WO1991006995A1

WO1991006995A1 - Gas-insulated electric switchboard

Info

Publication number: WO1991006995A1
Application number: PCT/EP1990/000825
Authority: WO
Inventors: Pietro Ciboldi
Original assignee: Abb Sace S.P.A.
Priority date: 1989-10-26
Filing date: 1990-05-22
Publication date: 1991-05-16
Also published as: IT1237503B; IT8922147A1; IT8922147A0

Abstract

A gas-insulated electric switchboard wherein at least one part of at least one wall of the cubicle housing is constructed as a heat exchanger between the interior of the cubicle and the environment.

Description

TITLE OF INVENTION

"Gas-insulated electric switchboard"

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a gas-insulated electric switchboard. Discussion of Background

Gas-insulated electric switchboards are used in the field of medium voltages and, because of the high dielectric strength of the gas SF₆, enable parts under voltage in the electrical apparatus installed to be disposed close to one another. It would be possible to reduce more substantially the dimensions of gas-insulated switchboards by disposing electrical equipments still more compactly. However, such equipments generate heat, which has to be dissipated.

For the dissipation of heat in traditional electric switchboards, that is to say switchboards which are not leaktight, it is known to install fans therein. This solution, however, cannot be applied to gas-in¬ sulated switchboards, since such switchboards are of hermetic construction in order to prevent the escape of the insulating gas.

It is also known to remove heat from traditional electric switchboards by using heat exchangers of the circulating air type, which are installed inside or outside the switchboard. These units have a box-like conformation defining two independent circuits, and the air passes into the heat exchange units through appropri- ate apertures. These units are provided with a fan for forced circulation of the air and may include refrigerat¬ ing circuits. They are therefore expensive units. When fitted inside the switchboards, these units take up a great deal of space. If installed outside the switch- board, these units are not only cumbersome but also require an air outlet from the cubicle for cooling purposes as well as means for subsequently returning the air into the cubicle.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a novel gas-insulated coolable electric switch¬ board which has effective cooling means, is of simple, inexpensive construction and takes up a limited space.

This aim is achieved with a gas-insulated switch- board wherein at least one part of at least one wall of the housing of the switchboard is constructed as a heat exchanger.

Particularly simple construction is achieved because the heat exchanger is made in one single piece. Another constructional facilitation is possible because the heat exchanger is composed of an inside part and an outside part, said parts being back to back fixed and with metallic continuity on the wall of the electric switchboard. It is advantageously possible to create automatic gas circultion inside the cubicle and to improve the cooling efficiency because of the fact that the inside part of the heat exchanger has a finned conformation with parallel fins definining vertically extending channels. A similar conformation is advantageously provided in the outside part of the heat exchanger.

More intensive cooling of the gas inside the switchboard can be obtained by the provision in the inside and outside parts of the heat exchanger of a circuit containing a refrigerant fluid, for carrying heat from inside to outside, freon gas or the like.

More intensive cooling can likewise be achieved by associating a forced circulation pump with the circuit containing the heat transport fluid, the refrigerant fluid, the freon gas or the like.

Faster cooling can also be obtained by associat¬ ing an external refrigerating compressor with the heat exchanger. In a simpler embodiment more intensive cooling is obtained by associating a fan with the outside part of the heat exchanger.

With the electric switchboard provided with a heat exchanger according to the invention the heat exchange takes place reliably by means of direct metallic conduction between a large surface inside the switchboard and a large outside surface.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by refer¬ ence to the following detailed description when con¬ sidered in connection with the accompanying drawings, wherein:

Figure 1 shows in perspective the housing of a gas-insulated electric switchboard provided with a heat exchanger according to the invention;

Figure 2 shows in perspective a first construc- tional variant of an electric switchboard according to the invention;

Figures 3 and 4 each show in section another constructional variant of an electric switchboard accord¬ ing to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in Figure 1 the reference numeral 1 designates the housing of a gas- insulated electric switchboard of any desired construc¬ tion, in the rear wall 2 of which is formed a heat exchanger given the general reference 3. The heat exchanger 3 comprises an inside part 4 and an outside part 5, these parts having a plurality of parallel ribs 6 defining between them vertically extending channels 7. The two parts 4 and 5 of the heat exchanger may consist of a single piece inserted into the wall 2 and fixed to the latter in such a manner as to form an integral part thereof, for example by means of brackets, perimetric frames or the like, in a manner not further illustrated. The two parts 4 and 5 of the heat exchanger may also consist of independent bodies fastened together or fastened back to back with metallic continuity on the wall 2. The conformation comprising fins 6 and channels 7 brings about the formation of automatic circulation of the gas inside the switchboard, as indicated by arrows in Figure 1.

In the embodiment illustrated in Figure 2, inside a heat exchanger 3 of the type shown in Figure 1 is provided a circuit or piping system 8 for the circulation in the heat exchanger of a fluid serving as a vehicle transporting heat from the inside to the outside. A fluid of this kind may for example consist of water. The piping system 8 may also carry a cooling fluid, for example freon gas, which extracts heat as the result of its change of state from liquid to gas and vice versa, as is known in refrigeration technique. The fluids conducted through the piping system 8 may be subjected to forced circulation by means of a pump 9.

In the embodiment illustrated in Figure 3 cooling of the outside part 5 of the heat exchanger 3 is effected by means of an external fan 10.

In the example illustrated in Figure 4 a com- pressor 11 is inserted into the piping system 8 provided in the heat exchanger parts 4 and 5, for the purpose of bringing about a refrigeration cycle.

The various embodiments illustrated have in common the feature that the heat exchanger 3 is composed of an inside portion 4 and an outside portion 5, which portions are connected together metallically to form a single body. With this conformation the heat that is to be dissipated, that is to say the temperature inside the cubicle, heats the inside portion 4 of the heat exchanger and, through metallic conduction, the outside portion 5 of the heat exchanger, said outside portion being in an environment of lower temperature. The outside part 5 and, through metallic conduction, the inside part 4 are thus cooled, with a consequent lowering of the temperature inside the switchboard. An extension of the body of the heat exchanger 3 over a substantial part of the length of the cubicle produces a substantially uniform circulation of gas over the entire length of the cubicle. This permits effective and reliable removal of heat from all the electrical equipment housed in the cubicle.

It is within the scope of the present invention also to provide a plurality of heat exchangers in the same wall and/or in different walls, for example for more effective cooling at determined points in the switch¬ board.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

WHAT IS CLAIMED AS NEW AND DESIRED TO BE SECURED BY LETTERS PATENT OF THE UNITED STATES IS;

1. A gas-insulated electric switchboard wherein at least one part of at least one wall of the housing of the switchboard is constructed as a heat exchanger.

2. The electric switchboard as claimed in claim 1, wherein the heat exchanger is made in one single piece.

3. The electric switchboard as claimed in claim 1, wherein the heat exchanger is composed of an inside heat exchanger part and an outside heat exchanger part, said parts being fixed back to back and with metallic con¬ tinuity on the wall of the electric switchboard.

4. The electric switchboard as claimed in claims 1 to 3, wherein the inside part and the outside part of the heat exchanger have a finned conformation with parallel fins defining vertically extending channels.

5. The electric switchboard as claimed in one or more of claims 1 to 4, wherein in the inside part and in the outside part of the heat exchanger a circuit is provided containing a refrigerant fluid, for carrying the heat from inside to outside, freon gas or the like.

6. The electric switchboard as claimed in claim 5, wherein a forced circulation pump is associated with the circuit containing the heat transport fluid, the refrigerant fluid, the freon gas or the like.

7. The electric switchboard as claimed in one or more of claims 1 to 4, wherein a fan is associated with the outside part of the heat exchanger.

8. The electric switchboard as claimed in one or more of claims 1 to 5, wherein an external refrigerating compressor is associated with the heat exchanger.

The whole essentially as described, illustrated and claimed for the aims and purposes specified above.