WO2014135205A1

WO2014135205A1 - Electrical transformer or choke and winding arrangement with spacer

Info

Publication number: WO2014135205A1
Application number: PCT/EP2013/054466
Authority: WO
Inventors: Markus Georg ORTNER; Friedrich Baumann; Robert Schwarz
Original assignee: Siemens Ag Österreich
Priority date: 2013-03-06
Filing date: 2013-03-06
Publication date: 2014-09-12

Abstract

The invention relates to an electrical transformer or choke comprising: a winding (1); an insulation-cooling medium (2) that surrounds the winding; and at and at least one spacer (3), each respective contact face (13) of which contacts a conductor (4, 5) or a machine part (19) in order to define a spacing. The spacer (3) has a transition region (11) located at a contact face (13) and formed as a fillet (7) with an edge (8) tapering to a point.

Description

description

Electric transformer or choke

Winding arrangement with spacers

Technical area

The invention relates to an electrical transformer or a reactor, with a winding, with an insulating cooling medium (eg transformer oil), which surrounds the winding, with at least one spacer, which is made of an electrical insulation material having side surfaces and opposing contact surfaces, to set a distance in an arrangement between adjacent conductors, or a conductor and a machine part.

The invention further relates to a winding arrangement for an electrical machine, in particular a

A power transformer or a choke, having a winding, with a Isoaltions cooling medium, which surrounds the winding, with at least one spacer made of an insulator having side surfaces and opposing abutment surfaces, to be arranged between adjacent

Ladders, or a ladder and a machine part, to specify a distance.

The present invention further relates to a

Spacer for a winding of an electrical machine, with a prismatic formed of an insulator

Body part having side surfaces and two opposing abutment surfaces, with which it rests in an arrangement between adjacent conductors or a conductor and a machine parts to thereby specify a defined distance. State of the art

Electric transformers or chokes, as in

Power distribution networks are used in a voltage range above 1000 V, may comprise windings, which are formed from a spirally wound electrical conductor. The axial distance between conductors can be specified by so-called spacers. A spacer may be a prismatic spacer made of an electrical insulator. A mechanical tensioning device compresses the winding arrangement in the axial direction, so that the spacers between the layers of the conductors are fixed by pressing. In

Circumferential spacers may also be present, which are arranged in a gap, so that for the purpose of cooling the cooling medium, e.g. Transformer oil, the

can flow around electrical conductor. The size of the distance depends, inter alia, on the insulation requirement, which also depends on whether the electrical conductors of the winding itself are insulated, e.g. with a strip of paper wrapped helically around the ladder. In order to specify a radial distance between conductors, can

Spacers come in the form of a bar used.

As insulation cooling medium transformer oil is usually used in a transformer or a choke. However, there are also electric machines using a gaseous isolation cooling medium, e.g. Own or

Foreign air cooled coil products in the high voltage range.

The material used for a spacer of an electrical winding usually has a permittivity that is different from the permittivity of the used isoaltion cooling medium. The consequence of this is that in the transition zone, that is, in the transition between side surfaces and contact surfaces of the spacer, due to the different dielectric constant of spacer material and insulating cooling medium (transformer oil), the electric field is not homogeneously distributed. In the page area can Peak values of the electric field strength occur, which can lead to a local overuse of the insulating cooling medium. This can lead to an electrical flashover.

To the inhomogeneity of the electric field strength in the

Side area of a transformer winding

used in the German patent application DE 24 01 237 opposite side surfaces of the spacer, which are wetted by transformer oil, are provided with recesses, wherein the conductor lying edges of the spacer are rounded (Figure 2 a) to Figure 2d) ). These curves, however, the goal of - to bring about a homogenization of the electric field - misses. In particular, an acute-angled cavity, a so-called "gusset", forms in each case in the transition region between the side surface and the contact surface through these curves, in this "gusset" the contact or insertion angle with which the transformer oil spacer and conductor are wetted is always less than 90 ° , An acute angle favors increased field strength values. Due to the convex shape in the area of the contact surface (rounding) of the spacer, a volume area with increased electrical stress of the insulating medium thus arises again.

Presentation of the invention

It is an object of the present invention to provide a

Indicate a transformer or a throttle, in which an improved dielectric strength is given.

It is a further object of the present invention to provide a winding arrangement with a winding which

also has an improved dielectric strength.

Another object of the invention is to provide a

To provide spacers for an electrical winding, so that when used in a winding with a liquid or gaseous isolation medium the dielectric strength can be improved.

This object is achieved with respect to a transformer or a choke with the features of claim 1, with respect to a winding assembly having the features of claim 11, and with respect to a spacer having the features of claim 21. According to one aspect of the invention is for a

Transformer or a throttle or for a winding arrangement of an electric machine

Spacer proposed in which the of a

Insulating cooling medium touched side surfaces are formed in the manner of a groove, so that in a transition region to a conductor or to a machine part a tapered, wedge-shaped foot part is formed. Compared to the prior art, in which spacers are always used which, viewed in cross-section, have a convex shape in the contact area, the invention is

Spacer there concave in cross section. This ensures that in the area of transition between

Side surface and contact surfaces of the spacer no unwanted gusset forms. As a result, the dielectric strength is better.

In the case of an electrical transformer or a choke, the winding is therefore provided with spacers which each have a transition region lying to a contact surface, which is formed as a groove with a tapered edge. In other words, according to the

Invention is the angle formed between the contact surface and side surface of the spacer not an acute angle, but an obtuse angle. In the following, this angle will be at the contact line between spacer and conductor

or machine part referred to as contact angle or as immersion angle. By making this angle dull, the side area is less

electric field strength. Is the contact angle sufficiently large, ie greater than 90 ° to a maximum of 180 °, dangerous peak values of the electric field strength can be largely avoided. The insulating property of a winding can be improved as a whole. The preparation of the spacer according to the invention is simple and requires no special manufacturing effort. When

Materials are basically all materials in question, which are used in transformer construction, e.g.

Cellulosic material such as pressboard or a plastic or other suitable material for electrical insulation.

To avoid local field concentrations, a design is favorable in which the contact angle is greater than 90 °. As already stated above, it is advantageous if the contact angle is not an acute angle, but an obtuse angle. By appropriate magnitude of this angle, the cause of partial electrical discharges, which may also feel electrical breakdown, is eliminated. Of particular advantage is the largest possible

Contact angle, in particular a contact angle of about 180 °. This allows a very uniform distribution of the electric field strength over the side surfaces of a

Reach spacers.

In a preferred embodiment it is provided that the shape of the recess is predetermined by a contour function, which is continuous in its derivative. Through this kink-free

Training the side surfaces will be the danger of that

Transformer oil is electrically overstressed, largely reduced.

But a substantially kink-free side surface can also be achieved in that at least in the transition region in each case opposite side surfaces by a

Contour function is given, which is formed by a polygon. In other words, a side surface can also be a composition of flat surface sections, provided that the number is big enough and not the field course

annoying kink arises.

The recess can be produced particularly easily if the contour function at least in one section

Circular arc has. This can be used with common

Tools are formed in a simple way, a kink-free side surface, which opens together with the investment / contact surface in a pointed foot part. In the area of the contact line the tangent goes in the

Contact surface without kink over.

To bridge a greater distance, it may be beneficial if several spacers each stacked with a concave cross-sectional profile. in the

Contact area between stacked

Spacer, no unwanted gusset forms (no lateral recesses). There are no recesses (gussets) in the side area of the stack. The electric

Field strength is widely distributed homogeneously. A

Overuse of the I solations cooling medium can thus be avoided. Another advantage is the fact that to overcome a greater distance prefabricated spacers (even different thickness) in one

Modular system can be used. A special preparation of a spacer is therefore not

required.

In a preferred embodiment, the spacer is in the form of a strip. Such a strip becomes radially in a winding during the winding production

installed, so that a defined axial distance between superposed conductors can be adjusted. An education of the spacer as a bar but is also advantageous if the radial distance between turns of a winding or between adjacent windings

should be set. In the latter case, the strip is installed in the axial direction in the manufacture of the electrical winding. With regard to the insulation material used is

Cellulose particularly suitable. The inventive

Spacer may e.g. be made of Transformerboard. Transformerboard can be resin impregnated. If particularly high insulation properties are required, can as a insulating material, a plastic, especially a

Polyamide be advantageous. The above statements regarding a transformer or throttle also apply mutatis mutandis to a winding arrangement of an electrical machine in general, which has a winding, provided that the permittivity of the spacers used is higher than the permittivity of the winding surrounding

Insulation cooling medium. The isolation cooling medium may also be gaseous.

With regard to a spacer is the beginning

This object is achieved in that the spacer has a lying to a contact surface transition region whose shape is formed as a groove, so seen in a cross section contact surface and side surface form a wedge with a sharp edge. A particularly preferred embodiment of the spacer is characterized in that the shape of the groove is formed by a recess on the side surfaces of a prismatic body, which by a curved

Contour function is given, the contour function is a continuous function. This ensures that the electric field strength does not change abruptly in the lateral area of a prismatic spacer.

Preferred is an embodiment of the spacer in the form of a bar, wherein the cross-sectional profile is concave. A bar can be equal to a coil

Setting a radial and axial distance use. As a preferred material for the strip cellulose, paper, Transformerboard or a plastic is used. With a particularly high dielectric strength, it may be advantageous if the spacer is made of a polyamide. In special applications, in particular a

Execution in aramid fiber, as known for example under the brands Kevlar® or Nomex®, preferred.

The spacer may preferably also in a

High voltage coil can be used, which is not surrounded by a liquid, but by a gaseous insulating cooling medium (air coil) are used.

Brief description of the drawing

To further explain the invention, reference is made in the following part of the description to drawings, from which further advantageous embodiments, details and developments of the invention can be found by way of non-limiting embodiments.

Show it:

Figure 1 shows a detail of an electrical winding in a three-dimensional view, wherein according to the invention, a spacer is used which has a concave cross-sectional profile;

Figure 2 is a cross-section through a spacer pressed between an upper and a lower conductor and having a concave cross-sectional profile;

3 shows a detail X of Figure 2 for a particular

preferred contact angle of 180 °;

FIG. 4 shows a detail X of FIG. 2 for a contact angle of 165 °; FIG. 5 shows a detail X of FIG. 2 for a contact angle of 150 °;

FIG. 6 shows a representation of the detail X, which is shown in FIG

Transition region shows the wedge-shaped foot of the spacer greatly enlarged;

Figure 7 shows another embodiment of the invention, in which a

Distance with several stacked on each other

Spacers is set, each having a concave cross-sectional profile, so that no gusset is formed between abutting contact surfaces; FIG. 8 shows a prismatic spacer in one

spatial representation, wherein on opposite side surfaces of the spacer recesses in the form of a groove are formed, whereby the cross-sectional profile is concave;

Figure 9 is a schematic representation which both the

Possible uses of an inventive

Spacer for adjusting a distance between adjacent conductors, as well as for adjusting a distance between a conductor and a machine part shows;

Figure 10 shows a known spacer, in which all four

Edges are rounded;

Figure 11 detail Y of Figure 10 with a contact angle of

0 °;

FIG. 12 shows detail Y of FIG. 10 with a contact angle of

15 °;

FIG. 13 shows detail Y of FIG. 10 with a contact angle of

30 °. Embodiment of the invention

FIG. 1 shows a section of an electrical winding 1 in a three-dimensional view. The individual conductors 4, 5 concentrically surround a shaft 17 around an axis 17

soft magnetic leg 16 of a transformer or a choke. The winding 1 may be of different design. The electrical conductors 4,5 can at a

Power transformer bare wires or insulated run. To the distance between two layers 14, 15 of the

to set annular conductor, are in Figure 1

Spacers 3, so-called spacers 3 of these spacers 3 are in Figure 1 representatively three extending in the radial direction strip-shaped

Spacer 3 drawn. Each of these strips 3 is between an upper winding layer 14 and a lower winding layer 15 in the axial direction by means of a

Clamping device (indicated in Figure 1 with the two opposing arrows 18) pressed. In Figure 1 indicates the

Arrow 2 to the flowing transformer oil 2, which flows around the entire winding 1 for the purpose of isolation and cooling. As can be clearly seen from FIG. 1, this is

Cross-sectional profile of the spacer 3 concave.

As already mentioned in the introduction, spacers are known in various designs. It is in the prior art so that in the area of the contact surface and the

Side surface of a spacer creates a so-called gusset in which the insulation cooling medium is electrically stressed. Spacers and insulation cooling medium usually have different electrical properties. Usually, transformer oil has a relevant frequency range (50 Hz or 60 Hz)

Dielectric constant or permittivity CR, which is lower than the permittivity of the material from the one

Spacer is made. It is also known that in the area of the contact surface with a sudden change in the Permittivity (dielectric constant), the normal component of the electric field strength leaps while its tangential component is steady. This means that the field image in the area of the transition zone between

Transformer oil and spacers is distorted. It occurs in the gusset locally an increase in the electric field strength. Particularly stressed is the insulation medium, which is located in the region of this gusset. This is where the invention intervenes. She hits you

Spacer ago, contrary to the prior art, not a convex, but a concave cross-sectional profile has (see Figure 1 and Figure 2). According to the invention, side surfaces of a spacer have recesses in the manner of a groove. This creates a wedge-shaped

Foot part, which counteracts a local field increase. There is no more dangerous gore. As a result, the transformer oil is electrically less stressed. The risk of electrical partial discharges, which may be the source of an electrical breakdown, can be greatly reduced by a concave cross-sectional profile.

The inventive design of the spacer 3 will be explained in more detail below.

FIG. 2 shows an embodiment of the invention

Spacer 3 in a cross section. The spacer 3 is pressed with its contact surfaces 13 between an upper conductor 4 and a lower conductor 5. The cross-sectional profile is concave, with opposite side surfaces 6, which are in contact with the transformer oil 2, with a

Recess in the form of a groove 7 are provided. These two recesses 7 are symmetrical on both sides. The

Contour function 10 of a side surfaces 6 sits in the

Cross-section seen together from a middle linear section to the top and bottom kink-free each followed by a circular arc 12. As can be easily seen from FIG. 2, each of the recesses 7 is designed such that in the area between the spacer 3 and the conductor there is a concave fillet, a groove, is formed, so that in each transition region 11 of spacer 3 and transformer oil left and right, a wedge-shaped foot part is formed, which tapers towards the edge 8 point. But it can also be provided with a groove in addition, the two end faces. Through the double wedge 11 along the longitudinal extent is achieved that in the lateral area of the plant no "gusset" can form, ie, that the endangered

Volume range (gusset) with excessive electrical

Field strength is virtually nonexistent. To illustrate this in more detail, a detail is marked in FIG. 2 with the reference symbol "X", which is shown enlarged in the following FIGS. 3, 4, 5 and will be explained in more detail below.

Figure 3 shows a particularly preferred embodiment of the

Foot part 11, in which the concave fillet seamlessly merges into the plane of the contact surface 13. At this

Embodiment is applied to the edge 8, opened to the transformer oil 2 contact angle 9 180 °. Further possible embodiments of the invention are shown in FIG. 4 with a contact angle 9 of 165 ° and in FIG. 5 with a contact angle of 150 °. FIG. 6 shows, in an even greater enlargement, the wedge-shaped foot part 11. The edge 8 is here expiring in a fibrous manner. This fibrous formation of the edge 8 is formed automatically in a machining production of

Spacer 3 and has a further advantageous

Effect, which is explained in more detail below. each

Side surface 6 is specified by a contour function 10. The contour function 10 is a curved function that is continuously differentiable, so it has no discontinuities. The side surface 6 merges seamlessly into the plane of the contact surface 13. Through this

geometric design of the side surface 6 of a

Spacer 3, the contact angle 9 is increased well beyond 90 °. As already stated, this has the consequence that the electrical stress of the transformer oil 3 in This transition zone is comparatively low. Another advantage is the fact that the foot part 11 resiliently yields during a mechanical pressure between two conductors. On the one hand, this means that an electrical conductor surrounded by insulation is less likely to be damaged by the pressing force. The elastic

Yield of the foot part 11 ensures that the

Spacer 3 is not pressed into the insulation of the conductor. On the other hand, this means that the of the

Side contour projecting edge 8 remains biased so that no cavity between the edge 8 and 4, 5 can form.

Figure 7 shows an embodiment of the invention in which a comparatively larger distance 23 between two conductors 4 and 5 is predetermined by a plurality of spacers 3 stacked on one another. Again, the respective side surfaces 6 of the stack are each provided with groove-shaped recesses in the form of a groove. As a result, contact surfaces lying on top of one another in the region of the stack are so stacked on one another that a dangerous gusset with overloaded insulation medium can not form between them. Even with a stack of superimposed spacers can be achieved by the concave profile that a lateral inhomogeneity of the electric field can be effectively counteracted.

FIG. 8 shows the spacer 3 according to the invention in a perspective view. The spacer 3 has a prismatic body part having a height 20, a width 21, and a length 22. The upper and lower

Contact surface 13 is flat. Depending on the use of the spacer 3, the length 22 can be very different: the length 22 is very short if it is to correspond to the width of a flat conductor; the length 22 corresponds to a radial arrangement between adjacent conductors about the radial thickness of a winding. When the spacer 3 for adjusting the distance between two in a radial Distance windings to be used,

corresponds to the length 22 of the coil length.

Figure 9 shows a schematic representation of the use of the spacer according to the invention in an electrical winding 1. The spacer 3 is to be seen once between a conductor 4 and a machine part 19, another time as an axial or radial spacer between two conductors 4 and 5. The spacer 3 with the concave cross-sectional profile can therefore not only in

Isolation system of a winding, but also in the

Barrier system can be used. The barrier system is used to insulate windings between each other or between windings and parts with ground potential. This differs from the isolation system

Barrier system in that at least one of the two contact surfaces of the spacer 3 is not in contact with a bare conductor 4,5 or an insulated conductor, but with a so-called barrier. It may be that the spacer and the barrier are made of the same material.

Spacers as known in the art are shown in Figs. 10-13. All four edges of the spacer 3 shown in Figure 10 are rounded, i. the cross-sectional profile of the spacer 3 is convex. Depending on the type of production and accuracy, these curves are formed. To illustrate, three contact or insertion angles 9 are drawn: FIG. 11 shows a known spacer with a contact angle 9 of 0 °; Figure 12 is a contact angle 9 of 15 °, Figure 13 is a contact angle 9 of 30 °. All these known

Spacers together so is the formation of a "gusset" 24. If the spacer 3 between two

Ladders 3 and 4 is pressed, also has the pressing force

Influence on the formation of the "gusset", since there is at least a slight deformation of the conductor insulation and the spacer in the area of the pressing surface, as already explained in the introduction, this is in this "gusset" 24 Isoaltions cooling medium 2 electrically stressed particularly strong. By the invention this becomes

Overuse of the I soaltions cooling medium avoided. The main advantage of the concave cross-sectional profile is thus to be seen in the fact that the field strength increase in the

Isolation system, at system voltages greater than 1000 V, can be greatly reduced. In particular, the undesirably high electric field strength in the region of the so-called "gusset" 24, which is formed in the prior art by rounded edges, can be avoided

Punch are occur less frequently thanks to the invention. The concave recess in the form of a groove

prevents this. The consequence of this is that compared to the prior art, a higher dielectric strength of the

Isolation system is possible. The probability of breakdowns due to voltage overstress is lowered.

As indicated above, another advantage is that through the formation of a stack, a

comparatively large distance, which at a high

Stress load is required, can be bridged without requiring a special preparation of a

Spacer would be required. In other words, the favorable effect of equalizing the electric field described with a single spacer is not achieved by the juxtaposition of superimposed layers

Lost spacers.

Another advantage is the fact that by the elastic property of the wedge-shaped foot part a

Insulation of the conductor is not damaged even at a higher pressing force. Due to the elasticity of the material, the projecting edge remains biased. It can also form no unfavorable cavity between the spacer and the conductor insulation. By the soft yielding Property of the foot does not come to depressions in the insulation. Favorable also affects the conditional by the production of fibrous formation of the edge. Although the invention in detail by the preferred

The invention has not been limited by the disclosed examples and other variations can be deduced therefrom by the person skilled in the art without departing from the scope of the present invention

To leave invention.

So it goes without saying that the in Figure 1

shown in the radial direction and for adjusting the axial distance between the winding layers 14, 15 provided spacers 3 of course also for

Setting a radial distance can be used. In this case, the strips are not arranged radially in the production of the winding, but in the direction of the leg axis 17.

The contour function does not necessarily have to be continuously curved, it is only important that the transition region is rounded concavely in the form of a groove and at the connection point kink-free in another

go over curved / rectilinear section

What is said above for a liquid Isoaltions cooling medium, in principle also applies to a gas. The term insulation cooling medium thus also includes gaseous media. An advantageous use of the spacer can therefore also be in so-called high-voltage air coils. Again, an embodiment in aramid fiber, as they are known for example under the brands Kevlar® or Nomex®, may be preferred. Compilation of the reference numbers used

1 electrical winding

2 insulation cooling medium

3 spacers

4 conductors of an upper layer 14

5 conductors of a lower layer 15

6 side surface

7 groove, recess

8 edge, contact line

9 contact angles

10 contour function

11 Transition area, foot part

12 circular arc

13 contact surface, contact surface

14 upper layer

15 lower layer

16 magnetic core

17 leg axis

18 arrow (tensioning device)

19 machine part

20 height of the spacer, distance

21 Width of the spacer

22 Length of the spacer

23 distance

24 gussets

Claims

claims

1. Electrical transformer or choke comprising:

a winding (1),

- Isoaltions cooling medium (2), which the

Winding (1) surrounds,

- At least one spacer (3) from a

Insulator, having side surfaces (6) and opposing abutment surfaces (13) to be arranged in an array between adjacent conductors (4,

5) or a conductor ((4, 5) and a machine part (19), a distance (23) to pretend, characterized in that the spacer (3) to a contact surface (13) lying transition region (11), as Cove (7) is formed with a tapered edge (8).

2. Transformer or choke coil according to claim 1,

characterized in that at the edge (8) formed contact angle (9) is greater than 90 °.

3. Transformer according to claim 2, characterized in that the contact angle (9) is approximately 180 °

4. Transformer or choke according to one of claims 1 to 3, characterized in that in

Transition area (11) each opposite

Side surface (6) by a curved contour function (10) is given, which is continuous in their derivative.

5. Transformer or choke according to one of claims 1 to 3, characterized in that in

Transition area (11) each opposite

Side surface (6) is at least partially predetermined by a contour function (10), which is formed by a polygon. Transformer or choke according to claim 4 or 5, characterized in that the contour function (10) has a circular arc, so that the side surface (6) kink-free in the plane of a contact surface (13)

opens.

Transformer or choke according to claim 1, characterized in that the distance (23) by a plurality of stacked spacers (3) is set.

Transformer or choke according to claim 1, characterized in that the at least one spacer (3) is made of a dielectric material whose permittivity is greater than that

Permittivity of the isolation cooling medium (2).

Transformer or choke according to claim 7, characterized in that the at least one spacer (3) has the shape of a strip.

Transformer or choke according to claim 1 or 9, characterized in that the spacer (3) or the strip made of cellulose or a plastic, preferably made of a polyamide.

11. Winding arrangement for an electrical machine, in particular a power transformer or

A choke comprising: a winding (1)

Isoaltions cooling medium (2), which surrounds the winding (1), at least one spacer (3) made of an insulator, with side surfaces (6) and each other

opposite abutment surfaces (13) in order to

Arrangement between adjacent conductors (4, 5) or a conductor (4, 5) and a machine part (19) to specify a distance (23), characterized in that the at least one spacer (3) each other opposite side surfaces (6) which are surrounded by the Isoaltions cooling medium (1), and at each of these side surfaces (6) has a recess (7) is formed such that a groove is formed, so that each side surface (6) with the their associated contact surface (13) to an edge (8) is formed tapering.

12. Winding arrangement according to claim 11, characterized

in that a contact angle (9) which opens into the isoaltion cooling medium (2) is greater than 90 °.

13. Winding arrangement according to claim 11, characterized

characterized in that the contact angle (9) is about 180 °.

14. Winding arrangement according to one of claims 11 to 13, characterized in that in the transition region (11) each opposite side surface (6) by a curved contour function (10) is predetermined, which is continuous in their derivative.

15. Winding arrangement according to one of claims 11 to 13, characterized in that in the transition region (11) each opposite side surface (6) by a contour function (10) is predetermined, which is at least partially formed of a polygon.

16. Winding arrangement according to claim 14, characterized

in that the contour function (10) is a circular arc at least in one section.

17. Winding arrangement according to claim 11, characterized

characterized in that the distance (23) through

stacked spacers (3) is predetermined.

18. Winding arrangement according to claim 11, characterized in that the at least one spacer (3) is made of a dielectric material whose permittivity is greater than that

Permittivity of the isolation cooling medium.

19. Winding arrangement according to claim 11, characterized

characterized in that the at least one spacer (3) has the shape of a strip.

20. Winding arrangement according to claim 19, characterized

characterized in that the material of the strip (3)

Cellulose or a plastic, especially a polyamide.

21. Spacer for a winding of a

electric machine, comprising: a prismatic body part formed of an insulating material, having side surfaces (6) and two opposing planar contact surfaces (13) with which it is arranged between adjacent conductors (4, 5) or a conductor (4, 5) and a machine part (19) defines a defined distance (23), thereby

in that the spacer (3) has a transition area (11) lying to a contact surface (13), the shape of which is in the form of a groove (7).

is formed, so seen in a cross section contact surface (13) and side surface (6) form a wedge with a sharp edge (8).

22. Spacer according to claim 21, characterized

characterized in that the shape of the groove (7) is formed by a recess which passes through a

curved contour function (10) is given, which is a continuous function.

23. Spacer according to claim 21, characterized

in that at the edge (8) the tangent of the contour function lying in a cross-sectional plane (10) with the contact surface (13) includes a contact angle (9) greater than 90 °.

24. Spacer according to claim 21, characterized

characterized in that the contact angle (9) is about 180 °.

25. Spacer according to one of claims 22 to 24, characterized in that the material of

Body part (3) Cellulose or a plastic, especially a polyamide.