Winding, transformer and transformer device

Abstract

The present disclosure relates to a winding (110) for a phase winding of a transformer (20). The winding (110) includes a plurality of winding portions (116) arranged along a coil axis (z). The plurality of winding portions (116) includes a first winding portion (116a) arranged at a first end (110a) of the winding (110) and a second winding portion (116b) arranged at a second end (110b) of the winding (110). The winding (110) further comprises at least a third winding portion (116c) arranged along the coil axis (z) between the first winding portion (116a) and the second winding portion (116b). The first winding portion (116a) and the second winding portion (116b) have a first winding portion stiffness as seen along the coil axis (z), and at least the third winding portion (116c) has a second winding portion stiffness as seen along the coil axis (z). The second winding portion stiffness is greater than the first winding portion stiffness. The third portion (116c) has a third portion center point (C3) located on the coil axis (z), the third portion center point being equidistant from the first winding portion (116a) and the second winding portion (116b) by a distance (d), the third portion center point (C3) being located closer to the first end (110a) of the winding (110) than the winding center point (C). The present disclosure also relates to a transformer (20) comprising a winding (110) and a transformer arrangement comprising a transformer (20).

Description

Technical Field

[0001] The present disclosure relates to a winding for a transformer. The present disclosure also relates to a transformer comprising such a winding and a transformer device comprising such a transformer. Background Art

[0002] Transformers, like any other industrial product, must comply with various requirements regarding noise levels. Load noise is generated by electromagnetic forces in the transformer windings. Due to the electrical operating frequency of 50 Hz or 60 Hz, the transformer vibrates at a mechanical frequency of 100 Hz or 120 Hz, respectively. Asymmetric and especially symmetrical vibration modes contribute to the generation of noise. Symmetrical vibrations cause the windings to perform piston-like movements, which in turn are transmitted to the transformer tank wall via the pressure plate, the support frame and the transformer oil, generating significant noise.

[0003] JPH04318905 A discloses a winding device having a spacer made of cardboard, and a central portion of the winding has a spacer having a larger compression elastic modulus, such as fiberboard or resin.

[0004] US3815068 A shows a winding with thicker spacers in the axial middle portion of the low voltage winding. The thicker spacers give the winding a larger gap between the coil turns, resulting in a reduced number of turns in the middle portion.

[0005] JP2013183151 A discloses that the mode shape of the winding can be changed by changing the material and thickness of the spacer. Summary of the invention

[0006] It is therefore an object of the present disclosure to provide an improved winding for a transformer. More specifically, it is an object of the present disclosure to provide a winding having reduced noise emissions and being cost-effective to construct and assemble. Another object of the present disclosure is to provide a transformer comprising such a winding and a transformer apparatus comprising such a transformer in a transformer box.

[0007] According to a first aspect of the present disclosure, this object is at least partly achieved by a winding according to claim 1 .

[0008] Therefore, a winding for a phase winding of a transformer is provided, the winding having coil turns around a coil axis. The winding has a first end and a second end, and a winding center point between the first end and the second end on the coil axis. The winding comprises a plurality of winding parts arranged along the coil axis. The plurality of winding parts comprises a first winding part arranged at the first end of the winding and a second winding part arranged at the second end of the winding. The winding further comprises at least a third winding part arranged between the first winding part and the second winding part along the coil axis. The first winding part and the second winding part have a first winding part stiffness as seen along the coil axis, and at least the third winding part has a second winding part stiffness as seen along the coil axis. The second winding part stiffness is greater than the first winding part stiffness. The third part has a third part center point located on the coil axis, the third part center point being equidistantly spaced from the first winding part and the second winding part at a certain distance. The third part center point is positioned closer to the first end of the winding than the winding center point.

[0009] A winding is a winding for a phase winding of a transformer. A phase winding may have multiple windings. For example, a three-phase transformer has three phase windings, each of which has at least two windings, such as an inner winding and an outer winding, where "inner" and "outer" refer to the relative positions of the windings around the coil axis. A single-phase transformer has only one phase winding.

[0010] A winding section is defined herein as a portion of a winding along the coil axis. When the winding is assembled with a phase winding of a transformer, the coil axis is a vertical axis. A first winding section and a second winding section sandwich a third winding section between them. Conventional windings have only a single winding section.

[0011] It has been found that the middle portion of the winding (wherein "middle" refers to the position along the coil axis) expands and contracts significantly more than other portions of the winding due to symmetrical vibrations at the operating frequency. Therefore, arranging the third winding portion with greater stiffness in the middle portion of the winding reduces / suppresses movement of the winding and thereby reduces noise emissions.

[0012] A distance between a center point of the third portion and the first end of the winding is shorter than a distance between a center point of the winding and the first end of the winding.

[0013] It has been observed that the maximum movement of the winding occurs closer to the first end than to the second end, i.e. not completely at the winding center point. It is therefore advantageous to make the winding stiffer in the portion closer to the first end than in the axial center of the winding. Therefore, a third winding portion, which is stiffer than the first and second winding portions, is arranged closer to the first end than to the second end. It follows from this that the extension of the first winding portion along the coil axis may be shorter than the extension of the second winding portion along the coil axis.

[0014] Optionally, the winding is provided with a plurality of spacers between the coil turns, wherein the first winding portion and the second winding portion are provided with at least one first type of spacer having at least one first elastic modulus, and the third winding portion is provided with at least one second type of spacer having at least one second elastic modulus, and wherein each of the at least one second elastic modulus is greater than the first elastic modulus.

[0015] The spacers are used to keep the coil turns of the windings separated and to avoid short-circuiting the coil turns. The elasticity / stiffness of the spacers affects the elasticity / stiffness of the windings. Therefore, different types of spacers can be used to adapt and configure the stiffness of the winding parts. According to the present disclosure, a harder type of spacer with a significantly larger elastic modulus is arranged between the coil turns of the third winding part compared to the spacers of the first winding part and the second winding part. As a result, the second winding part stiffness is greater than the first winding part stiffness.

[0016] Optionally, the third winding portion comprises a plurality of sub-portions arranged along the coil axis. Each sub-portion has a sub-portion stiffness as seen along the coil axis. Each sub-portion comprises a second type of spacer, and each sub-portion stiffness is greater than the first winding portion stiffness.

[0017] Thus, the second type of spacers is characterized in that they all have a greater stiffness than the first type of spacers. The second type of spacers may include different spacers so that each sub-section has a spacer of a specific stiffness (elastic modulus). The second type of spacers may, for example, include two types of spacers. Thus, the third winding section may have two different types of sub-sections, which are arranged along the coil axis, for example in an alternating configuration.

[0018] Optionally, the distribution of the multiple sub-portions forms an aggregate winding portion stiffness, wherein the multiple sub-portions are configured such that the aggregate winding portion stiffness of the third winding portion on a first side of the winding center point as seen along the coil axis is greater than the aggregate winding portion stiffness of the third winding portion on a second side of the winding center point as seen along the coil axis.

[0019] The aggregate winding section stiffness is to be understood as a collection of subsection stiffnesses which provide the winding section with a stiffness which is variable along the axial extent of the winding section. Since each subsection stiffness is stiffer than at least the first winding section stiffness and at least the second winding section stiffness, it is ensured that the third winding section is stiffer than the first winding section and the second winding section along the entire axial extent of the third winding section.

[0020] Thus, the stiffness of the third winding portion along the coil axis can be configured by arranging the sub-portions in a predetermined manner. By arranging one or more sub-portions with greater stiffness on a first side of the winding center point and arranging one or more sub-portions with lower stiffness on a second side of the winding center point, it is ensured that the third winding portion is stiffer closer to the first end than to the second end. Thus, large movements of the winding can be more efficiently suppressed.

[0021] Optionally, the first side of the winding centre point is located closer to the first end of the winding than to the second end.

[0022] It will be appreciated that the first side of the center point is the side closer to the first end of the winding, and the second side of the center point is the side closer to the second end of the winding.

[0023] Optionally, the elastic modulus of the first type of spacer may be 0.1 GPa-3 GPa, preferably 0.5 GPa-1.5 GPa, and most preferably 0.9 GPa-1.1 GPa. The elastic modulus of the at least one second type of spacer may be greater than 50 GPa, preferably greater than 80 GPa, and most preferably greater than 105 GPa. Further, the material of the first type of spacer may be a cellulose-based material (such as pressboard), and the material of the at least one second type of spacer may be a composite material (such as talc).

[0024] Conventional spacers are usually made of cardboard with an elastic modulus of about 1 GPa. It can be seen that the stiffness (elastic modulus) suggested for the second type of spacers is much higher than for the first type of spacers. Talc, with an elastic modulus of about 110 GPa, has been shown to have a particularly large damping effect on noise generation.

[0025] Optionally, the first end is an upper end of the winding when installed in a transformer, and the second end is a lower end of the winding when installed in a transformer.

[0026] Therefore, the maximum movement of the vibrating winding occurs slightly closer to the upper end of the winding than to the lower end.

[0027] Optionally, the first end is a lower end of the winding when installed in a transformer, and the second end is an upper end of the winding when installed in a transformer.

[0028] Therefore, the maximum movement of the vibrating winding occurs slightly closer to the lower end of the winding than to the upper end.

[0029] It is foreseen that the maximum movement of the vibrating winding occurs as an offset from the center of the winding towards the upper end of the winding or towards the lower end of the winding. The amount of offset depends on the configuration of the transformer in which the winding is included.

[0030] According to a second aspect of the present disclosure, this object is at least partially achieved by a transformer according to claim 11 .

[0031] Therefore, there is provided a transformer comprising at least one winding according to any one of the embodiments of the first aspect of the present disclosure.

[0032] Optionally, the transformer comprises at least one phase winding, the at least one phase winding having a winding according to any one of the embodiments of the first aspect of the present disclosure.

[0033] When the transformer comprises at least one winding according to the present disclosure, the acoustic power of each such winding can reduce the acoustic power of the transformer as a whole, such as when at least one of the three phase windings is a winding according to the present disclosure. Thus, the winding according to the present disclosure can be an inner winding or an outer winding of a phase winding. In other words, the winding according to the present disclosure can be a high voltage winding or a low voltage winding of a phase winding.

[0034] According to a third aspect of the present disclosure, this object is at least partly achieved by a transformer device according to claim 13 .

[0035] Hence, there is provided a transformer arrangement comprising a transformer according to any one of the embodiments of the second aspect of the present disclosure.The transformer may be immersed in an electrically insulating medium inside a transformer tank.

[0036] The transformer may be immersed in an electrically insulating medium such as oil in a transformer tank. By providing at least one winding according to the present disclosure, the symmetric mode of the transformer may be modified to reduce vibration and noise of the transformer. Thus, such a transformer in a transformer tank will cause the transformer tank wall to generate less noise to the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Further objects, advantages and features of the present disclosure will become apparent from the following description of one or more embodiments with reference to the accompanying drawings, in which:

[0038] FIG. 1 shows the noise power generated by a prior art transformer at a predetermined frequency.

[0039] Fig. 2 shows a prior art phase winding at maximum compression.

[0040] Fig. 3 shows a prior art phase winding at maximum expansion.

[0041] Figure 4 A schematic representation of a winding according to an embodiment of the first aspect of the present disclosure is shown.

[0042] Figure 5 A schematic representation of a winding according to an embodiment of the first aspect of the present disclosure is shown.

[0043] Figure 6 A transformer according to a second aspect of the present disclosure is shown.

[0044] Figure 7 A transformer arrangement according to a third aspect of the present disclosure is shown.

[0045] Figure 8 The noise reduction of the winding according to the first aspect of the present disclosure at various frequencies is shown. DETAILED DESCRIPTION

[0046] The present disclosure is described in more detail below with reference to the accompanying drawings showing examples of embodiments. The present disclosure should not be considered limited to the described examples of embodiments; on the contrary, the present disclosure is defined by the appended claims. Throughout the specification, similar reference numerals refer to similar elements.

[0047] FIG. 1 shows how the acoustic power of the prior art transformer 20' shown in FIGS. 2 and 3 varies with frequency due to the vibration of the winding 110'. The horizontal axis shows the mechanical vibration frequency. The curve represents the superposition of the vibration modes of the transformer 20' structure due to the vibration of the winding 110'. The interesting mode of the transformer 20' can be identified at the peak amplitude where the acoustic power is the largest. The peak amplitude of about 120 Hz shows a symmetrical vibration mode. It can be seen that it has the greatest impact on the acoustic power at 100 Hz and 120 Hz (i.e., at operating electrical frequencies of 50 Hz and 60 Hz, respectively).

[0048] Especially when mounted in a transformer tank (not shown), the symmetrical movement (piston-like displacement) of the transformer 20' (FIGS. 2 and 3) radiates significant noise to the far field compared to asymmetrical movement, because the symmetrical vibration displaces more air outside the transformer tank and thereby radiates sound more efficiently than asymmetrical movement. The winding 110' (see FIGS. 2 and 3) vibrates under load at a mechanical main frequency of typically 100 Hz or 120 Hz (i.e., a predetermined electrical operating (excitation) frequency of typically 50 Hz or 60 Hz multiplied by two).

[0049] 2 and 3 show simulated movement in a prior art transformer 20' having three phase windings in operation, each phase winding comprising a winding 110' having cardboard spacers between the coil turns. For clarity, movement in only one of the phase windings is shown. In normal operation, all three phase windings will move similarly, but there will be a phase difference between the oscillations. The phase windings are clamped between upper and lower pressure plates 212' and upper and lower support beams 214'. When the winding 110' vibrates, the vibrating movement is transferred to the pressure plates 212' and support beams 214' as shown. If the transformer 20' is enclosed in a transformer tank and immersed in an insulating medium, the movement will be further transferred to the transformer tank wall by the insulating medium.

[0050] The symmetrically vibrating piston-like movement causes the winding to undergo an oscillatory compression and expansion, especially along the coil axis z. FIG. 2 shows a moving phase winding at maximum compression Mc. FIG. 3 shows a moving phase winding at maximum expansion Me. The movement of the winding 110' varies along the coil axis, but FIGS. 2 and 3 show that both compression and expansion have maximum values ​​that are slightly offset from the winding center point C'. The present disclosure is intended to reduce and inhibit the movement of transformer windings.

[0051] Figure 4 A winding 110 for a phase winding of a transformer 20 according to a first aspect of the present disclosure is shown. The winding 110 has coil turns 120 around a coil axis z. The winding 110 further has a first end 110a and a second end 110b, and a winding center point C between the first end 110a and the second end 110b located on the coil axis z.

[0052] The winding 110 includes a plurality of winding portions 116 arranged along a coil axis z. The plurality of winding portions 116 include a first winding portion 116a arranged at a first end 110a of the winding 110 and a second winding portion 116b arranged at a second end 110b of the winding 110. The winding 110 further includes at least a third winding portion 116c arranged between the first winding portion 116a and the second winding portion 116b along the coil axis z. The first winding portion 116a and the second winding portion 116b have a first winding portion stiffness as seen along the coil axis z, and at least the third winding portion 116c has a second winding portion stiffness as seen along the coil axis z. The second winding portion stiffness is greater than the first winding portion stiffness.

[0053] The first winding portion 116a and the second winding portion 116b sandwich the third winding portion 116c therebetween. Conventional windings (such as illustrated in Figures 2 and 3) have only a single winding portion.

[0054] Since it has been found that the expansion and contraction of the middle portion of the winding 110 due to symmetrical vibrations at operating frequencies is significantly greater than other portions of the winding 110, arranging the middle portion of the winding 110 with greater stiffness reduces / inhibits movement of the winding 110 and thereby reduces noise emissions. The greater stiffness of the middle portion is achieved by the third winding portion 116c having a second winding portion stiffness that is greater than the first winding portion stiffness of the first winding portion 116a and the second winding portion 116b.

[0055] The third portion 116c has a third portion center point C3 located on the coil axis z, and the third portion center point is equidistantly spaced from the first winding portion 116a and the second winding portion 116b by a distance d. Figure 4 , the third portion center point C3 may be located closer to the first end 110a of the winding 110 than the winding center point C. It is also contemplated that the winding center point C and the third portion center point C3 are the same, such as when the third winding portion 116c is located axially in the middle of the winding 110.

[0056] Depending on the construction and design of the transformer and how the phase windings are mounted and assembled to each other, the maximum movement of the winding 110 may occur closer to the first end 110a than to the second end 110b, i.e., not exactly at the winding center point C. Therefore, it is advantageous to make the winding 110 stiffer in a portion closer to the first end 110a than in the axial center C of the winding. Therefore, the third winding portion 116c, which is stiffer than the first winding portion 116a and the second winding portion 116b, is arranged closer to the first end 110a than to the second end 110b. It follows that, if Figure 4 As illustrated in FIG. 1 , the axial extension a1 of the first winding portion 116 a may be shorter than the axial extension a2 of the second winding portion 116 b .

[0057] It should be understood herein that the first end 110a may be the upper end of the winding 110 when installed in the transformer 100, and the second end 110b may be the lower end of the winding 110 when installed in the transformer 100, or vice versa. Thus, in operation, the maximum movement of the vibrating winding 110 occurs slightly closer to the upper end 110a of the winding 110 than to the lower end 110b. Alternatively, the maximum movement of the vibrating winding 110 occurs slightly closer to the lower end 110a of the winding 110 than to the upper end 110b. The illustrated exemplary embodiment shows the first end 110a as the upper end and the second end 110b as the lower end.

[0058] The winding 110 is provided with a plurality of spacers 130 between the coil turns 120. The first winding portion 116a and the second winding portion 116b are provided with at least one first type of spacer 130a (composed of Figure 4 ). The third winding portion 116c is provided with at least one second type of spacer 130b (not shown) having at least one second elastic modulus. Each of the at least one second elastic modulus is greater than the at least one first elastic modulus.

[0059] The spacers 130 are conventionally distributed between the coil turns 120 along the axial length of the winding 110 so as to separate and electrically insulate the coil turns 120 of the winding 110 from each other. The elasticity / stiffness of the spacers 130 affects the elasticity / stiffness of the winding 110. Therefore, different types of spacers 130 can be used to adapt and configure the stiffness of the winding portion 116. According to the present disclosure, a second type of spacer 130b having a greater elastic modulus and being harder than the first type of spacer 130a of the first winding portion 116a and the second winding portion 116b is arranged between the coil turns 120 of the third winding portion 116c. As a result, the second winding portion stiffness is greater than the first winding portion stiffness.

[0060] exist Figure 5 In another embodiment illustrated in , the third winding portion 116c includes a plurality of sub-portions 116c1, ..., 116cn arranged along the coil axis z. Each sub-portion 116c1, ..., 116cn has a sub-portion stiffness as seen along the coil axis z, and each sub-portion 116c1, ..., 116cn includes a second type of spacer 130b. Each sub-portion stiffness is configured to be greater than the first winding portion stiffness.

[0061] Therefore, the second type of spacers 130b is characterized in that they all have greater rigidity than each of the at least one first type of spacers 130a. The second type of spacers 130b may include different spacers 130b so that each sub-portion 116c1, ..., 116cn has a spacer 130b of corresponding rigidity (elastic modulus). The second type of spacers 130b may, for example, include two types of spacers 130b. Thus, the third winding portion 116c may, for example, have two different types of sub-portions 116c1, 116c2 arranged along the coil axis, for example, multiple first sub-portions and additional multiple second sub-portions are arranged in an alternating configuration. Using the example of two different sub-portions, it is also conceivable that the first sub-portion 116c1 is arranged on the first side of the third portion center point C3 and the second sub-portion 116c2 is arranged on the second side of the third portion center point C3.

[0062] It is also conceivable that the first winding portion 116a and the second winding portion 116b are configured to have a first sub-portion and a second sub-portion (not shown), respectively. Each first sub-portion and each second sub-portion will then include a first type of spacer 130a. Each first sub-portion stiffness and second sub-portion stiffness will be configured to be less than each of the sub-portion stiffness of the third winding portion 116c. Then, the harder first sub-portion and the second sub-portion will be arranged closer to the third winding portion 116c than the less hard sub-portion and the second sub-portion, so that the first winding portion 116a and the second winding portion 116b exhibit higher stiffness near the third winding portion 116c rather than farther away from the third winding portion 116c.

[0063] The distribution of the plurality of sub-portions 116c1, ..., 116cn of the third winding portion 116c forms a polymerized winding portion stiffness of the third winding portion 116c. The plurality of sub-portions 116c1, ..., 116cn may be configured such that the polymerized winding portion stiffness of the third winding portion 116c on a first side of the winding center point C as seen along the coil axis z is greater than the polymerized winding portion stiffness of the third winding portion 116c on a second side of the winding center point C as seen along the coil axis z.

[0064] Therefore, the aggregate stiffness of the third winding portion 116c along the coil axis can be configured by arranging the sub-portions 116c1, ..., 116cn in a predetermined manner. By arranging one or more sub-portions 116c1, ..., 116cn with greater stiffness on the first side of the winding center point C and arranging one or more sub-portions 116c1, ..., 116cn with lower stiffness on the second side of the winding center point C, it is ensured that the third winding portion 116c is stiffer closer to the first end 110a than the second end 110b. As a result, a large movement of the winding 110 can be more efficiently suppressed.

[0065] It should be noted herein that the first side of the winding center point C is located closer to the first end 110 a of the winding 110 than to the second end 110 b .

[0066] The spacers 130 may be selected such that the elastic modulus of the first type of spacers 130a is 0.1 GPa-3 GPa, preferably 0.5 GPa-1.5 GPa, and most preferably 0.9 GPa-1.1 GPa. The elastic modulus of the at least one second type of spacers 130b may be selected to be greater than 50 GPa, preferably greater than 80 GPa, and most preferably greater than 105 GPa. In the preferred example above, the material of the first type of spacers 130a may be selected to be cardboard, and the material of the at least one second type of spacers 130b may be selected to be talc.

[0067] Conventional spacers 130 are usually made of cardboard with an elastic modulus of about 1 GPa. It can be seen that the stiffness (elastic modulus) suggested for the second type of spacers 130b is much higher than that for the first type of spacers 130a. Talc with an elastic modulus of about 110 GPa has been shown to have a particularly large damping effect on noise generation in combination with the first winding portion 116a and the second winding portion 116b provided with conventional cardboard spacers.

[0068] Figure 6 The transformer 20 according to the second aspect of the present disclosure is illustrated. The transformer 20 includes at least one winding 110 according to any one of the embodiments of the first aspect of the present disclosure. The transformer 20 may further include upper and lower pressing plates 212 and upper and lower support beams 214. The winding 110 is clamped between the support beam 214 and the pressing plate 212. At least one winding 110 of the transformer 20 may be a winding 110 according to the first aspect of the present disclosure, as described above. Therefore, the winding 110 may be an inner winding and / or an outer winding of a phase winding of the transformer 20.

[0069] Figure 7 A transformer device 30 according to the third aspect of the present disclosure is shown. The transformer device 30 comprises a transformer 20 according to any one of the embodiments of the second aspect of the present disclosure. The transformer may be immersed in an electrically insulating medium (such as oil) inside a transformer tank 300. By providing at least one winding 110 according to the present disclosure, the symmetric mode of the transformer 20 may be modified to reduce vibration and noise of the transformer. Therefore, such a transformer 20 in a transformer tank 300 will cause the transformer tank wall to generate less noise to the surrounding environment.

[0070] Figure 8 A graph showing simulation results for a winding 110 at different mechanical frequencies is shown. The horizontal line at 0 dB represents a reference conventional (prior art) winding 110'. The dashed line represents a winding according to the present disclosure having a first winding portion 116a, a second winding portion 116b, and a third winding portion 116c, wherein the third winding portion 116c is provided with a stiffer spacer than the first winding portion 116a and the second winding portion 116b. It can be seen that the noise reduction is at least -3.5 dB at 100 Hz, which is a significant and noticeable noise reduction.

Claims

1. A winding (110) for a phase winding of a transformer (20), the winding (110) having coil turns (120) around a coil axis (z), the winding (110) having a first end (110a) and a second end (110b), and a winding center point (C) located on the coil axis (z) between the first end (110a) and the second end (110b), in, The winding (110) comprises a plurality of winding portions (116) arranged along the coil axis (z), the plurality of winding portions (116) comprising a first winding portion (116a) arranged at the first end (110a) of the winding (110) and a second winding portion (116b) arranged at the second end (110b) of the winding (110), the winding (110) further comprising at least a third winding portion (116c) arranged between the first winding portion (116a) and the second winding portion (116b) along the coil axis (z), wherein the first winding portion (116a) and the second winding portion (116b) have a first winding portion stiffness as seen along the coil axis (z), and the at least third winding portion (116c) has a second winding portion stiffness as seen along the coil axis (z), and wherein the second winding portion stiffness is greater than the first winding portion stiffness, and Characterized in that the third part (116c) has a third part center point (C3) located on the coil axis (z), the third part center point is equidistant from the first winding part (116a) and the second winding part (116b) by a distance (d), and the third part center point (C3) is positioned closer to the first end (110a) of the winding (110) than the winding center point (C).

2. The winding (110) according to claim 1, wherein: The winding (110) is provided with a plurality of spacers (130) between the coil turns (120), and wherein the first winding portion (116a) and the second winding portion (116b) are provided with at least one first type of spacer (130a) having at least one first elastic modulus, and the third winding portion (116c) is provided with at least one second type of spacer (130b) having at least one second elastic modulus, and wherein each of the at least one second elastic modulus is greater than each of the at least one first elastic modulus.

3. The winding (110) according to any one of the preceding claims, wherein: The third winding portion (116c) includes a plurality of sub-portions (116c1, ..., 116cn) arranged along the coil axis (z), each sub-portion (116c1, ..., 116cn) having a sub-portion stiffness as seen along the coil axis (z), wherein each sub-portion includes a second type of spacer (130b), and wherein each sub-portion stiffness is greater than the stiffness of the first winding portion.

4. The winding (110) according to claim 3, wherein: The distribution of the multiple sub-portions (116c1, ..., 116cn) forms a polymerized winding portion stiffness, and wherein the multiple sub-portions (116c1, ..., 116cn) are configured so that the polymerized winding portion stiffness of the third winding portion (116c) on the first side of the winding center point (C) as seen along the coil axis (z) is greater than the polymerized winding portion stiffness of the third winding portion (116c) on the second side of the winding center point (C) as seen along the coil axis (z).

5. The winding (110) according to claim 4, wherein: The first side of the winding center point (C) is located closer to the first end (110a) of the winding (110) than to the second end (110b).

6. The winding (110) according to claim 2, wherein: The elastic modulus of the first type of spacer (130a) is 0.1GPa-3GPa, preferably 0.5GPa-1.5GPa, and most preferably 0.9GPa-1.1GPa, and wherein the elastic modulus of at least one second type of spacer (130b) is greater than 50GPa, preferably greater than 80GPa, and most preferably greater than 105GPa.

7. The winding (110) according to claim 6, wherein: The material of the first type of spacer (130a) is cardboard, and wherein the material of the at least one second type of spacer (130b) is talc.

8. The winding (110) according to any one of claims 1 to 7, wherein: The first end (110a) is an upper end of the winding (110) when installed in the transformer (100), and the second end (110b) is a lower end of the winding (110) when installed in the transformer (100).

9. The winding (110) according to any one of claims 1 to 7, wherein: The first end (110a) is a lower end of the winding (110) when installed in the transformer (100), and the second end (110b) is an upper end of the winding (110) when installed in the transformer (100).

10. A transformer (20) comprising at least one winding according to any one of claims 1 to 9.

11. The transformer (20) according to claim 10, comprising at least one phase winding, the at least one phase winding having at least one winding (110) according to any one of claims 1 to 9.

12. A transformer arrangement (30) comprising a transformer (20) according to any one of claims 10 or 11, said transformer being immersed in an electrical insulating medium inside a transformer tank (300).

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