EP0049642B1

EP0049642B1 - Gas insulated electrical apparatus

Info

Publication number: EP0049642B1
Application number: EP19810304666
Authority: EP
Inventors: Teruo Ina; Tatsuo Sato; Atsushi Yamauchi
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1980-10-07
Filing date: 1981-10-07
Publication date: 1985-05-02
Also published as: DE3170311D1; JPS5765207A; JPH0158725B2; EP0049642A1

Description

This invention relates to a gas insulated electrical apparatus.
A gas insulated electrical apparatus is known having a power transformer and switchgear, the latter comprising a circuit breaker, a disconnecting switch, an instrument current transformer, and instrument voltage transformer, a ground switch and the like disposed in separate housings, and with the two devices connected externally via bushings.
The known apparatus has the disadvantage that its structure is large and complicated, and therefore expensive.
British patent specification 1036101 discloses a dry flame-proof transformer with a tank, and a vacuum circuit breaker in a casing attached to the transformer tank, for use in mines or in an explosive atmosphere. Vacuum circuit breakers are however costly and unsuitable for general use particularly in high-power distribution apparatus.
The object of the present invention is to improve the known gas-insulated transformer and switchgear apparatus, to provide a more compact and less expensive construction.
According to the present invention there is provided a gas-insulated electrical apparatus which comprises a transformer and switchgear for connection between the transformer and electrically conductive supply lines, a transformer enclosure and a switchgear enclosure attached thereto, characterised in that the transformer enclosure and the switchgear enclosure are merged to form a single sealed housing which is divided by an internal partition into a transformer chamber and a switchgear chamber, in such a manner that it is possible to inspect the transformer and the switchgear separately, the transformer chamber is filled with SF₆ insulating gas, and the switchgear chamber is filled with SFs gas or air which insulates the switchgear. It is particularly advantageous if the transformer chamber is filled with the SF₆ gas, which insulates the transformer, and the switchgear chamber is filled with atmospheric air which insulates the switchgear, to facilitate inspection of the switchgear.
The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a side view showing a prior-art gas insulated electrical apparatus;
Figure 2 is a schematic circuit diagram of the electrical apparatus shown in Figure 1; and
Figure 3 is a side view showing an embodiment of a gas insulated electrical apparatus according to this invention.

Referring to Figures 1 and 2, transformer coils 1 are wound on a magnetic core 2. A sealed housing 3 contains the transformer coils 1, and is filled with an insulating gas such as SF₆ gas. Switchgear 4 is connected between the transformer coil 1 and a power cable 5. The switchgear 4 comprises a circuit breaker 401 and a disconnecting switch 402 which function to connect or disconnect the transformer coil ^-1 and the power cable 5, an instrument current transformer 403 which detects the current flowing through the transformer coil 1, an instrument voltage transformer 404 which detects the voltage applied to the transformer coil 1, and a ground switch 405 which earths the. transformer coil 1. A second sealed housing 6 contains the switchgear 4, and is filled with an insulating gas such as SF₆ gas. A bushing 7 is mounted on the second sealed housing 6 so as to pass through a wall thereof, and functions to connect an end 501 of the power cable 5 to the switchgear 4. A cable box 8 constructed of a metal material such as sheet iron, is mounted on the second sealed housing 6. The cable box 8 functions to protect the cable end 501 from dust etc., and also to prevent live parts such as the cable 501 from being physically exposed, thereby to prevent electric shock accidents.
A bushing 9 is mounted on the second sealed housing 6 so as to pass through a wall thereof, while a primary bushing 10 is mounted on the first sealed housing 3 so as to pass through the wall thereof. A conductor 11 is connected between the bushing 9 and the primary bushing 10, and functions to connect the switchgear 4 to the transformer coils 1. A conduit or duct 12 constructed of a metal material such as sheet iron, contains the conductor 11 therein. In addition, the duct 12 has its two end parts mounted on the first and second sealed vessels 3 and 6, to protect the conductor 11 etc. from dust, etc. and also to prevent live parts such as the conductor 11 from being physically exposed, thereby to prevent electric shock accidents. A secondary bushing 13 is mounted on the first sealed housing 3 so as to pass through a wall thereof, and functions to pass electric power transformed by the transformer coils 1.
Electric power supplied by the power cable 5 is applied to the transformer coils 1 through the switchgear 4, and is transformed by these transformer coils 1. Thereafter, the transformed power is passed via the secondary bushings 13.
The conventional gas insulated electrical apparatus thus constructed requires there to be the duct 12 which contains the conductor 11, that is to say the connection 2 between the transformer coil 1 and the switchgear 4, and the primary bushing 10 and the bushing 9 which are respectively mounted on the first and second sealed housings 3 and 6 so as to pass through the walls thereof. This has led to the disadvantage that the overall dimensions of the apparatus become large.
This invention has been made in order to eliminate the disadvantages of the prior art as stated above, and provides an SF₆ gas insulated electrical apparatus in which the switchgear 4 and the transformer coils 1 are contained in a single sealed housing, whereby the apparatus is rendered small in size as compared with the prior art apparatus.
Figure 3 is a side view showing an embodiment of an SF₆ gas insulated electrical apparatus according to this invention. In the figure, portions corresponding to those in Figure 1 are respectively assigned the same reference numerals.
The transformer coils 1 and the switchgear 4 are contained in the single sealed housing 3a, and the transformer coil 1 and the switchgear 4 are connected directly. Accordingly, the duct 12 and the primary bushing 10 as well as the bushing 9 in the conventional apparatus shown in Figure 1 are not required, and the apparatus can be made relatively small in size.
A partition wall 14 is mounted inside the sealed housing 3a and divides the interior of this sealed housing into a first chamber 3a1 on the side of the transformer coils 1 and a second chamber 3a2 on the side of the switchgear 4. A housing 15 is mounted on the partition wall 14, and functions to connect the switchgear 4to the transformer coil 1.
More specifically, the division of the sealed housing 3a into a first and second chambers 3a1 and 3a2 by the partition wall 14 makes it possible to inspect the transformer coils 1 and the switchgear 4 separately. Moreover, the inspection of the switchgear 4 can be further facilitated by filling only the first chamber 3a1 with SF₆ gas and insulating the second chamber 3a2 with atmospheric air.
As set forth above, according to this invention, the transformer coils and the switchgear are contained in a single sealed housing, so the apparatus can be made relatively small in size and the bus ducts in the conventional apparatus can be dispensed with, thereby reducing the overall cost of the apparatus.

Claims

1. A gas-insulated electrical apparatus which comprises a transformer (1) and switchgear (4) for connection between the transformer and electrically conductive supply lines, a transformer enclosure (3) and a switchgear enclosure (6) attached thereto, characterised in that the transformer enclosure and the switchgear enclosure are merged to form a single sealed housing (3a) which is divided by an internal partition (14) into a transformer chamber (3a1) and a switchgear chamber (3a2), in such a manner that it is possible to inspect the transformer and the switchgear separately, the transformer chamber is filled with SF₆ insulating gas, and the switchgear chamber is filled with SF₆ gas or air which insulates the switchgear.

2. A gas insulated electrical apparatus as claimed in claim 1, characterised in that bushings (15) are mounted on said partition wall (14), to connect said transformer (1) to said switchgear (2).