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The present disclosure is related to a coil block fixation system for a transformer and a corresponding transformer.
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Transformers are installed for example in wind-power facilities and can be subject to instantaneous accelerations due to high loads that may occur during operation, transportation and others. Such extreme loading conditions have to be counteracted to contribute to a longer service life and a reliable operation of the transformer and its windings. Consequently, it is a task to provide a system for a transformer that enables to withstand such challenging operational conditions.
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Thus, it is an objective to provide a coil block fixation system for a transformer that contributes to a longer service life and stable and reliable operation of the transformer.
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According to an embodiment, a coil block fixation system for a transformer comprises a coil block body with a bottom surface that is configured for coupling to a coil of the transformer. The coil block fixation system further comprises a supporting plate with a bottom surface that is coupled to an upper surface of the coil block body opposite the bottom surface of the coil block body. The coil block fixation system further comprises at least two rods that are coupled to an upper surface of the supporting plate opposite the bottom surface of the supporting plate for setting a load to the supporting plate towards the coil block body. The coil block fixation system further comprises at least two spring elements. At least one spring element is coupled to each rod such that each rod interacts with at least one spring element and such that the load set to the supporting plate is provided with a given flexibility with respect to a mounting direction from the coil block body to the rods.
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By use of the described fixation system a transformer is feasible and enables to withstand accelerations due to high loads during operation, transportation and others. The fixation system provides a specific configuration that combines an advantageous compromise between high stability and flexibility of the transformer in view of movements that are unavoidable.
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According to a further embodiment, the supporting plate comprises one or more protrusions that extend into corresponding one or more recesses of the coil block body and that form a respective movement limiter to counteract a translation and/or a rotation of the supporting plate relative to the coil block body. For example, the supporting plate comprises a lateral movement limiter formed at a side surface of the supporting plate extending into a lateral recess of the coil block body formed in an upper surface or wall of the coil block body. In particular, such a lateral movement limiter can reliably counteract an unwanted rotation of the supporting plate around an axis of rotation which may be parallel to a longitudinal axis of the elongated rod substantially. Additionally, such a lateral movement limiter can counteract an unwanted translation in directed limited by a recess contour of the coil block body.
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Alternatively or additionally, the supporting plate comprises a lower movement limiter formed at the bottom surface of the supporting plate extending into an upper recess of the coil block body formed in the upper surface of the coil block body. In particular, such a lower movement limiter can reliably counteract an unwanted translation of the supporting plate in a plane substantially perpendicular to the aforementioned axis of rotation. Additionally, such a lower movement limiter can counteract an unwanted rotation in the aforementioned plane and also in a transverse plane to it. The one or more protrusions forming limiters can be formed in one piece with the supporting plate, in particular.
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According to a further embodiment, the rods are formed as threaded pins each, and the coil block fixation system further comprises two or more nuts which are configured in coordination with the respective associated threaded pin. Due to the threaded pins and associated nuts as well as the spring elements the load set to the supporting plate is adjustable and fixable by means of the nuts screwed on the threaded pins. For example, the nuts are screwed on the threaded pins such that the nuts are arranged between the upper surface of the supporting plate and the one or more spring elements.
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According to a further embodiment, the coil block fixation system further comprises two or more positioning elements wherein at least one positioning element is coupled to each rod such that it is arranged between the associated nut and spring element with respect to a longitudinal direction of the corresponding rod. The positioning element forms a support for the one or more spring elements attached to the associated rod. Additionally or alternatively, the positioning element can form a fixing for the adjusted nut configured to prevent loosening of the set nut positioning and load to the supporting plate.
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According to a further embodiment, the spring elements are formed as spring washers surrounding the associated rod. The spring washers can be realize in a cost-saving manner as elastic metal rings providing a predetermined flexibility int the coil block fixation system. The springs washers can also be referred to as disc springs.
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According to a further embodiment, the coil block fixation system further comprises two or more sliding guiders wherein at least one sliding guider is coupled to each rod such that the associated spring element is slidable along a longitudinal direction of the rod by means of the sliding guiders. The sliding guiders can be realized as respective sleeves which surround the associated rod. Such sleeves would be arranged between the rod and the spring washer to provide guided and low-resistance sliding up and down along the longitudinal axis of the corresponding rod. The sliding guider can be formed in one piece with the positioning element described above forming a sleeve with a disc-like support surface which could comprise a kind of T-shaped tube with respect to a cross section.
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According to a further embodiment, the coil block fixation system further comprises three or more rods and corresponding spring elements. The rods are coupled to the upper surface of the supporting plate for setting a load to the supporting plate towards the coil block body. The three or more spring elements are coupled to the associated rod such that each rod provides a respective load to the supporting plate with a respectively given flexibility along the mounting direction from the coil block body to the rods. The three rods realize a three-point-contact to the supporting plate and can beneficially affect the stability and flexibility of the coil block fixation system and the corresponding transformer. Moreover, the three rods and the corresponding spring washers or spring element can provide equal or different local loads to the supporting plate. Different local loads can be realized by using different spring elements including different material or elastic properties and/or a different number of spring elements. This analogously applies to a configuration with two rods and associated spring elements.
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Alternatively, the coil block fixation system merely comprises one rod and at least one corresponding spring element coupled to the upper surface of the supporting plate for setting a load to the supporting plate towards the coil block body. In order to provide an enhanced stability and to withstand high loads two, three or more rods are preferred.
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According to a further embodiment, the supporting plate comprises an angular shape with one or more inner and/or outer edges. For example, the supporting plate comprises a substantially rectangular or cuboid shape with rounded edges, preferably. Alternatively, the supporting plate can comprise a trapezoidal shape or a triangular, a pentagonal or polygonal shape with sharp and/or rounded edges. The rods are fixed to the supporting plate closer to the outer edge of the supporting plate than to the inner edge of the supporting plate with respect to a mounted state of the coil block fixation system coupled to an annular shaped coil of the transformer, wherein the inner edge of the supporting plate faces a centre of the coil.
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The coils or windings of transformers are formed circularly in general and thus comprise a centre and an outer region. The aforementioned configuration can beneficially contribute to the stability and flexibility of the coil block fixation system and advantageously affect an operation of the transformer even despite unavoidable vibration movements. The specific location of the rods and their respective local load to the supporting plate can be adapted to the intended use and application of the associated transformer such that, for example, a higher level of stabilization is set up further outside than inside. Alternatively, the rods can be arranged further insider than outside or in a centre region of the supporting plate substantially.
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According to a further embodiment, the supporting plate comprises a T-shape with a lower protrusion and lateral plate portions with respect to a cross section along the mounting direction. The lateral plate portions extends laterally outwards from the protrusion and contacts the upper surface of the coil block body. Accordingly, the lateral portions of the supporting plate can reliably counteract an unwanted rotation around an axis of rotation which may be parallel to a main extension plane or to the extrusion axis of the supporting plate.
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According to a further embodiment, the coil block body can comprise at least one protrusion that extends into a corresponding recess of the supporting plate and that forms a respective movement limiter to counteract a translation and/or a rotation of the supporting plate relative to the coil block body. Such a configuration can also beneficially counteract an unwanted translation and/or rotation of the supporting plate relative to the coil block body.
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According to an embodiment, a transformer comprises a coil for converting voltage, and a coil block fixation system according to any of the preceding claims that is coupled to the coil. In general, the transformer comprises two or more coils and the coil block fixation system can be coupled to both coils. As a result of that the transformer comprises an embodiment of the coil block fixation system as described above, features and characteristics of the coil block fixation system are also disclosed with respect to the transformer and vice versa.
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It is a recognition of the present disclosure that transformers, which can be installed in wind-power facilities, can be subject to instantaneous accelerations due to mechanical and/or electromechanical loads that may occur during operation, transportation and others. Mechanical shocks can occur from a rapid stop of the wind turbine blades or from geometrical and material configurations and the associated resonance frequencies, for example. Electromechanical shocks can appear in view of frequency requirements which have to be fulfilled in view of the associated amplitudes or other operation parameters of the transformer. Such high loading conditions highlights the inherent structural weakness in conventional fixing systems. Accordingly, it is a challenge to improve a transformer's ability to withstand such demanding operational conditions.
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It is a further recognition of the present disclosure that the aforementioned problems are primarily focused on a structural weakness of a standard coil block itself which is vulnerable and has a tendency for structural failure. This can lead to disassembling further leading to potential performance and reliability degradation of the transformer. Another critical issue that can occur during testing is the tendency for nuts to loosen under the displacement induced by the extreme shocks and vibrations. These weaknesses highlights the need for a more robust coil-block design capable of withstanding the demanding conditions specified by the customer testing requirements.
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The described coil block fixation system can counteract the aforementioned adverse effects and shortcomings. The coil block fixation system can be realized as squared shaped flange fixation that allows for stable and reliable operation of the transformer in particular in view of shock and sine beat load requirements due to its spring washers and the specific design options which contribute to an enhanced overall robustness.
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The rods and associated spring elements in interaction with the specific supporting plate and coil block body are specifically engineered to withstand high acceleration shocks. Integrated in or attached to a transformer, the coil block fixation system can contribute to prevent structural damages and performance issues under extreme loading condition. The spring elements, preferably formed as spring washers, can reliably absorb thermal dilatation of a winding or coil of the transformer while maintaining beneficial stiffness, specifically tuned, to withstand dynamic loads. Thus, an overall resilience and performance of transformers can be improved even in view of high acceleration shocks. The described configurations of the coil block fixation system each represents a compromise between the necessity for having a stiff coil-block to support the windings or coils of the transformer being subject to extreme loads and, at the same time, providing a sufficient room for the thermal expansion of the windings or coils. The coil block body may comprise a bulky structure itself with some protrusions and/or recesses that serve as interface for the supporting plate and the assembled rods and spring washers. The rods form pins through which a proper pre-load on the coils of the transformer can be applied. The combination of the preload and spring washers' stiffness can advantageously contribute to required stability and robustness of the transformer.
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The described coil block fixation system can contribute to an enhanced lifetime or service life, can allow for easy mounting and also passes several tough requirements including sine beat tests based on increasing amplitudes with fixed frequency requirements by a customer. In addition, the coil block fixation system passes mechanical resonance checks due to the counteracting damping set up by the described configurations.
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Exemplary embodiments are explained in the following with the aid of schematic drawings and reference numbers. The figures show:
- Figure 1 an embodiment of a coil block fixation system for an transformer in a perspective view,
- Figure 2 a cross section side view of components of the coil block fixation system of figure 1,
- Figure 3 a further embodiment of the coil block fixation system for a transformer in a perspective view,
- Figure 4 a cross section side view of components of the coil block fixation system of figure 3, and
- Figure 5 an embodiment of a coupling structure including a plurality of the coil block fixation systems coupled to a transformer.
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The accompanying figures are included to provide a further understanding. Identical reference numbers designate elements or components with identical functions. In so far as elements or components correspond to one another in terms of their function in different figures, the description thereof is not repeated for each of the following figures. For the sake of clarity elements might not appear with corresponding reference symbols in all figures, possibly.
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Figure 1 illustrates a perspective view an embodiment of a coil block fixation system 30 for a transformer. The coil block fixation system 30 comprises a coil block body 10 with a bottom surface 24 and an upper surface 23 opposite the bottom surface 24. The bottom surface 24 is configured for coupling to a coil 19 of the transformer by means of a contact element 20, such as a rubber pad or silicon rubber.
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The coil block fixation system 30 further comprises a supporting plate 1 with a bottom surface 22 and an upper surface 21 opposite the bottom surface 22. The bottom surface 22 is coupled to the upper surface 23 of the coil block body 10. The coil block fixation system 30 further comprises two rods 3 that are coupled to the upper surface 21 of the supporting plate for setting a load to the supporting plate towards the coil block body. The rods 3 can be securely fixed to the supporting plate 1 by means of welding.
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The coil block fixation system 30 further comprises four spring elements which are formed as spring washers 2 two of which surround an associated rod 3. The rods 3 and the spring washers 2 are configured to set a predetermined load to the supporting plate 1 with a given flexibility with respect to a mounting direction from the coil block body 10 to the rods 3. According to coordinate system shown in the Figures 1 to 4, the mounting direction represents a vertical direction or z-direction. The z-direction also equals the longitudinal direction of the rods 3. The x- and y-direction represent horizontal directions and consequently span a horizontal plane.
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The rods 3 are formed as threaded pins each, and corresponding nuts 5 are configured in coordination with the threaded pins such that the load set to the supporting plate 1 is adjustable and fixable by means of the nuts 5 screwed on the threaded pins. The nuts 5 are screwed on the threaded pins such that the nuts 5 are arranged between the upper surface 21 of the supporting plate 1 and the two spring washers 2 above. With respect to the z-direction, a respective positioning element 4 is coupled to the rods 3 between the associated nut 5 and spring washer 2 (one rod 3 is illustrated without further elements above the washers 2 only for better illustration). The positioning element 4 forms a support for the above two spring washers 2 and also forms a reliable fixing of the adjusted nut 5 in order to prevent loosening of the set nut position and the adjusted load to the supporting plate 1.
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On the side of the washers 2 opposite the positioning element 4 a welding seam 17 and a rod sleeve 7 are illustrated to surround a respective portion of the rod 3 that extends through a coupling structure 26 of the transformer (see Fig. 5). The sleeve 7 is fixed to the coupling structure 26 by means of the welding seam 17 and limits an allowed movement of the washers 2 in z-direction and realize a stable movement guidance of the rods 3 and the corresponding coil block fixation system 30 in interaction with the coupling structure 26 of the transformer. The rod sleeve 7 limits the associated rod 3 and the positioning element 4 tilting while still leaving their translation in vertical direction free. Thus, precise setting a load to the supporting plate 1 is feasible by means of the described elements attached or coupled to each rod 3.
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The supporting plate 1 comprises a substantially rectangular shape with rounded edges and a lateral protrusion at an outer side surface. The lateral protrusion forms a lateral movement limiter 6 that extends into a lateral recess 11 formed in an upper wall 12 of the coil block body 10. The lateral movement limiter 6 counteracts an unwanted rotation of the supporting plate 1 relative to the coil block body 10 in the x-y-plane. Additionally, the lateral movement limiter 6 can counteract an unwanted translational movement of the supporting plate 1 along the y-direction.
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Additionally, as shown in Fig. 2, the supporting plate 1 comprises a protrusion forming a lower movement limiter 9 at the bottom surface 22 that extends into an upper recess 14 of the coil block body 10 formed in the upper surface 23 of the coil block body 10. The lower movement limiter 9 can be formed in a centre region at the bottom surface 22 or alternatively at outwards from the center region. Additionally, there can be a further protrusion at a lateral side surface and/or the bottom surface 22 of the supporting plate 1.
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According to Fig. 2, the supporting plate 1 comprises a T-shape with respect to the illustrated cross section in the y-z-plane with view in the x-direction. The supporting plate 1 comprises lateral plate portions 8 extending laterally outwards from the centre region or the protrusion 9 such that the lateral plate portions 8 each contacts an uppermost surface or at least the upper surface 23 of the coil block body 10 outside the recess 14. Accordingly, the lateral plate portions 8 can beneficially counteract an unwanted rotation of the supporting plate 1 relative to the coil block body 10 in the y-z-plane. Thus, the respective lateral plate portion 8 counteract lifting of the other lateral plate portion 8 on the opposite side from the coil block body 10.
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Figure 3 illustrates a further embodiment of the coil block fixation system 30. The supporting plate 1 comprises a trapezoidal shape in the x-y-plane tapering in direction of the centre of the coils 19. On the wider side portion of the supporting plate 1 there are two rods 3 attached, e.g. welded, onto the upper surface 21 of the supporting plate 1. Approximately in a middle of the supporting plate 1 there is a further rod 3 attached, e.g. welded, onto the upper surface 21 of the supporting plate 1. Thus, the illustrated embodiment according to the Figs. 3 and 4 comprises three rods 3 which set up three local loads on the supporting plate 1. Figure 4 shows a corresponding cross section of the embodiment according to Fig. 3 in the y-z-plane with view in the x-direction. The coil block body 10 can further comprise a circumferential protruding outer wall forming a kind of a frame surrounding a lower portion of the supporting plate 1 which can further counteract an unwanted translational and/or rotational movement of the supporting plate 1 relative to the coil block body 10.
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The three rods 3 will all comprise washers 2 and nuts 5 as already described in view of the embodiment according to the Figs. 1 and 2. The three threaded rods 3 and flexible local loads to the supporting plate 1 due to the washers 2 and nuts 5 can beneficially affect the stability and flexibility of the coil block fixation system 30 and the corresponding transformer. The three rods 3 and the corresponding spring washers 2 and nuts 5 can provide equal or different local loads to the supporting plate 1 which sum up to a given total load on the supporting plate 1.
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According to the described embodiments, the coil block fixation system 30 can be formed with the following components: the coil-block body 10, the threaded pins or rods 3, the spring washers 2, the nuts 5, a locking mechanism, e.g. realized by the positioning element 4 and the welding seam 17 as well as the rod sleeve 7 and a sliding guide 27 for the washers 2 which can be realized by a further sleeve surrounding the rod 3 such that it is arranged between the rod 3 and the washers 2 allowing a low-resistance movement of the washers 2 up and down in z-direction to a certain extent. Preferably, the positioning element 4 and the sliding guide 27 are formed from one piece realizing a sliding guide support sleeve allowing vertical translations of the spring washers 2, so that it can be compressed by vertical vibration of the coil 19, by vertical thermal dilatation of the coil 19 and during the clamping phase when setting the proper compression force on the coil 19.
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The coil block body 10 itself can be composed of a bulky insulating material which is in contact with the coils 19 through rubber pads 20. The coil block body 10 comprises a shape of an archway through which a screen 18 element extends. The coil block body 10 embeds also fins for the electrical clearance realizing a creepage structure 25. On the top surface or upper surface 23 of the coil block body 10 a specific pattern can be made to accommodate a pin supporting structure realized by the rods 3. The rods 3 can have a standard shape each, e.g. cylindrical. The threaded rods 3 are firmly welded on the supporting plate 1, preferably.
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The screen 18 increases the insulation between the coils 19. When the voltage between the two coils 19 is relatively high, a discharge or electrical arc can occur, melting the and damaging the coils 19. For such a reason, a minimum distance between the coils 19 is ensured and the higher the distance the higher the insulation and the lower the probability of electrical arcs. Using the screen 18 allows to increase the insulation between the coils 19 and consequently reduce the distance between them. This enables setting up more compact transformers and a smaller external coil 19 and hence less material usage by which the cost is reduced.
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The sliding guide 27 for the spring washers 2 is mounted on the rods 3 and is vertically free to move up to a given extent. The spring washers 2 are installed around the associated sliding guide sleeve 27 and can be vertically movable with it. The number and arrangement of the described elements, in particular the spring washers 2, depend on the required stiffness and displacement of the assembly and the intended use of the coil block fixation system 30 for a transformer.
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The nuts 5 enable fine-tuning the pre-load of the spring washers 2 and affect their interaction with the supporting plate 1 and the coil block body 10. The respective nut 5 serves a dual purpose of adjusting the pre-load and securing the coil block body 10 in place. The positioning element 4 can be realized as a specific spring element or a rigid member introduced to prevent the loosening of the respective nut 5 during excitation, ensuring the integrity of the entire assembly under dynamic conditions.
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Figure 5 shows an embodiment to couple a plurality of the coil block fixation system 30 to a transformer. The rods 3 of the respective coil block fixation systems 30 are coupled with each other and/or to the transformer or a transformer tank by means of one or more coupling elements or coupling structures 26 realizing a clamping profile, e.g. U-shaped metal supports.
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The embodiments shown in the figures 1 to 5 as stated represent exemplary embodiments of an improved coil block fixation systems 30 and a corresponding transformer; therefore, they do not constitute a complete list of all embodiments according to possible arrangements. Actual arrangements of the fixation system 20 and/or the transformer may vary from the embodiments shown in the figures.
Reference Signs
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- 1
- supporting plate
- 2
- spring washer
- 3
- rod
- 4
- positioning element
- 5
- nut
- 6
- lateral movement limiter
- 7
- fixation sleeve
- 8
- lateral plate portion
- 9
- lower movement limiter
- 10
- coil block body
- 11
- lateral recess of the block body
- 12
- upper wall of the block body
- 14
- upper recess of the block body
- 17
- welding seam
- 18
- screen element
- 19
- coil
- 20
- contact element
- 21
- upper surface of the supporting plate
- 22
- bottom surface of the supporting plate
- 23
- upper surface of the block body
- 24
- bottom surface of the block body
- 25
- creepage structure of the block body
- 26
- coupling structure
- 27
- sliding guide
- 30
- coil fixing system