EP2869313B1 - Dry transformer coil and dry transformer - Google Patents

Description

The invention relates to a dry-type transformer coil comprising a hollow-cylindrical coil with at least one radially inner and one radially outer winding. The invention also relates to a dry type transformer comprising a transformer core having at least two core legs.

It is generally known that dry-type transformers, for example in the rated voltage range of 6 kV, 10 kV, 20 kV, 30 kV, do without a special insulation medium such as oil. As a result, their construction can be simplified on the one hand in an advantageous manner. On the other hand, the use of air as an insulating medium due to their limited isolation ability increased insulation distances to live components. In addition, appropriate coolant for removing the heat loss occurring during operation of the dry transformer are provided, for example, axially extending cooling channels, which are usually arranged between radially adjacent winding segments.

An inherent protection against contact of a dry transformer, such as in the arrangement of a transformer in an oil-filled boiler, is not given. A disadvantage here proves that this leads to a threat to the operating and maintenance personnel, because live components could be touched accidentally due to negligence. Although a known arrangement of a transformer in a grounded housing on the one hand effective contact protection, but on the other hand leads to a disadvantageously increased size of the transformer housing, because of course, all the required dielectric distances between the live components of the transformer and the grounded housing must be adhered to. The patent document WO 2009/126977 discloses an electrostatic shield for an HVDC air choke, characterized by a jacket provided at at least one end with a substantially circumferential electrode collector electrode for connection to one of the terminals of the HVDC air choke, the jacket being electrostatically formed from a foil dissipative material is made.

Based on this prior art, it is an object of the invention to provide a dry-type transformer coil and a dry-type transformer with improved contact protection.

This object is achieved by a dry-type transformer according to claim 1. The basic idea of the invention is to realize the contact protection of a dry-type transformer coil in that its outer surface is provided with a barrier structure at least on the manually achievable surface areas, which is designed such that the stress load occurring during operation is maintained. Thus, it is possible to provide the radially outermost barriers wall with a grounded electrically conductive screen that can be safely touched by a person also at ground potential person. The structure of the barrier structure of insulating strips and protective wall carried therefrom is the structure of a typically between radially adjacent winding segments of a dry-type transformer coil arranged cooling channel similar and thus particularly easy to integrate into the radial outer surface of the dry-transformer coil.

As strip material, for example, glass fiber reinforced strips of a composite material are suitable, which are ideally arranged along the axial extent of the coil on the radially outer surface. The thereby radially supported barrier wall can, for example, shell-like segments a cylinder made of an insulating material, this simplifies the production in a special way. However, it is also optionally provided according to the invention, at least partially produce the radially supported barrier wall of a wound strip material such as a resin impregnated fiber roving or to fix the optionally present shell-like segments radially outward therewith. Such resin-impregnated fiber rovings, which are also known under the name "prepreg" in a dry intermediate state of the resin, are heated to a polymerization temperature after the actual winding process and form a mechanically very strong structure during the cooling process. Typically, axially extending channel-like cavities are formed by the barrier structure, which can be used in an advantageous manner as cooling channels.

According to a further embodiment of the dry-type transformer coil according to the invention, the electric screen is designed as a metallic shield or as a metallization. In the case of a metallic shield, for example, the radial outer surface or inner surface of the barrier structure is provided with a conductive sheet or a conductive foil, but it is also possible in principle to wrap such a metallic shield directly into the radially supported barrier wall, for example when using fiber rovings. This advantageously increases the mechanical stability of the dry-type transformer coil according to the invention.

In the case of a metallization, a metal layer is applied to the actually electrically insulating radially supported barrier wall, for example by vapor deposition or else the application of a metallically conductive lacquer material.

Following a further variant of the dry-type transformer coil according to the invention, at least parts of the barrier structure project beyond the axial ends of the hollow-cylindrical coil. As a result, an additional protection against contact of the dry transformer coil is achieved in their forehead areas in an advantageous manner.

According to a preferred variant of the invention, the barrier structure encloses the coil in its entirety. As a result, the touching of the entire radial outer surface of the dry transformer coil allows safe. This is especially true of Advantage, if there is no built-around the coil structure of a transformer, which is a contact protection for a portion of the coil surface.

According to a further variant of the dry-type transformer coil according to the invention, the terminals of the radially outer winding are guided on the face side out of the coil. As a result, the integrity of the electrical screen is not endangered. Even when using a housing, the dry-type transformer can be made smaller due to the barrier structure according to the invention than without barrier structure according to the invention, because then significantly fewer areas with critical potential differences are present within the housing. Thus, for example, the wall of a housing without additional isolation distance can be built up directly to the radial outer surface of a respective dry-type transformer coil.

In the event that the dry-type transformer has mechanical components which are earthed and which also constitute a mechanical contact protection for the surface regions of a respective dry-type transformer coil, a corresponding barrier structure can in principle also be dispensed with in these surface regions.

This is the case for partial regions of mutually facing coil surfaces adjacent arranged dry-type transformer coils. Here, at least accidental contact is excluded, because these areas are reset to the enveloping the dry transformer envelope inwards are. It is therefore provided that the electrical screens of at least two adjacent dry-transformer coils are not completely executed in partial regions of coil surfaces facing one another.

According to a particularly preferred embodiment of the dry-type transformer according to the invention, the electrical screens are designed and electrically connected to one another in such a way that the at least two adjacent dry-type transformer coils are enveloped by the connected screen. As a result, all manually reachable areas of the coil surfaces can be touched without risk.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Fig. 1

eine exemplarische Trockentransformatorspule,

Fig. 2

einen ersten exemplarischen Trockentransformator sowie

Fig. 3

einen zweiten exemplarischen Trockentransformator.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail. Show it:

Fig. 1

an exemplary dry-type transformer coil,

Fig. 2

a first exemplary dry-type transformer as well

Fig. 3

a second exemplary dry-type transformer.

Fig. 1 shows an exemplary inventive dry-type transformer coil 10 in a plan view. The dry-transformer coil 10 comprises a hollow-cylindrical radially inner winding 12 and an adjoining radially outer winding 14, which are nested one inside the other. A barrier structure is arranged completely around the radially outer surface of the coil formed by the windings 12, 14. The barrier structure has a plurality of star-like around the central axis of the coil and along its axial extent extending strips 16, through which a ring-like arranged around this barrier wall 18 is radially supported. The axial length of the barrier wall 18 slightly exceeds the axial length the coil, in order to increase the frontal protection against contact. Directly on the radial outer surface of the barrier wall 18, an electrical shield 20 is metallized, which is connected to ground potential 24. In this way, a safe contact with the radial outer surface of the dry-transformer coil is also made possible during its operation. The hollow cylindrical dry-type transformer coil is arranged around a core leg 26 of a transformer core.

Fig. 2 shows a first exemplary dry-type transformer 30 in a sectional view. To three parallel arranged in a common plane core leg of a three-limbed transformer core each have a dry-type transformer coil 32, 34, 36 is arranged. Each dry-transformer coil 32, 34, 36 has a barrier structure with an electric screen, which is not completely formed around the respective dry-transformer coil, but is interrupted in partial regions of mutually facing coil surfaces of adjacent dry-type transformer coils. The electrical shields respectively integrated in the barrier structures are mechanically and electrically connected together to form a grounded shield 44, which surrounds the three dry transformer coils 32, 34, 36 and ensures safe contact with the accessible surface areas of the dry transformer coils 32, 34, 36 is.

Fig. 3 shows a second exemplary dry-type transformer 50 in a sectional view. This corresponds essentially to that in the FIG. 2 Dry transformer 30 shown around three parallel in a common plane core leg of a three-leg transformer core, a respective dry-type transformer coil 52, 54, 56 is arranged. Each dry-transformer coil 52, 54, 56 has a separately grounded 64 electric screen 58, 60, 62, which is not fully pronounced around the respective dry-transformer coil, but is interrupted in some areas. Since the electrical screens are not mechanically connected to each other, theoretically contacting of mutually facing coil surfaces of adjacent dry-transformer coils 52, 54, 56 is possible, but unintentional contact is precluded due to the difficult accessibility of the respective surface areas.

LIST OF REFERENCE NUMBERS

10

exemplary dry-type transformer coil

12

radially inner winding

14

radially outer winding

16

Afford

18

radially supported barrier wall

20

electric screen

22

channel-like cavity

24

ground

26

core leg

30

first exemplary dry-type transformer

32

first coil of first dry-type transformer

34

second coil of the first dry-type transformer

36

third coil of first dry-type transformer

38

first portion of mutually facing coil surfaces

40

second subregion of mutually facing coil surfaces

42

sheath-like connected umbrellas

44

ground

50

second exemplary dry-type transformer

52

first coil of second dry-type transformer

54

second coil of second dry-type transformer

56

third coil of second dry-type transformer

58

Screen of first coil

60

Screen from second spool

62

Screen from third coil

64

ground

Claims (5)

1. Dry-type transformer comprising a transformer core having at least two core limbs, wherein a respective dry-type transformer coil (10, 32, 34, 36, 52, 54, 56), comprising a hollow-cylindrical coil with at least one radially inner winding (12) and one radially outer winding (14), is arranged around at least two core limbs (26), wherein the radially outer surface of the dry-type transformer coil (10, 32, 34, 36, 52, 54, 56) is provided with a barrier structure which is at least partially circumferential, extends at least over the axial length of the said dry-type transformer coil, has at least one layer of strips (16) which are composed of an insulating material, and has at least one barrier wall (18) which is radially supported by the said strips, wherein the radially outermost barrier wall (18) has an electrical screen (20, 42, 58, 60, 62) which is connected to earth potential (24, 44, 64),
   characterized
   in that the electrical screens (20, 42, 58, 60, 62) of at least two adjacent dry-type transformer coils (10, 32, 34, 36, 52, 54, 56) are not embodied fully in the regions of coil surfaces (38, 40), which face one another, over the entire axial extent of the said regions, and in that the electrical screens (20, 42, 58, 60, 62) are designed and electrically connected to one another in such a way that the at least two adjacent dry-type transformer coils (10, 32, 34, 36, 52, 54, 56) are surrounded by the connected screen (42) in the manner of a casing, so that protection against contact with the radial outer surfaces of the dry-type transformer coils (10, 32, 34, 36, 52, 54, 56) is achieved.
2. Dry-type transformer according to Claim 1, characterized in that the electrical screen (20, 42, 58, 60, 62) is embodied as a metal screen or as a metallization.
3. Dry-type transformer according to either of Claims 1 and 2, characterized in that at least parts of the barrier structure protrude beyond the axial ends of the hollow-cylindrical coil.
4. Dry-type transformer according to one of the preceding claims, characterized in that the barrier structure fully surrounds the coil.
5. Dry-type transformer according to one of the preceding claims, characterized in that the connections of the radially outer winding (14) are passed out of the coil at the end side.

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