Transformer Configuration

Abstract

The present disclosure relates to a transformer arrangement (100) comprising a transformer (10) comprising at least one phase winding (12). The phase winding (12) has a coil winding centered about a coil axis (c). The transformer arrangement (100) further comprises a transformer tank (20) having a wall (22) forming an enclosure in which the transformer (10) is disposed. The enclosure contains an incompressible medium in which the transformer (10) is immersed. A screen (30) is disposed within the transformer tank (20) between the wall (22) of the transformer tank (20) and the at least one phase winding (12) of the transformer (10). The screen (30) has an inner transformer-facing surface and an outer wall-facing surface. The screen (30) is further disposed away from the at least one phase winding (12) of the transformer (10). The transformer tank (20) has a first wall (22') extending transversely to a first axis (z) adjacent a first end of the transformer (10) and an opposing second wall (22") extending transversely to the first axis (z) adjacent a second end of the transformer (10). The screen (30) has at least one first portion (32') and at least one second portion (32") each extending transversely to the first axis (z), the at least one first portion (32') being disposed between the first end of the transformer (10) and the first wall (22') of the transformer tank (22) and the at least one second portion (32") being disposed between the second end of the transformer (10) and the second wall (22") of the transformer tank (20).

Description

[Technical Field]

[0001] Technical Field The present disclosure relates to transformer configurations for load noise reduction. [Background technology]

[0002] background Transformers must meet various requirements regarding noise levels. Transformers, immersed in electrically insulating oil in a transformer tank, vibrate during operation. Vibrations are transmitted from the transformer windings through the oil to the tank wall, potentially leading to significant vibration displacement of the tank wall and resulting noise. Three main noise sources can be identified in transformers: no-load or core noise caused by magnetostriction; load noise caused by electromagnetic forces in the windings; and noise from auxiliary equipment such as fans and pumps used in cooling systems. Of these three, load noise contributes significantly to the total noise, especially for large units.

[0003] Today's solutions for reducing noise are inefficient, costly, and applied far away from the source and primary transmission path of the load noise. Traditional solutions are also often bulky and impractical, such as sound panels and damping layers attached to the outside of the tank wall. Filling tank structural elements with sand is another low-noise solution, but it primarily reduces core noise and has limited impact on load noise. Traditional solutions are difficult to optimize and standardize for off-the-shelf routine design work due to the complex vibration and radiation characteristics of the transformer tank in which the transformer is enclosed. There can also be significant unit-to-unit variability.

[0004] According to its abstract, WO 0101425 relates to a sound-absorbing device for a stationary induction machine having an active part, an insulating fluid surrounding the active part, and a tank in which the insulating fluid is sealed. The sound-absorbing device comprises a gas-filled cavity and an elastic membrane surrounding the gas-filled cavity, thus resulting in a highly compressible sound-absorbing device. In an induction machine, the device is disposed between the active part of the induction machine and the tank and spaced from the inside of the tank. The sound-absorbing device preferably has an extent in one plane, whereby the device has a membrane portion facing the active part and a membrane portion facing the tank. Preferably, at least one of the membrane portions has at least one corrugated region, and a spacer membrane is disposed within the cavity contacting the membrane portion at at least two points.

[0005] According to its abstract, Japanese Patent Laid-Open Publication No. 10106854 relates to a fixed induction electrical device that can reduce noise even when the device has a compact configuration. A resonance silencer having an internal cavity with partial openings is provided on the inner surface of the tank. The silencer is set to a frequency that resonates with the frequency of noise generated within the tank, thereby reducing the noise generated within the tank by resonating with the noise frequency. This reduces noise radiated from the tank to the outside.

[0006] According to its abstract, Chinese Patent Application Publication No. 201732653 relates to a soundproof oil tank structure for a transformer having an oil tank body, in which the inner wall of the oil tank body is provided with a composite damping steel plate. If a magnetic shield is provided on the inner wall of the oil tank body, two layers of composite damping steel plate are provided on the inside and outside of the magnetic shield, respectively, sandwiched between the magnetic shield clamping plates. If a magnetic shield is not provided on the inner wall of the oil tank body, the composite damping steel plate is fixed by a mounting seat on the inner wall of the oil tank body. By disposing the composite damping steel plate on the inner wall of the transformer oil tank body, noise from the transformer body can be effectively reduced. The soundproof oil tank structure for a transformer has a simple structure and is easy to manufacture and install.

[0007] According to its abstract, Chinese Patent Application Publication No. 105810419 relates to a noise reduction device for a transformer, a transformer oil tank, and a transformer. The noise reduction device includes a noise reduction plate and an insulating layer for covering the surface of the noise reduction plate. The noise reduction plate includes at least two paperboard layers and a metal plate layer disposed between adjacent paperboard layers, with the top and bottom layers of the noise reduction plate both being paperboard layers. The noise reduction device has the advantages of low cost and good noise reduction effect. Furthermore, since the noise reduction device can be placed in the available space within the transformer oil tank, it does not require line avoidance or expansion of the transformer's volume. However, since the inner wall of the transformer is flat and linear, the structure of the noise reduction device can be simplified, which facilitates processing and industrial production.

[0008] According to its abstract, EP 0 073 401 A1 relates to a shielding wall that is supported on the tank side wall via a large-area compressible intermediate layer and at the same time represents an insulating wall for reducing noise radiation, since the natural frequency of the vibration system consisting of the part of the shielding wall located in each case between the attachment point and the relevant part of the intermediate layer is less than 0.7 times the main frequency. The use of this configuration is particularly economically applicable to high-power transformers.

[0009] According to its abstract, JP 2017011140 A relates to a transformer capable of reducing noise by improving the method of fixing a magnetic shield placed inside the transformer tank. The transformer comprises an iron core having iron core legs and an iron core yoke, a winding wound around the iron core legs, a tank containing the iron core and the winding, and a magnetic shield placed inside the tank facing the winding. After fixing a sheet to the inner surface of the tank, a buffer member is placed on the sheet, and the magnetic shield is fixed to the buffer member.

[0010] U.S. Patent Application Publication No. 3,175,173 relates to means for reducing audible noise generated by electrical equipment during normal operation, and more particularly to a noise reduction device for electrical induction devices of the type having flux-producing members housed within a metallic enclosure.

[0011] According to its abstract, U.S. Patent Application Publication No. 4,373,608 relates to a tuned noise barrier for machines that radiate sound primarily at several fixed, discrete frequencies, and includes an array of mechanical resonators distributed across the surface of the barrier. Each resonator in the array is tuned to present a high mechanical impedance to the transmission of mechanical vibrations at one of the discrete frequencies radiated by the source machine. The tuned noise barrier may be either a freestanding noise barrier or an attachment to the machine's housing.

[0012] According to its abstract, WO 2008080820 relates to an oil-immersed power transformer / reactor comprising a transformer / reactor core, a winding housed within a tank comprising a tank bottom plate and tank walls, and a foundation supporting the tank. An elongated continuous band forming a closed frame is disposed between the bottom plate and the foundation, and the outer periphery of the bottom plate extends outside the inner periphery of the frame, thereby enclosing an air volume within the frame, bottom plate, and foundation. The tank, support, reduces sound radiated from the transformer / reactor.

[0013] According to its abstract, Swedish Patent Application Publication No. 1651719 concerns a solution for attenuating low-frequency noise around electrical machines. A common solution is to enclose the machine in a wall that is not too costly and has a sufficiently high mass. The first aspect of the invention, with its sand-filled panels, is to efficiently reduce noise at low frequencies, particularly at 100 Hz and 120 Hz. This corresponds to the sound generated by the load noise of the main AC transformer and the Maxwell forces in the shunt reactor. Summary of the Invention [Problem to be solved by the invention]

[0014] overview It is therefore an object of the present disclosure to provide an improved transformer configuration that exhibits reduced noise emissions. More specifically, it is an object of the present disclosure to provide a transformer configuration that can reduce load noise. [Means for solving the problem]

[0015] According to a main aspect of the present disclosure, this object is achieved by a transformer configuration comprising a transformer with at least one phase winding. The phase winding has a coil winding centered on a coil axis. The transformer configuration further comprises a transformer tank having a wall forming an enclosure in which the transformer is disposed. The enclosure contains an incompressible medium in which the transformer is immersed. A screen is disposed within the transformer tank between the wall of the transformer tank and the at least one phase winding of the transformer. The screen has an inner surface facing the transformer and an outer surface facing the wall. The screen is further disposed away from the at least one phase winding of the transformer. The transformer has a first extension along a first axis parallel to the coil axis, a second extension along a second axis, and a third extension along a third axis. The first, second, and third axes are perpendicular to each other. The transformer has a side parallel to the coil axis, a first end along the first axis, and an opposite second end along the first axis. The transformer tank has a first wall adjacent the first end of the transformer and extending transversely to the first axis, and an opposite second wall adjacent the second end of the transformer and extending transversely to the first axis. The screen has at least one first portion and at least one second portion each extending transversely to the first axis, the at least one first portion being disposed between the first end of the transformer and the first wall of the transformer tank, and the at least one second portion being disposed between the second end of the transformer and the second wall of the transformer tank.

[0016] Research has shown that the main mechanisms behind oil mechanically exciting the tank walls are related to its incompressibility on the one hand and its inertia on the other. Acoustically incompressible oil means that any volume change caused by the vibration of the windings is necessarily converted into an equivalent volume change in the tank. The net tank volume change is realized by the tank's structural modes, which configure themselves to establish a net volume change. At low frequencies, this net volume change is considered the result of a so-called monopole tank velocity distribution. This global distribution is known to have such a high radiation efficiency that it can mask noise contributions from other local tank modal noise contributions. The latter is sometimes called a volume-preserving local dipole distribution, which has a much lower radiation efficiency than a global monopole distribution.

[0017] The fact that the entire oil volume can be considered acoustically incompressible also means that its inertia plays an important role in that the volume is nothing but a large acoustically reactive near-field, meaning that the oil excites the tank by its inertial forces rather than by compressible pressure. An incompressible medium is one whose volume or density does not change with pressure. True incompressibility exists only in theory. However, the meaning of the term "incompressible" as used in this disclosure is a term that indicates a medium that is nearly incompressible within the frequency range of interest to this disclosure. The medium, in this disclosure, may be an electrically insulating medium such as mineral oil.

[0018] Generally, one method for mitigating the noise radiation mechanism of a transformer tank wall is to insert a barrier between the winding and the tank wall to shield the tank wall from inertial forces of the incompressible medium. The disclosed transformer configuration places a noise-reducing screen between the transformer and the transformer tank wall, away from at least one phase winding. The screen is thus configured to block inertial forces of the incompressible medium emanating from the phase winding, isolating it from the source, i.e., direct structural vibrations of the transformer / phase winding, and to reduce the vibrations at the tank wall.

[0019] For purposes of this disclosure, a transformer is defined as having a height equal to the height of at least one phase winding. The height of the at least one phase winding is also defined to include the thickness of the backing plates at each end of the at least one phase winding. The term "height" is not limited to vertical extension; rather, it refers to extension generally along the coil axis.

[0020] To cover most of the vibration transmission path from the source, the screen may have a first portion and a second portion in addition to the side portions. The first portion and the second portion may be configured to block the inertial force of the incompressible medium at the first end and the second end of the transformer. In some transformer applications, space is limited along the sides of the transformer. In such cases, the first and second portions of the screen may still be positioned at the ends of the transformer.

[0021] Optionally, the screen is configured to have no structural resonance at twice the network frequency.

[0022] The network frequency is the frequency at which the transformer operates, resulting in mechanical vibrations at twice the network frequency. Network frequencies are typically 50 Hz or 60 Hz. Thus, by way of example, the screen is configured to be free of structural resonance at 100 Hz and / or 120 Hz. Preferably, the screen is configured to be free of structural resonance within a range of up to six times the network frequency.

[0023] This involves placing a stiff, ideally rigid, screen as a barrier between the windings and the tank. By rigid, we mean that the screen is constructed to exhibit structural resonances well above twice the network frequency, so that the remaining average static deflection of the screen due to the vibratory inertial forces of the surrounding incompressible medium is much smaller than the average particle displacement of the medium. This ensures that the inertial forces of the incompressible medium are not transmitted across the screen, or are at least significantly reduced across the screen.

[0024] Optionally, the inner surface of the screen comprises a volume compressible lining. Under the action of electromagnetic forces acting on the structural components of a transformer, they undergo both a change in shape and a change in volume. The latter is imposed on an incompressible medium to the same extent as the tank vibrations, resulting in a net volume change of the air surrounding the tank, resulting in a much higher noise level than if the net volume change of the tank were zero. This zero net volume change of the tank is proposed here to be caused by a volume-compressible lining that accounts for the volume change of the structural components of the transformer instead of the tank. The remaining inertial forces are blocked and reduced by the rigid section of the screen.

[0025] The bulk modulus of the lining must be significantly less than that of the surrounding incompressible medium. Bulk modulus describes the elastic properties of a solid or fluid when it is under pressure on all surfaces. Bulk modulus, sometimes referred to as incompressibility, is a measure of a material's ability to withstand a change in volume when compressed on all sides. As an example, electrical insulating transformer oil has a bulk modulus of approximately 1.7 GPa. In that case, the bulk modulus of the lining is preferably smaller, such as approximately 0.1 to 0.2 GPa or less.

[0026] Optionally, the screen comprises a granular material. The propagation of energy in an acoustic medium can generally be attenuated and redirected by introducing a change in impedance experienced by particle motion within the medium, and the present disclosure provides this change in impedance by introducing mass in the form of a granular compound, providing an inelastic and highly damped barrier with no inherent resonance.

[0027] As an alternative to a rigid screen, and as an alternative to a rigid screen that includes a volume-compressible lining, the screen can include a granular material. The screen may be configured as a plurality of pockets, which contain granular material, such as sand. The granular material must be heavier than the incompressible medium. As an example, electrical insulating transformer oil has a mass of approximately 870 kg / m 3 If the granular material has a density of 870 kg / m 3 more than 1600 kg / m 3 The density of the granular material may be 0.015 to 0.015.

[0028] Optionally, a screen may be placed in the wall of said transformer tank. Thus, the screen containing the granular material may be placed inside the wall of the transformer tank. In this way, the pockets or bags containing the granular material may be attached to the wall by conventional fastening means, preferably covering the wall.

[0029] Optionally, the screen is positioned away from the wall of the transformer tank. Any of the described rigid screens, composite screens, or heavy / flexible screens may be positioned within the transformer tank away from both the at least one phase winding of the transformer and the tank wall. In this way, the screen is not in direct mechanical contact with either the phase winding or the tank wall. This avoids direct transmission of mechanical vibrations from the at least one phase winding to the screen and from the screen to the tank wall.

[0030] Optionally, at any point on the screen, the distance between said point on the screen and the nearest portion of at least one phase winding of the transformer is less than the distance between said point on the screen and the nearest portion of a wall of the transformer tank.

[0031] Acoustically, it is advantageous for the screen to be located as close as possible to the vibration source in order to effectively block most of the inertial forces emanating from the transformer during operation.

[0032] Optionally, the transformer has sides parallel to the coil axis, and the screen has at least one side portion aligned with the sides of the transformer, and the at least one side portion of the screen circumscribes the transformer along a plane transverse to the coil axis.

[0033] The side portions of the screen are not limited to being aligned parallel to the sides of the transformer, but may be inclined relative to the coil axis.

[0034] From the perspective of load noise reduction, it is preferable for the screen to completely surround the transformer with no openings in the screen. However, in practice, design considerations require that an incompressible medium be able to flow relatively freely around at least one phase winding for cooling purposes. Additionally, the screen must allow for multiple electrical connections between the transformer and the outside of the transformer tank. Therefore, a side portion of the screen that surrounds or circumscribes the side of the transformer, or at least one phase winding, is considered the preferred configuration.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS Further objects, advantages, and features of the present disclosure will become apparent from the following description of one or more embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a perspective view of an exemplary embodiment of the present disclosure. [Figure 2] FIG. 1 is a perspective view of an exemplary embodiment of the present disclosure. [Figure 3] FIG. 1 is a perspective view of an exemplary embodiment of the present disclosure. [Figure 4] FIG. 1 is a perspective view of a screen according to an exemplary embodiment of the present disclosure. [Figure 5] FIG. 1 is a perspective view of an exemplary embodiment of the present disclosure. [Figure 6] FIG. 2 is a top view of a screen according to an exemplary embodiment of the present disclosure. [Figure 7]FIG. 2 is a perspective detail view of a screen according to an exemplary embodiment of the present disclosure. [Figure 8] FIG. 10 illustrates simulation results of an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0037] DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION The present disclosure will be developed in more detail below with reference to the accompanying drawings, which show example embodiments. The present disclosure should not be considered limited to the example embodiments described. Like numbers refer to like elements throughout the description.

[0038] FIG. 1 illustrates a transformer configuration 100 including a transformer 10 with at least one phase winding 12. The illustrated transformer 10 has three phase windings 12. The phase winding 12 has a coil winding centered about a coil axis c. The transformer configuration 100 further includes a transformer tank 20 having a wall 22 forming an enclosure within which the transformer 10 is disposed. In the illustrated example, the transformer tank 20 is shown open to the viewer to expose the transformer 10 therein. In reality, the transformer tank is apparently closed on all sides. The enclosure contains an incompressible medium within which the transformer 10 is immersed. A screen 30 is disposed within the transformer tank 20 between the wall 22 of the transformer tank 20 and the at least one phase winding 12 of the transformer 10. The screen 30 has a surface facing the inner transformer and a surface facing the outer wall. The screen 30 is positioned away from at least one phase winding 12 of the transformer 10. In other words, the screen is not in direct mechanical contact with any of the phase windings 12 of the transformer 10. This isolates the screen from direct structural vibrations of the at least one phase winding that occur during operation of the transformer. The screen 30 is configured to block the inertial force of the incompressible medium emanating from the phase winding 12 so that vibrations of the incompressible medium are reduced at the tank wall 22. As a result, the displacement of the tank wall 22 due to the movement of the incompressible medium is also reduced, which ultimately leads to a reduction in load noise radiated by the tank wall 22.

[0039] Transformers operate at a given network frequency. Typically, the network frequency is 50 Hz or 60 Hz, which results in structural vibration of at least one phase winding 12 at twice the network frequency, i.e., 100 Hz or 120 Hz, respectively. The screen 30 may be configured to be free of structural resonance at twice the network frequency. Preferably, the screen 30 is configured to be free of structural resonance within a range of up to six times the network frequency. This ensures that the screen 30 is not significantly excited by vibrations transmitted from at least one phase winding 12 through the incompressible medium to the screen 30.

[0040] Optionally, as shown in FIG. 6, the inner surface of the screen 30 may include a volume-compressible lining 34. The bulk modulus of the lining must be significantly less than the bulk modulus of the surrounding incompressible medium. As an example, the bulk modulus of electrical insulating transformer oil is approximately 1.7 GPa. In this case, the bulk modulus of the lining should be less than 1.7 GPa, preferably 0.1 to 0.2 GPa, or even less.

[0041] Alternatively, instead of being rigid, the screen 30 may contain granular material, such as heavy blocks, that have no rigidity but have significant inherent damping. The screen may be configured as a plurality of pockets 38, as shown in FIG. 7, which contain granular material, such as sand. The exemplary embodiment of FIG. 7 shows only a portion of the screen 30. As with the other embodiments, the screen 30 is intended to circumscribe the transformer 10. The granular material must be heavy relative to the incompressible medium. As an example, electrical insulating transformer oil has a mass of approximately 870 kg / m 3 The granular material preferably has a density of 870 kg / m 3 Higher, preferably at least 1600 kg / m 3 It should have a density of .

[0042] Such a screen 30 containing granular material may be placed in the wall 22 of the transformer tank. Thus, the screen 30 containing granular material may be placed inside the wall 22 of the transformer tank. In this manner, the pockets 38 containing granular material may be attached to the wall 22 by conventional fastening means, preferably completely covering the wall 22.

[0043] In addition to being spaced apart from the at least one phase winding 12 of the transformer 10, the screen 30 may also be positioned apart from the wall 22 of the transformer tank 20. Any of the rigid screens, composite screens, or granular screens described above may be positioned within the transformer tank 20 apart from both the at least one phase winding 12 of the transformer 10 and the tank wall 22. The screen 30 containing the granular material may be positioned apart from the tank wall 22 using a support structure (not shown) for suspending the pockets 38 containing the granular material in the incompressible medium.

[0044] The transformer 10 may have a first extension along a first axis z parallel to the coil axis c, a second extension along a second axis x, and a third extension along a third axis y. The first, second, and third axes are perpendicular to each other. The transformer 10 has a side parallel to the coil axis c.

[0045] The screen 30 may have at least one side portion 32 aligned with a side of the transformer 10. The at least one side portion 32 of the screen 30 circumscribes the transformer 10. The at least one side portion may have a height h along the first axis z. The height h of the at least one side portion 32 may be equal to the height H of the at least one phase winding 12. In the case of multiple side portions 32, the sum of the individual heights h may be less than or equal to the height H of the at least one phase winding 12. For purposes of cooling the at least one phase winding 32, the sum of the heights h of the individual side portions is preferably less than the height H of the at least one phase winding 12.

[0046] The transformer 10 may have a first end along a first axis z and an opposite second end along the first axis z. The transformer tank 20 further has a first wall 22′ extending transversely to the first axis z and an opposite second wall 22″ extending transversely to the first axis z.

[0047] As discussed in the Summary of this disclosure, the transformer 10 is defined as having a height equal to the height H of the at least one phase winding 12, which height also includes the thickness of the pressure plates 14', 14" disposed at the ends of the phase winding 12. Thus, the first end of the transformer 10 is defined herein as including at least one first pressure plate 14' of the at least one phase winding 12, and the second end of the transformer 10 is defined herein as including at least one second pressure plate 14" of the at least one phase winding 12.

[0048] As shown in FIG. 2 , at least one side portion 32 of the screen 30 may include two side portions 32. One side portion 32 is disposed at a first end of the transformer 10, and the other side portion 32 is disposed at a second end of the transformer. Such a configuration may be preferable because it is expected that the sound pressure in the incompressible medium is higher near the ends of at least one phase winding 12, i.e., the first and second pressure plates 14′ and 14″. Therefore, disposing the side portions 32 around the first and second ends of the transformer 10 may be an efficient way to resist the inertial force of the incompressible medium while leaving a large portion of the at least one phase winding 12 unscreened to improve the cooling efficiency of the incompressible medium around the at least one phase winding 12.

[0049] 3 and 4 show another configuration in which the screen 30 has a close-fitting contour relative to the at least one phase winding 12. In the illustrated example, the screen 30 includes two side portions 32 with three connected tubular sections 32a, 32b, 32c that each fit the cylindrical shape of the three-phase winding 12. In this manner, the screen 30 is equidistantly but closely spaced from the at least one phase winding 12 along the circumference of the coil winding, providing efficient shielding of the inertial forces of the incompressible medium.

[0050] FIG. 5 shows a further configuration of the screen 30, in which the screen 30 has at least one first portion 32′ and at least one second portion 32″, each extending transversely to the first axis z, where the at least one first portion 32′ is arranged between a first end of the transformer 10 and a first wall 22′ of the transformer tank 20, and the at least one second portion 32″ is arranged between a second end of the transformer 10 and a second wall 22″ of the transformer tank 20. This configures the screen 30 to cover most of the transmission path of inertial force resulting from vibration of the end of the at least one phase winding 12. When at least one side portion 32 and the first portion 32′ and second portion 32″ are applied in combination, the first portion 32′ and second portion 32″ may be mechanically connected to the side portion 32, for example, by welding.

[0051] The rigid screen including the volume-compressible lining 34 and the screen including the granular material may all be configured according to the embodiment shown in Figures 1 to 5. However, only the screen including the granular material may advantageously be placed directly on the transformer tank wall 22.

[0052] Figure 8 shows the results of a simulation of how acoustic forces in a transformer tank vary with frequency. Curve B shows the transformer configuration 100 according to the present disclosure, which includes a screen 30 with a volume-compressible lining 34. Curve A shows the transformer configuration without a screen, i.e., the conventional transformer configuration. It can be seen that the screen 30 significantly contributes to reducing load noise.

Claims

1. A transformer arrangement (100) comprising: a transformer (10) comprising at least one phase winding (12), the at least one phase winding (12) having a coil winding centered on a coil axis (c), the transformer having a first extension along a first axis (z) parallel to the coil axis (c), a second extension along a second axis (x) and a third extension along a third axis (y), the first axis, the second axis and the third axis being perpendicular to one another, the transformer (10) having sides parallel to the coil axis (c); a transformer tank (20) having walls (22) forming an enclosure in which the transformer (10) is placed, the enclosure containing an incompressible medium in which the transformer (10) is immersed; a screen (30) arranged in the transformer tank (20) between the wall (22) of the transformer tank and the at least one phase winding (12) of the transformer (10), the screen (30) having an inner surface facing the transformer and an outer surface facing the wall, the screen (30) being arranged away from the at least one phase winding (12) of the transformer (10); The transformer has a first end along the first axis (z) and an opposite second end along the first axis (z), the transformer tank (20) has a first wall (22') adjacent the first end of the transformer (10) and extending transversely to the first axis (z), and an opposite second wall (22'') adjacent the second end of the transformer (10) and extending transversely to the first axis (z), and the screens (30) each have a first wall (22') adjacent the first end of the transformer (10) and an opposite second wall (22'') adjacent the second end of the transformer (10) and extending transversely to the first axis (z). the transformer has at least one first portion (32') and at least one second portion (32") extending transversely to the axis (z), the at least one first portion (32') being disposed between the first end of the transformer (10) and the first wall (22') of the transformer tank (20), and the at least one second portion (32") being disposed between the second end of the transformer (10) and the second wall (22") of the transformer tank (20); The screen (30) has at least one side portion (32) aligned with the side of the transformer (10), and the at least one side portion (32) of the screen (30) surrounds the transformer (10).

2. 10. The transformer arrangement (100) of claim 1, wherein the screen (30) is configured to be free of structural resonance at twice the network frequency.

3. 3. The transformer arrangement (100) of claim 1 or 2, wherein the inner surface of the screen (30) comprises a volume-compressible lining (34).

4. 4. The transformer arrangement (100) of claim 3, wherein the volume compressible lining (34) has a bulk modulus of 1.7 GPa or less.

5. The transformer arrangement (100) of claim 1, wherein the screen (30) comprises a granular material.

6. The granular material has a viscosity of 870 kg / m ３ The transformer arrangement (100) of claim 5, having a density greater than

7. 7. The transformer arrangement (100) according to claim 5 or 6, wherein the screen (30) is arranged on the wall (22) of the transformer tank (20).

8. 3. The transformer arrangement (100) of claim 1 or 2, wherein the screen (30) is positioned away from the wall (22) of the transformer tank (20).

9. 9. The transformer configuration (100) of claim 8, wherein at any point on the screen (30), the distance between the point on the screen (30) and a nearest portion of the at least one phase winding (12) of the transformer is less than the distance between the point on the screen (30) and a nearest portion of the wall (22) of the transformer tank (20).

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