DE69629318T2 - HIGH VOLTAGE / LOW VOLTAGE TRANSFORMER WITH THERMOPLASTIC DRY INSULATION - Google Patents

Description

The present invention relates to Transformers and relates in particular to dry-type transformers.

Transformers as they are used for distribution of energy to the public used, have a nominal voltage covering the range between 5 kVA and 2500 kVA.

They serve to lower the voltage level of the network from a "medium voltage" level that between 5 and 36 kV is included, at a low voltage level that is smaller than 500 V, for the supply of electrical energy to private Households.

The transformers of the evergreen Type, with insulation by a dielectric liquid (usually oil) the size Majority in usage and current offer. Indeed it is mineral oil an inexpensive Material, a good insulator and a good heat exchanger for cooling the windings. however shows mineral oil as Disadvantage its good flammability on what in the case of an internal Arc flashover in the transformer is unfortunate.

The risk of fire associated with mineral oil dielectric liquids with a high flash point must be eliminated has been developed. Polychlorobenzene was the most used, but its Has been used in the meantime due to its lack of biodegradability and because of the harmfulness certain fire decomposition products prohibited. Silicone esters and -Oils could be better candidates to replace polychlorobenzene in the transformers. Indeed these products are not yet a standard and they are only made in very minor Dimensions used. Your commercial future is surely strained by the increasing Strict laws governing the use of dielectric liquids because of the risk of coolant contamination. The devices with solid insulation or dry fixtures were built after Ban on the use of polychlorobenzene is highly developed.

They are used everywhere in institutions the public received (real estate, businesses) to reduce fire risks. Their use in distribution remains minor because of the considerable Cost compared to devices with mineral oil.

Modern dry-type transformers have considerable ones Air lamellas that have an insulation function between windings and ensure between windings and ground, which takes up space, increase their mass and therefore their costs. To get rid of this Problem, some designers use surface metallization of the windings, which allows them to reduce the space requirement. This technology is difficult, expensive and difficult to be able to get to work.

There are two large families today of dry-type transformers: the enveloped and the soaked. The Manufacturing processes of these devices are certainly different, but the insulation materials used have in common, thermosetting too be and need a heat polymerization thing increased Manufacturing costs induced.

The invention aims to to solve the above-mentioned difficulties of dry-type transformers, by creating a transformer of a type that is both in terms of Space requirements as well as the price by reduction compared to an improvement on the currently known transformers with similar performance represents.

It is therefore aimed at a transformer with dry insulation, which has at least one high-voltage winding and at least has a low voltage winding on at least one Pillar of a magnetic circuit are attached, which are characterized is that their high-voltage winding in an insulating sleeve thermoplastic resin is included with a surface layer made of a thermoplastic, electrically conductive resin to fix the Potential enveloped is that with the insulating sheath compatible and is encased in an electrically conductive resin.

• – die Hülle der Oberspannungs-Wicklung weist an ihrer Seitenfläche Öffnungen zum Durchgang von Anschluß-Stiften der Wicklung auf;
• – die genannten Öffnungen zum Durchgang von Anschluß-Stiften der Oberspannungs-Wicklung sind an einem Seitenstreifen aus elektrisch isolierendem thermoplastischen Harz vorgesehen, der mit dem thermoplastischen Harz der Isolierhülle verträglich und bezüglich dieser in Überdicke ausgeführt ist;
• – der Transformator weist Schienen zum Anschließen einer Oberspannung auf, wobei jede Anschluß-Schiene einen von einem thermoplastischen isolierenden Harz umhüllten Mittelleiter aufweist, der von einem thermoplastischen elektrisch leitfähigen Harz umhüllt ist;
• – zwischen dem Mittelleiter der Anschluß-Schiene und ihrer isolierenden Hülle ist eine Zwischenschicht aus thermoplastischem elektrisch leitfähigem Harz eingefügt, die vorgesehen ist, Teilentladungen zu vermeiden, die Gefahr laufen zwischen dem Metall des Leiters und der Isoliation der Hülle zu erscheinen, falls der Metall-Isolator-Übergang nicht perfekt ist, oder falls ein Risiko seiner Verschlechterung aufgrund von thermischen oder mechanischen Belastungen besteht;
• – jede Anschluß-Schiene weist an jedem ihrer Enden ein Element zum Verbinden des Mittelleiters der Schiene mit einem Anschlussstift einer Oberspannungs-Wicklung auf, wobei eines der Verbindungselemente ein Verbindungselement nach Außen bildet, wobei die genannten Verbindungselemente jeweils mit einem Kopf aus thermoplastischem Harz umgeben sind, welcher einstöckig mit der Isolations-Umhüllung der Schiene geformt ist und welcher geeignete, an die Durchgangs-Öffnungen der Anschluß-Stifte der Oberspannungs-Wicklung angepasste Dimensionen aufweist, die in der Isolations-Hülle der genannten Wicklung vorgesehen sind, wobei der Kopf außerdem eine Umhüllung aus thermoplastischem elektrisch leitfähigen Harz aufweist, die einstöckig mit der elektrisch leitfähigen Umhüllung des Ganzen der Schiene geformt ist;
• – die genannte wenigstens eine Nie erspannungs-Wicklung ist direkt auf eine Hülse aus elektrisch leitfähigem Harz aufgespult, welche die zugehörige Säule des magnetischen Kreises umhüllt;
• – der magnetische Kreis weist außerdem Joche auf, die die Säulen des magnetischen Kreises verbinden, wobei die genannten Joche gleichermaßen von einer Harz-Hülle verkleidet sind;
• – die Harz-Hülle des wenigstens einen Joches des magnetischen Kreises weist Zonen in Überdicke zum Fixieren von Anschluß-Leitern der Niederspannungs-Wicklungen und für den Ausgang der Niederspannungs-Anschluß-Stifte des Transformator auf;
• – zwischen den Oberspannungs- und Niederspannungs-Spulen, sind Kanäle zum Zirkulieren eines Kühlfluids vorgesehen, begrenzt von Vorsprüngen aus dem Material von wenigstens einer der Umhüllungen der genannten Wicklungen;
• – zusätzliche Öffnungen für den Ausgang von Justage-Stiften sind in dem Seitenstreifen der Hülle der Oberspannungs-Wicklung vorgesehen, wobei jede dieser Öffnungen von einem Isolations-Stopfen verschlossen ist, der mit einer Schicht aus elektrisch leitfähigem Material verkleidet ist, zum Fixieren des Potentials im Kontakt mit der elektrisch leitfähigen Schicht der Umhüllung der Oberspannungs-Spule, um um die Kontinuität der elektrisch leitfähigen Schicht zum Fixieren des Potentials sicherzustellen.

In addition to other properties, the invention has:

• - The envelope of the high-voltage winding has openings on its side surface for the passage of terminal pins of the winding;
• - The said openings for the passage of pins of the high-voltage winding are provided on a side strip made of electrically insulating thermoplastic resin, which is compatible with the thermoplastic resin of the insulating sleeve and is made in excess thickness with respect to this;
• - The transformer has rails for connecting a high voltage, each connecting rail having a central conductor covered by a thermoplastic insulating resin, which is covered by a thermoplastic electrically conductive resin;
• - An intermediate layer of thermoplastic, electrically conductive resin is inserted between the center conductor of the connecting bar and its insulating sheath, which is intended to avoid partial discharges and run the risk of appearing between the metal of the conductor and the insulation of the sheath if the metal Insulator transition is not perfect, or if there is a risk of its deterioration due to thermal or mechanical loads;
• - Each connecting rail has at each of its ends an element for connecting the central conductor of the rail to a connecting pin of a high-voltage winding, with one of the connecting elements following a connecting element Forms outside, said connecting elements are each surrounded by a head made of thermoplastic resin, which is integrally formed with the insulation sheathing of the rail and which has suitable dimensions adapted to the through-openings of the connecting pins of the high-voltage winding are provided in the insulation sheath of said winding, the head also having a sheath made of thermoplastic electrically conductive resin which is integrally molded with the electrically conductive sheath of the whole of the rail;
• - The said at least one never-voltage winding is wound directly onto a sleeve made of electrically conductive resin, which envelops the associated column of the magnetic circuit;
• - The magnetic circuit also has yokes that connect the columns of the magnetic circuit, said yokes are equally covered by a resin shell;
• - The resin sheath of the at least one yoke of the magnetic circuit has zones of excess thickness for fixing connection conductors of the low-voltage windings and for the output of the low-voltage connection pins of the transformer;
• - Between the high-voltage and low-voltage coils, channels for circulating a cooling fluid are provided, delimited by protrusions made of the material of at least one of the wrappings of said windings;
• - Additional openings for the output of adjustment pins are provided in the side strip of the envelope of the high-voltage winding, each of these openings is closed by an insulation plug, which is covered with a layer of electrically conductive material, for fixing the potential in Contact with the electrically conductive layer of the envelope of the high-voltage coil in order to ensure the continuity of the electrically conductive layer for fixing the potential.

The invention will become apparent by reading the following Description can be better understood, which alone as an example is given and which refers to the accompanying drawings.

Here are:

1A to 1E schematic perspective views showing the phases of assembly of a three-phase transformer according to the invention;

2 an enlarged sectional view of the in 1E illustrated dry-type transformer;

3 a cross section along the line 3-3 in 2 ;

4 a sectional view taken along line 4-4 in 2 ;

5 a perspective view of the upper yoke provided with an insulating sheath of the transformer in 1E ;

6 a perspective view of the lower yoke provided with an insulating sheath of the transformer in 1E ;

7 a sectional view of a straight rail for coupling high-voltage coils of the transformers of 1 ; and

8th a sectional view of a curved rail with a structure analogous to that of 7 ,

In 1A to 1E , The different phases of the assembly of a three-phase transformer with dry insulation according to the invention are shown.

In 1A is a low voltage coil 1 shown, arranged on a column 2 the magnetic circuit of a three-phase transformer, which is more complete in the 1D and 1E is shown.

To implement the arrangement in 1A , start assembling the layered column according to a common procedure 2 the magnetic circuit of the transformer by stacking classic pre-cut sheets made of silicon steel. In the central part of the column 2 , ie between the end games 2A and 2 B which with regard to the later unification of the pillar 2 with the yokes for chamfering to close the magnetic circuit, a sleeve is formed 3 made of polymer resin.

This process is done by injection executed or by compressing the strips under the influence of heat, if used Polymer is thermoplastic.

However, the material used can also a thermosetting Resin. It is important that the material is thermally conductive, and as much as possible Dimensions. For this purpose, for example, in a suitable ratio Batch contain carbon, which has the additional advantage it alike easily become electrically conductive, in accordance with a preferred one embodiment of the invention, which is described below.

After positioning compression rings 4 ( 4 ) at the ends of the polymer resin sleeve 3 , you wind an electrically conductive metallic conductor directly on the surface of the sleeve 5 which will form the low voltage winding of the transformer, as in particular in 1D and equally in the 2 . 3 and 4 is shown.

That leader 5 can be in the form of large or flattened strips of aluminum or copper. It is encased in a classic way with oil paper.

Each of its ends is extended outwards to the classic connection rails 6 out.

The low chip realized in this way voltage winding is then done with one layer 7 encapsulated from dielectric polymer resin of a few millimeters, for example 3 mm, thickness. This envelope casing 7 Resin is made by compression under the action of heat from superimposed sheets of thermoplastic material, which are also thermally conductive to promote thermal exchange with the ambient air. This resin is also slightly electrically conductive, which makes it possible to improve the global security of the device to be realized by, as in 1A represented the point 7A is connected to earth potential.

This ends the production of one Low-voltage winding of the transformer according to the invention.

The sleeve 3 , even if it represents an intermediate unit that will disappear in the completed version, as in 1A is shown, nonetheless fulfills several essential tasks.

First, thanks to its rigidity, it provides the necessary mechanical stability of the column 2 forming sheet metal stack, whereas in the classic way this cohesion is ensured by means of screws and nuts.

Furthermore, the sleeve meets 3 play an important role as a heat exchanger to promote cooling of the column 2 or the winding 5 by means of heat conduction through the thermally conductive material from which said sleeve is formed.

In addition, if it is also made slightly electrically conductive, the safety of use of the finished device can be improved by simply laying the sleeve on earth. This is understandably facilitated if one provides that the sleeve 3 over the end of the winding 5 protrudes beyond a fully covered winding 5 to obtain.

In addition, as already indicated, it serves to support the winding of the electrically conductive metallic conductor 5 which is to be energized. In this way, among other advantages, the oil paper insulation that the conductor 5 enveloped, no longer at risk of being injured in the course of winding. So far, however, this risk has been avoided by interposing wooden regulating struts between the columns of the magnetic circuit and the low-voltage windings which are wound around these columns, which lengthen the conductor with moving edges, sometimes violate the magnetic circuit.

As in 1A are shown on the outer surface of the electrically conductive polymer resin of the shell 7 projections 8th provided in the form of longitudinal ribs, which form webs for the high-voltage coil, as in 1B is shown, and which rings the low-voltage location in 1A will be arranged.

These ribs, for example with a height of 3 to 50 mm, serve equally as channels between them 9 for circulating a cooling fluid, such as air, by means of convection between the low-voltage position and the high-voltage position, as described, for example, in 1C able to see.

In this example, the outer surface of the dielectric polymer resin shell faces 7 four ribs 8th on, offset from one another by 90 ° along the circumference of the envelope casing of the envelope 7 ,

In this way, as already indicated above, the envelope casing made of resin has the envelope or the encapsulation 7 preferably a certain degree of electrical conductivity, especially if it is made of a polymer resin loaded with electrically conductive particles or a naturally electrically conductive polymer resin.

Thanks to such an arrangement, an antistatic effect is obtained in order to avoid dusts, which the air inevitably has, on the wall of the cooling ducts 9 come to the deposit. It is equally possible to wrap the envelope 7 from resin to ground by electrically connecting them to earth, as in 7A is shown what allows the transformer safety in the event of failure or local damage to the oil paper insulation of the metallic conductor 5 improve under tension.

The complex of polymer resin parts, which the sleeve 3 and protective wrapping 7 can actually be conductive without danger, since the electrical voltage of the conductor 5 at the level of the low voltage level of a transformer usually does not exceed 400 to 500 volts.

The compression rings 4 are actually end flanges, intended to enclose the multi-layer wound metallic conductor on the side and are designed to take into account the spiral shape of the coil. It is necessary that the end turns of each layer of the preformed winding of the conductor 5 are continuously applied against these flanges over their entire length. This requires a ramp shape, either indenting or disengaging from the pressure surface of each ring 4 according to the helical orientation of the turns of the winding.

This is the reason why you two Concentric rings with inverted ramps for the commonly used two-layer Winding used.

These rings have an essential advantage in that they have a mass for closing the ends of the sleeve 3 can form what the molding by means of compression of sheets of thermoplastic resin 7 enabled in a satisfactory manner. Otherwise, the volume to be filled by the molded resin would be an injection Make ons process necessary, which is generally not intended for massive parts, and which is much less economical than compression.

In the 1A The low-voltage position shown is understandably carried out using examples in which the transformer to be constructed has phases.

The 1B to 1E schematically show the construction steps of a three-phase dry transformer. In 1B , a high-voltage coil is shown, intended to be used with the low-voltage coil in 1A to work together.

To realize this high voltage coil 10 , one begins by winding an electrical conductor covered by an insulating sheath to form a winding formed from coaxial turns, circular, oval or polygonal on one or more layers. The metallic conductor 11 ( 1D ) is generally copper or aluminum and the insulation sheath is generally an enamelling or wrapping in a generally paper insulator to isolate adjacent turns from one another.

The winding thus obtained is injected or compressed with a layer of electrically insulating thermoplastic resin 12 ( 2 ) envelops.

The case 12 has openings 14 on its side surface for the passage of connecting pins 15 the winding on.

The openings 14 for the passage of the pins of the high-voltage winding are in a side strip 16 made of electrically insulating thermoplastic resin provided with the thermoplastic resin of the insulating sleeve 12 is compatible, and compared to that in a greater thickness.

The side stripe is preferably 16 one-story with the shell 12 executed by molding. It can also be applied to the cover by means of compression under heat 12 be executed.

On the layer of the shell 12 is also by means of compression under heat, a layer a few millimeters thick 18 clad from a thermoplastic, electrically conductive resin, which overlaps the entire surfaces of the high-voltage winding, both outside and inside.

This one surface layer 18 forming resin ( 2 ) is with carbon particles 5 charged to make it electrically conductive, and it is of the same type as the insulating polymer that covers the sheath 12 forms.

In this way, the interfaces with the insulators free of voids be listed.

The high-voltage coil is now completed.

It remains to be specified that the thicknesses of the insulators on the winding are sufficient to withstand the dielectric loads, the maximum between the coil and the electrically conductive layer 18 , based on earth, or between the inner connections of the coil and the electrically conductive layer 18 , related to earth, or between the pins 15 the coil and the electrically conductive layer 18 related to earth.

The hard shoulder 16 made of thermoplastic resin, which is made of a stack of insulating thermoplastic material, similar or identical to that of the insulating sleeve 12 and which with an electrically conductive surface layer 18 is provided, the inner connections of the pins overlap 15 the output winding. The leader's rings 15 provided openings 14 are intended to allow the connection of the high-voltage coil to the network, or to connect the high-voltage coil to other high-voltage coils in such a way that an electrical coupling is realized, as described with reference to 1E and to connect an adjustable terminal to the high voltage coil, such as the ensemble of conductors 20 which in 1B in a square opening 22 appears, which in the hard shoulder 16 between the openings 14 is formed for the passage of the connection conductor of the high-voltage winding.

The high voltage coil 10 is then on the low voltage coil 1 in the in 1C arranged way arranged.

This is done on the pillar 2 attached low voltage coil 1 into the high voltage coil 10 introduced. The one on the outer circumference of the sheathing of the conductor 7 the ribs arranged on the low-voltage coil 8th allow the high voltage position to be centered on the axis of the magnetic column 2 the low-voltage coil, and allow one channel 9 for cooling by means of ambient air between the low voltage coils 1 and the high voltage coils 10 to provide, the ribs 8th in this way form webs between the two coils.

In this way, a paired Upper-voltage and low voltage situation educated.

The layers of this type are used to implement a three-phase transformer as in 1D and 1E is shown.

To do this, you assemble three low-voltage high-voltage layers and you build the columns 2 these layers by means of upper and lower yokes 24 and 26 together like this clearly in 2 is shown.

The yokes 24 and 26 are also made of layered magnetic sheet metal.

The yokes 24 and 26 are positioned so that they have vertical columns 2 interact, each of which is a low voltage winding 1 and a high voltage winding 10 contributes, creating a closed magnetic circuit with a central pillar and two side pillars is formed.

In terms of their assembly, the side columns 2 beveled ends 2A . 2 B on while the central pillar ends 2C . 2D with symmetrical points. The yokes 24 and 26 are complementary to the ends of the columns 2 trained with which they are composed. As in 1E each of the yokes 24 a case 28 . 30 made of thermoplastic resin. In the 1E shown wrappings 28 and 30 who are also equally in 2 . 5 and 6 appear mainly have the function, the mechanical hold between the yokes 24 and 26 ensure forming sheets among themselves, and the assembly of these yokes with the associated ends of the columns 2 , The wrappings 28 and 30 Resin forming resin preferably has the same chemical basis as that for the covering of the columns 2 is used to achieve a good connection between the two materials.

The shell of the yokes has the second function of protecting them from external interference. The shell of the yokes 24 and 26 also has the following functions.

It represents the positioning of the high voltage coils and low voltage coils 1 and 10 in terms of the yokes 24 and 26 for sure.

It also represents the mechanical cohesion of the low-voltage conductors 6 between the outputs of the low-voltage windings and the low-voltage pins of the transformer.

For this purpose, the envelope 28 of the upper yoke zones 32 in excess thickness for fixing the low-voltage connection conductors 6 on, and as an output for the corresponding low-voltage connection pins of the transformer. The case 28 of the upper yoke 24 also forms a base for the low-voltage pins of the transformer.

Understandably, it equally ensures the mechanical cohesion of the low-voltage connecting rails, which are equally thick due to the above-mentioned zones 32 are protected.

This envelope finally represents one Increase in the thermal exchange area of the yoke for sure for the Cooling, because the resin used is thermally conductive is.

In this way, as in 1E What can be seen is the complex, which forms the magnetic circuit from the upper and lower yokes covered by a shell 24 and 26 and one low-voltage winding each 1 and a high voltage winding 10 supporting pillars 2 has, then on a chassis 34 attached. The essential function of the chassis 34 is the positioning of the transformer on the floor. The axis of the transformer windings is preferably close to the vertical in order to improve the transformer cooling by means of natural convection from ambient air.

The chassis 34 can also serve to reinforce the wedging of the windings. This wedging is necessary in order to counteract electrodynamic forces which act on the windings, in particular due to short circuits in the network. You can therefore use the connecting rails 35 and 36 of the high-voltage windings in the 1E attach shown type.

In 7 , a straight connection rail is shown, like the rail 35 in 1E , This high-voltage connection rail has a conductive center conductor 37 on, covered with a thermoplastic insulating resin 38 , coated with a thermoplastic, electrically conductive resin 39 ,

Between the middle conductor 37 the connection rail and its insulating sheath 38 , is an intermediate layer made of thermoplastic, electrically conductive resin 40 inserted to avoid risky partial discharges between the metal of the center conductor 37 and the insulation of the shell 38 occur if the metal-insulator transition is not perfect, or if there is a risk of wear due to thermal or mechanical stress.

In the 8th illustrated conductive rail 36 , is a rail with bends 42 which are designed to allow her to use the straight rails 35 on the in 1E shown way to cross.

The structure of the connection rail 36 is otherwise the same as that of the connecting rails 35 ,

Each connection rail has a device at each of its ends 43 . 44 for connecting the center conductor 37 the rail with a pin of a high-voltage winding. The connection device 43 . 44 is from a head 45 . 46 Surrounded by thermoplastic resin, which is integral with the insulating jacket 38 molded together, and which one at the openings 14 for the passage of the pens 15 for connecting the high-voltage winding in the casing 12 has adapted dimensions of the mentioned winding. Each of the heads 45 . 46 also has an envelope 47 . 48 on, which is made of thermoplastic electrically conductive resin and in one piece with the electrically conductive sheath 39 of the rail complex is shaped.

Thanks to the arrangement just described, the accessible surface of the connection rails points 35 . 36 a potential based on ground, on the condition that assembly allows electrical continuity between the electrically conductive layers 39 . 47 . 48 the rails and the electrically conductive layers 18 of the high-voltage coils 10 sure.

In addition, each rail points to one of them Ends a device 50 to the external connection, which has a connecting pin and an element at both ends 52 for connection to a connecting pin of the high-voltage coil, this element having a suspension sleeve.

Especially with the appreciation of 6 and 7 , it should be noted that the envelope 28 . 30 each of the upper and lower yokes 24 . 26 of the three-phase transformer according to the invention on its faces facing the coil complexes forming the transformer, plug-in points 54 for positioning the coils with respect to the yokes.

The cover also covers 28 . 30 the yokes 24 and 26 the magnetic pillars 2 reshaping sleeve 3 by a few millimeters in length.

In addition, this cover creates a tight connection between the shell 28 . 30 and the sleeve 3 by shaping the shell 28 . 30 on the sleeve 3 ,

• – den mechanischen Zusammenhalt der Joche 24, 26 auf den Säulen 2,
• – den Schutz gegenüber äußeren Angriffen des aus den Jochen 24, 26 und den Säulen 2 gebildeten magnetischen Kreises.

This connection allows:

• - the mechanical cohesion of the yokes 24 . 26 on the pillars 2 .
• - Protection against external attacks from the yokes 24 . 26 and the pillars 2 formed magnetic circuit.

Referring again to 1E you can see that in the hard shoulder 16 the envelopes of the high-voltage coils carried by each transformer column 10 provided openings 22 as an output for the adjustment pins 20 the high-voltage windings are provided. These openings are preferably each with a plug 64 sealed, insulated with a layer 65 Made of electrically conductive material, which is used to fix the potential in contact with the electrically conductive layer 18 serves to sheath the associated high-voltage coil in order to ensure the continuity of the electrically conductive layer for fixing the potential.

Although in the just described Example applied the invention to a three-phase transformer would be is understandably it possible, them on execution to use a monophase transformer which has at least one Complex of low-voltage / high-voltage windings, which from a pillar of a closed magnetic circuit.

Claims (12)

Dry-insulated transformer with at least one primary winding and at least one secondary winding, which are attached to at least one column of a magnetic circuit, characterized in that its winding on the high-voltage side ( 10 ) In an insulating sheath ( 12 ) made of thermoplastic resin with a surface layer ( 18 ) is made of an electrically conductive thermoplastic resin, which is used for determining the potential and is compatible with the insulating sheath, and that its low-voltage winding ( 1 ) from an electrically conductive resin ( 7 ) is enveloped. Transformer according to claim 1, characterized in that the sheath of the winding on the high-voltage side has openings ( 14 ) for connecting pins ( 15 ) of the winding. Transformer according to claim 2, characterized in that the lead-through pins ( 15 ) the openings on the high-voltage winding ( 14 ) in a hard shoulder ( 16 ) are made of electrically insulating thermoplastic resin which is combined with the thermoplastic resin of the insulating sleeve ( 12 ) is compatible and protrudes from it and serves to cover the internal connections of the winding on the high-voltage side. Transformer according to one of the preceding claims 1 to 3, with rails ( 35 . 36 ) for connecting the upper voltage, characterized in that each connecting bar has a central conductor ( 37 ) comprising an insulating thermoplastic resin ( 38 ) is covered with an electrically conductive thermoplastic resin ( 39 ) is coated. Transformer according to claim 4, characterized in that between the central conductor ( 37 ) the connecting rail and its insulating sheathing ( 38 ) a previous shift ( 40 ) is inserted from electrically conductive thermoplastic resin, which is designed to prevent partial discharges that may occur between the metal of the central conductor and the insulator of the sheath, if the metal-insulator transition is imperfect or if there is a risk that the Insulator of the jacket deteriorated due to thermal or mechanical forces. Transformer according to one of claims 4 and 5, characterized in that each connecting rail ( 35 . 36 ) one organ at each end ( 43 . 44 ) for connecting the center conductor ( 37 ) of the rail to a connecting pin of an high-voltage winding, the connecting element being carried by a head ( 45 . 46 ) is surrounded by thermoplastic resin, which is integral with the insulating jacket ( 38 ) the rail is designed and has dimensions that correspond to those for the implementation of the connecting pins ( 15 ) the high-voltage winding and formed in the sheath of this winding openings ( 14 ) are adjusted, with the head ( 45 . 46 ) also a coating ( 47 . 48 ) made of electrically conductive higes thermoplastic resin, which is integral with the electrically conductive coating ( 39 ) the entire rail is formed. Transformer according to one of claims 1 to 6, characterized in that the at least one low-voltage winding ( 1 ) directly on a stick ( 3 ) is wound from electrically conductive resin, which the associated column ( 2 ) of the magnetic circuit. Transformer according to one of claims 1 to 7, characterized in that the magnetic circuit furthermore yokes ( 24 . 26 ) which the columns ( 2 ) of the magnetic circuit, the yokes also with a resin cover ( 28 . 30 ) are coated. Transformer according to claim 8, characterized in that the resin coating ( 28 ) at least one of the yokes ( 24 areas protruding from the magnetic circuit ( 32 ), which is used to attach the connection conductors of the windings and to lead out the low-voltage connection pins ( 6 ) of the transformer. Transformer according to one of claims 8 and 9, characterized in that the resin for coating the yokes ( 24 . 26 ) is a thermally conductive resin. Transformer according to one of claims 1 to 10, characterized in that between the high and low voltage windings channels ( 9 ) are designed to flow a cooling fluid, which are formed by ribs ( 8th ) are formed, which are in one storey with at least one of the envelopes ( 7 or 12 ) the windings are formed. Transformer according to one of claims 3 to 11, characterized in that in the side strip ( 16 ) additional openings in the high-voltage winding ( 22 ) are designed to lead out controller connections ( 20 ), these openings each with an insulating plug ( 64 ) are closed with a layer used to determine the potential ( 65 ) is coated from an electrically conductive material which is coated with the electrically conductive coating layer ( 18 ) of the high voltage winding ( 10 ) is in contact in order to ensure the continuity of the electrically conductive layer defining the potential.