EP1243059A1

EP1243059A1 - Electrical switchboard with device for cooling the internal components

Info

Publication number: EP1243059A1
Application number: EP00987413A
Authority: EP
Inventors: Marcello Garavaglia
Original assignee: ABB Service SRL
Current assignee: ABB Service SRL
Priority date: 1999-12-22
Filing date: 2000-12-06
Publication date: 2002-09-25
Also published as: WO2001047081A1; AU2366401A; ITMI992687A0; ITMI992687A1; IT1314312B1

Abstract

An electrical switchboard with a device for cooling the internal components of the switchboard, whose particularity consists of the fact that it comprises, inside the switchboard, means suitable to convert the heat generated inside the electrical switchboard into electric power for driving means for dissipating the heat.

Description

ELECTRICAL SWITCHBOARD WITH DEVICE FOR COOLING THE

INTERNAL COMPONENTS DESCRIPTION

The present invention relates to an electrical switchboard with a device for cooling the internal components.

It is known that electrical switchboards and their components, such as conducting bars, circuit breakers et cetera, generate heat during the operation of the components and that said heat must be dissipated appropriately in order to avoid damaging said components. Currently, cooling of an electrical switchboard is achieved according to various methods.

A first method provides for simple exchange by convection between the walls of the electrical switchboard and the outside environment.

A second method entails providing openings in the outer enclosure of the switchboard in order to facilitate the flow of fresh air inside said switchboard and thus increase the effectiveness of the natural convection inside the electrical switchboard.

A third method entails using fans which are powered directly by the electrical supply system and allow to move the air inside the switchboard and then facilitate its exit through appropriate openings.

Finally, a fourth method uses closed conditioning circuits, for example if a high degree of protection is required.

However, the above solutions have drawbacks. In particular, the first solution has the drawback that heat exchange is scarcely efficient. The second cooling method that is used instead has the drawback that it cannot be provided in the case of armored switchboards and/or switchboards requiring high degrees of protection.

The solution with fans instead has the drawback that arises from the fact that said devices need to be supplied with power tapped externally with respect to the switchboard and are generally not accepted favorably when the switchboards are not supervised by assigned personnel.

Finally, the fourth solution has the drawback that it is expensive and entails considerable space occupation due to the closed conditioning circuits.

The aim of the present invention is to provide an electrical switchboard with a device for cooling the internal components which is more efficient than the above cited known solutions. Within the scope of this aim, an object of the present invention is to provide an electrical switchboard with a device for cooling the internal components which is more compact and modular than currently known solutions. Another object of the present invention is to provide an electrical switchboard with a device for cooling internal components of the switchboard which does not require an external power supply of the cooling device. Another object of the present invention is to provide an electrical switchboard with a device for cooling internal components in which the electrical switchboard can be any chosen type of electrical switchboard. Another object of the present invention is to provide an electrical switchboard with a device for cooling internal components which is highly reliable, relatively simple to manufacture and at competitive costs.

This aim, these objects and others which will become apparent hereinafter are achieved by an electrical switchboard with a device for cooling the internal components of the switchboard, characterized in that it comprises, inside the switchboard, means suitable to convert the heat generated inside said electrical switchboard into electric power for driving means for dissipating said heat.

Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the electrical switchboard according to the invention, illustrated only by way of non- limitative example in the accompanying drawing of figure 1 which is a schematic view of a pair of cooling devices connected to a bar of an electrical switchboard according to the present invention. The invention uses means which are suitable to convert the heat generated inside said electrical switchboard into electrical power for driving heat dissipation means. Conveniently, the means for converting the heat into current comprise at least one thermoelectric cell, preferably a Peltier cell; alternatively, other converting means can be used, provided that they are suitable for the application. Advantageously, the invention uses an array of Peltier cells to power the heat dissipation means, which conveniently comprise at least one fan which is meant to cool the space inside the electrical switchboard. In particular, the Peltier cells allow to remove heat, converting the thermal energy dissipated by Joule effect into electric power used to drive the fans. Furthermore, the use of the fans allows to increase the heat exchange coefficient inside the electrical switchboard and therefore to increase the heat removed toward the outside environment.

The Peltier cells can conveniently be connected directly to the component whose heat is to be dissipated or to the internal walls of the electrical switchboard. Figure 1 illustrates schematically the arrangement of a pair of Peltier cells 1 on an electrical conducting bar 2 arranged inside an electrical switchboard; the constructive embodiments of the switchboard, the form of its elements and their relative arrangements are well known in the art and therefore they will not be described herein in details. The Peltier cells 1 therefore allow to power respective fans 3 and 4, by means of conductors 5 and 6, which ventilate the internal environment of the electrical switchboard.

As mentioned, the operating principle of the cells 1 is based on the thermoelectric effect and the electric power levels generated by said cells allow to move the fan 3 with DC power; the volumetric flow-rate of said fan is sufficient to effectively cool the internal components of the electrical switchboard.

In practice, the cells 1 operate with a thermal differential between the hot surfaces (the surface of the bar 2 in the case of figure 1) and the fluid contained in the switchboard. Assuming a difference in temperature between the faces of the cell of approximately 20-30°C, a cell with a surface of 15 cm² is capable of driving a fan having a volumetric flow-rate of 1 1/s. By using multiple cells arranged in series it is thus possible to drive multiple fans simultaneously and achieve a total flow-rate of approximately 5-6 1/s.

Said flow-rate, combined with the local cooling produced by the cell itself, is sufficient to ensure removal of the heat produced inside the switchboard by Joule effect, at the same time complying with the temperature values set by applicable standards. When the cells 1 are applied directly to the surfaces of components, one has the advantage of being able to remove the heat more directly. In the second case, i.e., when the cells 1 are placed on the internal surfaces of the switchboard, their installation is easier. The actuation speed of the fans 3 and 4 is directly proportional to the amount of heat produced by the electrical components inside the switchboard. In practice, the Peltier cells 1 are capable of producing more electric power as the heat generated by the electrical components increases and it is therefore possible to have self-adjustment of the actuation speed of the fans 3 and 4, thus having the advantage of being able to always perform optimum heat dissipation. In practice it has been found that the electrical switchboard according to the invention allows to fully achieve the intended aim and objects, since it is possible to achieve rapid and efficient heat dissipation without having to resort to an external power supply for the fans, with reduced space occupation and most of all with great modularity.

Depending on the type of electrical switchboard and on its dimensions, it is in fact possible to provide a variable number of fans driven by a corresponding number of Peltier cells. The electrical switchboard thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the dimensions, may be any according to the requirements and the state of the art.

1. An electrical switchboard with a device for cooling the internal components of the switchboard, characterized in that it comprises, inside the switchboard, means suitable to convert the heat generated inside said electrical switchboard into electric power for driving means for dissipating said heat.

2. The electrical switchboard according to claim 1, characterized in that said means suitable to convert heat into electric power comprise at least one thermoelectric cell. 3. The electrical switchboard according to claim 2, characterized in that said means suitable to convert heat into electric power comprise a plurality of thermoelectric cells which are mutually series-connected. 4. The electrical switchboard according to one or more of the preceding claims, characterized in that said at least one thermoelectric cell is a Peltier cell. 5. The electrical switchboard according to claim 4, characterized in that said at least one Peltier cell is applied directly to one of the components of said electrical switchboard.

6. The electrical switchboard according to claim 5, characterized in that said at least one Peltier cell is applied to the internal walls of the enclosure of said electrical switchboard.

7. The electrical switchboard according to one or more of the preceding claims, characterized in that said at least one Peltier cell generates a current which is proportional to the amount of heat transmitted to it.

8. The electrical switchboard according to claim 1 , characterized in that said heat dissipation means comprise at least one fan.