening of switch 110. Upward movement of rod 166 effects closing of contacts 138 and 135 of interrupters 130 and 131, respectively, and closing of switch 110. When switch is closed, a current path exists from line terminal 119, through stationary contact 1 17 and movable contact 135 of interrupter 131, through conductor 139, through movable contact 138 and stationary contact 136 of interrupter 130, fuse connector 152, fuse 144 and fuse connector 129, to load terminal 127. Fuse 144 is appropriately rated to protect against over-current conditions to which switch 110 may be subjected. Since fuse 144 is in series circuit with interrupters and 131, if the fuse blows, switch 110 is opened automatically. When this occurs, interrupters 130 and 131 are opened in response to actuation of the operating means by operating personnel, fuse 144 is then removed by means of a hook-stick and a new one installed in its place, and interrupters 130 and 131 are then reclosed to reestablish the circuit.

Third Embodiment REferring to FIG. 3 of the drawing, the numeral 210 designates a third embodiment of a vacuum switch in accordance with the invention which is rated, for example, at 69 KV. Switch 210 comprises a metal housing 212, a hollow support insulator means including an insulator 214, a housing 216, operating means comprising a linkage 264 having an insulated operating rod 266, and a motion translating means 237 similar to the elements designated l12,1l4,l16,164,166 and 137, respectively, hereinbefore described in connection with FIG. 2. In switch 210 the hollow support insulator means further comprises a second hollow support insulator 214a which is mounted on housing 216 in axial alignment with insulator 214. In addition, a second housing 2160 is mounted on the upper end of insulator 214a and a motion translating means 2370 is disposed therein. The motion translating means 237 and 237a are connected by an insulated operating rod 2660. Switch 210 comprises a first pair of series connected

vacuum interrupters

220 and 222 disposed on opposite sides of housing 216 and a second pair of series connected

vacuum interrupters

224 and 226 disposed on opposite sides of hous ing 216a. The

vacuum interrupters

220 and 222; 224 and 226 are understood to be similar to the vacuum interrupters 131 and 130, respectively, described in connection with FIG. 2. In switch 210 an insulated housing 228 for vacuum interrupter 222 also serves as a stand-off insulator for a replaceable fuse 244 which is similar in construction to fuse 44 hereinbefore described in connection with FIG. 1. The outer ends of the

interrupters

222 and 224 are provided with first and second fuse connector means 229 and 252, respectively. FUse 244 forms a series connection between the

interrupters

222 and 224. The outer ends of the

interrupters

226 and 220 are provided with first (line) and second (load) terminals 219 and 227, respectively. Linkage 264 is adapted to move to open and closed position in response to suitable electrical, mechanical, or electromeehanical control means, not shown. Downward movement of rods 226 and 226a effected by linkage 264 efl'ects separation of the contacts of interrupters 220,222,224 and 226 and opening of switch 210. Upward movement of rods 226 and 2264 efi'ects closing of the contacts of interrupters 220,222,224 and 226 and closing of switch 210. When switch 210 is closed, a current path exists from line terminal 219, through

interrupters

226 and 224, fuse connector 252, fuse 244, fuse connector 229, and

interrupters

222 and 220, to load terminal 227. Fuse 244 is appropriately rated to protect against overcurrent conditions to which switch 210 may be subjected. Since fuse 244 is in series circuit with the

interrupters

226, 224, 222 and 220, if the fuse blows, switch 210 is opened automatically. When this occurs, all

interrupters

220, 222, 224 and 226 are opened in response to actuation of the operating means by operating personnel, fuse 244 is then removed by means of a hook-stick and a new one installed in its place, and the interrupters are then reclosed to reestablish the circuit.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A vacuum switch comprising: a support chassis, hollow support insulator means mounted on said chassis, at least one vacuum interrupter supported by said support insulator means, vacuum interrupter operating means on said support chassis and comprising an insulating operating rod extending through said hollow support insulator means to effect operation of said vacuum interrupter, a replaceable cartridge fuse, and means for supporting said fuse on an axis which is parallel to the axis of said hollow support insulator means and for connecting said fuse in series with said vacuum interrupter, said means comprising: stand-off insulator means having one end supported adjacent the end of said hollow support insulator means most remote from said support chassis and disposed transversely with respect to said hollow support insulator means, first fuse connector means on said stand-off insulator means, and second fuse connector means supported by one end of said vacuum interrupter.

2. A switch according to claim 1 wherein said vacuum interrupter is disposed on an axis which is parallel to said fuse axis.

3. A switch according to claim 2 comprising first terminal means electrically connected to said vacuum interrupter at the end of the latter closest to said hollow support insulator means and further comprising second terminal means electrically connected to said first fuse connector means.

4. A switch according to claim 3 wherein said first terminal means is integral with a conductive support which supports said stand-off insulator means and wherein said second terminal means is integral with said first fuse connector means.

5. A vacuum switch comprising:

a support chassis;

at least one hollow support insulator means mounted on said chassis; at least one pair of series connected vacuum interrupters carried by said support insulator means;

vacuum interrupter operating means extending through said hollow support insulator means to effect operation of said vacuum interrupters;

at least a pair of stand-01f insulator means carried by said chassis and disposed transversely with respect to said hollow support insulator means, at least one of said stand-ofi insulator means serving as an insulator housing for at least one of said series connected vacuum interrupters;

a replaceable cartridge fuse; and,

fuse connector means carried by said stand-off insulator means and operable to releasably receive and connect said cartridge fuse in series with said vacuum interrupters.

6. A vacuum switch comprising:

a support chassis;

at least one hollow support insulator means mounted on said chassis;

a plurality of vacuum interrupters carried by said support insulator means;

vacuum interrupter operating means extending through said hollow support insulator means and operably connected to effect operation of said vacuum interrupters;

a plurality of stand-off insulator means carried by said chassis and disposed transversely with respect to said hollow support insulator means, said stand-ofi insulator means being operable to serve as insulator housing means for said vacuum interrupters;

a replaceable cartridge fuse; and,

fuse connector means carried by said stand-off insulator means and operable to releasably secure and connect said cartridge fuse in series between at least two of said vacuum interrupters in a manner to serve as a series connector therebetween.

Claims

5. A vacuum switch comprising: a support chassis; at least one hollow support insulator means mounted on said chassis; at least one pair of series connected vacuum interrupters carried by said support insulator means; vacuum interrupter operating means extending through said hollow support insulator means to effect operation of said vacuum interrupters; at least a pair of stand-off insulator means carried by said chassis and disposed transversely with respect to said hollow support insulator means, at least one of said stand-off insulator means serving as an insulator housing for at least one of said series connected vacuum interrupters; a replaceable cartridge fuse; and, fuse connector means carried by said stand-off insulator means and operable to releasably receive and connect said cartridge fuse in series with said vacuum interrupters.

6. A vacuum switch comprising: a support chassis; at least one hollow support insulator means mounted on said chassis; a plurality of vacuum interrupters carried by said support insulator means; vacuum interrupter operating means extending through said hollow support insulator means and operably connected to effect operation of said vacuum interrupters; a plurality of stand-off insulator means carried by said chassis and disposed transversely with respect to said hollow support insulator means, said stand-off insulator means being operable to serve as insulator housing means for said vacuum interrupters; a replaceable cartridge fuse; and, fuse connector means carried by said stand-off insulator means and operable to releasably secure and connect said cartridge fuse in series between at least two of said vacuum interrupters in a manner to serve as a series connector therebetween.