EP4044205A1

EP4044205A1 - Transformer assembly

Info

Publication number: EP4044205A1
Application number: EP21157375.3A
Authority: EP
Inventors: Slawomir Ciesielski
Original assignee: Hitachi Energy Switzerland AG
Current assignee: Hitachi Energy Ltd
Priority date: 2021-02-16
Filing date: 2021-02-16
Publication date: 2022-08-17

Abstract

According to the present disclosure a transformer assembly is provided which comprises a core having a yoke. The yoke comprises a plane surface portion and an edge portion (8), wherein the edge portion (8) protrudes beyond the plane surface portion into a direction defined by a surface normal (N) perpendicular to the plane surface portion. Further, the transformer comprises a clamping plate (10) for clamping the yoke in a direction perpendicular to the surface normal (N), wherein the clamping plate (10) comprises a plane portion (12) oriented parallel to the plane surface portion of the yoke. The plane portion (12) of the clamping plate (10) is shaped such that the edge portion (8) of the yoke lies outside a projection of the plane portion (12) of the clamping plate (10) along the surface normal (N). In this manner, it is possible to reduce a distance between the plane portion (12) of the clamping plate (109 and the plane surface portion of the yoke. This allows reducing the extension of insulation members measured parallel to the surface normal which may be disposed between the plane portion (12) of the clamping plate (10) and the plane surface portion of the yoke.

Description

The present invention relates to a transformer assembly.
A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or to multiple circuits. The transformer typically comprises a ferromagnetic core having vertical limbs extending between a lower yoke or bottom yoke and an upper yoke or top yoke. Coils are wound around the limbs. A varying current in any one of the coils produces a varying magnetic flux in the core, which induces a varying electromotive force across any other coil wound around the core.
The core usually comprises laminated sheets disposed in parallel vertical sheet planes. The bottom yoke is clamped horizontally and normal to the planes of the sheets by two bottom clamping plates which are pressed against the bottom yoke from two opposite sides. To this end, the bottom clamping plates are connected to each other by tie bars. The bottom clamping plates comprise a vertical plane portion and a horizontal plane portion, respectively, where the vertical plane portion is used for the described clamping mechanism, whereas the horizontal plane portion is disposed beneath the bottom yoke, respectively.
Bottom insulation members for electrical isolation between the core and the bottom clamping plates are disposed between the horizontal plane portions of the two bottom clamping plates and a downward facing surface of the bottom yoke.
The top yoke is clamped correspondingly by two top clamping plates, wherein the horizontal plane portions of those top clamping plates are disposed above the top yoke. Top insulation members are disposed between the horizontal plane portions of the two top clamping plates and an upward facing surface of the top yoke.
Fig. 8 illustrates a corresponding prior art arrangement, showing a top yoke 105 and a first top clamping plate 102, comprising a vertical plane portion 104 and a horizontal plane portion 106. A corresponding second top clamping plate 102' is merely indicated by weak lines for improved recognizability of the arrangement. Coils 103 are wound around limbs of the core.
The limbs of the core are shaped in such a way that they show a horizontal cross-section, respectively, which approximates a circular cross-section. The cross-section differs from a circle, since the structure of the core comprises the laminated sheets. In this manner, the limbs show vertical edges caused by the sheet structure of the core.
Similarly, the top yoke 105 shows corresponding horizontal edges 112. Thereby, the top yoke 105 includes a central upward facing surface portion 115 which is at least substantially plane and bordered by two of the horizontal edges 112 at opposite sides. Accordingly, a surface normal N of this central upward facing surface portion 115 is vertically oriented and pointing upwards.
Moreover, edge portions 114 of the core extending perpendicular to the sheet planes are formed which are called "weave zones" 114. Thus, the central upward facing surface portion 115 is bordered on the whole by two horizontal edges 112 and by two edge portions or weave zones 114.
The weave zones 114 bordering the central upward facing surface portion 115 are structures in such a way that they protrude beyond the central upward facing surface portion 115 upwards, i.e. into a direction defined by the surface normal N.
The top insulation members 108 are disposed between the horizontal plane portions 106 of the top clamping plates 102, 102' and the central upward facing surface portion 115 of the top yoke 105. The top insulation members 108 have a vertical extension which is approximately 10 mm. This height is chosen in order to eliminate a collision between the top clamping plates 102, 102' and the weave zones 114 of the central upward facing surface portion 115.
A corresponding situation is given with respect to the bottom yoke and the bottom clamping plates.
Further, as illustrated in Fig. 9, the horizontal plane portions of the bottom clamping plates are disposed on two foot elements 120. These foot elements 120 are fixed to the horizontal plane portions of the bottom clamping plates by screws.
The foot elements 120 are profiled and have a cross-section resembling a "Ω" or a "flanged C". More specifically, the cross section shows four 90° bends such that each foot element 120 provides space beneath the horizontal plane portions of the lower clamping plates which can be used for hiding the heads of the screws. The vertical extension of a foot element 120 is approximately between 20 mm and 22 mm.
As further known in the art, the described core arrangement may be disposed in a tank filled with oil. Thus, the foot elements 120 may be disposed on a bottom surface of the tank.
Typically, a transformer is a comparatively heavy and bulky device. Thus, handling a transformer is correspondingly difficult.
There is a need to provide a transformer assembly showing improved handling features.
This object is achieved by the independent claim. Dependent claims refer to preferred embodiments.
According to the present disclosure a transformer assembly is provided which comprises a core having a yoke, wherein the yoke comprises a plane surface portion and an edge portion, wherein the edge portion protrudes beyond the plane surface portion into a direction defined by a surface normal perpendicular to the plane surface portion. Further, the transformer comprises a clamping plate for clamping the yoke in a direction perpendicular to the surface normal, wherein the clamping plate comprises a plane portion oriented parallel to the plane surface portion of the yoke, wherein the plane portion of the clamping plate is shaped such that the edge portion of the yoke lies outside a projection of the plane portion of the clamping plate along the surface normal.
Various embodiments may preferably implement the following features:
Preferably, the yoke is a top yoke and the plane surface portion of the yoke is a central upward facing surface portion of the yoke, and the clamping plate is a top clamping plate.
Alternatively, preferably, the yoke is a bottom yoke and the plane surface portion of the yoke is a central downward facing surface portion of the yoke and the clamping plate is a bottom clamping plate.
Preferably, the edge portion is a weave portion.
Since the plane portion of the clamping plate is shaped such that the edge portion of the yoke lies outside a projection of the plane portion of the clamping plate along the surface normal, it is possible to reduce a distance between the plane portion of the clamping plate and the plane surface portion of the yoke. This further allows reducing the extension of insulation members measured parallel to the surface normal which may be disposed between the plane portion of the clamping plate and the plane surface portion of the yoke. In this manner, the corresponding extension of the insulation members can be reduced to a required minimum value which may be for example between 1 mm to 2 mm. Thus, the height of the transformer assembly can be reduced.
Further, it is possible to reduce the area or the volume of the plane portion of the clamping plate resulting in a reduction in the mass of the clamping plate and correspondingly, in the mass of the transformer assembly.
Moreover, the clamping plate can be designed shorter in a horizontal direction, also resulting in a mass reduction.
The shape of the clamping plate can be produced comparatively easily, for example by laser cutting. This is advantageous regarding manufacture.
Thus, compared with a transformer assembly according to prior art as described above, the mass of the transformer assembly can be reduced. Further, an extension of the transformer assembly parallel to the surface normal, that means for example the height of the transformer assembly can be reduced.
Based on typical values, the mass of the transformer assembly may be reduced by several kilograms. The height of insulation members can be reduced, e.g., from 10 mm to approximately 1 mm or 2 mm, i.e. the height of the transformer assembly can be reduced by approximately 9 mm. When the described arrangement is used with respect to the upperyoke and the bottom yoke, a corresponding height reduction of two times 9 mm, i.e. 18 mm can be achieved. The reduction in height is further advantageous in case the transformer assembly is designed to become immersed into oil filled in a tank, since the amount of required oil can be reduced correspondingly. Further, the volume of the insulation members can be reduced leading to reduced costs.
Preferably, the clamping plate further comprises a further plane portion which is oriented at least substantially perpendicular to the first mentioned plane portion of the clamping plate. The further plane portion is preferably oriented parallel to the sheet planes. Thus, the further plane portion allows for a particularly effective clamping of the yoke.
Preferably, the clamping plate is a one-piece component. This allows for a small volume design of the clamping plate and an easy manufacturing.
Preferably, the core comprises a plurality of laminated sheets, wherein the laminated sheets are oriented in planes perpendicular to the plane surface portion of the yoke. The edge portion is preferably oriented perpendicular to the planes of the sheets.
Preferably, the plane surface portion of the yoke is formed by a middle range portion of the plurality of laminated sheets. In other words, the plane surface portion of the yoke may be a central surface portion of the yoke.
Preferably, the transformer assembly further comprises an insulation member disposed between the plane surface portion of the yoke and the plane portion of the clamping plate. The insulation member is preferably designed to provide electrical insulation between the clamping plate and the core. This is advantageous regarding the functionality of the transformer assembly.
Preferably, the yoke extends along a longitudinal axis that is oriented perpendicular to the surface normal, wherein the edge region borders the plane surface portion of the yoke as seen along the longitudinal axis. Thus, the edge portion may be a weave portion.
Preferably, the yoke comprises two edge portions, wherein the two edge portions border the plane surface portion of the yoke as seen along the longitudinal axis at opposite sides. An extension of the clamping plate along the longitudinal axis is preferably larger than a distance between the two edge portions along the longitudinal axis. Thus, the clamping plate can protrude the plane surface portion and the edge portions of the yoke at two opposite sides. In this case, the plane portion of the clamping plate is preferably shaped such that both edge portions of the yoke lay outside the projection of the plane portion of the clamping plate along the surface normal.
Preferably, the clamping plate comprises an oblique rim portion extending obliquely with respect to the longitudinal axis. Particularly, the plane portion of the clamping plate preferably comprises the oblique rim portion. Further preferably, the oblique rim portion is bordered by rounded rim portions of the clamping plate. This allows for a reduction in the risk of injury.
Preferably, the further plane portion of the clamping plate comprises a rounded edge portion. This allows for a further reduction in the risk of injury.
Preferably, the transformer assembly further comprises a further clamping plate for clamping the yoke, wherein the further clamping plate is connected to the first mentioned clamping plate by a tie bar. This allows for an effective clamping mechanism.
Preferably, the tie bar is attached to the clamping plate as seen along the longitudinal axis at a position laterally outside the yoke. Further preferably, a further tie bar is attached correspondingly at an opposite end of the clamping plate.
According a second aspect of the present disclosure a transformer assembly is provided which comprises a core extending within a vertical plane and having a bottom yoke or lower yoke. The transformer assembly further comprises a clamping plate for clamping the lower yoke and an elongate foot element oriented perpendicular to the vertical plane and having an L-shaped cross-section such that the foot element comprises a first limb and a second limb connected by a bent section. The foot element is attached to the clamping plate such that the first limb of the foot element contacts the clamping plate evenly from below, wherein the second limb is oriented vertical with its free end facing upwards.
In this manner, solely the first limb of the foot element must be arranged between the clamping plate and a surface, e.g., a bottom surface of a transformer tank when mounting the transformer assembly. This allows for a reduction in height of the transformer assembly compared to a prior art transformer assembly as described above.
Various embodiments may preferably implement the following features:
Preferably, the bent section includes a through hole, wherein the clamping plate comprises a hook extending through the through hole for attaching the foot element to the clamping plate. This allows for facilitated assembling, since it is not necessary to handle screws for connecting the foot element and the clamping plate.
Preferably, the clamping plate comprises a cut-out designed and arranged for receiving the free end of the second limb of the foot element. This facilitates assembling further, since the foot element may simply positioned or "clicked" with its free end of the second limb into the cut-out.
Preferably, the transformer assembly further comprises a further foot element where the designed and arrangement corresponds to the first mentioned foot element. Preferably, the foot elements are arranged mirror symmetrical. Preferably, the first limbs of the foot elements are oriented so that they point towards each other.
The subject-matter of the disclosure will be explained in more detail with reference to preferred exemplary embodiments which are illustrated in the attached drawings, in which:

Fig. 1 is a schematic perspective view of a transformer assembly according to the present disclosure.
Fig. 2 is a top view of the transformer assembly.
Fig. 3a is a side view of the transformer assembly.
Fig. 3b is a cross-sectional view along line A-A indicated in Fig. 3a.
Fig. 4 is a perspective view of a region around the upper yoke of the transformer assembly.
Fig. 5 is a view of the transformer assembly from below.
Fig. 6 is a front view of a region around an end section of a lower clamping plate of the transformer assembly.
Fig. 7a is a rear view of the transformer assembly.
Fig. 7b is a cross-sectional view along line B-B indicated in Fig. 7a.
Fig. 8 is a perspective view of a region around an upper yoke of a transformer assembly according to prior art.
Fig. 9 is a perspective view of the transformer assembly according to prior art.

Fig. 1 is a schematic perspective view of a transformer assembly according to the present disclosure. Fig. 2 is a top view of the transformer assembly. Fig. 3a is a side view of the transformer assembly, Fig. 3b is a cross-sectional view along line A-A indicated in Fig. 3a.
The transformer assembly may be designed to be submerged into an oil filled in a transformer tank (not shown in he figures).
The transformer assembly comprises a core 2 having a yoke 4. The core 2 particularly comprises a plurality of laminated sheets oriented in vertical sheet planes.
The core 2 further comprises at least one limb 3, for example three limbs 3, and a further yoke 5, wherein the at least one limb 3 extends between the yoke 4 and the further yoke 5. The following description refers to the case that the at least one limb 3 extends vertically, where the yoke 4 is a top yoke and the further yoke is a bottom yoke 400 of the core 2. However, the transformer assembly may generally oriented otherwise. Further, the figures refer to the case that the yoke 4 is an upper yoke, however, the arrangement can be used with respect to a lower yoke correspondingly. Coils 5 are wound around the limbs 3 as known as such in the art.
The yoke 4 extends along a longitudinal axis L. The yoke 4 comprises a plane surface portion 6. The plane surface portion 6 is oriented perpendicular to the sheet planes. The plane surface portion 6 is formed by a middle range portion of the plurality of sheets. In other words, the plane surface portion 6 is a central upward facing surface portion as described above with respect to prior art.
Further, the yoke 4 comprises an edge portion 8. The edge portion 8 particularly is a so called "weave" portion as described above with respect to prior art. The edge portion 8 is elongate, extending perpendicular to the sheet planes. The edge portion 8 borders the plane surface portion 6 of the yoke 4 as seen along the longitudinal axis L.
More specifically, the yoke 4 comprises two edge portions 8, wherein the edge portions 8 border the plane surface portion 6 of the yoke 4 as seen along the longitudinal axis L at two opposite sides.
Fig. 4 is a perspective view of a region around the yoke 4. The orientation of the plane surface portion 6 is defined by a surface normal N which is - in the present case - pointing vertically upwards.
As indicated in Fig. 4, the edge portion 8 protrudes beyond the plane surface portion 6 into a direction defined by a surface normal N, i.e. in this case vertically.
The transformer assembly further comprises a clamping plate 10 for clamping the yoke 4 in a direction perpendicular to the surface normal N and perpendicular to the sheet planes. The clamping plate 10 extends along the longitudinal axis such that it protrudes the yoke 4 at both lateral sides.
The clamping plate 10 comprises a plane portion 12 oriented parallel to the plane surface portion 6 of the yoke 4. In the present case, the plane portion 12 of the clamping plate constitutes a horizontal plane portion 12.
The plane portion 12 of the clamping plate 10 is shaped such that the edge portion 8 of the yoke 4 lies outside a projection of the plane portion 12 of the clamping plate 10 along the surface normal N, i.e. here outside a vertical projection of the horizontal plane portion 12 of the clamping plate 10. If two edge portions 8 border the plane surface portion 6 of the yoke 4 as seen along the longitudinal axis L at two opposing sides, the plane portion 12 of the clamping plate 10 is advantageously shaped such that both edge portions 8 of the yoke 4 lay outside the projection of the plane portion 12 of the clamping plate 10 along the surface normal N. In other words, the arrangement at the two end regions 8 of the yoke 4 as seen along the longitudinal axis L is analogously.
A dashed line in Fig. 2 indicates the border of a corresponding clamping plate according to the prior art described above. As can be seen, a clamping plate according to the present disclosure can be designed shorter.
The clamping plate 10 preferably further comprises a further plane portion 14, here a vertical plane portion 14 which is oriented at least substantially perpendicular to the first mentioned plane portion 12 of the clamping plate 10. The further plane portion 14 is oriented perpendicular to the sheet planes of the core 2.
Advantageously, the clamping plate 10 is a one-piece component. The plane portion 12 and the further plane portion 14 may be connected via a bent portion of the clamping plate 10, for example solely via the bent portion.
The transformer assembly further comprises at least one insulation member 16 disposed between the plane surface portion 6 of the yoke 4 and the plane portion 12 of the clamping plate 10. This allows for suited insulation between the core 2 and the clamping plate 10.
As can be seen for example in Fig. 2, the clamping plate 10 preferably comprises an oblique rim portion 22 extending obliquely with respect to the longitudinal axis L. The oblique rim portion 22 is advantageously bordered at both sides by rounded rim portions of the clamping plate 10. This significantly allows for a reduction in risk of injury.
As can be seen for example in Figures 1 and 4, the clamping plate 10 preferably comprises a further rounded rim section 24 at a lateral end of its vertical plane portion 14.
The transformer assembly further comprises a further clamping plate 18 for clamping the yoke 6. Note that in Fig. 4, the further clamping plate 18 is merely indicated by weak lines. The further clamping plate 18 is connected to the first mentioned clamping plate 10 by a tie bar 20. The tie bar 20 is preferably oriented horizontally and perpendicular to the sheet planes, i.e. perpendicular to the surface normal N of the plane surface portion 6 of the yoke 4. The design with respect to the further clamping plate 18 may be symmetrical with respect to a vertical plane of symmetry intersecting the core 2 symmetrically.
The tie bar 20 is preferably attached to the clamping plate 10 as seen along the longitudinal axis L at a position outside the yoke 4. Thus, the tie bar 20 can be arranged within the height range of the yoke 4 and does not require extra height of the transformer assembly.
The transformer assembly preferably further comprises a further tie bar arranged correspondingly at the opposite side of the yoke 4. The clamping plate 10 has an extension along the longitudinal axis L that is greater than the distance between the tie bar 20 and the further tie bar in such a way that the clamping plate 10 allows for a secure connection between the clamping plate 10 and the tie bars 20.
As can be seen in Figure 1, 3b and the bottom view of Fig. 5, the transformer assembly comprises the lower yoke 400 and a lower clamping plate 100 for clamping the lower yoke 400. Fig. 6 is a front view of a region around an end section of the lower clamping plate 100. Note that dashed lines in Figures 5 and 6 indicate the border of a corresponding clamping plate according to the prior art described above.
Fig. 7a is a rear view of the transformer assembly. Fig. 7b is a cross-sectional view along line B-B indicated in Fig. 7a. The transformer assembly preferably comprises an elongate foot element 500 oriented perpendicular to the lower yoke 100. As can be seen for example in Fig. 6, the foot element 500 has an L-shaped cross-section such it comprises a first limb 520 and a second limb 540 connected by a bent section 560.
The foot element 500 is attached to the clamping plate 100 such that the first limb 520 of the foot element 500 contacts the clamping plate 100 evenly from below, wherein the second limb 540 is oriented vertical with its free end facing upwards. This allows for a further reduction in the height of the transformer assembly as compared to the prior art transformer assembly described above. For example, the height can be reduced in this manner by approximately 16 mm.
That means, a transformer assembly according to the present disclosure allows for a height reduction of approximately two times 9 mm plus 16 mm, i.e. 34 mm.
The transformer assembly further comprises a further foot element 510 designed and arranged correspondingly to the first-mentioned foot element 500. The further foot element 510 is arranged analogously to an opposing end region of the lower clamping plate 100. The arrangement of the foot elements 500, 510 is advantageously such that it is symmetrical with respect to a vertical plane crossing the center of the core 2 perpendicular to the sheet planes. The first limbs 520 of the foot elements 500, 510 may be pointing to each other. This is advantageous with respect to the stability of the mounted transformer assembly.
As can be seen for example in Fig. 5, the transformer assembly further comprises a further lower clamping plate 110. The arrangement is analogous to the above-mentioned clamping plate 10 which may be a top clamping plate and the above mentioned further clamping plate 18 which may be a further top clamping plate.
The foot element 500 and the further foot element 510 are arranged such that they protrude perpendicularly with respect to the sheet planes of the core 2 beyond the lower clamping plate 100 and the further lower clamping plate. Thus, the transformer assembly can be put stable for example on a base surface of a transformer tank with the first limbs 520 of the foot elements 500, 510.
As can be seen in Fig. 5, the bent section 560 preferably includes a through hole 580, wherein the clamping plate 100 comprises a hook 120 extending through the through hole 580 for attaching the foot element 500 to the clamping plate 100. Moreover, as can be seen in Fig. 6, the clamping plate 100 advantageously comprises a cut-out 140 designed and arranged for receiving the free end of the second limb 540 of the foot element 500. This arrangement allows for a facilitated and quick assembly of the foot elements 500, 510 to the lower clamping plates 100, 110.
The advantages of a transformer assembly according to the present disclosure particularly comprise the following points:

A height of the transformer assembly can be reduced, e.g. by approximately 33 mm to 35 mm.
A mass of the transformer assembly can be reduced, e.g. by approximately 12 kg to 40 kg, due to a reduction in the mass of the clamping plates and the foot elements.
The height of insulation members disposed between a horizontal plane portion of a clamping plate and a yoke can be reduced leading to a reduction in the mass of the insulation members.
Assembling of the transformer assembly is facilitated.
A risk of injury is reduced.

While the subject-matter of the present application has been described in detail in the drawings and forgoing description, such description is to be considered illustrative or exemplary and not restrictive. Variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain elements are recited in distinct claims does not indicate that a combination of these elements cannot be used to advantage, specifically, in addition to the actual claim dependency, any further meaningful claim combination shall be considered disclosed.

Claims

A transformer assembly, comprising
a core (2) having a yoke (4), wherein the yoke (4) comprises a plane surface portion (6) and an edge portion (8), wherein the edge portion (8) protrudes beyond the plane surface portion (6) into a direction defined by a surface normal (N) perpendicular to the plane surface portion (6); and
a clamping plate (10) for clamping the yoke (4) in a direction perpendicular to the surface normal (N), wherein the clamping plate (10) comprises a plane portion (12) oriented parallel to the plane surface portion (6) of the yoke (4), wherein the plane portion (12) of the clamping plate (10) is shaped such that the edge portion (8) of the yoke (4) lies outside a projection of the plane portion (12) of the clamping plate (10) along the surface normal (N).
The transformer assembly of claim 1, wherein the clamping plate (10) further comprises a further plane portion (14), which is oriented at least substantially perpendicular to the first mentioned plane portion (12) of the clamping plate (10).
The transformer assembly of claim 1 or 2, wherein the clamping plate (10) is a one-piece component.
The transformer assembly of any of the preceding claims, wherein the core (2) comprises a plurality of laminated sheets, wherein the laminated sheets are oriented in planes perpendicular to the plane surface portion (6) of the yoke (6).
The transformer assembly of claim 4, wherein the plane surface portion (6) of the yoke (4) is formed by a middle range portion of the plurality of laminated sheets.
The transformer assembly of any of the preceding claims, further comprising an insulation member (16) disposed between the plane surface portion (6) of the yoke (4) and the plane portion (12) of the clamping plate (10).
The transformer assembly of any of the preceding claims, wherein the yoke (4) extends along a longitudinal axis (L) that is oriented perpendicular to the surface normal (N), and wherein the edge portion (8) borders the plane surface portion (6) of the yoke (6) as seen along the longitudinal axis (L).
The transformer assembly of claim 7, wherein the clamping plate (10) comprises an oblique rim portion (22) extending obliquely with respect to the longitudinal axis (L).
The transformer assembly of claim 8, wherein the oblique rim portion (22) is bordered by rounded rim portions of the clamping plate (10).
The transformer assembly of any of the preceding claims, further comprising a further clamping plate (18) for clamping the yoke (6), wherein the further clamping plate (18) is connected to the first mentioned clamping plate (10) by a tie bar (20).
The transformer assembly of claim 10, comprising the features of claim 7, wherein the tie bar (20) is attached to the clamping plate (10) as seen along the longitudinal axis (L) at a position outside the yoke (6).
A transformer assembly, comprising
a core (2) extending within a vertical plane and having a lower yoke (400);
a clamping plate (100) for clamping the lower yoke (400); and
an elongate foot element (500) oriented perpendicular to the vertical plane and having an L-shaped cross-section such that the foot element (500) comprises a first limb (520) and a second limb (540) connected by a bent section (560),
wherein the foot element (500) is attached to the clamping plate (100) such that the first limb (520) of the foot element (500) contacts the clamping plate (100) evenly from below, wherein the second limb (540) is oriented vertical with its free end facing upwards.
The transformer assembly of claim 12, wherein the bent section (560) includes a through hole (580), wherein the clamping plate (100) comprises a hook (120) extending through the through hole (580) for attaching the foot element (500) to the clamping plate (100).
The transformer assembly of claim 12 or 13, wherein the clamping plate (100) comprises a cut-out (140) designed and arranged for receiving the free end of the second limb (540) of the foot element (500).