Transformer with heated radiator member

Abstract

An electrical device for connecting to a high-voltage power grid has a boiler, which is filled with an insulating fluid and in which a magnetizable core and at least one winding, which surrounds a section of the core, are arranged, and a cooling system which includes at least one radiator which is arranged outside the boiler and is connected thereto via the radiator in order to circulate the insulating fluid, wherein the radiator has at least two heat exchange elements which are connected in parallel with one another. In order to enable a cold start to be accelerated and to be carried out even at relatively low temperatures only one of the heat exchange elements has a heat-conducting connection, as a heated heat exchange element, to a heat source which generates heat when the operation of the electrical device is started.

Claims

1. An electrical device for connecting to a high-voltage power grid, the electrical device comprising: a boiler filled with an insulating fluid; a magnetizable core and at least one winding, which surrounds a section of said core, disposed in said boiler; a cooling system having at least one radiator arranged outside said boiler, said cooling system including an inflow line and a return flow line each connecting said boiler to said radiator in order to circulate the insulating fluid; and at least one heat pipe; said radiator having at least two heat exchange elements connected in parallel with one another, said at least one heat pipe forming a heat conducting connection between only one of said at least two heat exchange elements and at least one component selected from the group consisting of said boiler and the insulating fluid; and said one of said at least two heat exchange elements being a heated heat exchange element due to heat transferred thereto from said at least one heat pipe.

2. The electrical device according to claim 1, wherein said heat source is an electrical heating source.

3. The electrical device according to claim 1, wherein said at least one heat pipe has a heat-receiving end in contact with an outer wall of said boiler and a heat-outputting end in contact with said heated heat exchange element.

4. The electrical device according to claim 1, wherein said at least one radiator has an upper inflow line and a lower return flow line which are each connected to said boiler and to one another via said heat exchange elements, wherein said heated heat exchange element is at a shortest distance from said boiler.

5. The electrical device according to claim 4, which comprises heat pipes extending both in a region of said upper feed line and in a region of said lower return line between said heated heat exchange element and said boiler.

6. The electrical device according to claim 1, wherein said cooling system is a passive cooling system.

7. The electrical device according to claim 1, wherein said at least one radiator of said cooling system is one of a plurality of radiators, but only one of said radiator has a heated heat exchange element.

Description

(1) Further refinements and advantages of the invention are the subject matter of the following description of exemplary embodiments of the invention with reference to the figures of the drawing, wherein identically acting components are provided with the same reference symbols, and wherein

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(2) FIG. 1 shows a commercially available radiator in a side view,

(3) FIG. 2 shows a heat exchange element of the radiator according to FIG. 1 in a plan view, and

(4) FIG. 3 shows an exemplary embodiment of the electrical device according to the invention in a schematic side view.

DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows an exemplary embodiment of a commercially available radiator 1 in a schematic side view. It is apparent that the radiator 1 has an upper inflow line 2, which is connected hydraulically to a return flow line 4 via heat exchange elements or radiator elements 3. The inflow line 2 and the return flow line 4 each have an input opening or output opening which points to the left and via which the radiator 1 communicates, after being mounted, with the interior of a boiler (not illustrated in FIG. 1). The insulating fluid of said boiler can then be circulated via the inflow line 2, the heat exchange element 3 and the return flow line 4 via the radiator 1 with its heat exchange elements 3. The heat exchange elements 3 are fabricated from a heat-conductive material such as a metal and are in thermal contact with the external atmosphere. If the insulating fluid is conducted via the heat exchange elements, heat is therefore output to the colder external atmosphere by the heated insulating fluid.

(6) FIG. 2 shows a heat exchange element 3 in an end view. It is apparent that the heat exchange elements 3 are embodied in a plate shape. In other words, the radiator 1 shown in FIG. 1 is a so-called plate radiator. The plate-shaped heat exchange elements 3 each bound flow ducts through which the insulating fluid circulated via the heat exchange elements 3 is conducted. Finally, the insulating fluid passes into the collecting return line 4 and passes from there as cooled insulating fluid back into the interior of the boiler.

(7) FIG. 3 shows an exemplary embodiment of the electrical device 5 according to the invention which is embodied here as a transformer. The transformer 5 has a boiler 6 which is filled with an insulating fluid 7. Furthermore, arranged in the boiler 6 are a magnetizable core 8 and windings 9, of which, however, only one winding is illustrated schematically in FIG. 3. However, the windings 9 comprise here a so-called high-voltage winding and a so-called low-voltage winding which are arranged concentrically to form a limb 10 as a core 8. The method of functioning of such a transformer is, however, known to a person skilled in the art, with the result that at this point more details will not be given on this. The necessary connecting lines for connecting the windings to a high-voltage power grid are likewise not illustrated figuratively for reasons of overview.

(8) The transformer 5 is equipped with a cooling system 11 which is attached to the outside of the boiler 6 and comprises here merely one radiator 1 according to FIG. 1. It is apparent that the inflow line 2 and the return flow line 4 open into the interior of the boiler 6. Since the inflow line 2 and the return flow line 4 are connected to one another via heat exchange elements 3, circulation of the insulating fluid 7 via the radiator is made possible. A heat exchange element 3 which is at the shortest distance from the boiler 6, the so-called innermost radiator element 12, has a heat-conducting connection to the outer wall of the boiler 6 via schematically indicated heat pipes 13.

(9) After a relatively long stationary state of the electrical device 5, the insulating fluid 7 is completely cooled. In particular at low external temperatures, for example in the range of 10 to 50 degrees, the insulating fluid 7 has such a high viscosity, is in other words so viscous, that even after a relatively long starting process it is no longer circulated via the radiator 1. For this reason, the heat pipes 13, with which an improved transfer of heat between the boiler 6 and the innermost heat exchange element 12 is made available, are provided. Therefore, within the scope of the invention the high-voltage winding of the windings 9 can be connected to the high-voltage power grid. The low-voltage winding is, in contrast, applied to a resistor which is expedient for this purpose, with the result that the transformer 5 is not operated under full load. In this context, gradual heating occurs of the insulating fluid 7 and therefore of the outer wall of the boiler 6. Part of the heat which is produced in this context is transferred by means of the heat pipes 13 to the heated heat exchange element 12 which is thus heated, including the insulating fluid 7 arranged therein. The temperature of the heated heat exchange element 12 is therefore higher than that of the heat exchange elements 3 lying further toward the outside. The viscosity of the insulating fluid in the heated heat exchange element therefore decreases. Nevertheless, a difference in temperature occurs between the insulating fluid 7 within the boiler 6 and the insulating fluid within the heated heat exchange element 12, with the result that a pressure difference and therefore circulation of the insulating fluid via the innermost heat exchange element 12 occurs owing to the different densities of the insulating fluid 7. In this context, relatively warm insulating fluid continuously passes via the feed line 2 to the heated heat exchange element 12, wherein gradual heating of the heat exchange elements 3 which lie further toward the outside takes place. Finally, the insulating fluid 7 is also circulated via the heat exchange elements 3 which lie further toward the outside. The transformer can subsequently be operated under full load.

(10) Finally it is to be noted that the load regulation in the case of a cold start can be varied as desired within the scope of the invention. In contrast with the ways of implementing the cold start mentioned above, the electrical device according to the invention can also be started under full load.