GB2200254A - Protection of electric power equipment - Google Patents

Abstract

An enclosure for a transformer cooled by a vaporisable liquid has passages 25 through the wall lousing connections eg. to associated gas filled switchgear the passages being located and devised so that the connections are maintained immersed in the liquid and vapour does not accumulate around them. <IMAGE>

Description

Prdtection .aQ-'electric power equipment This invention relates to vaporisation - cooled transformers in sealed enclosures filled with a degassed and dehydrated insulant. It is a development of the invention claimed in Claim 1 of our co-pending British patent application 8517608 (2161 989).

With electrical power equipment, such as power transformers, operating at high voltages, it is desirable to avoid or-minimise exposure of electrical connections to air and other gases which have poor insulation properties.

According to the present invention there is provided an enclosure containing electric power equipment said enclosure being filled with vaporisable electrically insulating liquid which is non-flammable or of low flammability said enclosure having at least one electrical connection extending along at least one passage through at least one wall of the enclosure the or each said passage being arranged so that vapour produced from said liquid in the enclosure rises above said connection or connections which are maintained immersed in said liquid without any undue accumulation therearound of vaporised liquid or gases released from said liquid.

When the electric power equipment is a tran-sformer it may be used in conjunction with gas-filled metal clad switchgear (including gas-filled busbar assemblies), the transformer and switchgear (or busbar) being located close to each other and arranged so that the said connection or connections connect directly with the switchgear or busbar without rewiring any intermediate connection or conductor which is exDosed to the air.The or each said connection 'navy comprise se a cable or a conductor passing through a bushing along said passage which at one side is connected within the liquid-filled transformer tank and at the other side is connected within a gas-filled enclosure of the switcbgear. The passage and/or the connection and mounting parts thereof may be flexible to allow for relative movements e.g. during pressure and temperature changes. Various arrangements are possible to avoid accumulation of gas around the connection in . the transformer tank. Thus, the passage may be arranged in a side wall of the tan-k horlzontally or preferably inclined to the horizontal so that the transformer side of the passage is higher than the other side thereof (e.g. the switchgear side).Alternatively the passage may be arranged at the top and an upper gas accumulation chamber or venting arrangement or the like may be provided. A further possibility is to arrange the passage at the bottom of the transformer tank, this being particularly convenient in the case where the transformer is to be connected with an underground gas-filled busbar system.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Fig.1 is a plan view of a transformer filled with vaporisable liquid and provided with electrical connections in accordance with one embodiment of the invention; and- Figs.2 and 3 are elevations of transformers with alternative connection arrangements.

Figure 1 shows the tank of a transformer with electrical connections -20,21 (of two different kinds), passing through walls 22,23 of the tank 24 so as to connect the transformer windings wirh adjacent gas-filled metal clad switchgear. The electrical connections may comprise cables 21, conductors extending through bushings 20 or the like and such connections pass through and are sealed relative to diaphragms or barriers between the transformer and the switchgear. As shown, such barriers are disposed within passages 25 along which the connections extend and these passages 25 are so inclined to the horizontal that gas and/or vapour within the tank 24 will not enter the passages 25 or ' accumulate in or adjacent to the connections 20,21 where this could result in reduced electrical insulation strength.

With this arrangement it will be appreciated that the connections are insulated on one side by the liquid in the tank 24 and on the other side by the gas filling in the metal clad switchgear. The connections are not exposed to the atmosphere at any stage.

Figure 2 shows an arrangement in which connections 31 pass in passages 33 through the base of the transformer tank 32. With this arrangement it will be appreciated that there is little or no tendency for gas or vapour to accumulate alongside the connections 31 (since evolved gas or vapour rises). Conveniently the connections may connect with gas-filled metal clad switchgear busbars in conduits beneath the transformer (e.g. underground).

Figure 3 shows an arrangement in which connections 41 pass along passages through the top of the transformer tank 42 but incorporate a chamber or chambers 43 above such connections in which gas and/or vapour may safely accumulate or from which gas and/or vapour may be removed.

The invention is not intended to be restricted to the details of the above embodiments which are described by way of example only.

Claims (6)

1 An enclosure containing electric power equipment said enclosure being filled with vaporisable electrically insulating liquid which is non-flammable or of low flammability and having at least one electrical connection extending along at least one passage through at least one wall of the enclosure the or each said passage being arranged so that vapour produced from said liquid in the enclosure rises above said connection or connections which are maintained immersed in said liquid without any undue accumulation therearound of vaporised liquid or gases released from said liquid.

2 Equipment according to claim 1, which-comprises an electric power transformer used in conjunction with gas-filled metal clad switchgear and wherein the or each said connection comprises a cable or a conductor passing through a bushing along said passage which at one side is connected within the liquid-filled transformer tank and at the other side is connected within a gas-filled enclosure of the switchgear.

3 Equipment according to claim 2 wherein the passage is arranged in a side wall of the tank so that the transformer side of the passage is higher than the other side thereof.

4 Equipment according to claim 2, wherein the passage is arranged at the top of the tank and an upper gas accumulation chamber or venting arrangement is provided.

5 Equipment according to claim 2, wherein the passage is at the bottom of the tank.

6 A method according to claim 1, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as -follows 6 Equipment according to caiw. ', substantially es hereinbefore described with, reference to and as illustrated in the accompanying drawings.