EP3001435A1 - Dry transformer core - Google Patents

Abstract

A dry-transforming core (1) comprising an iron core (2) with a number of legs (8) designed for winding, which are interconnected by a number of yokes (10), should on the one hand be particularly easy to produce and, on the other hand, particularly well Be protected against corrosion. For this purpose, the dry-transformer core (1) comprises a housing (4) integrally formed on the iron core (2) and surrounding the iron core (2) substantially flush.

Description

The invention relates to a dry-type transformer core comprising an iron core having a number of legs designed for winding connected by a number of yokes.

A dry-type transformer is a transformer which does not contain liquid insulating materials such as e.g. B. contains transformer oil. Dry transformers are commonly used as power transformers, in particular as such in electrical energy networks. They are therefore often three-phase designed as a three-phase AC transformer. Dry transformers are used especially where due to the proximity to persons or property oil-filled transformers or only with significant fire protection measures such. B. fire walls, can be placed. Also, oil catchment pits do not contribute to groundwater protection.

Dry transformer cores, like liquid-filled transformers, are usually designed as two-core or three-core iron cores made of double-sided insulated electrical steel sheets. The legs, which are provided with the coil windings are connected on both sides by yokes. Due to the use of thin magnetic sheets for core production, it must be held, fastened and pressed in various places. This has so far been achieved by bandaging, screwing and compression. If very thin, amorphous sheets are used, the mechanical stabilization of the core is even more complex.

If dry-type transformers are to be operated in open air, in or under water, special corrosion protection measures must be provided for the entire transformer or, if installed without a protective housing, for the iron core. Because of the geometric shape of the iron core here is a elaborate coating necessary to ensure corrosion protection because the core is not surrounded by oil.

It is therefore an object of the invention to provide a dry-transformer core of the type mentioned, on the one hand is particularly easy to manufacture, and on the other hand is particularly well protected against corrosion.

This object is achieved according to the invention in that the dry-transformer core comprises a housing molded onto the iron core, which surrounds the iron core substantially flush.

The invention is based on the consideration that both of the above-mentioned objects could be achieved by a housing, which on the one hand ensures the mechanical strength of the iron core by enclosing it flush, d. H. so that the individual electrical panels are held by the enclosure form-fitting in position, and on the other hand ensures by a complete encapsulation for a good corrosion protection.

In order for the enclosure not adversely affect the magnetic properties of the transformer, it is advantageously made of a non-magnetic material.

In particular, the non-magnetic enclosure advantageously has an average permeability of between -1.01 and 1.01, preferably between -1.001 and 1.001. In this case, the permeability number refers to the ratio of the permeability (ratio of the magnetic flux density to the magnetic field strength) of the housing to that of the vacuum. The enclosure is thus advantageously made of a material whose permeability as far as possible corresponds to that of the vacuum.

To the magnetic properties of the transformer and not by a too high distance of the enclosure enclosing windings to the actual iron core negative to the wall thickness of the enclosure is advantageously less than 1 cm. Under the wall thickness in this case the distance of the outer surface of the enclosure is understood to the outer surface of the iron core.

In an advantageous embodiment of the dry-transformer core, the enclosure is predominantly made of a plastic. By plastic is meant here an organic, polymeric solid which is produced synthetically or semi-synthetically from monomeric organic molecules or biopolymers. Plastics usually meet the requirement of non-magnetisability, are easy to shape and have sufficient stability.

In an alternative advantageous embodiment of the dry-transformer core, the enclosure is predominantly made of steel. Here are non-magnetic steels such. As chromium-nickel steels are used, which have a corresponding permeability. Also, such steels are relatively flexible moldable and have the necessary strength to stabilize the iron core. In addition, steels are electrically conductive, so that electric field strength peaks are reduced, especially when the enclosure is rounded.

Advantageously, in this case the housing is also grounded.

In a further advantageous embodiment of the dry-transformer core, the enclosure is designed in several parts, one of the parts essentially enclosing one of the yokes. Overall, the enclosure should be designed so that the iron core can be inserted in its individual sections, assembled and assembled. In particular, the enclosure is designed so that coils can be guided over the individual iron core legs and their Umhausungsteil, and then a yoke can be applied. This is in turn enclosed by appropriate Umhausungsteilen.

Advantageously, the enclosure on its outside on a number of fastening devices. This can include both the fastening devices for the installation of the transformer itself, as well as for the attachment of the windings.

The iron core is advantageously made of amorphous films. Especially with such iron cores, which need to be stabilized without housing particularly complex and where attachment is particularly difficult to accomplish, the use of a housing with corresponding fastening devices of very particular advantage.

Remains by a slightly larger education of the enclosure a gap between iron core and housing, it is advantageously filled with a suitable mass. This increases the stability of the resulting transformer core.

The enclosure advantageously comprises an insulating part, which is designed such that no closed conductor loop is formed around the iron core. In an electrically conductive housing, it is necessary to design these with a non-conductive interruption, which can be arranged virtually arbitrarily, only topologically so expanded and arranged that no closed loop can be formed around the iron core. As a result, namely short circuit turns are avoided. The interruption can be made of a suitable insulating material.

A dry-type transformer advantageously comprises a described dry-type transformer core and a number of coils wound around the legs enclosed by the enclosure.

A trained according to the aforementioned type of dry transformer is advantageously for a rated voltage of more designed as 1 kV and / or a rated power of more than 50 kVA. Especially in the case of dry transformers of this performance class, the enclosure of the iron core described above is of considerable advantage in the design.

The dry-type transformer is advantageously designed as a cast-resin transformer, d. H. The insulation of the high voltage windings consists of cast resin.

The advantages achieved by the invention are, in particular, that the mechanical strength of the dry transformer core is ensured by the installation of the iron core in a non-magnetic housing as a supporting component, without consuming core bandages, core fittings or Kernpressvorrichtungen would be needed. The result is a completely encapsulated iron core, which is protected against corrosive influences. In addition, the noise level is reduced, as this is essentially generated by the magnetostriction of the iron core, which is shielded by the housing.

The shape of the enclosure can follow the iron core shape and can also be made for round, oval or rectangular iron core sections. The assembly of the enclosure can take place with consideration of an isolation with all known joining methods.

FIG 1

einen Trockentransformatorkern mit einer abgerundeten Umhausung, die den Eisenkern umschließt,

FIG 2

einen Trockentransformatorkern mit einer abgerundeten Umhausung, die den Eisenkern umschließt, und die eine Mehrzahl von Befestigungsvorrichtungen aufweist, und

FIG 3

einen Trockentransformatorkern mit einer im Schenkelquerschnitt rechteckigen Umhausung, die den Eisenkern umschließt, und die eine Mehrzahl von Befestigungsvorrichtungen aufweist.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

a dry-transformer core with a rounded enclosure surrounding the iron core,

FIG. 2

a dry-transforming core having a rounded enclosure surrounding the iron core and having a plurality of fastening devices, and

FIG. 3

a dry-transformer core having a leg-shaped rectangular enclosure surrounding the iron core and having a plurality of fastening devices.

Identical parts are provided with the same reference numerals in all figures.

All the figures described below show dry-transformer cores 1, which are designed for cast-resin transformers with a rated voltage of more than 1 kV and / or a rated power of more than 50 kVA and therefore have a corresponding size. They are particularly suitable as power transformers in electrical energy networks. In the following, the similarities of the three figures will first be described.

The illustrated dry-transformer cores 1 have an iron core 2 which is layered out of electric sheets. In other exemplary embodiments, the core is made up of amorphous foils. He is shown in dashed lines in all figures, since he is located within the housing 4. The electrical steel sheets have a height decreasing in height and width to the edge of the iron core 2, so that result in the stacked in the electric sheets by the smaller dimension in each layer stages 6. As a result, a slightly rounded shape of the iron core 2 is achieved. In other, not shown embodiments, it may also be economical, for. B. amorphous sheets have a rectangular core cross-section without rounding of the edges.

Basically, a distinction is made in transformers between sheath transformers and core transformers, or the terms in English "shell type" and "core type". In both types, the windings comprise a common iron core 2. Are winding and iron core 2 enclosed by outer iron paths or is most of the conductive windings, e.g. B. may consist of copper or aluminum, from Iron enclosed, one speaks of shell transformers. However, the dry-transformer cores 1 shown in the figures are designed for core transformers.

Here, the leg 8 to be wound (also main leg) are connected at their ends by yokes 10 with each other. The design of transformer cores is specified in a coding consisting of two numbers. The first number describes the number of wound legs 8, the second the number of return legs (this is understood to mean outer unwound legs in the shell transformer).

Each figure shows a 3/0-Trockentransformern core 1, d. H. a three-legged dry-transforming core 1 without a yoke leg, whose three legs 8 are provided for a winding. However, the embodiments are only an example, the enclosure shown here with all the described properties can also be produced for any other configurations.

The housing 4 is made in all figures of a non-magnetic material, d. H. a material having a permeability number in the range of -1.01 to 1.01. For this purpose, in embodiments a plastic or in other embodiments, chromium-nickel steel can be used.

In the figures, the housing 4 is in each case integrally formed integrally with the iron core 2, that is to say it is designed such that it holds together the iron sheets of the iron core 2 in a form-fitting manner. It encloses the iron core 2 completely, so encapsulates it. The enclosure 4 in this case each has a wall thickness of less than 1 cm, ie a few mm. Between the iron core 2 and enclosure 4 remaining void is filled with a suitable material. The housing 4 is in each case made of several parts: First, a first part 12 is provided, which surrounds the upper yoke 10 and a second part 14, which surrounds the legs 8 and the lower yoke 10.

Both parts 12, 14 are in turn constructed in two parts as half-shells, so that in the manufacturing process, the iron core 2 can be inserted into the first half-shell and then connected the second half-shell for stabilization with the first half-shell.

The differences of the exemplary embodiments in the various figures are explained below.

FIG. 1 shows a dry transformer core 1 with a housing 4 with a round cross-section over the yokes 10 and legs 8. It follows the outer contour of the iron core. 2

FIG. 2 shows a dry-transformer core 1 with a housing 4 also round in cross-section over the yokes 10 and legs 8, which is shaped as well as the enclosure in FIG 4. However, it additionally has fastening devices 16, 18 in the manner of externally attached to the housing 4 eyelets on. There are fastening devices 16 for fixing the dry transformer core 1 when installing the transformer z. B. provided on carriers 20. Further fastening devices 18 serve to fix the windings, not shown.

In contrast to the FIG. 1 and FIG. 3 is the housing 4 in the FIG. 2 made of an electrically conductive material, for. As the already mentioned chromium-nickel steel. Here, the housing 4 is initially grounded. Furthermore, it includes two in FIG. 2 shown insulating parts 22 which are formed so that no closed conductor loop can form around the iron core 2. In the embodiment of FIG. 2 The sides of the insulating parts 22 each form a rectangle whose sides run parallel to the axis of the respective leg 8 or yoke 10 on the inside, ie the surface of the wall 4 facing the adjacent leg 8 or yoke 10 and form a closed line here. The insulating members 22 here interrupt the otherwise conductive body of the enclosure 4. Through the sides of the insulating parts 22 is a current flow avoided in the transformation 4 around the legs 10 and yokes 8 around.

FIG. 3 shows a dry-transforming core 1, the housing 4, the same fastening devices 16, 18 as that of the FIG. 2 having. However, the cross section of the enclosure 4 is rectangular over the yokes 10 and legs 8.

Claims (15)

A dry-transforming core (1) comprising an iron core (2) having a number of wrapping legs (8) interconnected by a number of yokes (10), said dry-transforming core (1) integrally formed with said iron core (2) Enclosure (4), which encloses the iron core (2) substantially flush. Dry transformer core (1) according to claim 1, wherein the enclosure (4) is non-magnetic. Dry transformer core (1) according to one of the preceding claims, in which the enclosure (4) has an average permeability of between -1.01 and 1.01, preferably between -1.001 and 1.001. Dry transformer core (1) according to one of the preceding claims, in which the wall thickness of the enclosure (4) is less than 1 cm. Dry transformer core (1) according to one of the preceding claims, in which the enclosure (4) is predominantly made of a plastic material. Dry transformer core (1) according to one of Claims 1 to 4, in which the enclosure (4) is predominantly made of steel. Dry transformer core (1) according to one of the preceding claims, in which the enclosure (4) is earthed. Dry transformer core (1) according to one of the preceding claims, wherein the housing (4) is designed in several parts, wherein one of the parts (14) substantially encloses one of the yokes (10). Dry transformer core (1) according to one of the preceding claims, in which the enclosure (4) has on its outside a number of fastening devices (16, 18). Dry transformer core (1) according to one of the preceding claims, in which the iron core (2) consists of amorphous foils. Dry transformer core (1) according to one of the preceding claims, in which a gap remaining between iron core (2) and housing (4) is filled. Dry transformer core (1) according to one of the preceding claims, wherein the housing (4) comprises an insulating part, which is designed such that no closed conductor loop is formed around the iron core (2). A dry type transformer comprising a dry transformer core (1) according to any one of the preceding claims and a number of coils wound around the leg (8) enclosed by the enclosure (4). Dry transformer according to claim 13, designed for a rated voltage of more than 1 kV and / or a rated power of more than 50 kVA. Dry transformer according to claim 13 or 14, which is designed as a cast resin transformer.

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