EP4312236A1 - Transformer housing, transformer having such a transformer housing, and arrangements of these - Google Patents

Abstract

The invention relates to a transformer housing (6) with a metal foam (1) implemented within the transformer housing (6), the transformer housing (6) being double-walled and thus a double wall (2) with an inner chamber (6c ), wherein the chamber (6c) is occupied by the metal foam (1). The invention further relates to a transformer with such a transformer housing (6) and arrangements thereof.

Description

The invention relates to a transformer housing with a metal foam implemented within the transformer housing, a transformer with such a transformer housing and arrangements of the aforementioned products.

In the power transformers currently regularly available, the conductor coils of the power transformer are usually wound on a U-shaped iron core profile and the magnetic circuit to be formed is then closed with an iron yoke arranged on the U-shaped iron core profile. Due to the design, magnetic stray losses occur during operation of the power transformer. These magnetic scattering losses and the low utilization of the iron core of such a power transformer in relation to the conductor length result in a larger thermal loss on the iron core, which, in combination with further thermal losses, leads to heating of the power transformer.

In order to dissipate the resulting heat, the power transformers are usually filled with oil and have an oil cooling circuit that is actively operated with oil pumping equipment. This is by far the most maintenance-intensive part of a power transformer.

Furthermore, due to the relatively poor utilization of the iron core, the number of windings per iron core section is usually chosen to be high in order to achieve the highest possible utilization of the magnetic field. This creates very compact winding structures, which, due to their compactness, lead to a concentration of thermal power loss at these points. These relatively hot spots lead to that the transformer oil of the power transformer and/or the conductor insulation, here the insulating varnish and/or the insulation paper of the conductor, degrades relatively more quickly depending on the mode of operation.

As the temperature of the transformer oil increases, the ability to absorb water in the transformer oil also increases, with the water being absorbed in particular by the conductor's insulation paper. The water absorbed reduces the insulation ability and promotes electrical discharges, which can result in defects in the power transformer. An improved dissipation of heat from the power transformer is therefore advantageous.

In connection with improved heat dissipation, this describes DE 11 2009 005 222 B4 a transformer of a dry type, correspondingly with a primary and a secondary coil, at least one of the coils having two conductor layers, each with a plurality of flat turns. In this case, several heat pipes are arranged between the conductor layers, in particular to improve the dissipation of heat from the flat turns. This makes it possible to provide a transformer with a higher power density, which is of particular interest for applications in which available space is limited. A heat pipe is understood to mean a 2-phase heat pipe that is filled with a liquid that has a liquid-gaseous phase transition. Although such heat pipes have very good heat conduction, they are structurally complex due to the use of the liquid and are expensive to operate.

In addition to the possibility of defects in a power transformer due to the heating already described, the increased thermal losses also lead to an increased operating noise level that can be viewed as disadvantageous. However, especially as the energy supply switches to renewable energies, there is an increased need for power transformers, which also leads to an increased density of arrangement in public spaces. A power transformer with a low operating noise level is therefore extremely advantageous because it can be placed closer to residential buildings. A low operating noise level is also advantageous in the offshore area, particularly in the arrangement of power transformers underwater, as this can ensure a low impact on the underwater fauna. A low operating noise level can therefore simplify or shorten the location selection and the associated approval procedures.

Solutions for a reduced operating noise level are already known from the prior art. That's how it works CN 2 07 165 354 U remove a transformer housing of a dry-type transformer, a plate made of foamed aluminum being inserted perpendicular to an upper and a lower housing wall of the transformer housing. Furthermore, a further sound insulation plate is glued to the side housing wall at a distance from this aluminum foam plate, so that an air-filled cavity is formed between the plates. If sound waves now penetrate through the aluminum foam plate, reflected waves are formed under the interaction of the aluminum foam plate, the air layer in the cavity and the sound insulation plate and interference attenuation occurs, so that the operating noise level emanating from a transformer having the transformer housing is minimized. However, due to the sound waves that propagate differently in air and transformer oil, the aforementioned design is only inadequately suitable for use in oil-filled power transformers.

With such oil-filled power transformers, there is still the problem of undesirable leakage of transformer oil, with the power transformers usually being double-walled to minimize this. Nevertheless, leakage cannot be completely avoided because cracks and/or microcracks occur in the transformer housing due to changing loads and the associated expansion cycles. To address this problem, oil collection trays are regularly installed under the transformer locations to collect leaking transformer oil. On the one hand, this option is not very satisfactory and is also not feasible when arranging power transformers underwater.

Against this background, the invention is based on the object of designing a transformer housing of the type mentioned in such a way that it has improved heat dissipation, a reduced operating noise level and increased tightness. Furthermore, the object is to provide a transformer with such a housing and arrangements thereof with improved heat dissipation, a reduced operating noise level and increased tightness.

This object is achieved according to the invention with a transformer housing according to the features of claim 1. The further embodiment of the invention can be found in the subclaims.

According to the invention, a transformer housing is provided with a metal foam implemented within the transformer housing. Here, the transformer housing is double-walled - at least in sections - and thus has - at least in sections and / or at least - a double wall with an inner chamber. The chamber is occupied - at least in sections - by the metal foam.

This significantly increases the thermal conductivity through the chamber. This in turn leads to improved heat dissipation from the transformer housing, whereby improved cooling of a transformer active part of a transformer having the transformer housing, in particular a power transformer, can be achieved or is achieved. Locally occurring and relatively hot spots on the transformer active part, especially on the core and/or the windings, can be minimized or even avoided in this way.

A transformer active part or simply active part regularly comprises a composite of core, windings, pressed parts, in particular press frames and/or press rods and derivation.

In addition, the metal foam has an acoustically dampening effect, particularly due to the large number of transitions between acoustically dense and thin medium and the associated reflection and interference, so that the operating noise level of a transformer having the transformer housing is reduced.

The tightness of the transformer housing can also be increased with the design according to the invention.

For this purpose, it should be stated that the transformer housing at least partially encloses a housing interior of the transformer housing, in which at least one transformer active part can be arranged. The interior of the housing is preferably filled with a dielectric insulating medium. The interior of the housing is particularly preferably filled with a transformer oil. This forms the dielectric insulating medium.

The respective double wall also has an inner housing wall adjacent to and/or facing the housing interior and an inner housing wall facing the housing interior spaced outer housing wall adjacent to and/or facing the environment or an ambient medium.

If the dielectric insulating medium and/or the transformer oil now enters the chamber filled with the metal foam, for example due to a crack forming in the inner wall of the housing, the insulating medium and/or the transformer oil largely gets caught in the metal foam, with the result that it is less likely to penetrate to the outer wall of the housing and, for example, . B. in turn can emerge from the transformer housing or a transformer having the transformer housing due to cracks that have arisen and / or are present in the outer wall of the housing.

In addition, the metal foam allows deformation of the double wall and in particular the outer housing wall and/or can serve as a crumple zone in the event of a shock from an object and/or an impact of an object on the double wall and in particular the outer housing wall. As a result, the energy of the shock and/or impact is reduced, whereby particularly extensive damage resulting from the formation of cracks or openings in the double wall and in particular in the outer housing wall can be avoided. This also allows the tightness of the transformer housing to be increased.

The transformer housing can basically have any shape. What is conceivable here is, for example, a substantially rectangular and/or cuboid design of the transformer housing. A cylindrical design is also conceivable.

However, the transformer housing can also be annular and/or hollow cylindrical, such an annular and/or hollow cylindrical transformer housing having a radially inner and a radially outer double wall. These double walls and in particular a respective outer housing wall then border on the environment and/or an ambient medium.

In an extremely advantageous development of the invention, the metal foam lies directly on the double wall, here in particular on an inner housing wall forming the double wall and an outer housing wall, at least in one, in particular first - thermal - operating point and/or, in particular first - thermal - operating region of the transformer housing . There is therefore the possibility that the metal foam is in a further, in particular second - thermal - operating point and/or - thermal - operating range, in which lower temperatures are present than in the in particular first - thermal - operating point and / or in particular first - thermal - operating range, is not or only partially in contact with the double wall. Consequently, the metal foam would only come into contact with the double wall during the transition from the second to the first - thermal - operating point and / or - thermal - operating range, ie in particular when there is heating and an associated expansion of the transformer housing, and then in particular in the first - thermal - operating point and / or in particular first - thermal - operating range rest on the double wall.

In principle, however, there is also the possibility that the metal foam is always, i.e. H. in each - thermal - operating point and/or - thermal - operating range on a respective double wall, i.e. H. on the inner wall of the housing and the outer wall of the housing.

A further advantageous embodiment of the invention is that the metal foam is an open-pored metal foam.

The design as an open-pore metal foam offers the advantage that additional materials can be introduced or stored in the pores of the metal foam. These materials could serve to further increase the thermal conductivity of the metal foam and thus the heat dissipation from the transformer housing and/or a transformer having the transformer housing. It would also be conceivable that the material serves to increase the tightness and/or the acoustic damping and thus to reduce the operating noise level of the transformer housing and/or a transformer having the transformer housing.

An embodiment of the invention also proves to be promising if the metal foam is made of aluminum.

Aluminum has an extremely advantageous high thermal conductivity or a high thermal conductivity coefficient. With the metal foam made of aluminum, i.e. an aluminum foam, better heat transport can be achieved from the interior of the housing to the environment and/or an ambient medium than would be possible, for example, with a solid wall made of steel.

Furthermore, in an advantageous embodiment of the invention it is provided that the metal foam is in the form of at least one mat, in particular one mat or several mats, is introduced into the chamber. This offers the advantage that the transformer housing with different thicknesses or chamber thicknesses can be filled with metal foam without having to provide a metal foam with an individual, corresponding thickness for each thickness of a chamber. The mats, on the other hand, can be easily adapted to the thickness of the chamber in several rows and/or when cut to size. This advantageously reduces the manufacturing costs for the transformer housing.

A further development can also be viewed as promising if a phase change material is embedded and/or deposited in the cavities or spaces of the metal foam, in particular the open-pored metal foam, and/or on its surface.

By storing and/or depositing the phase change material in the metal foam, it is extremely advantageous to further increase the heat transfer or heat dissipation, in particular from the inside of the housing, the tightness of the transformer housing and the acoustic damping of the transformer housing and thus the operating noise level of the transformer housing and/or or a transformer having the transformer housing.

It is furthermore advantageous if, in one embodiment of the invention, the phase change material forms a latent heat storage and/or a latent cold storage. However, the phase change material preferably forms a latent cold storage.

First of all, it should be briefly stated that a transformer, here in particular a power transformer, is often subject to a heating cycle and a cooling cycle alternately due to changing loads, with a - thermal - operating point and / or - thermal - at a respective end and / or beginning of such a cycle. Operating range of the transformer housing and / or a transformer having the transformer housing is present, in which a temperature and / or a temperature range prevails. The phase change material is chosen in such a way that it is present in a different phase at the end and/or beginning of a respective cycle and thus in different - thermal - operating points and / or - thermal - operating areas and consequently in the cycles or a transition between the - thermal - operating points and / or - thermal - operating areas a phase transition or phase change takes place. During the phase change, the temperature of the phase change material - as is known - remains constant, with the recorded and / or Heat released, i.e. thermal energy, during the phase change, in particular significantly exceeds the heat absorbed and/or released between the - thermal - operating points and / or - thermal - operating areas and the phase change. In this way, the phase change can be used to very advantageously dissipate heat from the interior of the transformer housing, preferably from the transformer oil of a transformer having the transformer housing.

The thermal activation of the cold storage is homogenized in the spatial structure, corresponding to the metal foam. This means a z. B. Heating of the phase change material, in particular within a heating cycle, takes place largely homogeneously over the thickness of the chamber due to the storage and / or attachment to the metal foam. A progressive phase change, in particular starting on the inner wall of the housing, would be avoided in this way, which advantageously represents a short response time to a heating cycle and thus a load change of a transformer having the transformer housing. However, depending on the temperature of the environment and/or the surrounding medium of the transformer housing and/or a transformer having the transformer housing, a section of the metal foam with the phase change material directly adjacent to the outer wall of the housing can have a temperature and/or a temperature range due to the existing heat dissipation , in which the phase change material does not undergo a phase change and is therefore, in particular, always in its first phase.

In the above context, starting from the beginning of a heating cycle, which is caused in particular by a load change of a transformer having the transformer housing, it should be explained again by way of example that the phase change material, which is in a first phase, initially heats up while absorbing heat from the interior of the housing until this has reached the phase transition point. When the phase transition point is reached, this now changes from the first phase into a second phase with further absorption of heat from the interior of the housing, with the temperature of the phase change material - as is known - remaining constant during the phase transition. After the phase change has taken place, the temperature of the phase change material would increase again. The load change occurs accordingly from a low load, in which a temperature of the phase change material is below the phase transition point, to a higher and/or high load, due to which a temperature of at least parts of the phase change material is reached corresponding to and/or above the phase transition point.

In principle, a phase transition or a phase change between liquid and gaseous could be carried out by the phase change material and/or could be carried out by the phase material.

However, a further particularly advantageous embodiment of the invention is preferably that a phase change between solid and liquid can be carried out by the phase change material, in particular in at least one - thermal - operating point and / or operating range of the transformer housing or a transformer having the transformer housing and/or is carried out by the phase material. In addition to the already explained, fundamental improvement in heat dissipation from the inside of the transformer housing, the design of a phase change between solid and liquid offers the advantage of increased tightness of the transformer housing or a transformer having the transformer housing. The phase change material can thus penetrate into existing or created cavities, in particular cracks, in the double wall, here in the inner wall of the housing and/or in the outer wall of the housing, and close these, in particular after a new phase change into the solid phase. However, such closing of cavities such as cracks can also take place without a transition to the liquid phase if the phase change material is, for example, pasty and/or waxy. Furthermore, the phase change material can also increase the tightness on its own, for example due to its material properties. It is therefore conceivable that the phase change material is hydrophobic and thus also minimizes penetration of an ambient medium such as water into the transformer housing or a transformer having the transformer housing.

The metal foam with the embedded and/or attached phase change material is - essentially - incompressible. This can be critical in the operation of a transformer having the transformer housing, since there is a temperature gradient from the inside of the housing to the environment and/or an ambient medium and thus also between the inner wall of the housing and the outer wall of the housing. This temperature gradient causes a different thermal expansion of the double wall, here consequently the inner wall of the housing and the outer wall of the housing, which in turn causes pressure on the metal foam with the phase change material. If the metal foam cannot escape with the phase change material, this would, in the worst case scenario, result in damage and/or even destruction of the transformer housing due to its incompressibility.

In an advantageous embodiment of the invention, it is envisaged that at least one area without metal foam and/or phase change material, i.e. in particular at least one at least partially gas-filled or air-filled area, is formed in the metal foam embedded and/or attached with phase change material. Due to the lack of filling of the areas with metal foam and/or phase change material, the metal foam present in the remaining areas with the phase change material can expand into the compressible areas without metal foam and/or phase change material, so that any resulting pressure on the double wall can be avoided or is avoided.

In a design-favorable development of the invention, at least one area without phase change material also includes an insert made of a closed-cell metal foam, in particular a closed-cell aluminum foam. This offers the advantage that compressibility of the area or areas as well as increased thermal conductivity in this area or these areas can be guaranteed. The closed-pore design of the metal foam advantageously prevents phase change material from penetrating, so that compressibility is maintained even during long-term operation.

A further promising embodiment of the invention is that the transformer housing has a gas-filled or air-filled compensation space, in particular a head space, towards and/or into which the metal foam and/or the phase change material can be stretched or expanded. This also makes it possible, taken alone or in combination with at least one area without a metal foam and/or a phase change material, to avoid pressure arising on the double wall due to uneven thermal expansion of the double wall.

In a practical design, the phase change material is also paraffin. The paraffin is ideally suited as a phase change material, as the phase change of the paraffin can be implemented in a range from 25 °C to 60 °C with the associated formation of a self-regulating (latent) heat and/or cold storage.

The phase transition point of the paraffin can thus be adapted to the - thermal - operating points and / or operating ranges of the transformer housing and / or a transformer having the transformer housing, so that at least part of the paraffin, but preferably largely or completely, in a particularly first - thermal - operating point and/or a particularly first - thermal - operating range of the transformer housing or a transformer having the transformer housing is present in the liquid phase above the phase transition point. The temperature and/or the temperature range of the paraffin in the liquid phase can be between 20°C and 70°C, preferably 25°C and 65°C, particularly preferably 35°C and 65°C. In a further, in particular second - thermal - operating point and/or a further, in particular second - thermal - operating range below the phase transition point, at least part of the paraffin, but preferably largely or completely, is in the solid phase. The temperature and/or the temperature range of the paraffin in the solid phase can be between 0 °C and 25 °C, preferably 2 °C and 20 °C, particularly preferably 2 °C and 15 °C.

In principle, the invention can also include a transformer with an aforementioned transformer housing, in particular a transformer housing according to claims 1 to 12. Such a transformer can have an overpressure within the transformer housing, for example in the head space and/or the chamber between the double wall, in order to minimize the probability of a leakage of dielectric insulating medium, in particular transformer oil, or even to avoid such a leakage. An active oil circuit or forced convective cooling of transformer active parts can be dispensed with due to the inventive design of the transformer housing and/or the transformer.

However, the task mentioned at the beginning is also achieved according to the invention with a transformer according to the features of claim 13.

According to the invention, a transformer, in particular a power transformer, is therefore provided, wherein the transformer has a transformer housing according to the invention and the transformer is also designed to be stackable.

The stackability of the transformer can z. B. be given by running the high-voltage connections from the side of the transformer housing. In addition, corresponding spacers and/or anchors can be provided on the transformer housing, via which at least two transformers can be connected to one another.

In this embodiment of the transformer according to the invention, an excess pressure can also be present within the transformer housing, for example in the head space and/or the chamber between the double wall, in order to reduce the likelihood of dielectric leakage Insulating medium, especially transformer oil, to minimize or even avoid such a leak. An active oil circuit or forced convective cooling of transformer active parts can in turn be dispensed with due to the inventive design of the transformer housing and/or the transformer.

Due to the stackability, heat dissipation from the transformer in particular can be further improved, since when a stack of transformers is implemented, increased convection and / or, with appropriate arrangement, a chimney effect to increase the heat dissipation from the double wall of a transformer housing and in particular the Housing outer wall is present and / or can be used.

According to the invention, the task mentioned at the outset is also achieved with an arrangement according to the features of claim 14.

According to the invention, an arrangement of at least two aforementioned transformers according to the invention is provided, these being stacked one above the other to form a transformer stack or several such transformer stacks.

As already explained, stacking transformers leads to an increase in heat dissipation from the stacked transformers due to increased convection. When designing several stacks, in particular arranged at a corresponding distance from one another, a chimney effect can also be created and thus the heat dissipation can be increased even further.

The increased mass of such a transformer stack also allows the operating noise level of the transformer stack to be minimized. In addition to increasing the heat dissipation from the transformers and reducing the operating noise level, the design of a transformer stack is also advantageous in terms of minimizing the space or area required for an installation area. This applies both on land and in the offshore area, either on an offshore platform or underwater.

The transformer also has at least one transformer active part inside the transformer housing, which z. B. can have a U-core profile or an E-core profile with windings applied to the U-core or E-core. It is also conceivable to design it as a toroidal core transformer or a quasi toroidal core transformer. This would be the quasi toroidal transformer respectively Polygonal transformer made up of individual, in particular linear or arcuate iron core segments with windings at least partially applied to the iron core segments. The iron core segments can be connected to one another via iron core segment locks to form a closed magnetic circuit.

The object is also achieved according to the invention with an arrangement according to the features of claim 15.

According to the invention, an arrangement and/or use of a transformer housing according to the invention, a transformer according to the invention or an arrangement of transformers according to the invention to form a transformer stack is provided, wherein the transformer housing, the transformer or the arrangement to form a transformer stack is arranged and/or used underwater becomes.

Precisely due to the high tightness of the transformer housing against an exit of the dielectric insulating medium used as a cooling medium inside the housing, in particular a transformer oil, as well as the reduced operating noise level, the transformer housing or the transformer having the transformer housing and / or a transformer stack made of these is extremely advantageous for underwater arrangement. In this way, any negative impact on the underwater flora and fauna can be advantageously minimized. The existing ambient medium of water then also causes a further improvement in heat dissipation from the inside of the housing and thus improved cooling of transformer active parts.

Fig. 1

eine Ausführungsform eines stapelbaren Transformators mit quaderförmigem Transformator-Gehäuse;

Fig. 2, 3

Horizontalschnitte eines Metallschaums;

Fig. 4

eine erste Ausführung eines Transformatorstapels aus stapelbaren Transformatoren mit quaderförmigem Transformator-Gehäuse;

Fig. 5

ein hohlzylindrisch ausgebildetes Transformator-Gehäuse;

Fig. 6

eine zweite Ausführung eines Transformatorstapels aus stapelbaren Transformatoren mit hohlzylindrisch ausgebildetem Transformator-Gehäuse.

The invention allows for various embodiments. To further clarify their basic principle, some of them are shown in the drawing and are described below. The drawing shows in

Fig. 1

an embodiment of a stackable transformer with a cuboid transformer housing;

Fig. 2, 3

Horizontal sections of a metal foam;

Fig. 4

a first embodiment of a transformer stack consisting of stackable transformers with a cuboid transformer housing;

Fig. 5

a hollow cylindrical transformer housing;

Fig. 6

a second version of a transformer stack made of stackable transformers with a hollow cylindrical transformer housing.

The Figure 1 shows an embodiment of a stackable transformer 12, here a power transformer, in a schematically very simplified cross section.

The transformer 12 has the transformer housing 6, the transformer housing 6 with the double wall 2 consequently being double-walled and thereby having the inner chamber 6c. Here, the chamber 6c is occupied by the open-pored metal foam 1, which, as shown, lies against the double wall 2 at every operating point of the transformer 12. In order to ensure the best possible heat conduction through the metal foam 1, it is made of aluminum.

In addition, the double wall 2 each has the housing inner wall 15 and the housing outer wall 16 spaced apart from the housing inner wall 15, between which the chamber 6c is correspondingly formed.

The phase change material 5 is also embedded and deposited in the spaces 4 of the open-pored metal foam 1 as well as on its surface, with a phase change between solid and liquid being able to be carried out by the phase change material 5 in a - thermal - operating point of the transformer 12. For this purpose, the phase change material 5 is a paraffin 11. By designing the phase change material 5, here the paraffin 11, in such a way that a phase change between solid and liquid can be carried out in a - thermal - operating point of the transformer 12, the phase change material 5 becomes a latent -Heat storage and/or a latent cold storage is formed.

Furthermore, in the housing interior 17 enclosed by the transformer housing 6, the transformer active part 18 shown is arranged, which is surrounded by the dielectric insulating medium 7, here the transformer oil 19, which, in addition to the insulating function, also functions as a cooling medium for the transformer active part 18.

Such a transformer 12 is subject to changing loads, e.g. B. changing network loads, usually alternating between a heating cycle and a cooling cycle. At the beginning of a heating cycle, the load on the transformer 12 increases and the transformer active part 18 begins to heat up, which is caused by the transformer active part 18 generated heat is absorbed via the transformer oil 19, in particular convectively, and transferred to the housing inner wall 15, which in turn leads to heating of the housing inner wall 15. Due to the occupation of the chamber 6c with the metal foam 1, this heat is transferred to the outer housing wall 16 in a significantly improved manner compared to a gas-filled chamber 6c, since the metal foam 1 made of aluminum has a significantly higher thermal conductivity coefficient than a gas, for example air, and thus a There is higher heat conduction between the inner housing wall 15 and the outer housing wall 16. The heat then passes from the outer housing wall 16, in particular by convection, to the surrounding medium 8, which is formed as water due to the arrangement of the transformer 12 underwater. At the same time, the phase change material 5, here the paraffin 11, also heats up while absorbing heat from the housing interior 17. This occurs largely homogeneously over the thickness of the chamber 6c due to the storage and attachment to the metal foam 1. The phase change material 5 is heated until it has reached its phase transition point, in this case its melting point. When or after reaching the phase transition point, the phase change material 5 now passes from its first, here solid phase into its second, here liquid phase, with further absorption of heat from the housing interior 17 or from the housing inner wall 15, the temperature of the phase change material 5 during the phase transition - as is well known - remains constant. The heat absorbed by the phase change material 5 to complete the phase change or phase transition significantly exceeds the heat absorbed up to the phase transition point by the phase change material 5 and/or the metal foam 1. In this way and in combination with the transfer of heat through the metal foam 1 to the housing outer wall 16, a disproportionately improved heat dissipation from the housing interior 17 and in particular the transformer oil 19 can be ensured.

Furthermore, the tightness of the transformer 12 and in particular the transformer housing 6 is also improved by the design of the metal foam 1 and the phase change material 5 incorporated and/or deposited therein, here the paraffin 11. As explained above, the transformer 12 is subject to heating and cooling cycles, as a result of which the inner housing wall 15 in particular also heats up and cools down alternately. As a result, the housing wall 15 also alternately expands and contracts again, which can cause cracks, in particular microcracks, in the material of the housing wall 15. These cracks are now penetrated and/or filled by the phase change material 5 during the transition of the phase change material 5 into its liquid phase and thus in particular also during cooling and the associated transition of the phase change material 5 sealed into the solid phase. This significantly minimizes or even prevents the insulating medium 7, here the transformer oil 19, from escaping from the housing interior 17.

In addition, there will also be an escape of phase change material 5, here paraffin 11, from the transformer housing 6 and/or penetration of the surrounding medium 8, in this case water, into the transformer 12 and here the transformer housing 6, especially if the transformer is damaged Transformer housing 6 and in particular the housing outer wall 16 is minimized. This is caused by the fact that the section of the phase change material 5, here the paraffin 11, which is closely adjacent to the housing outer wall 16, is water in a body of water such as a lake or preferably a sea, in which the transformer 12, for example, due to the low regular temperature of the ambient medium 8 . B. would preferably be arranged underwater in an offshore area, in particular always in the solid phase. Damage such as openings and/or cracks in the outer housing wall 15 are thus closed by the pasty or waxy phase change material 5, here in the form of paraffin 11. In addition, the paraffin 11 is hydrophobic, which further reduces the probability of penetration of the surrounding medium 8, here water.

Since the housing inner wall 15 is also subject to a higher expansion than the housing outer wall 16 compared to the housing outer wall 16 due to the comparatively greater heating within a heating cycle of the transformer 6, the volume of the chamber 6c is reduced during such a heating cycle. In order to avoid damage to the transformer housing 6 due to the incompressibility of the filling medium 6d of the chamber 6c formed by the metal foam 1 and the phase change material 5, the transformer housing 6 has the compensation spaces 14, towards which and/or into which the Metal foam 1 and/or the phase change material 5 is stretchable.

Furthermore, due to the acoustic dampening effect of the filling medium 6d consisting of metal foam 1 and phase change material 5, the acoustic emissions of the transformer 12 and thus its operating noise level are reduced.

From the Figures 2 and 3 There are also horizontal sections through the metal foam 1.

This shows Figure 2 an embodiment of the metal foam 1, the metal foam 1 in the form of several mats 3 in the in Figure 1 chamber 6c shown is introduced.

The Figure 3 It can also be seen that in the open-pore metal foam 1 provided with phase change material 5, several areas 9 are formed without phase change material 5. In this development, these areas 9 without phase change material 5 include inserts 10 made of a closed-cell metal foam 1, which has gas-filled and in particular air-filled pores. This makes it possible to do this even without executing the in Figure 1 shown compensation spaces 14 an extension of the also in Figure 1 housing inner wall 15 set out can be ensured without damage to the transformer housing 6 occurring due to incompressibility of the filling medium 6d made of metal foam 1, phase change material 5 and inserts 10. Due to the compressibility of the gas enclosed in the pores of the closed-cell metal foam 1, in particular air, the inserts 10 enable the filling medium 6d to be compressed.

From the Figure 4 a transformer stack 13 now emerges, which is an arrangement of several stacked one on top of the other and from the Figure 1 known transformers 12 includes. Through the transformer stack 13, improved heat dissipation from the housing interior 17 of the transformers 12 can be achieved through the resulting natural convection of the surrounding medium 8 along the transformer stack 13. The convection is in the Figure 4 indicated by arrows. The transformer stack 13 is arranged underwater, so that the ambient medium 8 in this embodiment of the arrangement of the transformer stack 13 is water, in particular seawater. Due to the arrangement of the transformers 12 as a transformer stack 13, there is also a very small space or area requirement for the large number of transformers 12. This is particularly the case when arranged in a sea, e.g. B. in the offshore area of a sea, especially on the seabed, to be seen as very advantageous in order to be able to ensure the least possible influence on the underwater fauna and flora. To set up the transformer stack 13, here in particular on the seabed, the transformer stack 13 is connected to the base plate 21 via the stand structure 20, which is essentially permeable to the surrounding medium 8. This also enables heat to be dissipated on the bottom side of the lowest transformer 12, which is arranged adjacent to the base plate 21. In order to enable compensation processes for the dielectric insulating medium 7, here the transformer oil 19, and in particular to ensure that the housing interior 17 of the transformers 12 is always completely filled, the transformer stack 13 has the compensation container 22 at its uppermost position, i.e. the position furthest away from the base plate 21 for the dielectric insulating medium 7, here the transformer oil 19.

Through the Figure 5 A second embodiment of a transformer housing is further disclosed.

The transformer housing is in the Figure 5 shown in horizontal section and designed as annular or hollow cylindrical. The transformer housing thus has a - radially - inner and a - radially - outer double wall.

Between the respective double walls, the inner chamber 6c is formed, which is filled with the filling medium 6d made of the thermally conductive open-pored metal foam and the intermediate space filling paraffin.

The dielectric insulating medium 7 is carried out inside the housing between the double walls. In this case, metal sheets that are flush with the surface of the chambers 6c or the double walls can be designed inside the housing.

The transformer housing is also surrounded by the ambient medium 8. This applies both outside and in the annular space.

The annular space is the radially inner and/or central space of the transformer housing.

The heat flow Q through the - respective - heat conduction-improved housing wall is also shown. A respective housing wall comprises a double wall with the filling medium 6d of the inner chamber 6c.

The Figure 6 again shows a transformer stack consisting of several transformers with the dielectric insulating medium 7 inside the housing in the form of the stacked rings 6.1. The transformers are therefore designed as ring transformers with, in particular, ring-shaped transformer active parts. The transformers have corresponding ring-shaped or hollow cylindrical transformer housings.

The transformer stack is also connected to the base plate via a support structure. The framework is permeable to the surrounding medium 8. Natural draft cooling - here a convective heat transfer into the surrounding medium - can already occur Figure 5 executed annular space.

The oil expansion tank 6.11 is also arranged in the top position of the transformer stack.

REFERENCE SYMBOL LIST

1 metal foam 11 paraffin 2 Double wall 12 transformer 3 mat 13 Transformer stack 4 space 14 Compensation room 5 Phase change material 15 Housing inner wall 6 Transformer housing 16 Housing outer wall 6.I stacked ring 17 Housing interior 6.II Oil expansion tank 18 Transformer active part 6c chamber 19 Transformer oil 6d Filling medium 20 Stud structure 7 dielectric insulating medium 21 base plate 8th Ambient medium 22 surge tank 9 Area Q Heat flow 10 inlay

Claims (15)

Transformer housing (6) with a metal foam (1) implemented within the transformer housing (6), characterized in that the transformer housing (6) is double-walled and thus has a double wall (2) with an inner chamber (6c) has, the chamber (6c) being occupied by the metal foam (1). Transformer housing (6) according to claim 1, characterized in that the metal foam (1) lies against the double wall (2) at least in one operating point and/or operating range of the transformer housing (6). Transformer housing (6) according to claim 1 or 2, characterized in that the metal foam (1) is an open-pored metal foam (1). Transformer housing (6) according to at least one of the preceding claims, characterized in that the metal foam (1) is made of aluminum. Transformer housing (6) according to at least one of the preceding claims, characterized in that the metal foam (1) is introduced into the chamber (6c) in the form of at least one mat (3). Transformer housing (6) according to at least one of the preceding claims, characterized in that a phase change material (5) is embedded and/or deposited in the cavities or spaces (4) of the metal foam (1) and/or on its surface. Transformer housing (6) according to at least one of the preceding claims, characterized in that the phase change material (5) forms a latent heat storage and/or a latent cold storage. Transformer housing (6) according to at least one of the preceding claims, characterized in that a phase change between solid and liquid can be carried out by the phase change material (5). Transformer housing (6) according to at least one of the preceding claims, characterized in that in the metal foam (1) embedded and/or attached with phase change material (5), there is at least one area (9) without metal foam (1) and/or phase change material (5 ) is trained. Transformer housing (6) according to at least one of the preceding claims, characterized in that at least one area (9) without phase change material (5) comprises an insert (10) made of a closed-cell metal foam (1). Transformer housing (6) according to at least one of the preceding claims, characterized in that the transformer housing (6) has at least one compensation space (14) towards and/or into which the metal foam (1) and/or the phase change material (5) is stretchable. Transformer housing (6) according to at least one of the preceding claims, characterized in that the phase change material (5) is paraffin (11). Transformer (12) comprising a transformer housing (6) according to at least one of the preceding claims, characterized in that the transformer (12) is designed to be stackable. Arrangement of at least two transformers (12) according to at least one of the preceding claims to form a transformer stack (13) of transformers (12) arranged one above the other. Arrangement and/or use of a transformer housing (6), a transformer (12) or a transformer stack (13) according to at least one of the preceding claims, characterized in that the transformer housing (6), the transformer (12) or the Transformer stack (13) is arranged underwater and/or is used.

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