EP2515313A1 - High voltage feed-through - Google Patents

Abstract

The high-voltage bushing has, in a coaxial arrangement, a conductor (10) guided along an axis (A) and an insulator (20) attached to the conductor and encompassing the conductor, containing a hardened polymer mass (22). A capacitor winding (40) with electrically insulated capacitor layers (41) is embedded in the hardened polymer mass (22) and spaced apart in the radial direction by an insulating film (42) wound around the axis (A). Furthermore, the bushing in a coaxial arrangement also has a mounting flange (30) attached to the insulator (20) and a shielding (21) extending from the mounting flange (30) to a connection (11) of the conductor (10). The shielding (21) is molded into a jacket surface of the insulator (20) which is formed by the hardened polymer mass (22) and is arranged radially outwards at a distance from the capacitor winding (40). The high-voltage bushing can be manufactured easily and is nevertheless characterized by a high level of operational reliability.

Description

• einen längs einer Achse geführten Stromleiter,
• einen am Stromleiter befestigten und den Stromleiter umfassenden Isolator, enthaltend eine gehärtete Polymermasse,
• einen in die gehärtete Polymermasse eingebetteten Kondensatorwickel mit voneinander elektrisch isolierten Kondensatorbelägen, die in radialer Richtung durch eine um die Achse gewickelte Isolierfolie mit Abstand voneinander gehalten sind,
• einen am Isolator befestigten Montageflansch und
• eine vom Montageflansch auf einen Anschluss des Stromleiters erstreckte Beschirmung.

The present invention relates to a high voltage feedthrough comprising in coaxial arrangement:

• a guided along an axis conductor,
• an insulator attached to the conductor and comprising the conductor, comprising a hardened polymer composition;
• a capacitor winding embedded in the cured polymer composition and having condenser linings electrically insulated from one another, which are held apart in the radial direction by an insulating film wound around the axis;
• a mounting flange attached to the insulator and
• a shield extending from the mounting flange to a terminal of the conductor.

Such a high-voltage bushing connects a conductor arranged in a metal-encapsulated component of a high-voltage installation and insulated with a solid, liquid and / or gaseous insulating means with respect to the metal enclosure with an outer conductor which is generally insulated by the surrounding air, but which is also insulated other insulating means, such as a solid, oil or SF ₆ , isolated and may be part of a high voltage cable, a cable end closure, a cable sleeve or a gas-insulated switchgear. The mechanical installation of the implementation in the component, for example in a transformer, is carried out by means of a mounting flange which is fixed to an insulator containing the capacitor winding.

A typical embodiment of such a bushing includes a field-controlling capacitor winding which is wound onto a round body designed as a metal solid or hollow cylinder. The capacitor winding comprises an insulating film formed of paper or plastic, in which capacitor linings are inserted at certain intervals during winding. The insertion can be done by inserting metal foils, such as based on aluminum or by printing conductive material on the insulating film. The capacitor pads are then arranged in the form of concentric cylinders. The lengths of the capacitor pads are graded so that the capacitances between two successive pads are substantially equal. Therefore, larger diameter capacitor pads have a shorter length in the axial direction. It is thus achieved with the capacitor winding a finely graded control of an electric field, which in operation of the implementation between the then high voltage potential and operating current leading round body and the metal encapsulation of the component, which is typically designed as a transformer acts.

In the area of the bushing exposed to the ambient air, a portion of the capacitor coil is surrounded by weatherproofing, such as weather, pollution and radiation, by means of a weatherproof cover. The weather protection is in general as a porcelain housing (weather protection system A) or as a polymer housing with a hollow, typically fiber reinforced plastic pipe and mounted on the outer surface of this pipe shield of an elastomeric polymer, in particular a silicone or an EPDM (weather protection system B) formed but also have only a shield of the elastomeric polymer, which is poured directly onto the embedded in the cured polymer composition capacitor winding (weather protection system C).

The aforementioned three weather protection systems A, B and C provide a barrier against the ingress of water. Accordingly, they prevent the penetration of moisture into the cured polymer mass and therefore ensure that the moisture content in the capacitor winding does not increase and, accordingly, the electrical properties of the Implementation, such as in particular the electrical loss factor, even after several years of operation, the implementation does not change significantly.

In the weather protection system B, the plastic pipe substantially increases the mechanical strength of the bushing as it absorbs the majority of the forces acting on the bushing upon application of a mechanical load, typically a static or dynamic bending force.

STATE OF THE ART

Bushings of the type mentioned are described for example in EP 1 284 484 B1 . EP 1 417 689 B1 . EP 1 771 866 B1 and WO 2009/053147 A1 , The bushings described are each intended for installation in a metal housing of a high-voltage electrical apparatus, for example a transformer, and each have a capacitor winding integrated in an insulator. Attached to the insulator is a mounting flange which separates a portion of the capacitor coil located above the mounting flange from a portion of the capacitor coil located below the mounting flange and, after installation of the leadthrough into the apparatus, in an insulator devoid of air, typically oil or SF ₆ , is arranged. A region of these bushings exposed to the surrounding air in each case has a shield which acts as weather and radiation protection and which encloses the section of the capacitor winding located above the mounting flange.

The shielding can be like in EP 1 284 484 B1 and EP 1 771 689 B1 may be integrated into a porcelain insulator or made of silicone and fastened on a fiber-reinforced plastic pipe. But it can also - as in EP 1 417 689 B1 and WO 2009/053147 A1 described - applied directly to the between the mounting flange and a power terminal of the implementation extended outer surface of the capacitor winding receiving insulator.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object is to provide a high-voltage bushing of the type mentioned, which is easy to manufacture and at the same time characterized by a high level of reliability.

According to the present invention there is provided a high voltage feedthrough comprising in coaxial arrangement a current conductor routed along an axis and an insulator fixed to the current conductor and comprising the current conductor, comprising a hardened insulating compound. In the cured polymer composition a capacitor winding is embedded with mutually electrically insulated capacitor pads, which are held in the radial direction by a wound around the axis insulating foil with distance from each other. Furthermore, the implementation in a coaxial arrangement has a mounting flange attached to the insulator and a shielding extending from the mounting flange to a terminal of the current conductor. The shield is formed in a lateral surface of the insulator, which is formed by the cured polymer composition and is arranged radially outwardly at a distance from the capacitor winding.

In the practice of the invention, the shield is molded into the cured polymer composition. Since in the manufacture of the implementation in any case uncured polymer composition is required to impregnate the preformed by winding capacitor winding initially in a mold with the uncured polymer composition, this mold can be used advantageously in manufacturing technology, the shield in a suitable manner in a lateral surface of the Harden mold forming isolator. For this purpose, the casting mold only requires circular depressions guided around the axis of the bushing, which are spaced from one another in the axial direction and formed in the inner wall of the casting mold.

Since the capacitor winding integrating insulator and the shield can be made using only a single mold, eliminating the need for the prior art with the weather protection systems B or C second mold for an elastomeric shielding. Since such a mold is determined by specifications of a supplier, now the material and the Design of the shielding can be set independently of external factors and so the performance of the implementation can be optimized. In addition, a time- and cost-intensive mechanical processing of the capacitor winding receiving insulator in the field of shielding is eliminated.

In the manufacture of the implementation accounts for both a complex attachment and a labor-intensive installation of a weather protection system A or B and a failure-prone interface between the insulator and applied to the insulator, elastomeric shielding a weather protection system C. There will also be a special equipment and additional time avoided, as occurs in the manufacture of the implementation with the weather protection system C. Likewise, a gap between the capacitor winding and the weather protection system A or B is avoided, so that now a dry filler to fill the gap and a necessary equipment are unnecessary. It also eliminates an often lasting one to two days period, which is needed to harden the initially introduced in liquid form in the gap filler. Furthermore, accounts for after filling the gap with filler and after curing of the filler forming, susceptible to interference two interfaces between the capacitor winding and the dry filler, respectively. the dry filler and the weather protection system A or B. In addition separate separate flanges, which are otherwise at the top and at the foot of the weather protection systems A or B have to carry implementation. In contrast to bushings with the weather protection system B or C, the implementation of the invention is largely protected against destruction by animals (animal food).

In order to protect the capacitor winding against external disturbing factors, such as moisture, radiation or the introduction of mechanical load, the shell surface of the insulator, as determined by the shielding, has a suitably dimensioned spacing radially outward relative to the capacitor winding.

The implementation of the invention can therefore be manufactured inexpensively and at the same time has a high reliability.

As the polymer of the cured polymer composition, a thermoset, in particular a polyurethane or an epoxy resin, may be selected, which is advantageously a cycloaliphatic epoxy resin in view of good outdoor resistance.

To increase the outdoor resistance of the cured polymer composition, the surface of the shield may be coated with a hydrophobic material, particularly an organopolysiloxane.

The mechanical strength of the implementation and in particular of the shielding can be increased if the polymer composition comprises an inorganic filler, in particular a powder based on SiO ₂ and / or Al ₂ O. If the proportion of the filler in the polymer composition is 60 to 80 percent by weight, the implementation can be subjected to particularly high mechanical and thermal stress.

In order to achieve an additional increase in the mechanical strength of the bushing, a reinforcement may be embedded in the polymer compound, which may optionally also extend into at least one screen of the screen.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht auf eine längs einer Achse A erstreckte erste Ausführungsform der Durchführung nach der Erfindung, die links der Achse geschnitten dargestellt ist,

Fig.2

eine Vergrösserung eines umrandet dargestellten Teils der Durchführung nach Fig.1, und

Fig.3

ein gemäss Fig.2 dargestelltes Teil einer zweiten Ausführungsform der Durchführung nach der Erfindung.

With reference to drawings, the invention will be explained in more detail below. Hereby shows:

Fig.1

a plan view of a along an axis A extending first embodiment of the implementation of the invention, which is shown cut left of the axis,

Fig.2

an enlargement of an outlined portion of the implementation after Fig.1 , and

Figure 3

one according to Fig.2 illustrated part of a second embodiment of the implementation of the invention.

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals designate like-acting parts. The in the FIGS. 1 and 2 shown, aligned along the axis A embodiment of the inventive implementation includes in coaxial arrangement a guided along the axis A current conductor 10, a conductor attached to the conductor and the insulator comprising insulator 20, a mounted on the insulator 20 mounting flange 30, an integrated capacitor 20 in the capacitor winding 40 and a formed in the insulator 20 Shield 21st

The current conductor 10 may be electrically connected at its lower end, not shown, to a power connection of a conductor of an electrical apparatus, typically a transformer, arranged in an insulating medium-filled metal housing. Its upper end formed by the power connection 11 can be electrically conductively connected to a high-voltage conductor which is generally free-air-insulated.

The shield 21 is guided along the axis A from the mounting flange 30 to the power connector 11. It serves as weather and radiation protection.

The capacitor winding 40 has mutually electrically insulated capacitor pads 41, which are held in the radial direction by a wound in the form of a spiral insulating film 42, which is typically made of paper and / or plastic, at a distance from each other. The lengths of the capacitor pads 41 above the mounting flange 30, so in an air exposed portion 24 of the implementation, as well as below the mounting flange 30, so in a the insulating of the metal-clad apparatus exposed, only partially shown section 26 of the implementation shrink with increasing, radial distance to the conductor 10 steady.

The capacitor winding 40 is used to control an electric field, which forms during operation of the implementation between the then located at high voltage potential conductor 10 and then located at the potential of the metal housing of the transformer mounting flange 30. The insulating film 42 and the capacitor pads 41 of the Capacitor coils 40 are embedded in a matrix of hardened polymer mass 22. The shield 21 is formed in a radially outwardly spaced from the capacitor winding 40 held portion of the cured polymer composition. The polymer mass 22 has a thermoset, filled or unfilled polymer. Particularly suitable is a thermoset based on a polyurethane or a cycloaliphatic epoxy resin. The filler used is generally an inorganic powder based on SiO ₂ and / or Al ₂ O ₃ with particle sizes which are typically between 0.01 and 2 mm. To ensure a particularly high mechanical strength of the implementation, the proportion by weight of the filler in the polymer mass 22 is advantageously 60 to 80 weight percent.

To make the implementation is - as in WO 2009/053147 A1 described the typically paper or plastic containing insulating film 42 wound on the rotatably mounted conductor 10 to form a spiral and the typically metal foil-containing capacitor pads 41 are inserted during the winding process in the individual turns of the spiral.

A thus formed, the conductor 10 and the capacitor winding 40 containing winding body is arranged in a mold, not shown. The mold has in its inner wall along the axis A from each other at a distance from each other and annularly guided around the axis depressions. Further, the mold has two openings, one of which is the vacuum-tight implementation of the upper power connector 11 and the other of the vacuum-resistant implementation of the lower power connector, not shown.

The capacitor winding 40 is then - generally under vacuum - dried and then - generally also under vacuum - impregnated in the mold with the uncured polymer composition. According to the state of the art WO 2009/053147 A1 described insulating film 42 and optionally also the capacitor pads 41 have permeable pores and channels for the uncured polymer composition. The uncured, at a high filler content, a high viscosity polymer composition may Therefore, even at high viscosity quickly penetrate into the interior of the capacitor winding 40.

Subsequently, the polymer composition in the mold to form the matrix and thus also to form the insulator 20 and the shield 21 - generally at elevated temperatures - cured. Then, the shield 21 and the stator 20 attached to the current conductor 10 containing moldings of the mold is removed. In this molding a seat for the mounting flange 30 is machined. The mounting flange 30 is typically fixed by gas or liquid tightness by gluing or cold shrinking on the insulator 20, so that after installation of the implementation in the metal housing of the high voltage component neither air into the interior of the metal housing still oil can escape from the housing.

If the polymer composition contains a cycloaliphatic epoxy resin, then a bushing produced as described above is generally sufficiently protected against solar radiation, moisture and contamination. Unlike a prior art bushing with a shield 21 made of an elastomer such as a silicone, the shield 21 has high mechanical strength. It is achieved by the integration of the shield 21 in the insulator 20 not only a significant simplification of the production of the implementation, but also avoided that the individual screens of the shield 21 of animals - can be damaged - for example by Frass.

An improved protection against penetration through moisture is achieved if a surface exposed to the weathering of the screen 21 is coated with a hydrophobic material. An organopolysiloxane, which has been used as a coating material, has proven effective as in US 2011/0027532 A1 described in liquid form can be applied to the surface.

In the embodiment according to Figure 3 is in contrast to the embodiment of the FIGS. 1 and 2 integrated in the insulator a largely axially symmetrical reinforcement 23 formed. This reinforcement supports the predominantly formed from the relatively brittle, cured polymer mass 22 Insulator 20 and thus increases its mechanical strength. The reinforcement may be integrated into the exposed outdoor section 24 of the insulator, but may also be integrated into a section 25 of the duct through the mounting flange 30. Alternatively, the reinforcement 21 may also be integrated into only one of the two sections 24 or 25 or else into the section 26 of the insulator 20 situated below the mounting flange 30, that is to say in a region of the bushing exposed to the insulating means of the transformer. The reinforcement has at least one layer 23a of a planar semifinished fiber product which is guided in the circumferential direction around the capacitor winding 40 and which advantageously contains at least one woven fabric, a scrim, a mat or a fleece. Suitable fibers are inorganic fibers, for example based on glass or basalt, or inorganic fibers, for example based on aramid. How out Figure 3 can be seen, the reinforcement 23 may also have predominantly radially aligned, annularly guided around the layer 23a deposits 23b, which extend from the position 23a radially outwardly into the individual screens of the shield 21 and increase the mechanical strength of the shield.

In the manufacture of the implementation of the conductor 10 and the capacitor winding 40 containing winding body and the reinforcement 23 are arranged in the previously described, not shown mold and dried as described above under vacuum, impregnated with the uncured polymer composition and the polymer composition to form the insulator 20th hardened.

LIST OF REFERENCE NUMBERS

10

conductor

11

power connection

20

insulator

21

canopy

22

hardened polymer composition

23

reinforcement

23a

Layer of semi-finished fiber

23b

Inserts made of semi-finished fiber

24, 25, 26

Portions of the insulator 20

30

mounting flange

40

capacitor winding

41

capacitor plates

42

insulation

A

axis

Claims (10)

High voltage bushing, containing in coaxial arrangement: a current conductor (10) guided along an axis (A), an insulator (20) fixed to the current conductor (10) and comprising the current conductor (10), containing a hardened polymer compound (22), a capacitor winding (40) embedded in the hardened polymer mass (22) with capacitor linings (41) electrically insulated from one another and spaced apart from one another in the radial direction by an insulating foil (42) wound around the axis (A), a mounting flange (30) fastened to the insulator (20) and a shielding (21) extending from the mounting flange (30) onto a connection (11) of the current conductor (10), characterized in that the shield (21) is formed in a lateral surface of the insulator (20) formed by the cured polymer mass (22) and arranged radially outwardly at a distance from the capacitor winding (40). Bushing according to claim 1, characterized in that a duroplastic, in particular a polyurethane or an epoxy resin, is chosen as the polymer of the cured polymer composition. Bushing according to claim 2, characterized in that the thermoset is a cycloaliphatic epoxy resin. Feedthrough according to one of claims 1 to 3, characterized in that the surface of the shield (21) is coated with a hydrophobic material. Bushing according to claim 4, characterized in that the coating is formed by an organopolysiloxane. Feedthrough according to one of claims 1 to 5, characterized in that the polymer composition comprises an inorganic filler. Feedthrough according to claim 6, characterized in that the filler contains a powder based on SiO ₂ and / or Al ₂ O ₃ . Feedthrough according to one of claims 6 or 7, characterized in that the proportion of the filler in the polymer composition is 60 to 80 percent by weight. Feedthrough according to one of claims 1 to 8, characterized in that in the polymer mass a reinforcement (23) is embedded. Bushing according to claim 9, characterized in that the reinforcement extends into at least one screen of the shield (21).

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