EP2406799B1 - Winding arrangement for a transformer or for a choke - Google Patents

Description

Technical area

The invention relates to a winding arrangement for a transformer or a choke, with an annular winding cover, which is arranged on a front side winding, wherein one of the winding facing side surface of the winding cover part covers an end face of the winding.

State of the art

In transformers or chokes high power rating, the electrical windings are usually arranged concentrically around a leg of a soft magnetic core and are usually permanently clamped by a press construction. Part of this press design are so-called pressure or compression rings, with which the axial pressing force is divided as evenly as possible on the individual windings. The pressing rings are usually arranged between the end face of the windings and the yoke transverse to the leg.

Such a press ring for a power transformer is for example from the US 3,750,070 known. This press ring has a body part, which has the shape of a Circular disk has. The two faces of the disc are flat. The circular disk is in each case with the interposition of an insulating material with a side surface on the end faces of the windings. Radial grooves formed in the body part are filled with sheet metal laminates in order to conduct the stray magnetic flux back into the transformer core with as little loss as possible.

Also from the US 3,366,907 is a similar press ring out, which consists of a metal wrap.

It is known that when operating a transformer or a throttle noises occur that are undesirable for operation. It is endeavored to guide the magnetic flux so that the magnetostriction and the forces acting on the conductors of the winding during operation are as small as possible.

The operating behavior of a transformer or a choke can also be affected by peak values of the electrical voltage. Particularly endangered conductors of the winding are at risk. If, in the region of the end face of a winding, the electric field strength exceeds a critical value, a flashover between the winding and the yoke may occur. This can destroy the insulation of the winding.

To protect the insulation of a winding in a transformer from critical field strengths, the DE 35 34 843 A1 a shield ring, which is arranged on the front side of the winding. A special protective effect can be achieved if the shield ring is galvanically connected to the respective edge conductor of the winding. Of the Umbrella ring is curved at a side facing away from the winding side surface, so that critical values of the electric field strength are avoided as possible. In contrast to the pressing rings mentioned above, which have no electrostatic protective effect, this shield ring comes exclusively to an electrical protective function. An umbrella ring represents a separate component and thus means an additional effort in the production.

The US 3,983,523 A. discloses a winding assembly according to the preamble of claim 1.

The invention is based on the object of specifying a winding arrangement for a transformer or for a choke in such a way that the operating behavior is improved in the simplest possible way and the winding is well protected electrostatically.

This object is achieved by a winding arrangement with the features of claim 1. Advantageous embodiments of the invention are defined in the dependent claims.

• Zum einen wird durch die magnetisch leitfähige Ausbildung des Wicklungs-Abdeckteils erreicht, dass das magnetische Feld in Stirnbereich der Wicklung in eine axiale Richtung des Schenkelkerns gelenkt wird. Im Bereich der Stirnseite der Wicklung ist damit die radiale Komponente der magnetischen Feldstärke geringer. Die Rotationssymmetrie der Flussführung ist besser. Bei Betrieb eines Transformators oder einer Drossel kann dadurch die auf die Leiter wirkende Kraft, sowie Wirbelstromverluste in den Wicklungen und im Eisenpaket,
• niedrig gehalten werden. Dadurch treten weniger Geräusche und geringere Verluste auf. Eine geringe Geräuschemission ist insbesondere dann von Vorteil, wenn der
• Leistungstransformator oder die Drossel in der Nähe eines Wohnbereichs installiert ist. Da die Verlustverteilung in der Wicklung homogener wird, ergeben sich Vorteile in der thermischen Auslegung. Von großem Vorteil ist ferner, dass im Falle eines Kurzschlusses auf die elektrischen Wicklungen geringere axiale Kräfte wirken.

The winding arrangement according to the invention has, on each end face of a winding, an annular winding cover part which is magnetically conductive at least in a partial region and has a convex side face facing away from the winding. These two design features, the magnetic conductivity and the curved side surface, contribute to a reduction of noise and an electrostatic protective effect:

• On the one hand, it is achieved by the magnetically conductive formation of the winding cover part that the magnetic field in the end region of the winding is directed in an axial direction of the leg core. In the region of the end face of the winding so that the radial component of the magnetic field strength is lower. The rotational symmetry of the flux guidance is better. When operating a transformer or a choke thereby the force acting on the conductors, as well as eddy current losses in the windings and in the iron package,
• kept low. This results in less noise and lower losses. A low noise emission is particularly advantageous if the
• Power transformer or the choke is installed near a living area. As the loss distribution in the winding becomes more homogeneous, there are advantages in the thermal design. It is also of great advantage that lower axial forces act on the electrical windings in the event of a short circuit.

At the same time, an electrostatic shield is easily produced by the convexity of the yoke side surface of the annular winding cover member. In the front area of the electrical winding, the equipotential surfaces are no longer close together, but farther away. The change in the electrical potential and thus the electric field strength is lower. The front edges of a winding are better protected against critical electric field strengths, since the gentle curvature of the side surface mitigates the problem of the so-called "peak effect". As a result, the risk of a rollover between Winding and magnetic core lower compared to an unshielded winding.

A particularly simple construction can for example be given by the fact that the annular winding cover member is made entirely of a flat or radially stacked laminated core or a coil of a ferromagnetic material or a combination thereof. The lying away from the winding side surface of the laminated core or the angle is convex. Thus, the winding cover member functions as a magnetic flux guide member and as an electrical shield. Advantageously, in the manufacture of sheets can be used, as they are used in the production of the core of the transformer or the throttle anyway. For handling, it may be favorable if the individual lamellae of the toroidal laminated core are held together by an adhesive.

An embodiment may be constructed in that the winding cover part has a body formed of an insulating material in which one or more laminated cores are inserted or embedded. The body part may have the shape of a Torusabschnitts whose outer surface is covered by an electric screen. The capacitive coupling between the screen and the edge conductors of the winding causes an electrostatic shielding effect. For the body part commonly used insulation material, such as pressboard and wood can be used. A particularly good shielding effect can be achieved by the laminated core or the screen, by means of a per se known electrical contact device with a Edge conductor of the winding is electrically connected. This allows a very effective electrostatic shielding and at the same time a favorable influence on the magnetic flux can be achieved.

It may be advantageous if the laminated core embedded in the body part of the winding cover part is composed of several layers. These layers can be arranged one above the other in stages. The individual layers are designed according to shape and material properties so that the radial component of the magnetic flux density in the forehead area is reduced as much as possible. As a result, caused by magnetostriction vibration excitation and as a result of the radiated sound power is lower. In addition, the eddy current losses in the magnetic core are lower. In the event of a short circuit, smaller short-circuit forces act on the conductors of the windings.

The electric screen can be produced in a simple manner by a banding of the body part with an electrically conductive strip material or with a wire mesh or a wire spun.

But it is also conceivable that the electrical screen is produced by the surface of the body part is coated electrically conductive, for example by applying a conductive powder.

In order to make the winding cover part magnetically conductive at least in a partial region, it is also possible to use soft-magnetic mold sintered parts as an alternative to the laminated core. It may consist of the entire winding cover part of a single permeable solid body or Be composed of sintered parts. The soft magnetic solid body or the sintered parts may also be inserted or embedded in an insulating body part.

For the electrostatic shielding effect, it may be favorable if the mold sintered part has the shape of a torus section and is pulled down like a bead on the side lying to the winding. In this case, it may be favorable to design the lateral surface lying to the winding with the convex side surface continuously in one another. Since there are no sharp edges, the peak effect of the electric field strength is reduced. The risk of electrical flashover between the winding and the yoke is thereby reduced.

For the production of the body part of the winding cover part, a polymeric material can be used in addition to the already mentioned insulating materials. An education in plastic, for example, has the advantage that due to the elastic property of the (injection) casting material, the vibration propagation is attenuated.

In a preferred embodiment it can be provided that an insulating layer is arranged between the end face of the winding and the opposite side face of the winding cover part.

Also preferred is an embodiment of the invention in which the winding consists of a plurality of part windings arranged concentrically about a leg axis and each end face of these hollow cylindrical winding parts is each covered separately by a winding cover part. Everyone is Winding part to the adjacent yoke part electrostatically well shielded.

In a preferred construction, the winding cover members are incorporated in a power flow effected by a support and tensioning device, the support and tensioning device being supported on an upper and / or a lower yoke portion of the transformer or choke.

In this case, it may be favorable if the convex side surface has a flattening in a middle region. As a result, the press force is transferred to a correspondingly large circular ring.

It is expedient if a sheet material is used in the production of the laminated core or the toroidal core, as it is also used in the production of the yoke or the legs of the transformer or the throttle.

Brief description of the drawings

Figur 1

einen Leistungstransformator in einer Ansicht von oben in Richtung der Schenkelachse gesehen mit einer erfindungsgemäßen Wicklungsanordnung;

Figur 2

eine Schnittzeichnung gemäß der Linie A-A der Figur 1;

Figur 3

eine vergrößerte Darstellung des Detail X in Figur 2, in welcher der Verlauf der magnetischen Feldlinien im Bereich der Stirnflächen der Transformator-Wicklungen dargestellt ist, wobei erfindungsgemäße Wicklungs-Abdeckelemente vorhanden sind;

Figur 4

eine Darstellung des Feldverlaufs wie in Figur 3, jedoch ohne die erfindungsgemäßen Wicklungs-Abdeckteile;

Figur 5

ein Wicklungs-Abdeckteil, das aus Blechlammellen eines ferromagnetischen Material hergestellt ist, in einer vergrößerten Querschnittsdarstellung;

Figur 6

ein Wicklungs-Abdeckteil, wobei der magnetisch leitfähige Teilbereich durch Einbettung von Blechpaketen in dem Körperteil gebildet ist, in einer vergrößerten Querschnittsdarstellung;

Figur 7

ein Wicklungs-Abdeckteil, wobei der magnetisch leitfähige Teilbereich ein Formsinterteil ist, in einer vergrößerten Querschnittsdarstellung;

Figur 8

ein Wicklungs-Abdeckteil gemäß der Figur 7, bei dem ein Randbereich des Körperteils wulstförmig beidseits der Wicklung heruntergezogen ist.

To further explain the invention, reference is made in the following part of the description to the drawings, in which further advantageous embodiments, details and further developments of the invention can be found.
It shows:

FIG. 1

a power transformer in a view from above in the direction of the leg axis seen with a winding arrangement according to the invention;

FIG. 2

a sectional drawing along the line AA the FIG. 1 ;

FIG. 3

an enlarged view of detail X in FIG. 2 in which the course of the magnetic field lines in the region of the end faces of the transformer windings is shown, wherein winding cover elements according to the invention are present;

FIG. 4

a representation of the field course as in FIG. 3 but without the winding cover parts according to the invention;

FIG. 5

a winding cover member made of sheet metal laminates of a ferromagnetic material in an enlarged cross-sectional view;

FIG. 6

a winding cover member, wherein the magnetically conductive portion is formed by embedding laminations in the body member, in an enlarged cross-sectional view;

FIG. 7

a winding cover member, wherein the magnetically conductive portion is a mold sintered portion, in an enlarged cross-sectional view;

FIG. 8

a winding cover member according to the FIG. 7 in which an edge region of the body part is pulled down like a bead on both sides of the winding.

Embodiment of the invention

The FIG. 1 shows a transformer 1 in the region of a transformer leg 2, which carries a multi-part winding 5. The individual parts of the winding 5 are arranged concentrically around a leg axis 4. A supporting and tensioning device 8 formed of insulating material (pressboard) presses on a pressing ring 7. The supporting and tensioning device 8 is supported on yoke-pressing plates 9. The transformer leg 2 consists of highly permeable electrical sheet.

The drawing of the FIG. 2 shows a sectional view along the line AA FIG. 1 , The support and clamping device 8 presses the individual windings 5 in the axial direction (direction of the leg axis 4) together. In the power flow lie the winding cover 6, which are each arranged on the end faces of the winding parts 5. As explained in more detail below with reference to exemplary embodiments, the winding cover parts 6 on the one hand cause a steering of the magnetic flux in the front region of the winding 5, on the other hand they constitute a barrier for an electrical flashover between the winding and the yoke. The winding cover parts 6 will be described hereinafter because of their magnetic conductivity also referred to as permeable rings. The contact pressure generated by the support and tensioning device 8 is transmitted in each case via a press ring 7 and by means of non-illustrated power transmission elements 14 on the permeable rings 6. Each of these permeable rings 6 in each case covers an end face 10 of a winding 5.

The FIG. 3 shows in an enlarged view the detail X of FIG. 2 , As I said, that causes magnetic conductive formation of the winding cover 6, that the magnetic field lines 3 are directed in the direction parallel to the leg axis 4. This distraction becomes clear when looking at the magnetic field lines 3 in FIG. 3 with those in the FIG. 4 compares where also the field image is shown in the area of the end faces, in contrast to FIG. 3 but in FIG. 4 no permeable rings are present (prior art).

As a result, this comparison of FIG. 3 with the FIG. 4 clearly that the radial component of the magnetic field strength in the region of the end faces can be reduced by the winding arrangement according to the invention, in which the end faces of the windings 5 are covered with magnetically conductive rings 6. A smaller radial component improves the rotational symmetry of the flux with respect to the leg axis 4. The scattering losses are thereby reduced. The force acting on each conductor of the winding 5 respectively axial force 12 is lower thanks to the invention (the size of the axial force is in FIG. 3 and in FIG. 4 each represented by an arrow). The lower force on the conductors improves the load noise emission. In the case of an electrical short circuit, the mechanical load on the winding is also lower.

In the drawing of the FIG. 5 is a winding cover 6 enlarged in a cross-sectional view drawn. Shown is the front end of a winding 5. The winding cover 6 has the shape of a Torusabschnitts. This curved ring lies with a lying to the winding 5 flat side or annular surface 22 with the interposition of a Insulation layer 26 on the end face 10 of the winding 5. The end face 10 is thereby completely covered. The annular surface 23 facing away from the end face 10 is convexly curved in cross-section and provided with a flat 29 in a central region. The permeable ring 6 is formed here by a laminated core 25. The individual laminations of the laminated core 25 are aligned in the direction of the leg axis 4 and held together by an adhesive. An electrical contact device 27 contacts the laminated core 25 with an edge conductor 19 of the winding 5.

The FIG. 6 In contrast, shows an embodiment of the invention, in which body 24 of the winding cover 6 consists of an electrical insulator (pressboard), in which a of a plurality of layers 15, 16, 17, 18 existing laminated core 25 is embedded. The laminated core 25 forms within the body part 24, the magnetically conductive portion 21. The body part 24 has the shape of a Torusabschnitts also in this embodiment of the invention. The lateral surface of the Torusabschnitts is surrounded by an electric screen 13. The screen 13 consists of a Umbandelung with an electrically conductive sheet material, but may also be a wire spun or a coating. The screen 13 encloses here the entire surface of the body part 24 and forms an equipotential surface. The ring curvature 11 is dimensioned so that the electric field strength is minimized. As a result, the winding 5 is well protected against electrical flashovers on the front side. The individual layers, 15, 16, 17, 18 are formed by laminated cores and toroidal cores, which are each made of a ferromagnetic material and are arranged stacked stacked. The envelope surface of the electric screen 13 is surrounded by an electrical insulation 20. The convex side surface 23 points in the direction of the magnetic yoke, which is not shown here. The side surface 22 facing the winding 5 rests on the end face 10 of the winding 5.

The FIG. 7 shows another exemplary arrangement in which the permeable ring 6 is formed from a mold sintered part 28. The mold sintered part 28 again has the shape of a ring arched towards the yoke. The molding sintered part 28 is surrounded by a screen 13. The screen 13 is electrically connected to an electrical contact device 27 with a lying at the winding edge conductor 19 of the winding 5. Again, an insulating layer 26 is disposed between the side surface 22 and the end face 10.

The FIG. 8 shows one opposite FIG. 7 slightly modified exemplary arrangement. Here, the side surface 22 of the winding cover part 6 lying to the winding 5 is wider. The bead-shaped edge of the mold sintered part 28 is pulled down slightly to the left and right on the winding 5. Between the mold sintered part 28 and the end face 10 of the winding 5 there is an insulation layer 26. The convex side surface 23 merges continuously into the side surface 22. There are therefore no sharp edges. The convex side surface 23 is provided in the region of the curvature 11 with an electric screen 13, which is produced by surface coating. The electrical potential of the screen 13 is again by means of the contact device 27 on the potential of the edge conductor 19 of the winding 5. The convex curvature of the curvature 11 is in each case formed so that the critical field strength for a electric flashover between winding and yoke is not reached during operation.

Compilation of the reference numbers used

1

transformer

2

transformer leg

3

yoke

4

leg axis

5

winding

6

Winding cover

7

pressure ring

8th

Supporting and clamping device

9

Yoke-press plates

10

face

11

bulge

12

axial force

13

umbrella

14

Power transmission elements

15

Permeable position

16

Permeable position

17

Permeable position

18

Permeable position

19

Rand Director

20

isolation

21

subregion

22

Side surface, ring surface

23

convex side surface, ring surface

24

body part

25

laminated core

26

insulation layer

27

contact device

28

Inter form part

29

flattening

Claims (12)

1. Winding arrangement for a transformer or for a reactor, having an annular winding cover part (6) disposed on the end face of a winding (5), wherein a side surface (22) of the winding cover part (6) facing the winding (5) overlaps an end face (10) of the winding (5), wherein the annular winding cover part (6) comprises a body part (24), in which a magnetically conductive partial area (21), formed from at least one laminated core (25) or at least one permeable moulded sintered part (28), is disposed and wherein the body part (24) comprises a convex side surface (23) facing away from the winding (5), and is surrounded by an electrical shield (13), characterised in that the magnetically conductive partial area (21) is embedded in the body part (24).
2. Winding arrangement according to claim 1, characterised in that the at least one laminated core (25) or the shield (13) is connected by means of an electrical contact device (27) to an edge conductor of the electrical winding (4).
3. Winding arrangement according to claim 1, characterised in that the at least one laminated core (25) is composed of layers (15, 16, 17, 18) located one above the other in a staggered manner.
4. Winding arrangement according to one of claims 1 to 3, characterised in that the electrical shield (13) is produced by wrapping the annular body part (24) in an electrically conductive strip or a wire mesh.
5. Winding arrangement according to claim 1 to 3, characterised in that the electrical shield (13) is formed by coating the surface of the body part (24).
6. Winding arrangement according to claim 1, characterised in that the at least one moulded sintered part (28) has the form of a torus section, in that the side surface (22) of the winding cover part (6) facing the winding (5) projects beyond the end face (10) of the winding (5) and is constructed so as to continuously merge with the convex side surface (23).
7. Winding arrangement according to any one of claims 1 to 5, characterised in that the body part (24) is produced from a polymer material.
8. Winding arrangement according to any one of claims 1 to 7, characterised in that an insulating layer (26) is arranged between the end face (10) and the side surface (22).
9. Winding arrangement according to any one of claims 1 to 7, characterised in that the winding (5) is formed from winding parts which are concentrically arranged around a leg axis (4) and each end face (10) of a winding part is covered by an associated winding cover part (6) respectively.
10. Winding arrangement according to claim 9, characterised in that each winding cover part (6) is integrated in a magnetic flux, acting in the direction of the leg axis (4), which is induced by a supporting and tensioning device (8), which is supported on an upper and/or on a lower yoke (3) of the transformer or the reactor.
11. Winding arrangement according to claim 10, characterised in that each winding cover part (6) is provided with a flat portion (29) at the convex side surface (23).
12. Transformer or reactor with a winding arrangement according to claim 1, characterised in that the same ferromagnetic material is used for the at least one laminated core (25) as for the core of the transformer or reactor.

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