GAS-INSULATED SWITCHGEAR APPARATUS

Abstract: A gas-insulated switchgear apparatus comprises a set of gas-insulated circuit breakers (l) for three phases juxtaposed on a first horizontal plane, first phase-separated main buses (24) respectively confronting one end of the set of gas-insulated circuit breakers (l) and arranged on second horizontal planes of different levels which are orthogonal to the first horizontal plane, second phase-separated main buses (25) respectively confronting the one end of the set of gas-insulated circuit breakers (l) and arranged on third horizontal planes of different levels which are orthogonal to the first horizontal plane, and a coupling bus (5) and breakers (7, 9) for connecting each gas-insulated circuit breaker (l) to each first phase-separated main bus (24) and each second phase-separated main bus (25) for the same phase. The coupling buses (5) for respective phases have the same length, the breakers (7) for respective phases provided for the first phase-separated main buses (24) lie on a common vertical plane, the breakers (9) for respective phases provided for the second phase-­ separated main buses (25) lie on another common vertical plane, the first phase-separated main buses (24) for three phases close to the set of gas-insulated circuit breakers (l) are respectively arranged on upper installation planes of different levels above the breakers (7), and the second phase-separated main buses (25) for three phases remote from the set of gas-insulated circuit breakers (l) are respectively arranged on lower instal­ lation planes of different levels below the breakers (9). This construction can reduce the overall size of the gas-­ insulated switchgear apparatus of phase-separated type to simplify the production thereof and permits easy maintenance inspection.

Description: BACKGROUND OF THE INVENTION This invention relates to a gas-insulated switchgear apparatus, especially, a phase-separated, double main bus type gas-insulated switchgear apparatus. Typically, in gas-insulated switchgear apparatus of the double main bus type, gas-insulated circuit breakers are arranged horizontally and one end of each gas-insulated circuit breaker is connected to first and second sets of main buses in succession through breakers. Accordingly, the apparatus is of a construction which extends in the axial direction of the gas-insulated circuit breaker. Conventionally, in the gas-insulated switchgear apparatus, main buses are used in a three-phase common busbar type or a phase-separated type. Exemplarily, three-phase common busbars are used in the gas-insulated switchgear apparatus in a way as disclosed in, for example, JP-A-56-62006, according to which gas-insulated circuit breakers for U.V and W phases are juxtaposed on a horizontal plane, each having one end connected to a coupling bus. First and second three-phase common main buses are arranged under the coupling buses to lie on a horizontal plane which is orthogonal to the horizontal plane, and a conductor for each phase of each of the first and second three-phase common main buses is connected to a conductor of the coupling bus for each phase through a breaker. Phase-separated main buses are exemplarily used in the gas-insulated switch-gear apparatus as disclosed in JP-A-58-15410 (underlying the first part of claim 1) according to which gas-insulated circuit breakers for three phases are also juxtaposed on the same horizontal plane, each having one end connected to a coupling bus. First phase-separated main buses are arranged above the coupling buses to lie on a first horizontal plane which is orthogonal to the coupling buses, second phase-separated main buses are arranged under the coupling buses to lie on a second horizontal plane which is orthogonal thereto, and the first and second phase-separated buses are connected to the gas-insulated circuit breakers through the coupling buses and breakers. In the former type, thanks to the grouped three- phase main buses, the entire arrangement area can advantageously be reduced but disadvantageously, if a conductor of any phase becomes defective, this defective conductor can hardly be inspected and repaired without having the influence upon conductors of the remaining phases. To eliminate this inconvenience, the latter type, in which the main buses for three phases are separated like phase separation in the juxtaposed gas-insulated circuit breakers, is also generally used at the cost of an increase in installation space. However, when incorporating the upper set of first phase-separated main buses arranged above the installation horizontal plane for the gas-insulated circuit breakers and the lower set of second phase-separated main buses arranged below that installation horizontal plane into the gas-insulated switchgear apparatus, it is impossible, because of limited arrangements of the breakers, to connect the conductors of the first and second phase-separated main buses to the coupling buses through the breakers by maintaining identity of U,V and W phase sequence between the upper and lower sets, whereby an operator may erroneously recognize the phase of the main buses during maintenance inspection and repair. To solve this problem, it is conceivable to arrange the upper set of first phase-separated main buses and the lower set of second phase-separated main buses in the same sequence of phases. This expedient, however, requires that the breakers for connection or disconnection of the conductors be arranged in an artificially sophisticated fashion and that the distance between the horizontal plane for the upper or lower set of phase-separated main conductors and the installation horizontal plan for the gas-insulated circuit breakers be large, thus increasing the overall size, especially height, of the gas-insulated switchgear apparatus and degrading its vibration-proof characteristics. To cope with this problem, both the first and second phase-separated main buses may be juxtaposed under the installation horizontal plane for the gas-insulated circuit breakers. This arrangement however can not be realized without increasing the size in the direction of the juxtaposition of the phase-separated main buses on the side of one end of each gas-insulated circuit breaker. This space must be large enough for drawing out or removing the gas-insulated circuit breakers and phase-separated main buses or the phase-separated main buses themselves and will increase the size of the gas-insulated switchgear apparatus, requiring a larger building for accommodating a large-sized apparatus and a larger ground area for foundation of the large building. In addition, since the phase-separated main buses are positioned differently, the length of the coupling bus connected to one end of the gas-insulated circuit breaker differs from phase to phase. Therefore, the individual coupling buses are not interchangeable and are unsuitable for mass production. FR-A-2,377,102 discloses a variety of further embodiments of three-phase switchgear apparatus. In Figure 19 of this document, a circuit breaker is in a horizonzal arrangement. In Figures 15 to 17, main buses are arranged in horizontal planes above the level of gas-insulated circuit breakers. Reference is also made to an arrangement where the main buses are disposed in different horizontal planes. Common to all embodiments of this document, however, is the fact that the three phases of each set are disposed in a common main bus, which results in the difficult inspection and repair set forth above. SUMMARY OF THE INVENTION It is an object of the invention to provide a gas-insulated switchgear apparatus in which the space in the direction, in which the first and second main buses are juxtaposed, is reduced and which still reserves sufficient space for inspection of the gas-insulated circuit breakers and other components. This object is met by the invention characterized in claim 1. Useful developments of the invention are set forth in the subclaims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic front view, partly sectioned, showing a gas-insulated switchgear apparatus according to an embodiment of the invention. Figure 2 is a side view as viewed from the right in Figure 1. Figure 3 is a plan view of Figure 1. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figs. 1 to 3, there is illustrated a gas-insulated switchgear apparatus of phase-separated double bus type embodying the invention. A set of U,V and W phase gas-insulated circuit breakers 1 for connection to peripheral devices through bushings and cable heads are arranged on the same horizontal plane in substantially parallel relationship with each other. Each gas-insulated circuit breaker 1 has at least one breaking element 1A in a cylindrical container which is supported substantially horizontally. As well known in the art, a movable contact of the breaking element 1A is operated to open or close by means of a mechanism built in an operation box 2 or a driver unit. The gas-insulated circuit breaker 1 for each phase is supported on a suitable frame 1B and its axially opposite ends are gas-sectioned by insulating spaces 3. Connected to one end of each gas-insulated circuit breaker 1 is a coupling bus 5 having one end gas-tightly sealed by the insulating spacer 3 and the other end gas-sectioned by an insulating spacer 6. The coupling bus 5 includes an internal coupling conductor 5A and a current transformer 4 fitted on the outer circumferential surface of the coupling bus. Each coupling bus for each phase measures the same length so that exchangeability between the coupling buses for respective phases can be ensured. Each coupling bus for each phase is connected to a first breaker 7 through the insulating spacer 6 and also to a second breaker 9 through an insulating spacer 8. Accordingly, the first breakers 7 for respective phases lie in one vertical plane and the second breakers 9 for respective phases lie on another vertical plane, these vertical planes being orthogonal to the horizontal plane on which the set of gas-insulated circuit breakers 1 are juxtaposed. A first phase-separated main bus 24 connects to the gas-insulated circuit breaker 1 through the first breaker 7 and a second phase-separated main bus 25 connects to the same gas-insulated breaker 1 through the second breaker 9 as will be described later. The breakers 7 and 9, whose internal structure will be described later, have enclosures 10 and 11, respectively. Each of the enclosures 10 and 11 has a substantially cruciform longitudinal section and is of a four-arm configuration. One vertically extending arm of the enclosure 10, perpendicular to an extension of the axial line of the gas-insulated circuit breaker 1, forms a connection part to the first phase-separated main bus 24 and one vertically extending arm of the enclosure 11 likewise forms a connection part to the second phase-separated main bus 25. The breaker 7 is held such that its connection part is directed upwards and conversely, the breaker 9 is held with its connection part directed downwards. An electrical conductor 12 of the breaker 7 is horizontally supported within the enclosure 10 by means of a suitable insulating support and an electrical conductor 13 is similarly supported within the enclosure 11. The condutor 12 connects to the coupling conductor 5A through the insulating spacer 6 and the conductor 13 connects to the conductor 12 through the insulating spacer 8. The electrical conductor 12 carries a movable contact 16 which can be operated to slide vertically by means of a manipulator 14 provided on the side opposite to the connection part of the enclosure 10. Similarly, the electrical conductor 13 carries a movable contact 17 which can be operated to slide vertically by means of a manipulator 15 provided on the side oposite to the connection part of the enclosure 11. A stationary contact 18 opposing the movable contact 16 is mounted to one end of a branch conductor 20 extending to the phase-separated main bus 24 for each phase, and a stationary contact 19 opposing the movable contact 17 is mounted to one end of a branch conductor 21 extending to the phase-separated main bus 25 for each phase. The connection parts of the enclosures 10 and 11 are gas-sectioned by insulating spacers 22 and 23 which support the branch conductors 20 and 21. It should be understood that the above arrangement of the breakers 7 and 9 permits the two breakers to be of the same construction and also permits easy separation of the movable contacts 16 and 17, illustrated in Fig. 1 from the stationary contacts 18 and 19, by using the manipulators 14 and 15 provided on the side opposite to the branch conductors 20 and 21. Considering the phase-separated main buses, it will be seen from the drawings that the respective first phase-separated main buses 24 for respective phase being close to the respective gas-insulated circuit breakers 1 are arranged above the breaker 7, that is, they are arranged on different horizontal levels above the installation horizontal plane for the gas-insulated circuit breakers 1 and conversely, the respective second phase-separated main buses 25 for respective phases being more remote from the respective gas-insulated circuit breakers 1 are arranged below the breaker 9, that is, they are arranged on different horizontal levels below the installation horizontal plane for the gas-insulated circuit breakers 1. In addition, the respective first phase-separated main buses 24 converge to the same vertical plane on which the respective breakers 7 lie and likewise, the respective second phase-separated main buses 25 similarly converge to the same vertical plane in which the respective breakers 9 lie, leaving behind a space which is below the coupling bus 5 and between the set of gas-insulated circuit breakers 1 and the set of second phase-insulated main buses 25. This space may conveniently be utilized for inspection of the operation box 2 for the gas-insulated circuit breaker 1 and of other components of apparatus or as a working space for moving the phase-separated main buses 25. For each phase, the first and second phase-separated main buses 24 and 25 respectively connect to branch buses 28 and 29 coupled to the connection parts of the breaker enclosures 10 and 11, thereby forming unitary structures, and main bus conductors 26 and 27 electrically connect to the branch conductors 20 and 21 extending to the breakers 7 and 9. For the purpose of reducing the installation spacing, the respective phase-separated main buses 24 for three phases may possibly be juxtaposed in the same horizontal plane above the installation horizontal plane for the gas-insulated circuit breaker 1, converging to a common vertical plane and similarly the respective phase-separated main buses 25 for three phases may be juxtaposed in the same horizontal plane below that installation horizontal plane, converging to another common vertical plane. But in this case, a large width is disadvantageously required for the juxtaposition in the same horizontal plane. Accordingly, in the illustrated embodiment, only one phase-separated main bus for a specified phase is arranged on an installation horizontal plane which is different from that for the other two phase-separated main buses for the remaining phases, so that the respective phase-separated main buses for three phases are located at apices of a triangle as viewed in Fig. 1. Especially, the triangle is an isosceles triangle having a base longer than the remaining sides and the respective phase-separated main buses are located at apices of this isosceles triangle, thereby ensuring that a considerable increase in the installation width can be avoided without requiring a large level difference between the installation horizontal planes for respective phases. Accordingly, the arrangement of the first phase-separated main buses 24 is defined by an isosceles triangle existing above the installation horizontal plane for the gas-insulated circuit breaker 1, and the arrangement of the second phase-separated main buses 25 is defined by an inverted isosceles triangle existing below that installation horizontal plane. Therefore, the two arrangements are symmetrical with each other with respect to that installation horizontal plane, and interchangeability therebetween simplifies the production of the phase-separated main buses. Because of this triangular arrangement of the set of first phase-separated main buses 24, the buses 24 respectively merge into a straight branch bus 28 for central phase and bent or arcuate branch buses 28 for lefthand and righthand phases, the respective branch buses 28 branching upwards from the respective breakers 7 lying on the same vertical plane which is orthogonal to the installation horizontal plane for the set of juxtaposed three-phase gas-insulated circuit breakers l. Likewise, because of the triangular arrangement of the set of second phase-separated main buses 25, the buses 25 respectively merge into a straight branch bus 29 for central phase and bent or arcuate branch buses 29 for lefthand and righthand phases, the respective branch buses 29 branching downwards from the breakers 9 for respective phases lying on the same vertical plane. The upper arrangement of the phase-separated main buses 24 for respective phases is supported by the branch buses 28 and the lower arrangement of the phase-separated main buses 25 for respective phases is supported on the foundation through supporting members 30. The gas-insulated circuit breakers l for three phases are juxtaposed in sequence of U,V and W phases on the same horizontal plane, and the first and second phase-separated main buses 24 and 25 respectively connected to the gas-insulated circuit breakers l through the breakers 7 and 9 are also arranged in sequence of U,V and W phases, starting from a phase close to the gas-insulated circuit breaker l. Specifically, assuming that the illustrated gas-insulated circuit breaker l in the example of Fig. l is for U phase, the first and second phase-separated main buses 24 and 25 on the lefthand side are for U phase, those at the center are for V phase and those on the righthand side are for W phase. This makes it possible for an inspector to correctly recognize the corresponding phases upon maintenance inspection or repair of the phase-separated main buses. In the gas-insulated switchgear apparatus of the invention described so far, the set of gas-insulated circuit breakers l for respective phases are juxtaposed horizontally but alternatively, they may be juxtaposed vertically. In any case, a similar arrangement can be obtained by connecting respective horizontally extending coupling buses 5 and respective breakers 7 and 9 to one end of the set of gas-insulated circuit breakers l, arranging the set of phase-separated main buses 24 close to the gas-insulated circuit breakers l above the coupling conductor 5A and electrical conductors l2 and l3, and arranging the set of phase-separated main buses 25 remote from the gas-insulated circuit breakers l below the coupling conductor 5A and electrical conductors l2 and l3. As described above, according to the invention, the set of first phase-separated main buses and the set of second phase-separated main buses are connected to one end of the set of gas-insulated circuit breakers through the coupling buses and breakers in such a manner that the first phase-separated main buses for respective phases close to the gas-insulated circuit breakers branch upwards from the respective breakers on a common vertical plane and the second phase-separated main buses for respective phases remote from the gas-insulated circuit breakers branch downwards from the respective breakers on another common vertical plane. Therefore, the individual first phase-separated main buses as well as the individual second phase-separated main buses can partially overlap in one direction (vertical direction in the illustrated embodiment) to thereby reduce the size of the gas-insulated switchgear apparatus in the other direction (horizontal direction in the illustrated embodiment) in which the first phase-separated main buses as well as the second phase-separated main buses are juxtaposed. In addition, a space can be reserved between the set of gas-insulated circuit breakers and the lower set of second phase-separated main buses and can be efficiently utilized for maintenance inspection. Further, the coupling bus and the first and second breakers as well as the first and second phase-separated main buses can be of the same construction for respective phases. This simplifies the production of the gas-insulated switchgear apparatus.

Claims: A gas-insulated switch gear apparatus comprising gas-insulated circuit breakers (1) for three phases juxtaposed in a common horizontal plane, each having one end connected to a coupling bus (5), first and second sets of phase-separated main buses (24, 25) generally arranged on first and second horizontal planes above and below said common horizontal plane, and first and second breakers (7, 9) provided for each phase for connecting and disconnecting each gas-insulated circuit breaker (1) and the respective one of said first and second main buses (24, 25) of the same phase, characterized in that the coupling buses (5) of all three phases have the same length, that said first breakers (7) lie on a first common vertical plane and said second breakers (9) lie on a second common vertical plane, that said first set of main buses (24) arranged above said common horizontal plane is disposed relatively close to said gas-insulated circuit breakers (1) and the second set of main buses (25) arranged below said common horizontal plane is disposed further remote from said gas-insulated circuit breakers (1) in partially overlapping said first set of main buses (24) in the horizontal direction, that the three buses (24, 25) in each set are disposed on different horizontal levels at the apices of an isosceles triangle, and that said first and second main buses (24, 25) are arranged in the same sequence of phases. The apparatus of Claim 1, wherein said upper and lower sets of main buses (24, 25) are symmetrical to each other with respect to said common horizontal plane. The apparatus of Claim 1 or 2, wherein each of said first breakers (7) is gas-tightly sealed from the associated coupling bus (5), first main bus (24) and second breaker (9) through insulating spacers (6, 22, 8), and each of said second breakers (9) is gas-tightly sealed from the associated second main bus (25) through a further insulating spacer (23). The apparatus of any one of Claims 1 to 3, wherein each of said first and second breakers (7, 9) has an enclosure (10, 11) of a substantially cruciform longitudinal section with a vertically extending connection part coupled to the associated main bus (24, 25) through a branch bus (28, 29). The apparatus of any one of Claims 1 to 4, wherein each of said first and second breakers (7, 9) has a movable contact (16, 17) which is operated vertically by a manipulator (14, 15) provided on the side opposite to the associated main bus (24, 25).

Inventors: MITOMO, TOSHIHIDE, MIWADA, SATOSHI, TAKEUCHI, SHIGETAKA
Applicants: HITACHI, LTD.
Application year: 1986
Main classification: H02B13
IPC codes: H02B13, H02B5