GB2160020A - Gas insulated combined switching apparatus - Google Patents

Abstract

A gas insulated combined switching apparatus comprises one or more groups of three switches 40, 50, 60 housed in a hermetically-sealed container 100 in which an electrically insulating gas is sealed. Each group of three switches comprises a sealed-type switch 50 disposed midway between two other switches 40, 60 which can be open-type switches. As the sealed-type switch is not affected by the arc gas produced by the arcing of the other two switches, the distance between the switches can be greatly decreased, permitting a small-sized apparatus. If the open-type switches are rotary-action switches, the sealed-type switch is preferably displaced from the planes in which the contacts of the rotary-action switches move, thereby reducing any effects of the arc gas on the sealed-type switch. All of the switches are preferably supported by a single surface of the container. If the single surface of the container is a detachable bottom surface, the assembly, inspection, and maintenance of the switches can be conveniently performed outside of the container. <IMAGE>

Description

SPECIFICATION Gas insulated combined switching apparatus We, MITSUBISHI ELECTRIC COMPANY, a Japanese company residing at 2-2-3 Marunouchi, Chiyoda Ward, Tokyo, Japan do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to improvements in a gas insulated combined switching apparatus having a plurality of switches housed in a single container.

In particular, it relates to a gas insulated combined switching apparatus the size and weight of which can be reduced while still maintaining ample insulation among the switches and other portions of the apparatus.

A gas insulated combined switching apparatus is an apparatus in which a number of gas insulated switches and their periperhal equipment (bushings, grounding switches, supports, and the like) are housed within a hermetically sealed container filled with an electrically insulating gas such as SF6. Figure 1 shows a schematic front cross-sectional view of a conventional gas insulated combined switching apparatus. A container 1 filled with an insulating gas 2 has three bushings 3, 4, and 5 mounted on the bottom of the container 1. Three switches 6, 7, and 8 are respectively mounted on the tops of the bushings 3, 4, and 5.The moveable contacts 9, 10, and 11 of the respective switches 6, 7, and 8 can swing between fixed contacts 12, 13, and 14, respectively, supported by the container 1 from above, and ground terminals 15, 16, and 17, respectively, also supported by the container 1.

Since all of the switches 6, 7, and 8 are of the open type, some means must be provided for preventing the ionized arc gas which forms when the contacts of a switch opens from short circuiting the adjacent switches. Accordingly, a vertical partition 18 is provided between switch 6 and switch 7, and another partition 19 is provided between switch 7 and switch 8. The provision of the partitions 18 and 19 increases the weight of the apparatus, which is undesirable, but if partitions are not used, the spacing between the switches must be increased to insulate them from one another, in which case the widthwise dimensions of the container 1 must be increased, in which case the weight of the container 1 still increases.Therefore, in this conventional apparatus employing opentype switches, it is difficult to achieve decreases in size and weight while maintaining adequate insulation between the switches.

In the assembly of a conventional combined switching apparatus, the switches and other peripheral equipment are mounted on the various inner surfaces of the container 1 and then electrically connected to each other. This means that most of the assembly must be performed inside the container 1, making assembly difficult and requiring that the container 1 be large enough to allow working space around the various switches and other equipment.

Also, final inspection and testing of the apparatus must be performed inside the container 1, making inspection and testing difficult and imposing further space requirements which enlarge the size of the container 1.

Therefore, the overall size of the container 1 ends up being much larger than the sum of the sizes of each of the parts housed inside it.

Furthermore, since the assembly, inspection, and testing must be performed within the container 1, dirt, dust, and other contaminants harmful to the withstand voltage of the apparatus are inevitably introduced into the container 1 during these operations, and these materials may cause functional problems later on.

In addition, since the walls of the container must support the weight of various pieces of equipment in addition to resisting the pressure of the insulating gas sealed within the container, considerable strength is required of the walls, and to give the walls sufficient strength, the weight of the container 1 must be increased. Furthermore, if the distances between the equipment housed in the container 1 must be precise, it is difficult to produce a satisfactory container 1 by welding, since welding produces distortion of the dimensions of the container 1. Therefore, it is often necessary to machine the walls of the container 1, which greatly increases the cost of the container 1 and places limitations on its shape.

It is the object of the present invention to overcome the above-described drawbacks of a conventional apparatus and to provide a gas insulated combined switching apparatuses which can be narrower than a conventional apparatus while still maintaining ample insulation between adjoining switches.

It is another object of the present invention to provide a gas insulated combined switching apparatus which can be almost completely assembled and tested outside of the container in which it is to be housed, making assembly and testing easier and more reliable.

It is yet another object of the present invention to provide a gas insulated combined switching apparatus having a lower overall weight and in particular a lighter container.

It is a further object of the present invention to provide a gas insulated combined switching apparatus which can be assembled and inspected without the introduction of dirt and other contaminants into the container of the apparatus.

In a gas insulated combined switching apparatus according to the present invention, one or more groups of 3 switches are housed in a hermeticallysealed container in which an electrically insulating gas is sealed. Each group of 3 switches comprises a second switch of a sealed type disposed substantially midway between a first and a third switch which can be closed to connect to one side of the second switch. Since the second switch is of a sealed type, arc gas produced at the time of opening either the first or third switch does not affect the second sealed switch, and the second sealed switch does not discharge any arc gas which can affect the other two switches. The widthwise dimension of the apparatus can thereby be reduced by about 1/3. The first and third switches can be linear-action switches or rotary-action switches.If of the latter type, the second switch of the sealed type is preferably displaced from the plane in which the moving contacts of the other switches rotate, thereby moving the second switch out of the path of the arc gas produced when the first or third switches are opened. By supporting all of the switches on a single surface of the container, the weight of the container can be decreased and it becomes possible to assemble and test the apparatus almost entirely outside of the container, making assembly and inspection much easier.

A number of embodiments of the present invention will now be described by way of example, reference being made to the accompanying drawings in which: Figure 1 is a schematic cross-sectional view of a conventional gas insulated combined switching apparatus; Figure 2 is a schematic cross-sectional view of a first embodiment of a gas insulated combined switching apparatus according to the present invention; Figure 3 is a schematic cross-sectional view of a second embodiment of the present invention; ure 4 is a schematic cross-sectional view of a third embodiment of the present invention; Figure 5 is a schematic top view of a fourth embodiment of the present invention in which the central row of switches is displaced with respect to the side rows;; Figure 6 is a schematic cross-sectional view of a fifth embodiment of the present invention in which an auxiliary bushing is connected to the central switch; Figure 7 is a schematic cross-sectional view of a sixth embodiment of the present invention showing a different connection between the auxiliary bushing and the central switch; Figure 8 is a schematic cross-sectional view of a seventh embodiment of the present invention in which all of the bushings are supported by the bottom of the container; Figure 9 is a schematic top view of the embodiment of Figure 8; Figure 10 is a schematic cross-sectional view of an eighth embodiment of the present invention in which the centrally-disposed switches are supported by auxiliary bushings; Figure ii is a schematic top view of the embodiment of Figure 10; and Figure 12 is a schematic cross-sectional view of a tenth embodiment of the present invention in which an opened-bottomed supporting housing is provided inside the container.

A first embodiment illustrated schematically in Figure 2 will now be explained. A gas insulated combined switching apparatus according to this embodiment has a rigid container 100 in which is sealed an electrically insulating gas 120. A first bushing 31 and a third bushing 33 are mounted on the bottom surface of the container 100, while a second bushing 32 is mounted on the top surface of the container 100. Mounted on the bottom surface of the container 100 midway between the first bushing 31 and the third bushing 33 is an electrically insulating support member 80. A first switch 40 of an open type is mounted on the top of the first bushing 31, and a third switch 60 also of an open type is mounted on the top of the third bushing 33, while a second switch 50 of a sealed type is supported directly above the support member 80 through a common bus 90.In this embodiment, the first switch 40 and the second switch 60 are rotary-action switches having rotating contacts 41 and 61, respectively, rotatably supported by the support member 80 and electrically connected to one another and to the common bus 90 in the form of a Junction. Furthermore, the fixed contacts 42 and 62 of the first and third switches 40 and 60 are respectively mounted on the tops of the first and third bushings 31 and 33. The rotating contacts 41 and 61 can rotate between three positions; a horizontal position in which they contact the fixed contacts 42 and 62, a vertical position in which they contact two ground terminals 71 and 72, respectively, mounted on the sides of the container 100, and a neutral position when the rotating contacts are diagonally disposed between the fixed contacts and the ground terminals.

The second switch 50 is a sealed switch such as a vacuum switch electrically connected between the second bushing 32 and the common bus 90 and supported so as to be above the other switches 40 and 60. In this embodiment, the second switch 50 is a rotary-action switch having an unillustrated rotating contact which is closed when in a nearly horizontal position. The second switch 50 serves as a load switch, while the first switch 40 and the third switch 60 serve as line switches.

The operation of this embodiment will now be explained. If all three of switches 40, 50, and 60 are initially closed, a loop current will flow through the line switches 40 and 60 and a load current will flow through the load switch 50. If the first switch 40 is then opened by an unillustrated operating mechanism, an arc will develop between the contacts 41 and 42 of the first switch 40 and a large amount of ionized arc gas will be discharged around the switch 40. As this arc gas disperses, it will reach the vicinity of the centrally-located second switch 50. However, since the second switch 50 is sealed, it will not be affected by this arc gas. Furthermore, the first switch 40 is sufficiently far removed from the third switch 60 that the arc gas from the one will not affect the other. Similarly, arc gas produced by the opening of the third switch 60 will not affect the sealed second switch 50, and as the second switch 50 does not release any arc gas into the container 100, the opening of its contacts does not adversely affect either of the other switches.

Therefore, it is not necessary to provide a partition between adjacent switches in order to ensure adequate insulation. Moreover, the widthwise dimensions of the container 100 can be decreased to about 2/3 of the width of the container for a con ventional apparatus such as that illustrated in Figure 1. The above structure thus provides a reduction in the size and weight of the container 100.

Figure 3 shows a second embodiment of the present invention which differs from the first embodiment in that the movable contacts 41 and 61 of the first switch 40 and the third switch 60 are rotatably mounted atop the first bushing 31 and the third bushing 33, respectively, while the fixed contacts 42 and 62 of these switches are secured to the top of the support member 80. The fixed contacts 42 and 62 are electrically connected to one another and to a common bus 90 in the form of a T-junction, the common bus 90 connecting to one side of the second switch 50. Furthermore, the second switch 50 is a linear-action switch of a sealed type. This embodiment provides the same advantages as does the first embodiment of a reduction in width and weight of the container 100.

Figure 4 shows a third embodiment of the present invention which employs the same principles as the first embodiment. In this embodiment, all three of the bushings 31, 32, and 33 are mounted on the bottom surface of the container 100 in a row. The first switch 40 and the second switch 60 are still mounted on top of the first bushing 40 and the second bushing 60, but unlike the first embodi ment the rotating contacts 41 and 61 of the switches are rotatably mounted on the bushings, while the fixed contacts 42 and 62 are supported from above and electrically connected with one another by a common bus 90 in the form of a T-junction. The second switch 50 is a linear-action switch which is directly supported by the second bushing 32 instead of by a support member 80.The ground terminals 71 and 72 are arranged at approximately the same level as the second switch 50. As in the first embodiment, arcing between the contacts of the first switch 40 or the third switch 60 does not affect the second switch 50 which is sealed, and the first switch 40 and the third switch 60 are sufficiently far apart so that arcing between the contacts of the one does not effect the other switch.

Therefore, as in the previous embodiment, a decrease in the width of the container 100 can be achieved.

This embodiment provides the further advantage that all of the bushings are mounted on the bottom surface of the container 100. Therefore, the weight which the other walls of the container 100 have to support is decreased, and the weight of those walls can accordingly be decreased. Furthermore, their dimensions do not need to be as precise as when they support equipment, and an inexpensive container produced by welding is fully adequate.

In each of the previous embodiments, the switching apparatus was shown as having only three switches. However, a switching apparatus according to the present invention can be used for a plurality of phases. In particular, it is appropriate as a switching apparatus for 3-phase power, in which a different group of switches is provided for each phase, each group of switches comprising three switches arranged in the manner of any of the above embodiments.

Figure 5 is a schematic top view of a fourth embodiment of the present invention in which the apparatus comprises three groups of three switches for switching 3-phase power. A front view of this embodiment would appear identical to Figure 3 with a first and third switch 40 and 60 positioned below and to both sides of a sealed-typed second switch 50, and has therefore been omitted.Each group of 3 switches for a single phase comprises a first switch (40, 40a, or 40b) mounted on a first bushing (31, 31a, or 31b), a third switch (60, 60a, or 60b) mounted on a third bushing (33, 33a, or 33b), and a second switch (50, 50a, or 50b) of a sealed type supported from below by an electrically insulating support member (80, 80a, or 80b) through a common bus (90, 90a, 90b) and electrically connected to a second bushing (32, 32a, or 32a) mounted on the upper surface of the container 100.

In this embodiment, although the first and third switches and the support member of each group of 3 switches lie in substantially the same vertical plane, the second switch (50, 50a, or 50b) of each group is displaced from this vertical plane. For example, in Figure 5, each of the second switches is shown as being displaced from the plane of the other two switches of the same phase group by a distance P/2, where P is the distance between adjacent groups of switches. The distance P/2 is only given as an example, and the amount by which the second switches are displaced from the plane of the first and third switches of the same phase group can be different.

By displacing each of the second switches 50, 50a, and 50b in this manner, the insulating characteristics of the apparatus can be further increased.

Namely, the rotating contact 41 of the first switch 40 rotates in the above-mentioned vertical plane passing through the center of the first bushing 31 and the third bushing 33. When the rotating contact 41 separates from the fixed contact 42, the arc which forms is caused to bend outwards in this plane by an electromagnetic field towards the third switch 50, and the ionized arc gas formed by the arc also moves substantially in this plane.Therefore, by displacing the second switch 50 out of this plane, much less of the arc gas reaches the vicinity of the second switch 50, and the width of the apparatus, i.e., the distance between the first switch 40 and the third switch 60 can be further reduced without the second switch 50 being affected by the arcing of one of the other switches, even in a circuit such as an exciter circuit or a charging circuit in which the breaking current and recovery voltage are large and the arcing time is long. The same applies for the other two groups of switches.

Although in this embodiment the bushings and switches are arranged in the manner of the embodiment of Figure 3 with the movable contacts of the first and third switches disposed on the tops of the respective bushings and with the second bushings (32, 32a, and 32b) mounted on the top surface of the container 100, the configurations shown in Figures 2 and 4 can also be used.

Figure 6 shows a fifth embodiment of the pres ent invention which differs from the previous embodiments in that the second switch 50 is supported from below not by an insulating support member 80 but by an expansion bushing 34 which is mounted on the bottom surface of the container 100 and electrically connected to the second bushing 50 by a common bus 90.The expansion bushing 34 horizontally supports the fixed contact 42 of the first switch 40 and the fixed contact 62 of the second switch 60 which are electrically connected to one another and to the common bus 90. With this configuration, it is possible to connect the expansion bushing 34 with the three switches by the shortest possible path without the common bus 90 having to cross any other lines.Preferably, the second switch 50 is displaced from the vertical plane of the first switch 40 and the second switch 60 in the manner of the embodiment of Figure 5. Although only three switches are shown in the illustration, three groups of three switches corresponding to 3 different phases of 3-phase power can be connected in this manner, arranging the corresponding switches and bushings of the three phase groups into three rows of 3, as shown in Figure 5.

Figure 7 shows a sixth embodiment of the present invention in which the second switch 50 is supported from below by the second bushing 32 which is mounted on the bottom surface of the container 100, and the expansion bushing 34 is mounted on the top surface of the container 100, opposite to the position in Figure 6. The first switch 40 and the third switch 60 are shown as linear-action switches, but rotary-action switches may be used instead, in which case the second switch 50 is preferably displaced from the vertical plane of the first and third switches. The first switch 40, the third switch 60, and the expansion bushing 34 are connected to the second switch 50 by a common bus. Furthermore, the expansion bushing 34 is electrically connected to an expansion switch 130 housed in a second container 140 separate from the container 100 housing the other switches.This embodiment provides the same advantages as the previous embodiment.

Figures 8 and 9 show a front cross-sectional view and a top view of a seventh embodiment of the present invention comprising three groups of three switches each, each group of switches corresponding to a different phase of 3-phase power. As in the embodiment of Figure 5, each of the second switches (50, 50a, and 50b) is supported from below by an electrically insulating support member (80, 80a, or 80b), and each of the second switches is displaced from the vertical plane of the other two switches of the same phase group.However, in this embodiment, each of the second bushings (32, 32a, and 32b) is mounted on the bottom surface 102 of the container 100 directly below the corresponding switch (50, 50a, and S0b).Therefore, all of the bushings and switches are supported by a single surface of the container 100, which in this case is the bottom surface 102. Preferably the bottom surface 102 can be detached from the upper portion 101 of the container 100. In some cases, it may desirable to attach an auxiliary support member to the bottom surface 102 to help support the equipment mounted on the bottom surface 102.

This arrangement provides a number of important advantages. Since all of the bushings and switches are supported by a single surface, i.e., the bottom surface 102, the other surfaces of the container 100 are no longer load-bearing members and can be of lighter construction than when they must support various parts. Furthermore, since the upper portion 101 has no parts mounted on it, its dimensions can be less exact and a satisfactory container 100 can be cheaply produced by welding.

In particular, the provision of the bushings and switches on the bottom surface of the container 102 greatly simplifies assembly and inspection.

Namely, the equipment to be housed in the container 100 can be installed on the bottom surface 102 and the top portion 101 of the container 100 can be then be placed over the bottom surface 102 and sealingly connected thereto after substantially all the assembly and testing have been completed.

Not only is assembly and testing simplified, but the size of the container 100 can be decreased, since it is not necessary to leave working room between the walls of the container 100 and the equipment inside it. This arrangement also simplifies repair and service of the apparatus if the bottom surface 102 is detachable, since the top portion 101 of the container 100 can be removed from the bottom surface 102 to allow easy access.

Futhermore, since it is not necessary to enter inside the container 100 to perform installation and inspection, the amount of contamination introduced into the container 100 can be greatly reduced.

This embodiment of course also allows a decrease in the width of the apparatus as in the previous embodiments by the use of a sealed-type second switch 50.

Figures 10 and 11 are a schematic cross-sectional view and a schematic top view of another embodiment of the present invention. As in the previous embodiment, all of the bushings are mounted on the bottom surface 102 of the container 100. However, instead of being supported by the supporting members 80, 80a, and 80b, the second switches 50, 50a, and 50b are supported from below by expansion bushings 34, 34a, and 34b mounted on the bottom surface 102 of the container 100. This embodiment provides the same advantages as the previous embodiment.

Figure 12 shows a ninth embodiment of the present invention. As in the previous embodiment, the first, second and third bushings 31, 32, and 33, respectively are mounted on the bottom surface 102 of the container 100, and the movable contacts 41 and 61 of the first and third switches 40 and 60 are rotatably mounted atop the first and third bushings 31 and 33. However, the fixed contacts 42 and 62 are supported from above by an electrically insulating support member 111 which is secured to the top surface of an open- bottomed box-shaped supporting housing 110 which has a shape similar to the upper portion 101 of the container 100 and fits inside it. Like the upper portion 101, the supporting housing 110 is secured to the bottom surface 102 of the container 100 at its bottom end.

The fixed contacts 42 and 62 are connected to one another and to the second switch 50 by a common bus 90 in the form of a Junction. Preferably, the bottom surface 102 can be detached from the upper portion 101 of the container 100 and from the supporting housing 110.

This embodiment provides the same effects as the embodiments of Figures 8 through 11. Namely, installation and inspection can be performed outside of the container 100, making these operations much easier and more efficient. The dimensions of the container 100 can be reduced, since it is not necessary to provide working space inside it, and it can be lightened, since the weight of the equipment housed inside it is borne by the bottom surface 102 only. Maintenance and inspection can be easily performed by removing the bottom surface 102 and the supporting housing 110 as a single unit from the container 100, and less dirt and other contaminants are introduced into the container 100 during assembly and inspection. In addition, the widthwise dimensions of the apparatus can be decreased, as in the previous embodiments.

Figure 12 shows only one group of three switches 40, 50, and 60. However, just as in the previous embodiments, other groups of three switches each connected in the manner shown in Figure 12 can be provided in parallel with the illustrated switches as explained with respect to the previous embodiments to provide the same effects.

Claims (11)

1. A gas insulated combined switching apparatus comprising: a hermetically-sealed container; an electrically insulating gas sealed within said container; and at least one group of three switches housed inside said container, each group comprising a sealed-type switch disposed substantially midway between two other switches which when closed electrically connect to one side of said sealed-type switch.

2. A gas insulated combined switching apparatus as claimed in Claim 1, wherein there are three groups of three switches disposed substantially parallel to each other, each group of three switches corresponding to a different phase of 3-phase power.

3. A gas insulated combined switching apparatus as claimed in Claim 1, wherein said sealed-type switch is a vacuum switch.

4. A gas insulated combined switching apparatus as claimed in Claim 1, wherein said two other switches are rotary-action switches each having a rotating contact, and said sealed-type switch is displaced from the planes in which said rotating contacts rotate.

5. A gas insulated combined switching apparatus as claimed in Claim 4, wherein said rotating contacts of said two other switches rotate in the same vertical plane, and said sealed-type switch is displaced from said vertical plane.

6. A gas insulated combined switching apparatus as claimed in Claim 1, wherein all of said switches are supported by a single surface of said container.

7. A gas insulated combined switching apparatus as claimed in Claim 6, wherein said single surface is the bottom surface of said container.

8. A gas insulated combined switching apparatus as claimed in Claim 7, wherein said bottom surface is detachable from the top portion of said container.

9. A gas insulated combined switching apparatus as claimed in Claim 6, further comprising a supporting housing having substantially the same shape as said container and which fits inside of said container, said housing having an open end and being secured to said single surface of said container, at least a portion of each of said switches being supported by said supporting housing.

10. A gas insulated combined switching apparatus as claimed in Claim 9, wherein said single surface of said container is the bottom surface of said container and said supporting housing is detachable from said bottom surface.

11. Gas insulated switching apparatus substantially as herein described with reference to Figures 2 to 12 of the accompanying drawings.