EP2932516B1 - Expansion radiator for a hermetically closed electrical transformer - Google Patents

Description

Technical area

The invention relates to a Dehnradiator for a hermetically sealed electrical transformer or a throttle, which is supplied to a heat exchange fluid via an inlet means, by a Dehnwellen cavity formed by a Dehnwelle and an associated cover member, and then discharged via drainage means.

State of the art

Electric transformers or chokes, as used in power distribution networks, are usually cooled with an insulating oil. To absorb the fluctuations in the oil volume that occur during operation, a compensating vessel is provided on the cover of the transformer tank. In spite of the dehumidifier, this expansion tank in contact with the ambient air absorbs moisture and oxygen in the insulating oil, which accelerates the aging process of the insulating paper and reduces the service life. To counteract this accelerated aging process of the insulating paper, it is also known to seal off the transformer hermetically against the external environment.

To compensate for volume and pressure fluctuations so-called Dehnradiatoren are known as cooling device, which are connected via connecting lines to the transformer tank and can cope with a certain range of fluctuation of the oil volume by bulging of their cooling elements. A Dehnradiator but can not design-related course an arbitrarily large expansion volume, but only one of its design associated maximum expansion volume compensate.

A cooling device for transformers in which individual radiator members compensate for fluctuating volumes by bulging is known, for example, from US Pat DE 100 10 737 C2 known. It is formed from two sheet metal parts provided with a plurality of beads, wherein the two sheet metal parts are connected / welded together at the edge and are additionally connected to one another by welds in the beads. In contrast to conventional radiators, the two sheets are connected to each other only every other one of the plurality of beads in order to obtain a larger expansion volume and without losing the mechanical stability. To achieve the most efficient cooling, the bulges in the DE 10 2005 002 005 B4 bounded by a spacer strip. In both embodiments, the two sheet metal parts of the radiator members are circumferentially welded together, which makes consuming expensive to manufacture.

From the DE 10 2009 015 377 B4 is a comparatively simpler to produce this Kühlradiator known, which is formed of a support plate and a single corrugated metal sheet. The individual shafts are supplied by headers, so-called collectors, with heat exchange fluid (coolant). However, this cooling fluid does not flow at the same time when entering in the direction of the bow of the sheet metal parts, but obliquely downward in the cavity of a Dehnwelle. As a result, however, the upper part of the corrugated sheet only contributes to a reduced extent to the cooling effect.

Presentation of the invention

It is an object of the present invention to provide a strain radiator for a hermetic electric transformer or reactor which has a better cooling effect, but at the same time is inexpensive to produce.

This object is achieved by a Dehnradiator according to the features of claim 1. Advantageous embodiments of the invention are defined in the dependent claims

According to the invention, the stretch radiator has expansion shafts, in each of which a flow-guiding part is arranged in the mouth region. The flow guide deflects the incoming heat exchange fluid on entering the cavity of the Dehnwelle toward the outer edge, that is to the bow of the Dehnwelle. The consequence of this is that the cooling effect of the upper part of the radiator, which is close to the manifold, is comparatively larger. Overall, a better cooling effect means that the operating temperature of the transformer oil is lower. The consequence of this is that the fluctuation range for the volume of oil in the transformer tank is reduced. A lower volume fluctuation mean, however, that less bulging is required by the radiator. Material fatigue and stress on the joints of the individual parts of the Dehnradiators are therefore lower or it can be controlled a greater power loss. This is favorable for the life. It is particularly advantageous that the flow guide can be integrated in a simple manner in the production of the manifold, so that the total cost of the Dehnradiator invention can be kept relatively low.

A preferred embodiment of the Dehnradiators can be constructed so that the Strömungsleitteil is formed so that the cross section of the projecting into the Dehnwelle Strömungsleitteils decreases seen in the direction of the end face to the outflowing collecting pipe. As a result, the cooling medium is efficiently directed in the direction of the bugs, but the further liquid flow experiences a lower flow resistance. This effect of the initial steering of the flow in the direction of the bow and subsequent flow in the direction of the end face of a Dehnwelle, can be effected by different shaping of the Strömungsleitteils.

In a particularly preferred embodiment of the invention, the flow guide projecting into the interior of the expansion shaft may be a plate-shaped part, e.g. a sheet that has the shape of a trapezoid.

In another preferred embodiment, the flow guide projecting into the expansion shaft may be pointed towards the bow, e.g. in the form of a wedge.

In a very particularly preferred embodiment, the flow-guiding part is trapezoidal in its surface shape and its cross-section is tapered in the direction of the bow.

It is also conceivable that the flow guide is designed as a cone or similar thereto. It is only important that the guide element protrudes into the expansion shaft and deflects the inflowing transformer oil in the direction of the outer edge side, where the heat dissipation is particularly favorable.

With regard to the manufacturing cost, it is particularly advantageous if the Dehnradiator is formed from two rows of Dehnwellen, each Dehnwellen series is formed of a single welded on a cover plate corrugated metal.

The strain radiator according to the invention is advantageously applicable to distribution transformers in energy supply networks.

Brief description of the drawings

To further explain the invention, reference is made to drawings in the following part of the description which further advantages, embodiments, details and effects of the invention can be found by way of non-exclusive embodiments.

Figur 1

einen erfindungsgemäßen Dehnradiator in einer perspektivischen Ansicht;

Figur 2

den Dehnradiator gemäß Detail "M" in Figur 1;

Figur 3

den Dehnradiator gemäß Figur 1 von der Seite gesehen;

Figur 4

eine Detaildarstellung gemäß Schnitt "P-P" in Figur 3;

Figur 5

eine heraus gerissene Dehnwelle in einer geschnittenen Darstellung, bei der gemäß einer besonderen Ausführung der Erfindung, der Strömungsleitteil in der Form eines Keils ausgebildet ist.

Show it:

FIG. 1

a Dehnradiator invention in a perspective view;

FIG. 2

the Dehnradiator according to detail "M" in FIG. 1 ;

FIG. 3

the strain radiator according to FIG. 1 seen from the side;

FIG. 4

a detailed representation according to section "PP" in FIG. 3 ;

FIG. 5

a broken-out Dehnwelle in a sectional view, is formed in accordance with a particular embodiment of the invention, the flow guide in the form of a wedge.

Embodiment of the invention

The FIG. 1 shows in a perspective view a Dehnradiator invention 1. The Dehnradiator 1 consists essentially of two rows of expansion shafts 9, which are respectively disposed on both sides of an upper manifold 2 and a lower manifold 12 (collectors). The expansion shafts 9 are welded at their back in the region of the inside between the two headers 2,12 with a cover plate 6 by means of a weld 11. Likewise, the front sides of the expansion shaft are welded liquid-tight top and bottom. The cross section of the manifold 2 is rectangular in the example shown and opens into a circular tube with a flange for connection to a transformer or a throttle. In operation, in the direction of arrow 10, the heat exchange medium (insulating oil, for example Transformer oil) and leaves the Dehnradiator 1 at its lower manifold 12. The structural design is symmetrical with respect to an imaginary passing through the collectors 2, 12 center plane. The two expansion shafts 9 are each formed from a single corrugated sheet (folding plate). In a practical example of a distribution transformer, an expansion shaft (cooling fin) protrudes about 100 to 300 mm, has a thickness of about 10 mm (with a plate thickness of about 1 mm) and a distance of about 50 mm. Each expansion shaft 9 encloses an elongated expansion shaft cavity 7 seen in the longitudinal extension of the expansion shaft (see FIG. 5 ). This cavity 7 is welded liquid-tight at each end and, as already said liquid-conducting connected to an upper and lower manifold 2,12 (inlet and outlet).

Each Dehnwelle 9 comes in a Dehnradiator a double function: on the one hand, the transported during operation of the transformer / throttle through the cooling medium zoomed amount of heat to be dissipated to the environment; On the other hand, an operational fluctuation of the pressure in the hermetically sealed transformer tank should be compensated. This compensation of the oil volume or the oil pressure is effected by a corresponding elastic deformation of the Dehnwelle 9. Each Dehnwelle 9 is constructed in the manner of a pillow. In the event of an overpressure in the transformer tank, bulging of the cushion occurs. With regard to the volume compensation, it is advantageous if the expansion shaft 9 itself is made of an elastic, easily yielding material. In FIG. 1 the upper header 2 is cut in the region of a section "M".

FIG. 2 shows an enlarged view of the section "M" of FIG. 1 , The sectional view makes the view free to mouth areas 4 in the manifold cavity 3. Through each of these mouth areas 4, the transformer oil flows into a Dehnwelle 9, according to the invention, this flow through a flow guide 5 (FIG. FIG. 4 ) towards the outside Edge, that is the bend of the corrugated sheet, the bow 8. The partially cut representation of the FIG. 2 also shows that the manifold 2 is formed from two mutually with their legs directed U-profiles.

FIG. 3 shows the Dehnradiator 1 according to the invention in a side view.

FIG. 4 shows a sectional view of a detail according to the line "PP" of FIG. 3 , The flow guide 5 is very easy to recognize here. According to the embodiment of the invention shown here, it is a plate-shaped part of the shape of a trapezoid. It is welded to the lower U-profile of the manifold 2 and protrudes with increasingly lower height in the expansion shaft cavity 7 inside. As a result, the cooling medium (arrow 14) flowing into the opening region 4 is directed to the outer edge of the expansion shaft 9, that is to the bow 8. Subsequently, the flow direction follows the arrow 15 in the direction of the drain. As far as the cooling effect is concerned, the in FIG. 4 Cut shown upper portion of a Dehnwelle 9 a higher proportion of the cooling of the insulating coolant, as was previously the case with Kühlradiatoren. As the representation of FIG. 4 can also be seen, the upper manifold 2 is formed of two with their legs facing each other U-profiles. The manifold cavity 3 is rectangular in cross section. The flow part 5 is a sheet metal part which is welded to the lower of these U-profiles.

FIG. 5 shows in an exploded magnified spatial representation of a single expansion shaft 9 and the associated cover plate 6. The Dehnwelle 9 consists of a bent by 180 ° sheet metal (corrugated metal or folding plate), in which the two legs extend almost parallel to the bow 8. In Dehnwellen cavity 7 is again the flow guide 5 can be seen, which tapers to a point in the direction of the bow 8, on the other hand, however, has the shape of a trapezoid. As a result, the heat exchange medium flowing in the direction of the arrow 14 is achieved in a particularly efficient manner (Isolation coolant, eg transformer oil) to the outer edge of acting as cooling fins Dehnwelle 8 and thereby to improve the cooling effect.

Although the invention has been further illustrated and described in detail with reference to the preferred embodiments described above, the invention is not limited by the disclosed examples. In particular, other variations can be deduced therefrom by those skilled in the art without departing from the scope of the invention.

1

Dehnradiator

2

Sammelrohr

3

Sammelrohr-Hohlraum

4

Mündungsbereich

5

Strömungsleitteil

6

Abdeckblech

7

Dehnwellen-Hohlraum

8

Bug

9

Dehnwelle

10

Pfeil

11

Schweißnaht

14, 15

Strömungsrichtung

Compilation of the reference numbers used

1

Dehnradiator

2

manifold

3

Manifold cavity

4

mouth area

5

flow guide

6

Cover plate

7

Extensional corrugations cavity

8th

bow

9

extensional wave

10

arrow

11

Weld

14, 15

flow direction

Claims (11)

1. Expansion radiator for a hermetically sealed electrical transformer or a choke, to which a heat exchange fluid is supplied via an inflow means (2), guided through an expansion corrugation cavity (7) formed by an expansion corrugation (9) and an associated cover part (6), and then drained via outflow means (12), characterised in that a flow guiding part (5) directing the flow direction of the heat exchange fluid is disposed in an orifice region (4) between the inflow means (2) and expansion corrugation cavity (7), which projects into the expansion corrugation cavity (7).
2. Expansion radiator according to claim 1, characterised in that the flow guiding part (5) is designed to direct the heat exchange fluid in the direction of the nose (8) of the expansion corrugation (9).
3. Expansion radiator according to claim 2, characterised in that the flow guiding part (5) is trapezoidal-plate-shaped.
4. Expansion radiator according to claim 2, characterised in that the flow guiding part (5) is wedge-shaped.
5. Expansion radiator according to claim 3 and 4, characterised in that the trapezoidal plate tapers toward the nose (8).
6. Expansion radiator according to claim 1, characterised in that the flow guiding part (5) is cone-shaped.
7. Expansion radiator according to claim 1, characterised in that the expansion corrugations (9) are disposed symmetrically with respect to the plane of symmetry running through the inflow means (2) and outflow means (12).
8. Expansion radiator according to claim 7, characterised in that the expansion corrugation cavity (7) is formed by a corrugated sheet welded to a cover sheet (6).
9. Expansion radiator according to claim 1, characterised in that the inflow means (2) is constituted by two U-sections with their legs aligned to one another and the flow guiding part (5) is a metal piece welded to one of these U-sections.
10. Expansion radiator according to claim 9, characterised in that the orifice region (4) is implemented as a rectangular slit in one of the U-sections.
11. Use of the expansion radiator according to one of claims 1 to 10 for an electrical distribution transformer incorporated in a power grid.

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