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(11) | EP 0 049 641 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Gas insulated electrical apparatus |
| (57) A gas insulated electrical apparatus wherein a power transformer apparatus (2) and
a switchgear device (4) are contained in a single sealed housing (3) filled with a
gas insulator, the two devices being electrically connected inside the housing, and
the switchgear device (4) being electrically connected to power cables by means of
detachable connecting terminals (16, 18). |
[0002] A gas insulated electrical apparatus is known which comprises a power transformer and switchgear including a circuit breaker, a disconnecting switch, an instrument current transformer, an instrument voltage transformer, a ground switch and the like disposed in separate stationary housings, and with the switchgear electrically connected directly to power cables. This resulted in the dimensions of the whole gas insulated electrical apparatus being large, and complicated the maintenance and inspection of the electrical apparatus.
[0003] With a view to mitigating the foregoing disadvantages, the present invention provides a gas insulated electrical apparatus including a transformer and switchgear connected to the said transformer arranged within a sealed armour housing filled with an insulating gas, wherein terminals connected to the switchgear are mounted on said sealed housing so as to pass through a wall thereof, and are detachably connectible to connection terminals provided on the cables to be connected to the electrical apparatus.
[0004] The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
Figure 1(a) is a side view showing a prior-art gas insulated electrical apparatus.
Figure 1(b) is a plan view of the apparatus in Figure 1(a);
Figure 2 is a schematic circuit diagram of the apparatus shown in Figures 1(a) and 1(b);
Figure 3(a) is a side view showing an embodiment of a gas insulated electrical apparatus according to this invention.
Figure 3(b) is a plan view of the apparatus in Figure 3(a); and
Figure 4 is a partial sectional side view showing the details of a bushing terminal and a connection terminal for the cable.
[0005] In Figures 1(a) and l(b) and Figure 2, a gas insulated electrical apparatus of two banks is shown. Transformer coils la, lb wound on magnetic cores 2a, 2b are contained in sealed housings 3a, 3b which are filled with an insulating gas such as SF6 gas. Switchgear 4a, 4b are connected between the transformer coils la, lb and power cables 5a, 5b. The switchgear 4a, 4b comprises circuit breakers, 401a, 401b and disconnecting switches 40?a, 402b which function to connect or disconnect the transformer coils la, 1b to or from the power cables 5a, 5b; instrument current transformers 403a, 403b which detect the currents flowing through the transformer coils la, lb; instrument voltage transformers 404a, 404b which detect the voltages applied to the transformer coils la, lb; and ground switches 405a, 405b which earth the transformer coils la, lb.
[0006] The sealed housings 6a, 6b contain the switchgears 4a, 4b, and are filled with an insulating gas such as SF6 gas. Bushings 7a, 7b are mounted on the sealed housings 6a, 6b so as to pass through the walls of the respective housings, and function to connect the ends 501a, 501b of the power cables 5a, 5b to the switchgears 4a, 4b. Cable boxes 8a, 8b are mounted on the sealed housings 6a, 6b. The cable boxes 8a, 8b function to protect the cable ends 501a, 501b from dust etc., and also to prevent live parts such as the cable ends 501a, 501b from being physically exposed, in order to prevent electric shock accidents.
[0007] Bushings 9a, 9b are mounted on the sealed housings 6a, 6b so as to pass through the walls of the housings, while primary bushings 10a, 10b are counted on the scaled housings 3a, 3b so as to pass through a walls of the latter. Conductors lla, llb are connected between the bushings 9a, 9b and the primary bushings 10a, 10b, to connect the switetgerars 4a, 4b to the transformer coils la, lb. Ducts 12a, 12b are constructed of a metal material such as sheet iron, and house the conductors lla, llb therein. In addition, these ducts have the two end parts mounted on the sealed housings 3a, 3b and the sealed housings 6a, 6b, to electrically protect the conductors lla, 11b etc. from dust etc. and also to prevent live parts such as the conductors lla, 11b from being physically exposed, thereby to prevent electric shock accidents.
[0008] Secondary bushings 13a, 13b are mounted on the sealed housings 3a, 3b so as to pass through the walls of the housings, and function to pass electrical power transformed by the transformer coils la, lb. A circuit breaker 14 is connected between the power catles, 5a, 5b and a power cable 15. Electric power supplied from the power cable 15 to the power cables 5a, 5b through the circuit breaker 14 is applied to the transformer coils la, lb through the switchgears 4a, 4b and is transformed by these transformer coils la, lb. Thereafter, the transformed power is drawn from the secondary bushings 13a, 13b.
[0009] The prior-art gas insulated electrical apparatus thus constructed necessitates ducts 12a, 12b to housethe conductors lla, llb being the connective conductors between the transformer coils la, lb and the switchgears 4a, 4b; and the primary bushings 10a, lOb and the bushings 9a, 9b which are respectively mounted on the sealed housings 3a, 3b and the sealed housings 6a, 6b so as to pass through the walls thereof. This has led to the disadvantage that the apparatus becomes large in size. Moreover, in crder to inspect the switchgear 4a, the circuit breaker 14 must be opened. This has led to the drawback that power supply is cut off on the side of the switchgear 4b, also.
[0010] This invention seeks to mitigate the disadvantages of the prior art as stated above, and provides a gas insulated electrical apparatus in which the switchgear 4a or 4b and the transformer coils la or lb are contained in a single sealed housing, and in which the power cables 5a and 5b are detachably connected to the switchgears 4a and 4b. Hereinbelow, an embodiment of this invention will be described with reference to the drawings.
[0011] Figure 3(a) is a side view showing an embodiment of the gas insulated electrical apparatus according to this invention, while Figure 3(b) is a plan view corresponding to Figure 3(a). Figure 4 is a partial sectional side view showing the details of a bushing terminal and a line side terminal device. In these figures, portions corresponding to those in Figures l(a) and l(b) are respectively assigned the same reference numerals.
[0012] Referring to Figures 3(a) and 3(b) and Figure 4, sealed housings 3A, 3B respectively contain the two transformer coils la, lb and the switchgears 4a, 4b and are each filled with an insulating gas such as SF6 gas. The bushing terminals 16a, 16b are male in form in the present embodiment. These bushing terminals 16a and 16b are supported by the bushings 7a, 7b and have convex parts at their respective fore ends. Flanges 17a, 17b are formed integrally with the bushinps 7a, 7b and are mounted on walls of the sealed housings 3A, 3B. Connecting terminals 18a, 18b on the cable side function to detachably connect the power cables 5a, 5b to the bushing terminals 16a, 16b. As illustrated in Figure 4, the terminals 18a, 18b comprise female form connective terminals 181a, .181b which are connected to the cable ends 501a, 501b and which are connected to the convex parts at the fore ends of the bushing terminals 16a, 16b with the latter received snugly therein. Bushings 183a, 183b serve to mount the connective terminals 181a, 181b on cable boxes 182a, 182b; and cable beds 184a, 184b (Figures 3(a) and 3(b)) which support the power cables 5a, 5b. Wheels 19 are mounted on the sealed housing 3A, 3B and function to allow the sealed housings to be moved.
[0013] In the gas insulated electrical apparatus thus constructed, the transformer coil la or lb and the switchgear 4a or 4b are contained in a single sealed housing 3A or 3B, and the transformer coil la or lb and the switchgear 4a or 4b are directly connected by means of the conductor lla or llb. Accordingly, the ducts 12a, 12b and the primary bushings 10a, lOb as well as the bushings 9a, 9b as in the prior-art apparatus shown in Figures 1(a) and l(b) are not required, and the apparatus can be reduced in overall size. Further, the sealed vessels 3A, 3B are provided with the wheels 19. Therefore, in order to inspect the switchgear 4a, the bushing terminals 16a and the connective terminals 181a maybe separated by moving the sealed vessel 3A to the right as viewed in Figures 3(a) ana 3(b). Thus, the switchgear 4a can be inspected without opening the circuit breaker 14 shown in Figure 2, and the power supply on the side of the sealed housing 3B reed not be cut off. Although, in the embodiment illustrated in Figures 3(a) and 3(b), the wheels 19 are mounted on the sealed vessels 3A, 3B, it could equally be the line side connection terminals 18a, 18b that are rendered movable to allow disconnection.
[0014] As set forth above, the transformer coils and the switchgear are contained in single sealed housing, allowing the apparatus to be made small in size, and the ducts of the prior-art apparatus to be dispensed with, which also brings about the benefit that the apparatus is reduced in cost. Furthermore, the power cables and the switchgears are detachably connected, so that when the gas insulated electrical apparatus is arranged in a plurality of banks, it is possible to disconnect only a desired one or ones of the switchgears from the power cables.
1. A gas insulated electrical apparatus including a transformer and switchgear connected
to the said transformer arranged within a sealed armour housing filled with an insulating
as, wherein terminals connected to the switchgear are mounted on said sealed housing
so as to pass through a wall thereof, and are detachably connectible to connection
terminals provided on the cables to be connected to the electrical apparatus.
2. A gas insulated electrical apparatus as claimed in claim 1, wherein at least one
of said sealed housing and the connection terminals provided on the cables is constructed
so as to be movable, electrical contact between the terminals being made and broken
by moving said sealed housing and the cable connection terminals towards and away
from each other, respectively.
3. A gas insulated electrical apparatus as claimed in claim 1 or 2, wherein said bushing
terminals connected to said switchgear are male in form, while said connective terminals
of said line side terminal device are female in form.
4. A gas insulated electrical apparatus as claimed in claim 3, wherein said each bushing
terminal connected to said switchgear is formed unitarily with a bushing having a
flange mounted on the sealed housing wall.
A gas insulated electrical apparatus as claimed in claim 3, wherein said connection
terminals on the cables are mounted on a cable box by means of bushings which receive
the respective bushing terminals connected to said switchgear.