FIELD OF THE INVENTION
The present invention pertains to current interrupting switchgear for power distribution systems. More particularly, the present invention relates to a three-phase, four-way, submersible loadbreak vacuum interrupter switchgear with internal ground switches for power distribution systems. More particularly, the present invention relates to a design that can be utilized to make three-phase, multi-way vacuum interrupter switchgear with internal ground switches for power distribution systems.
BACKGROUND
Electric utility power distribution systems are frequently constructed underground for a variety of reasons ranging from objections to the above-ground aesthetics, the premium of above-ground space in dense urban locations, and safety concerns. Accordingly, power distribution systems heretofore constructed of poles, wires, and pole-mounted switches and transformers are being superseded and even replaced by underground systems in underground “vaults”.
In an electric utility power distribution system, switchgear is the combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults down the line. Switchgear is also used to distribute power to different areas within the system. Thus, this type of equipment is important to the distribution of reliable electricity within a power system.
The size and weight of three-phase switchgear govern their installation to on-surface or underground locations. While overhead space is relatively open and unrestricted, surface space is somewhat restricted and space in underground installations is more so and at a higher premium. Thus, switchgear have dimensional restrictions imposed on them, especially for underground installations. The size of a regular switchgear using only air as an insulating medium is quite large. In order to reduce size, oil or SF6 gas was, and is, currently used in many switchgear. However, current environmental concerns discourage the use of these insulating medium. Oil and SF6 gas can be flammable and/or explosive, and present environmental problems when leakage occurs and when emissions are created.
Three-phase, two-way, vacuum interrupter switchgear have been manufactured for use in power distribution systems. The common design of these switchgear is to entirely encapsulate the vacuum bottles in a polymeric material. This design does not allow an operator to visually confirm that the switchgear is in an “open” state and may not safely contain an explosion if the switchgear closes into a fault. These safety hazards were addressed in published U.S. Patent Application No. US-2011-0253675-A1 (the content of which is hereby incorporated by reference) by adding a disconnect switch with viewing window and by encasing the vacuum bottle assemblies within a sturdy stainless steel case. The addition of a viewing window and disconnect switch to the encapsulated design does not, however, address the potential explosion hazard if the switchgear were to close into a fault.
SUMMARY OF THE INVENTION
The present invention pertains to three-phase, multi-way submersible loadbreak vacuum interrupter switchgear designed to replace oil-insulated and SF6 gas-insulated switchgear used in three-phase power distribution systems. Aside from the environmental safety aspects addressed by the elimination of oil and SF6 gas, switchgear constructed in accordance with the present invention also address operational safety aspects by integrating ground switches and using interlocking operating mechanisms to ensure proper operating procedures. Moreover, the preferred component arrangement within switchgear thus constructed embodies a design that can be utilized to easily provide three-phase, multi-way (i.e., 2-way, 3-way, 4-way, 5-way, etc.) vacuum interrupter switchgear with internal ground switches.
Accordingly, a three-phase, multi-way submersible loadbreak vacuum interrupter switchgear is described which provides an internal ground switch and meets the dimensional constraints imposed by utility demands while providing the safety and ecological benefits of a vacuum interrupting switch.
When switchgear is “turned off”, some residual current may still remain. Vacuum interrupter switch gear herein employs ground switch assemblies associated with the disconnect switch assembly and the vacuum bottle assembly to ground such residual current as part of the deactivation process so that it is safe to have maintenance work performed.
A ground can be external or made internal to the switchgear. When a ground switch assembly is built into the switchgear, an interlocking mechanism ensures that the deactivated disconnect switch assembly, deactivated vacuum interrupter bottle switch assembly and the corresponding ground switch assembly are switched in a sequence that ensures proper and safe operation. Conversely, the interlocking mechanism ensures that an activated disconnect switch assembly, activated vacuum interrupter bottle switch assembly and the corresponding ground switch assembly are switched in a sequence that ensures proper and safe operation. an interlocking mechanism can be used to force proper and safe operation.
By way of example, a 4-way submersible loadbreak vacuum interrupter switchgear is described and illustrated, but those of ordinary skill in the art will recognize that the number of “ways” may be more or less than 4 without departing from the scope of the invention; the preferred component configuration can in fact simply be repeated sufficiently to make three-phase multi-way switchgear with internal ground switches serving the desired number of branches. Switchgear constructed in accordance with the invention minimizes potential hazards such as oil and gas leakage and explosion in a populated surface location and/or within the confined space of an underground power distribution vault.
Other objects, advantages and significant features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the invention.
It will be understood that orientations described in this specification, such as “up”, “down”, “top”, “side” and the like, are relative and are used for the purpose of describing the invention with respect to the drawings. Those of ordinary skill in the art will recognize that the orientation of the disclosed device can be varied in practice, and that the orientation used herein has been chosen for explanatory purposes only. Similarly, it will be recognized by those skilled in the art that the materials referred to herein, and particularly those identified by trademark, are examples of materials that meet the requirements and specifications mandated by safety concerns and by the use of the invention with electric power lines. Accordingly, other acceptable materials are within the scope of the invention whether known by generic names and/or other trademarks, or comprising other functionally equivalent material.
DESCRIPTION OF THE DRAWING
In the drawing,
FIG. 1 is a right front perspective view of a preferred three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch constructed in accordance with the invention;
FIG. 2 is a right front perspective view of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 1, partially broken away to illustrate some internal components;
FIG. 3 is a cut-away front elevation view, in schematic, illustrating the internal layout of the ground switch, disconnect switch, and vacuum interrupter bottle switch assemblies in the preferred building block design of the invention;
FIG. 4 is a top view, in schematic, of a single-phase building block of FIG. 3;
FIG. 5 is a top view, in schematic, of the three-phase building block design of FIG. 3;
FIG. 6 is a cut-away right side elevation view, in schematic, of the building block design of FIG. 3, illustrating the internal layout of the ground switch assembly components;
FIG. 7 is a cut-away right side elevation view, in schematic, of the building block design of FIG. 3, illustrating the internal layout of the disconnect switch assembly components;
FIG. 8 is a cut-away right side elevation view, in schematic, of the building block design of FIG. 3, illustrating the internal layout of the vacuum interrupter bottle assembly components;
FIG. 9 is a front elevation view, in schematic, illustrating a preferred design of a three-phase, two-way submersible loadbreak vacuum interrupter switchgear with internal ground switch;
FIG. 10 is a cut-away front elevation view, in schematic, of a three-phase, three-way submersible loadbreak vacuum interrupter switchgear with internal ground switch based on FIGS. 3 and 8, illustrating the internal layout of components for the ground switch, disconnect switch and vacuum interrupter bottle switch assemblies;
FIG. 11 is a cut-away top plan view, in schematic, of a three-phase, three-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 10, illustrating the internal layout of components for the ground switch, disconnect switch and vacuum interrupter bottle switch assemblies;
FIG. 12 is a cut-away front elevation view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 1, illustrating the internal layout of components for the ground switch, disconnect switch and vacuum interrupter bottle switch assemblies;
FIG. 13 is a cut-away top view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 12, illustrating the internal layout of connection buses to the ground switch, disconnect switch and vacuum interrupter bottle switch assemblies;
FIG. 14 is a front elevation view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 12, illustrating the viewing windows and positions of the handles and rods for the ground and disconnect switches;
FIG. 15 is a top elevation view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 14, illustrating the switch status indicators;
FIG. 16 is a front elevation view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 14, illustrating the attachment of power cables;
FIG. 17 is a top elevation view, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 15, illustrating the attachment of power cables;
FIGS. 18A-H are schematic illustrations of the operating handles' preferred interlocking mechanism for ensuring proper opening and closing of the switch assemblies within the switchgear.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
For the sake of brevity, it will be understood that a description of a component having an “a” suffix following its reference numeral will also serve as a description of a corresponding component having a “b”, “c”, “d”, etc. suffix service unless otherwise stated in the specification or as evident from the Figures. Likewise, a set of three corresponding components may be referred to with the suffix “a-c”, “d-f”, “g-i”, and “j-l” following the reference numeral. All corresponding components may be referred to, when appropriate, with the suffix denoting all the corresponding components following the reference numeral: e.g., “a-l”.
The currently preferred vacuum interrupter bottle switch assemblies used in the preferred switchgear described herein are the same as the ones in published International Patent Application PCT WO 2009-108729 and the disconnect switch assemblies used are the same as the ones in published U.S. Patent Application No. US-2011-0253675-A1. The content of the foregoing two patent applications are hereby incorporated by reference and, thus, these assemblies will not be discussed in detail here for the sake of brevity.
Referring to FIGS. 1 and 2, a currently preferred three-phase, four-way, submersible loadbreak vacuum interrupter switchgear with internal ground switch 5 constructed in accordance with the invention is illustrated. The switchgear comprises an outer case 10 formed from a sturdy, corrosive-resistant material. The preferred material is stainless steel. Switchgear case 10 is filled with dry air or nitrogen. Neither oil nor SF6 gas is used. Case 10 preferably has left side 11a (not illustrated), front side 11b, right side 11c, and back side 11d (not illustrated), bottom 13, and cover 12 welded together along the abutting edges. Front side 11b has operating handles 521a-d, 522a-d, and 523a-d. Front side 11b also has viewing windows 55a, 55b, 55c, and 55d. As will become clear later, the viewing window permits personnel to view power interruption switches inside the sealed case in order to determine if the switches are open or closed. Four sets of three power bushings (302a-c, 302d-f, 302g-i and 302j-l) extend out from cover 12. Power bushings 302a-c extend up from the far left region of the cover, power bushings 302d-f extend from the near left region of the cover, power bushings 302g-i extend from the near right region of the cover, and power bushings 302j-l extend from the far right region of the cover. Bushing wells can be used in place of power bushings; however, power bushings are the preferred component for this invention. For ease of discussion, this description will refer to each of the foregoing “regions” as a “set”. For example, one can see that there are four sets of power bushings: a first set of bushings 302a-c, a second set of bushings 302d-f, a third set of bushings 302g-i and a fourth set of bushings 302j-l. It will be understood that the sets could be defined by other combinations of bushings without departing from the scope of the invention. It will also be understood that outer case 10 is illustrated in FIGS. 1 and 2 with lines of demarcation visually separating adjacent “sets” of components, that each set is preferably identical in content and layout, and that the following description will be of the preferred arrangement. The lines of demarcation may or may not be present (in whole or in part) on switchgear constructed in accordance with the invention, and the sets may or may not be identical in content or layout, without departing from the scope of the invention.
FIG. 3 is a cut-away front elevation view illustrating the preferred layout of a single-phase building block module 600a which is composed of a ground switch assembly 200a, a disconnect switch assembly 300a, and a vacuum interrupter bottle switch assembly 100a. For ease of discussion, assemblies 200, 300, 100 and their components with suffixes “a”, “d”, “g”, or “j” are considered “A Phase”. Assemblies 200, 300, 100 and its components with suffixes “b”, “e”, “h”, or “k” are considered “B Phase”. Assemblies 200, 300, 100 and its components with suffixes “c”, “f”, “i”, or “l” are considered “C Phase”.
As used herein, the terms “building block” and “building block module” will be used as a convenient short-hand expression to denote a group of components whose configuration is repeated a number of times to form the preferred ground switch assembly. Those of ordinary skill in the art will recognize that the term does not necessarily connote the need for a separate housing for each building block, or the need for a visually identical subassembly from block to block, since the term is used in its conceptual sense only. As will be seen, the preferred embodiment of the invention uses visually identical building blocks within a single housing, but it should be noted that the invention is not limited to that preferred configuration.
FIG. 4 is a top view of single-phase building block 600 which illustrates the mechanical and electrical coupling between ground switch assembly 200a and disconnect switch assembly 300a via connection bus 240a. FIG. 4 also illustrates the mechanical and electrical coupling between disconnect assembly 300a and vacuum interrupter bottle switch assembly 100a via connection bus 140a.
To construct a three-phase building block module 900, a single-phase building block module 600b extends vertically upward and out of cover 12 behind single-phase building block module 600a and generally parallel thereto. A single-phase building block module 600c extends vertically upward and out of cover 12 behind single-phase building block module 600b and generally parallel thereto. This is best illustrated in FIG. 5 which is a cut-building away top view illustrating the preferred layout of the building blocks 600a-c for a three-phase block 900a. A front elevation view for a three-phase building block 900a would be the same as illustrated in FIG. 3. For ease of discussion, when two or more three-phase building blocks 900 are referenced in the design, the one designated 900a will be considered the “input power” block or “feeder” block and the remaining will be considered as distribution blocks.
FIG. 6 is a cut-away right side elevation view of the three-phase building block design 900a of FIG. 3, illustrating the preferred internal layout of the ground switch assemblies 200a-c. As illustrated in FIGS. 3 and 6, ground switch assembly 200a-c is generally comprised of an insulator 202a-c, an insulating shield 204a-c, a connector 220a-c, a top contact 206a-c, a bottom contact 212a-c, and a contact rod 208a-c. Ground switch assembly 200a extends vertically upward and out of cover 12. Ground switch assembly 200b extends vertically upward and out of cover 12 behind ground switch assembly 200a and generally parallel thereto. Ground switch assembly 200c extends vertically upward and out of cover 12 behind ground switch assembly 200b and generally parallel thereto. The ground switch assemblies 200a-c are connected to a ground bus which in turn is connected to a ground terminal where a ground cable/wire is attached to the switchgear during installation. Grounding occurs when contact rods 208a-c are pushed up and into top contacts 206a-c. Ground switch assemblies 200a-c are mechanically and electrically coupled to disconnect switch assemblies 300a-c via connection buses 240a-c and function to ground the electrical components within the building block design 900a so that no residual current remains.
FIG. 7 is a cut-away right side elevation view of the three-phase building block design 900a of FIG. 3, illustrating the preferred internal layout of the disconnect switch assemblies 300a-c. As illustrated in FIGS. 3 and 7, disconnect switch assembly 300a-c is generally comprised of a power bushing 302a-c, an insulating shield 304a-c, a transparent insulating shield 318a-c, a connector 320a-c, top contact 306a-c and bottom contact 312a-c, a contact rod 308a-c, an insulating shield 314a-c, and a push-pull insulator 316a-c. Disconnect switch assembly 300a extends vertically upward and out of cover 12. Although, for reasons that will be understood by those of ordinary skill in the art, the disconnect switch can be made without a transparent insulating shield, the preferred embodiment utilizes one for increased safety purposes.
Disconnect switch assembly 300b extends vertically upward and out of cover 12 behind disconnect switch assembly 300a and generally parallel thereto. Disconnect switch assembly 300c extends vertically upward and out of cover 12 behind disconnect switch assembly 300b and generally parallel thereto. Disconnect switch assemblies 300a-c function to allow power to either enter or exit each building block design 900a. Besides being connected to ground switch assemblies 200a-c, disconnect switch assemblies 300a-c are also mechanically and electrically coupled to vacuum interrupter bottle switch assemblies 100a-c via connection buses 140a-c.
FIG. 8 is a cut-away right side elevation view of the three-phase building block design 900a of FIG. 3, illustrating the preferred internal layout of the preferred vacuum interrupter bottle switch assemblies 100a-c. As illustrated in FIGS. 3 and 8, vacuum interrupter bottle switch assembly 100a-c is generally comprised of a mounting insulator 102a-c, an insulation shield 104a-c, a top connector 130a-c, a vacuum interrupter bottle switch 108a-c, a common bus connector 110a-c, an insulation shield 134a-c, a push-pull insulator 116a-c, and an operating mechanism assembly 150a-c. Vacuum interrupter bottle switch assembly 100a extends vertically upward and out of cover 12. Vacuum interrupter bottle switch assembly 100b extends vertically upward and out of cover 12, behind vacuum interrupter bottle switch assembly 100a and generally parallel thereto. Vacuum interrupter bottle switch assembly 100c extends vertically upward and out of cover 12, behind vacuum interrupter bottle switch assembly 100b and generally parallel thereto. Vacuum interrupter bottle switch assemblies 100a-c function to connect power to or break load from three-phase building block designs 900 which are connected to 900a via connection buses 145.
FIG. 9 is a cut-away front elevation view of a preferred design for a three-phase, two-way submersible loadbreak vacuum interrupter switchgear with internal ground switch based on the current invention. This preferred design uses only one three-phase building block 900a comprised of ground switch assembly 200a-c, disconnect switch assembly 300a-c, and vacuum interrupter bottle switch assembly 100a-c. Mounting insulator 102a-c of vacuum interrupter bottle switch assembly 100a-c is replaced with a power bushing 103a-c. This is the preferred design and results in a compact switchgear. A three-phase, two-way submersible loadbreak vacuum interrupter switchgear can be constructed using two three-phase building blocks 900, but would be twice the size of the preferred design. Bushing wells can also be used instead of power bushings; however, the preferred modification is to use power bushings.
When expanding to a three-phase, three-way submersible loadbreak vacuum interrupter switchgear with internal ground switch as illustrated in FIG. 10, building block modules 900a, 900b, and 900c are positioned staggered to one another as best illustrated in FIG. 11. Referring to FIGS. 10 and 11, each phase (A, B, and C) is electrically coupled in series with connection buses 145. A-Phase building block 600a is coupled mechanically and electrically to A-Phase building block 600d with connection bus 145a at vacuum interrupter bottle assembly connector 130a and 130d, respectively. A-Phase building block 600d is coupled mechanically and electrically to A-Phase building block 600g with connection bus 145d at vacuum interrupter bottle assembly connector 130d and 130g, respectively. The same connections are made for B-Phase building blocks 600beh via connection buses 145b and 145e and C-Phase building blocks 600cfi via connection buses 145c and 145f.
FIG. 12 is a cut-away front elevation view, in schematic, of the preferred switchgear of FIG. 1. As illustrated in FIG. 12, disconnect switch assemblies 300a-l are mechanically and electrically coupled to ground switch assemblies 200a-l through connection buses 240a-l at connectors 320a-l and 220a-l, respectively. Vacuum interrupter bottle switch assemblies 100a-l are mechanically and electrically coupled to disconnect switch assemblies 300a-l through connection buses 140a-l.
FIG. 13 is a cut-away top elevation view of the preferred switchgear of FIG. 1, in schematic, and best illustrates the internal layout of connection buses 140a-l, 240a-l, and 145a-i to the ground switch assemblies 200a-l, disconnect switch assemblies 300a-l, and vacuum interrupter bottle switch assemblies 100a-l. Disconnect switch assemblies 300a-l are mechanically and electrically coupled to ground switch assemblies 200a-l through connection buses 240a-l at connectors 320a-l and 220a-l, respectively. Vacuum interrupter bottle switch assembly 100a is mechanically and electrically coupled to vacuum interrupter bottle switch assembly 100d through connection buses 145a at connectors 130a and 130d, respectively. Vacuum interrupter bottle switch assembly 100d is mechanically and electrically coupled to vacuum interrupter bottle switch assembly 100g through connection buses 145d at connectors 130d and 130g, respectively. Vacuum interrupter bottle switch assembly 100g is mechanically and electrically coupled to vacuum interrupter bottle switch assembly 100j through connection buses 145g at connectors 130g and 130j, respectively. The same connection method is repeated for vacuum interrupter bottle switch assemblies 100b to 100e to 100h to 100k at connectors 130b, 130e, 130h, and 130k, respectively, via connection buses 145b, 145e, and 145h. This connection method is also repeated for vacuum interrupter bottle switch assemblies 100c to 100f to 100i to 100l at connectors 130c, 130f, 130i, and 130l, respectively, via connection buses 145c, 145f, and 145i.
FIG. 14 is a front elevation view of the preferred switchgear of FIG. 1 in schematic, illustrating the viewing windows 55a-d and positions of the operating handles of the ground switch, disconnect switch, and vacuum interrupter switch assemblies. All operating handles have “open” and “closed” positions. In the preferred design, the open positions have the operating handles pointed in a downward “8 o'clock” direction. The closed positions have the operating handles pointed in a “10 o'clock” direction. The operating handles rotate in a clockwise direction to change from the open to closed position. The operating handles rotate in a counterclockwise direction to change from the closed to open position. As illustrated in FIG. 14, operating handles 521a-c, 522d, and 523a-c are in the closed position. Operating handles 521d, 522a-c, and 523d are in the open position. As illustrated, when disconnect switch handles 523a-c are in the closed position, disconnect contact rods 308a-c, 308d-f, 308g-i can be seen through viewing windows 55a, 55b, and 55c, respectively. With disconnect switch handle 523d in the open position, disconnect contact rods 308j-l are not seen in viewing window 55d. As illustrated, when ground switch handles 522a-c are in the open position, ground contact rods 208a-c, 208d-f, 208g-i cannot be seen through viewing windows 55a, 55b, and 55c, respectively. With ground switch handle 522d in the closed position, ground contact rods 208j-l are seen in viewing window 55d. With the handles in the positions illustrated, three-phase building blocks 900a, 900b, and 900c are in the closed position and ready for operation. Three-phase building block 900d is in the open position, grounded, and not in operation.
FIG. 15 is a top elevation view of the described invention and best illustrates the positions of power bushings 302a-l of disconnect switch assemblies 300a-l and switch status indicators 85a-l on cover 12. Switch status indicators 85a, 85d, 85g, and 85j show the open or closed status for ground switch assemblies 200a-c, 200d-f, 200g-i, and 200j-l, respectively. Switch status indicators 85b, 85e, 85h, and 85k show the open or closed status for disconnect switch assemblies 300a-c, 300d-f, 300g-i, and 300j-l, respectively. Switch status indicators 85c, 85f, 85i, and 85l show the open or closed status for vacuum interrupter bottle switch assemblies 100a-c, 100d-f, 100g-i, and 100j-l, respectively. These indicators show switch status to an operator who is viewing the switchgear from above.
FIGS. 16 and 17 are front and top elevation view, respectively, in schematic, of the three-phase, four-way submersible loadbreak vacuum interrupter switchgear with internal ground switch of FIG. 14, illustrating the attachment of power cables onto power bushings 302a-l which provide power to the switchgear and out to branch circuits. Any ABC set of power cables can be used as the incoming three-phase power feeder with the remaining sets used to distribute three-phase power to branch circuits.
Referencing FIGS. 12 and 13, the electrical flow will be described using three-phase building block 900a as the power input and three-phase building blocks 900b, 900c, and 900d as the power outputs for distribution to the branch circuits. As shown in FIGS. 12, 900a, 900b, and 900c are in the closed position and 900d is in the open position. Electricity enters 900a through power bushings 302a-c and into vacuum interrupter bottle assemblies 100a-c though connection bus 145a-c. The electricity travels to 900b, 900c, and then 900d through connection buses 145a-c, 145d-f, and 145g-i, respectively. In 900b and 900c, electricity passes through vacuum interrupter bottles 108d-f and 108g-i and out through disconnect switch assemblies 302d-f and 302g-i via connection buses 145d-f and 145g-i, respectively. Electricity does not pass through 900d since vacuum interrupter bottles 108j-l are open.
Interlocking operating mechanisms are utilized to ensure proper operating procedures when switch assemblies within the switchgear are opened or closed. Referring initially to FIG. 1, operating handles 521a, 522a and 523a have previously been described as having “open” and “closed” positions wherein the open positions preferably have the operating handles pointed in a downward “8 o′clock” direction, while the closed positions have the operating handles pointed in a “10 o′clock” direction, with the operating handles being rotated in a clockwise direction to change from the open to closed position and in a counterclockwise direction to change from the closed to open position. Operating handles 522a, 523a and 521a are operatively coupled to the ground switch assembly, vacuum bottle switch assembly, disconnect switch assembly and vacuum bottle switch assembly, respectively, of block 900a. Likewise, 522b, 523b and 521b are operatively coupled to the ground switch assembly, vacuum bottle switch assembly, disconnect switch assembly and vacuum bottle switch assembly, respectively, of block 900b, etc. FIG. 18A schematically illustrates the positions of the operating handles at the front 11b of the switchgear case 10 when the block 900a, 900b, 900c, 900d is non-conducting, as it would be prior to access for maintenance or during installation and set-up. Since the position and operation of corresponding operating handles is the same from block to block, the letter suffix of each numeric identifier is omitted for brevity.
With the handle 522 in its “closed” 10 o'clock position, the ground switch assembly is closed in order to shunt any residual current to ground. Disconnect switch handle 523 and vacuum bottle switch handle 521 are both in the “open” 8 o'clock position, and the switch assemblies to which they are linked are accordingly in their open-circuit positions.
FIG. 18B schematically illustrates the relevant linkages behind the front 11b of the switchgear case 10 for the handle positions of FIG. 18A. Ground switch handle 522 rotates about axis 524 as illustrated in FIG. 18A, and FIG. 18B illustrates a clevis 525 that rotates about axis 524 on the back side of front surface 11b in response to the handle rotation.
Likewise, a clevis 527 (FIG. 18B) rotates about axis 526 when the disconnect switch handle 523 (FIG. 18A) rotates about axis 526. A pin 527a, however, extends from disconnect switch clevis 527 to contact ground switch clevis 525 in such a way, when the handles are in the illustrated position, that disconnect switch handle 523 is prevented from rotating into its “closed” position when the ground switch handle is in its closed position and the ground switch assemble is thereby closed. Similarly, a pin 529a extends from a clevis 529 coupled to the vacuum bottle switch handle 521 for rotation therewith around axis 528, so as to contact disconnect switch clevis 527 and prevent the vacuum switch handle 521 from being rotated to its “closed” position (to thereby close the vacuum bottle switch) when the disconnect switch handle is in its “open” position. Thus, it is not possible to close the disconnect switch or the vacuum bottle switch when the ground switch is closed, and no current can accidentally be permitted to flow into and through the block and be short-circuited to ground. Such a short circuit could result in a huge and dangerous current flow. Similarly, it is not possible to close the disconnect switch assemblies after the vacuum switch assemblies have been closed, or to open the disconnect switch assemblies while the vacuum switch assemblies are closed, thereby preventing arcing across the electrical contacts of the disconnect switches that might occur if the disconnect switch assemblies were switching power current on or off in an otherwise completed circuit. Consequently, such switching occurs within the relatively safe confines of the vacuum bottle switch assemblies.
Turning to FIGS. 18C and 18D, the ground circuit handle 522 has been moved to its “open” 8 o'clock position, thereby rotating clevis 524 away from pin 527a. With the ground switch assembly now open, the disconnect assembly switch can be safely closed, as illustrated next in FIGS. 18E-F. With disconnect switch handle rotated into its “closed” 10 o'clock position, disconnect switch clevis 527 is rotated away from pin 529a to thereby permit rotation of vacuum bottle switch clevis.
As next illustrated in FIGS. 18H-G, the rotation of the vacuum bottle switch handle to its “closed” 10 o'clock position, and the consequential rotation of its clevis 529, causes pin 529a to once again contact disconnect switch clevis 527 in such a way that the disconnect switch handle cannot be rotated to its “open” position while the vacuum bottle switch is closed.
As a result of all of the foregoing, the only way the block 900 can be open circuited is the safest way: its vacuum bottle switch, followed by its disconnect switch, followed by the closing of its ground switch. Conversely, the block can only be activated the safest way: opening the ground switch, followed by closing the disconnect switch, followed by closing the vacuum bottle switch. In addition, the rods of the ground switch and disconnect switch are visible through the viewing window 55 when the respective switch is closed for visual confirmation of same.
Because the state of the vacuum bottle switch assembly prevents the disconnect switch assembly from making or breaking an active circuit, no arcing can occur across the electrical contacts of the disconnect switch; accordingly, the transparent shield is not mandatory, but is highly preferred as a safety precaution in any event. The ground switch assemblies, on the other hand, do not need transparent insulating shields in the preferred embodiment because the contact rod is permanently connected to ground.
Those skilled in the art will recognize that other type of shaft movement may be utilized besides shaft rotation as described above. For example, the mechanisms can be configured to permit one or more of the handles of each building block to be pushed or pulled to thereby selectively engage more than one driven clevis with a single handle-driven shaft. Similarly, structures other than a clevis can be used, and a structure other than a pin can provide blocking. This is all within the knowledge and ability of mechanical designers, and within the scope of the invention.
Further, it may be desirable to replace each of the illustrated viewing windows 55 with two smaller windows that are each sized and positioned to permit the view of only a respective one of the two rods. This alternative configuration may better focus the attention of installation and maintenance personnel on the presence or absence of an expected rod since the presence or absence of the rod will be more apparent with a narrowed more targeted view for a single item.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention defined by the appended claims.
Patent Application
20130292358
