GROUNDING-SWITCH DEVICE
United States Patent 3603752
A grounding switch device is provided capable of utilizing the same type of mechanism as a circuit breaker, and adapted for substitution for the circuit breaker structure in metal-clad switchgear equipment. Each pole-unit is provided with a selector switch capable of being manually positioned in either one of two positions, for grounding either the line terminal or the bus terminal, and, additionally, the pole-unit includes a grounding switch capable of being actuated by the quick-acting circuit breaker type of operating mechanism. The grounding device is of the same dimensions and can be rolled into the same cell structure of the metal-clad switchgear equipment which accommodates the circuit breaker unit.
US Patent References:
Multi-break compressed-gas circuit interrupters with rotating gasconducting bridging members
Colclaser, Jr. et al. - December 1967 - 3356809
Disconnect switch
McKinnon - December 1967 - 3356798
Multi-break compressed-gas circuit interrupters with rotating gasconducting bridging members
Colclaser, Jr. et al. - December 1967 - 3356809
Disconnect switch
McKinnon - December 1967 - 3356798
Application Number:
05/003182
Publication Date:
09/07/1971
Filing Date:
01/15/1970
Export Citation:
Assignee:
Westinghouse Electric Corporation (Pittsburgh, PA)
Primary Class:
Other Classes:
200/50.230, 218/5, 218/84
International Classes:
H02B11/22; H02B11/28; H02B11/00; H01H33/00
Field of Search:
200/148B,148F,148H,148R,15B,15C
View Patent Images:
Primary Examiner:
Macon, Robert S.
Claims:
I claim as my invention
1. In metal-clad switchgear equipment, the combination of:
2. The combination of claim 1, wherein the grounding switch device is interchangeable with a circuit-breaker unit and may be rolled into the cubicle structure of metal-clad switchgear equipment.
3. The combination of claim 1, wherein the grounding switch device comprises a tank structure having the movable selector switch and the movable grounding switch disposed together within the tank structure.
4. The combination of claim 1, wherein the grounding switch device includes a mechanical linkage which is in toggle in the closed position of the movable grounding switch.
5. The combination of claim 1, wherein the grounding switch device includes a mechanical linkage which is in toggle in the closed position of the selector switch.
6. The combination of claim 1, wherein the grounding switch device has a mechanical linkage for both the selector switch and the movable grounding switch, each of which is in toggle in the closed position of the respective switch.
7. The combination of claim 3, wherein the tank structure encloses a high insulating gas having high dielectric properties.
8. The combination of claim 1, wherein the grounding switch device has the selector switch and grounding switch both rotatively mounted upon an insulator barrier plate.
9. The combination of claim 8, wherein two spaced insulating barrier plates in parallel relation are used.
10. The combination of claim 3, wherein an insulating barrier plate is removably disposed within the tank structure and rotatively supports both the selector switch and the grounding switch.
11. In metal-clad switchgear equipment, the combination of:
12. The combination of claim 11, wherein the selector-switch assembly and grounding-switch assembly are rotatively supported on an insulating barrier plate.
13. The combination of claim 3, wherein a viewing window is located between the bus and line terminals.
14. The combination of claim 11, wherein a viewing window is located between the line and bus terminals.
1. In metal-clad switchgear equipment, the combination of:
2. The combination of claim 1, wherein the grounding switch device is interchangeable with a circuit-breaker unit and may be rolled into the cubicle structure of metal-clad switchgear equipment.
3. The combination of claim 1, wherein the grounding switch device comprises a tank structure having the movable selector switch and the movable grounding switch disposed together within the tank structure.
4. The combination of claim 1, wherein the grounding switch device includes a mechanical linkage which is in toggle in the closed position of the movable grounding switch.
5. The combination of claim 1, wherein the grounding switch device includes a mechanical linkage which is in toggle in the closed position of the selector switch.
6. The combination of claim 1, wherein the grounding switch device has a mechanical linkage for both the selector switch and the movable grounding switch, each of which is in toggle in the closed position of the respective switch.
7. The combination of claim 3, wherein the tank structure encloses a high insulating gas having high dielectric properties.
8. The combination of claim 1, wherein the grounding switch device has the selector switch and grounding switch both rotatively mounted upon an insulator barrier plate.
9. The combination of claim 8, wherein two spaced insulating barrier plates in parallel relation are used.
10. The combination of claim 3, wherein an insulating barrier plate is removably disposed within the tank structure and rotatively supports both the selector switch and the grounding switch.
11. In metal-clad switchgear equipment, the combination of:
12. The combination of claim 11, wherein the selector-switch assembly and grounding-switch assembly are rotatively supported on an insulating barrier plate.
13. The combination of claim 3, wherein a viewing window is located between the bus and line terminals.
14. The combination of claim 11, wherein a viewing window is located between the line and bus terminals.
Description:
CROSS-REFERENCES TO RELATED APPLICATION
Applicant is not aware of any related application pertinent to the present invention; however, the circuit-breaker structure is described in a number of applications, such as U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,740, by Russell E. Frink and William H. Fischer, entitled "Fluid-Blast Circuit Interrupter With Piston Assembly and Electromagnetic Driving Means," and assigned to the assignee of the instant application.
BACKGROUND OF THE INVENTION
It is desirable to be able to ground high-voltage electrical circuits to ensure the safety of workmen working on either these circuits, or associated apparatus. In the case of metal-clad switchgear, all conductors are so insulated that the only points available to safely apply grounds through a circuit are at the primary disconnecting contacts, thereby making it necessary to provide a grounding device for use with these contacts, namely the bus or line contacts, in the metal-clad switchgear.
There is some hazard involved in case the operator makes a mistake, and starts to ground a live circuit. In order to avoid this risk to life and property, various devices have been made for checking and interlocking against applying grounds to a live circuit. However, under certain conditions it may be desirable to ground a live circuit, providing the grounding device is capable of making the ground connection with safety. The device should, consequently, provide for grounding either the bus, or the line circuits available in a metal-clad switchgear housing.
In any electrical power system, it is frequently necessary to make repairs or alterations to the equipment connected to the circuit. The usual operation procedure in such a case always is to connect the electrical circuit of such equipment to ground potential, thereby establishing conditions, such that contact with the electrical circuit will not be injurious either to personnel, or to the equipment. Such precaution is, of course, necessary to prevent dangerous working conditions. The dangers of contact with energized circuits at high voltages will thereby be removed. The dangers of contact with energized circuits, after previously being deenergized, will, correspondingly, be decreased.
It has been common practice to use a ground-and-test device in conjunction with metal-clad switchgear during maintenance periods. This is, of course, a device which is interchangeable with a circuit breaker, which can ground either bus or line circuits in the switchgear cell.
Such a device must have the same insulation level and the same momentary and short-time current ratings as the switchgear. Because it must be able to ground a circuit, which may be energized, without damage or danger to personnel, it must be mechanism-operated. Such devices are available for 5 and 15 kv. metal-clad switchgear, but for high voltages, such as 23 and 34.5 kv. which may be insulated with sulfur-hexafluoride (SF 6 ) gas, or other dielectric gas, available space prevents following established design practice.
SUMMARY OF THE INVENTION
It is, accordingly, a general object of the present invention to provide an improved grounding switch device, which will be simple and efficient in operation, and which may be economically manufactured and installed.
Another object of the present invention is to provide an improved grounding switch device, which will facilitate the grounding of any given electrical circuit, such as a bus or line circuit, within an enclosed-type switchgear installation.
Still a further object of the present invention is to provide an improved grounding switch device for metal-clad switchgear, which is interchangeable with the circuit-breaker unit, which is normally used within the cell structure, and is removable therefrom.
Another object of the present invention is to provide an improved grounding switch, which will selectively ground either the line or bus terminals with a selector-switch mechanism.
Another object of the present invention is the provision of an improved grounding switch having both a separately operable selector switch and a grounding switch, with the grounding switch preferably being operated from a circuit-breaker mechanism of usual type.
Another object of the present invention is to provide an improved grounding switch in which the operator may be able to see directly the position of the selector switchblade before the device is inserted into the cell structure.
In accordance with a preferred embodiment of the invention, a tank-type grounding switch is provided capable of retaining a highly insulating gas, such as sulfur-hexafluoride (SF 6 ) gas, involving both a selector switch, which is preferably manually operated to one of two desired positions, and additionally enclosing a grounding switch, which is capable of operation by a circuit-breaker type of mechanism.
In accordance with a preferred embodiment of the invention, the grounding switch is rotatably actuated to move a conducting blade into the finger-contact structure of the associated rotatable selector switch, the latter having an insulating link connection to an operating shaft, which may be manually operated to a desired selected position externally of the tank structure. This would involve contact with either the bus or line terminals.
In a three-phase installation, preferably the crankarm structures for all the selector switches of the several pole-units are all tied together, and may be operated manually externally of the equipment.
Further objects and advantages will become readily apparent upon reading the following specification, taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view, partly in section, of the grounding switch of the present invention moved into the metal-clad switchgear cell structure, and showing its association with related line-and-bus equipment;
FIG. 2 is an enlarged end front elevational view of the grounding-switch structure of FIG. 1;
FIG. 3 is a side elevational view of the grounding-switch structure of FIG. 2, with the grounding switch shown in the open position;
FIG. 4 is a longitudinal sectional view taken through the enclosed tank structure indicating the position of the grounding switch device, in which the front bus terminal bushing is grounded;
FIG. 5 is a sectional end view taken substantially along the line V--V of FIG. 4;
FIG. 6 is a detailed view of the selector-switch supporting structure; and,
FIG. 7 is an end elevational view of the selector-switch supporting structure of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It is common practice to use a ground-and-test device in conjunction with metal-clad switchgear during maintenance periods. This is a device which is interchangeable with a circuit breaker, which can ground either circuit in the metal-clad switchgear cell structure. Such a device must have the same insulation level and the same momentary and short-time current ratings as the switchgear. Because it must be able to ground a circuit, which may be energized, without damage or danger to personnel, it must be mechanism-operated. Such devices are available for 5 and 15 kv. metal-clad switchgear, but for high voltages, say 23 and 34.5 kv. which may be insulated, for example, with sulfur-hexafluoride (SF 6 ) gas, or other dielectric gas, available space prevents following established design practice.
The present invention relates to a grounding switch device, which is adaptable for grounding either the bus or line circuits of metal-clad switchgear equipment. As shown in FIGS. 1-3, essentially, the device 1 comprises three grounded metallic tanks 3 equipped with porcelain bushings 5, 7, and an operating mechanism 9, all mounted on a structural steel frame 11, which may be equipped with wheels 13, for motion into a cell structure 15 in place of the usually employed circuit-breaker unit, as illustrated in FIG. 1 of the drawings.
A section of the individual pole-unit "A" is shown in FIGS. 4 and 5 of the drawings. Generally, the tank assembly 3 is similar to the tanks, which have been employed for circuit-breaker use, such as set forth in U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,740, by Russell E. Frink and William H. Fischer, and assigned to the assignee of the instant application. Reference may be had to FIG. 35 of the aforesaid patent application, Ser. No. 576,740, to show the use of the circuit-breaker structure within the associated cell structure 15.
With reference to FIGS. 4 and 5, it will be noted that there is provided an additional rotating shaft 17 provided at the lower right-hand end of the tank assembly 3 to cause the operation of a selector switch, generally designated by the reference numeral 19. Also, an additional change from the circuit-breaker application is an access port 21, which has been provided between the terminal bushings 5, 7 to visually determine the position of the selector switchblade 23.
A contact-and-barrier assembly 25, shown in more detail in FIGS. 6 and 7, has been provided within the tanks 3 being secured to the end plates 3a, 3b by mounting bolts 27. Generally, the contact-and-barrier assembly 25 comprises two barriers 25a, 25b, formed on insulating material, between which are clamped connector assemblies 29, 31, and the selector-switch assembly 19, which is rotatably actuated. The connector assemblies 29, 31 clamp to the lower ends of the terminal bushings 5, 7, and carry sets of finger contacts 29a, 31a, which cooperate with the blade 23 of the selector switch 19. The hinge member 19a of the selector switch assembly 19 also carries a set of contact fingers 19b, which cooperate with a grounding switchblade, designated by the reference numeral 33. The hinge member 35 of the grounding switch blade 33 is bolted to a pad 36 welded in the bottom of the tank 3. Externally, a ground bus 38 is bolted to the bottoms of the pads 36 in all three tanks 3, and is connected to the ground contact 40 (FIG. 3) of the grounding switch. The blades 33 of the grounding switch 1 are connected by insulating links 42 to a lever 44, which is pinned to an operating shaft 46. Another lever 48, which may be secured, as by welding, to the outside end of this operating shaft 46 is connected by links 50 to the circuit-breaker operating mechanism 9, so that opening and closing the mechanism 9 causes the respective opening and closing of the grounding switch 1. The selector switchblade 23 is operated by an insulating link 52, which attaches to a lever 54, which is pinned to the shaft 17. Externally of the tank structure 3, the levers 56 (FIG. 5) of the shaft assemblies 17 are connected by links 58 to a cross-shaft 60, which is connected to a manually-operable handle, designated by the reference numeral 62 in FIG. 2.
OPERATION OF GROUNDING SWITCH 1
In operation, the tanks 3 are filled with a suitable insulating gas 64, such as sulfur-hexafluoride (SF 6 ) gas, under pressure. If it is desired to ground the circuits, which are connected to the rear breaker studs, which may be the line circuits, the selector switch 19 is connected to the rear terminal bushings 7 by operating the handle 62 manually to connect the selector switch 19 with the rear terminal bushings 7. The handle 62 is then removed, and the grounding device 1 is inserted within the cell structure 15 in place of the circuit breaker. Closing the breaker mechanism 9 operates the grounding switch 33, which grounds the selector switch 19 and consequently the rear terminal bushings 7.
If the selector switch 19 had been connected to the front terminal bushings, such as the bus terminals, for example, grounding-switch operation would correspondingly ground the front terminal bushings 5.
It will be noted that the linkages 42, 52 of both the grounding switch 33 and the selector switch 19 have been designed in such a way that in the connected positions, such as illustrated in FIGS. 4 and 5, the linkages 42, 52 are in toggle, which prevents their blowing open due to high-fault currents.
Based on experience at the lower voltages, some utility customers require that the operators be able to see directly the position of the selector switchblade 23 before the device 1 is inserted into the cell structure 15. If this is the case, the access port 21 between the terminal bushings 5, 7 may contain a transparent window 21a.
From the foregoing description, it will be apparent that there has been provided an improved grounding switch 1 incorporating a selector switch 19 and a grounding switch 33. The selector switch 19 is capable of movement to either one of two selected positions, for grounding either the front or rear terminal bushings 5, 7 of the cell structure 15, and the grounding switch 33 is capable of operation by the operating mechanism 9, similar to that used for circuit breakers, but of a lighter construction. The visible port 21 enables a visual inspection of the position of the selector switch blade 23, when desired.
Although there has been illustrated and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.
Applicant is not aware of any related application pertinent to the present invention; however, the circuit-breaker structure is described in a number of applications, such as U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,740, by Russell E. Frink and William H. Fischer, entitled "Fluid-Blast Circuit Interrupter With Piston Assembly and Electromagnetic Driving Means," and assigned to the assignee of the instant application.
BACKGROUND OF THE INVENTION
It is desirable to be able to ground high-voltage electrical circuits to ensure the safety of workmen working on either these circuits, or associated apparatus. In the case of metal-clad switchgear, all conductors are so insulated that the only points available to safely apply grounds through a circuit are at the primary disconnecting contacts, thereby making it necessary to provide a grounding device for use with these contacts, namely the bus or line contacts, in the metal-clad switchgear.
There is some hazard involved in case the operator makes a mistake, and starts to ground a live circuit. In order to avoid this risk to life and property, various devices have been made for checking and interlocking against applying grounds to a live circuit. However, under certain conditions it may be desirable to ground a live circuit, providing the grounding device is capable of making the ground connection with safety. The device should, consequently, provide for grounding either the bus, or the line circuits available in a metal-clad switchgear housing.
In any electrical power system, it is frequently necessary to make repairs or alterations to the equipment connected to the circuit. The usual operation procedure in such a case always is to connect the electrical circuit of such equipment to ground potential, thereby establishing conditions, such that contact with the electrical circuit will not be injurious either to personnel, or to the equipment. Such precaution is, of course, necessary to prevent dangerous working conditions. The dangers of contact with energized circuits at high voltages will thereby be removed. The dangers of contact with energized circuits, after previously being deenergized, will, correspondingly, be decreased.
It has been common practice to use a ground-and-test device in conjunction with metal-clad switchgear during maintenance periods. This is, of course, a device which is interchangeable with a circuit breaker, which can ground either bus or line circuits in the switchgear cell.
Such a device must have the same insulation level and the same momentary and short-time current ratings as the switchgear. Because it must be able to ground a circuit, which may be energized, without damage or danger to personnel, it must be mechanism-operated. Such devices are available for 5 and 15 kv. metal-clad switchgear, but for high voltages, such as 23 and 34.5 kv. which may be insulated with sulfur-hexafluoride (SF 6 ) gas, or other dielectric gas, available space prevents following established design practice.
SUMMARY OF THE INVENTION
It is, accordingly, a general object of the present invention to provide an improved grounding switch device, which will be simple and efficient in operation, and which may be economically manufactured and installed.
Another object of the present invention is to provide an improved grounding switch device, which will facilitate the grounding of any given electrical circuit, such as a bus or line circuit, within an enclosed-type switchgear installation.
Still a further object of the present invention is to provide an improved grounding switch device for metal-clad switchgear, which is interchangeable with the circuit-breaker unit, which is normally used within the cell structure, and is removable therefrom.
Another object of the present invention is to provide an improved grounding switch, which will selectively ground either the line or bus terminals with a selector-switch mechanism.
Another object of the present invention is the provision of an improved grounding switch having both a separately operable selector switch and a grounding switch, with the grounding switch preferably being operated from a circuit-breaker mechanism of usual type.
Another object of the present invention is to provide an improved grounding switch in which the operator may be able to see directly the position of the selector switchblade before the device is inserted into the cell structure.
In accordance with a preferred embodiment of the invention, a tank-type grounding switch is provided capable of retaining a highly insulating gas, such as sulfur-hexafluoride (SF 6 ) gas, involving both a selector switch, which is preferably manually operated to one of two desired positions, and additionally enclosing a grounding switch, which is capable of operation by a circuit-breaker type of mechanism.
In accordance with a preferred embodiment of the invention, the grounding switch is rotatably actuated to move a conducting blade into the finger-contact structure of the associated rotatable selector switch, the latter having an insulating link connection to an operating shaft, which may be manually operated to a desired selected position externally of the tank structure. This would involve contact with either the bus or line terminals.
In a three-phase installation, preferably the crankarm structures for all the selector switches of the several pole-units are all tied together, and may be operated manually externally of the equipment.
Further objects and advantages will become readily apparent upon reading the following specification, taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view, partly in section, of the grounding switch of the present invention moved into the metal-clad switchgear cell structure, and showing its association with related line-and-bus equipment;
FIG. 2 is an enlarged end front elevational view of the grounding-switch structure of FIG. 1;
FIG. 3 is a side elevational view of the grounding-switch structure of FIG. 2, with the grounding switch shown in the open position;
FIG. 4 is a longitudinal sectional view taken through the enclosed tank structure indicating the position of the grounding switch device, in which the front bus terminal bushing is grounded;
FIG. 5 is a sectional end view taken substantially along the line V--V of FIG. 4;
FIG. 6 is a detailed view of the selector-switch supporting structure; and,
FIG. 7 is an end elevational view of the selector-switch supporting structure of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It is common practice to use a ground-and-test device in conjunction with metal-clad switchgear during maintenance periods. This is a device which is interchangeable with a circuit breaker, which can ground either circuit in the metal-clad switchgear cell structure. Such a device must have the same insulation level and the same momentary and short-time current ratings as the switchgear. Because it must be able to ground a circuit, which may be energized, without damage or danger to personnel, it must be mechanism-operated. Such devices are available for 5 and 15 kv. metal-clad switchgear, but for high voltages, say 23 and 34.5 kv. which may be insulated, for example, with sulfur-hexafluoride (SF 6 ) gas, or other dielectric gas, available space prevents following established design practice.
The present invention relates to a grounding switch device, which is adaptable for grounding either the bus or line circuits of metal-clad switchgear equipment. As shown in FIGS. 1-3, essentially, the device 1 comprises three grounded metallic tanks 3 equipped with porcelain bushings 5, 7, and an operating mechanism 9, all mounted on a structural steel frame 11, which may be equipped with wheels 13, for motion into a cell structure 15 in place of the usually employed circuit-breaker unit, as illustrated in FIG. 1 of the drawings.
A section of the individual pole-unit "A" is shown in FIGS. 4 and 5 of the drawings. Generally, the tank assembly 3 is similar to the tanks, which have been employed for circuit-breaker use, such as set forth in U.S. Pat. application filed Sept. 1, 1966, Ser. No. 576,740, by Russell E. Frink and William H. Fischer, and assigned to the assignee of the instant application. Reference may be had to FIG. 35 of the aforesaid patent application, Ser. No. 576,740, to show the use of the circuit-breaker structure within the associated cell structure 15.
With reference to FIGS. 4 and 5, it will be noted that there is provided an additional rotating shaft 17 provided at the lower right-hand end of the tank assembly 3 to cause the operation of a selector switch, generally designated by the reference numeral 19. Also, an additional change from the circuit-breaker application is an access port 21, which has been provided between the terminal bushings 5, 7 to visually determine the position of the selector switchblade 23.
A contact-and-barrier assembly 25, shown in more detail in FIGS. 6 and 7, has been provided within the tanks 3 being secured to the end plates 3a, 3b by mounting bolts 27. Generally, the contact-and-barrier assembly 25 comprises two barriers 25a, 25b, formed on insulating material, between which are clamped connector assemblies 29, 31, and the selector-switch assembly 19, which is rotatably actuated. The connector assemblies 29, 31 clamp to the lower ends of the terminal bushings 5, 7, and carry sets of finger contacts 29a, 31a, which cooperate with the blade 23 of the selector switch 19. The hinge member 19a of the selector switch assembly 19 also carries a set of contact fingers 19b, which cooperate with a grounding switchblade, designated by the reference numeral 33. The hinge member 35 of the grounding switch blade 33 is bolted to a pad 36 welded in the bottom of the tank 3. Externally, a ground bus 38 is bolted to the bottoms of the pads 36 in all three tanks 3, and is connected to the ground contact 40 (FIG. 3) of the grounding switch. The blades 33 of the grounding switch 1 are connected by insulating links 42 to a lever 44, which is pinned to an operating shaft 46. Another lever 48, which may be secured, as by welding, to the outside end of this operating shaft 46 is connected by links 50 to the circuit-breaker operating mechanism 9, so that opening and closing the mechanism 9 causes the respective opening and closing of the grounding switch 1. The selector switchblade 23 is operated by an insulating link 52, which attaches to a lever 54, which is pinned to the shaft 17. Externally of the tank structure 3, the levers 56 (FIG. 5) of the shaft assemblies 17 are connected by links 58 to a cross-shaft 60, which is connected to a manually-operable handle, designated by the reference numeral 62 in FIG. 2.
OPERATION OF GROUNDING SWITCH 1
In operation, the tanks 3 are filled with a suitable insulating gas 64, such as sulfur-hexafluoride (SF 6 ) gas, under pressure. If it is desired to ground the circuits, which are connected to the rear breaker studs, which may be the line circuits, the selector switch 19 is connected to the rear terminal bushings 7 by operating the handle 62 manually to connect the selector switch 19 with the rear terminal bushings 7. The handle 62 is then removed, and the grounding device 1 is inserted within the cell structure 15 in place of the circuit breaker. Closing the breaker mechanism 9 operates the grounding switch 33, which grounds the selector switch 19 and consequently the rear terminal bushings 7.
If the selector switch 19 had been connected to the front terminal bushings, such as the bus terminals, for example, grounding-switch operation would correspondingly ground the front terminal bushings 5.
It will be noted that the linkages 42, 52 of both the grounding switch 33 and the selector switch 19 have been designed in such a way that in the connected positions, such as illustrated in FIGS. 4 and 5, the linkages 42, 52 are in toggle, which prevents their blowing open due to high-fault currents.
Based on experience at the lower voltages, some utility customers require that the operators be able to see directly the position of the selector switchblade 23 before the device 1 is inserted into the cell structure 15. If this is the case, the access port 21 between the terminal bushings 5, 7 may contain a transparent window 21a.
From the foregoing description, it will be apparent that there has been provided an improved grounding switch 1 incorporating a selector switch 19 and a grounding switch 33. The selector switch 19 is capable of movement to either one of two selected positions, for grounding either the front or rear terminal bushings 5, 7 of the cell structure 15, and the grounding switch 33 is capable of operation by the operating mechanism 9, similar to that used for circuit breakers, but of a lighter construction. The visible port 21 enables a visual inspection of the position of the selector switch blade 23, when desired.
Although there has been illustrated and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.