DE102018119476A1 - Material for directional control of an electrical field - Google Patents

Abstract

The invention relates to a material (1) for controlling an electrical field, comprising a matrix material (2) and textile fibers (3) which are held in the matrix material (2), at least some of the fibers (3) having a predetermined orientation is arranged in the matrix material (2).

Description

The invention relates to a material for controlling an electrical field, a component for controlling an electrical field, a method for producing a material for controlling an electrical field and the use of textile fibers. The invention is particularly suitable for use in field control in high-voltage technology.

The improvement of electrical field distributions in facilities for electrical energy supply with the help of targeted field control measures represents an important area of responsibility for high voltage technology. Such field control measures are used, for example, in cable fittings, bushings, transformers, rotating electrical machines, isolators or surge arresters. In this context, field tax measures contribute to the provision of reliable and economical equipment. The term "field control" includes in particular all measures that serve to lower local electrical field strengths to such an extent that the electrical strengths of the insulating materials and the interfaces are never exceeded. In principle, one can differentiate between field-controlling measures in the volume of an insulating material and along interfaces. In the narrower sense, field control means measures to influence electrical field strengths along interfaces, which often represent special weak points in an insulation system.

The control of the electrical load of insulation systems, especially at interfaces, is therefore a major challenge for the design of long-lasting and reliable (high-voltage) components in which high voltages or electrical field strengths can occur. This includes not only energy supply systems (such as the implementation of transformers, connecting elements of cable systems, implementation of encapsulated switchgear, etc.), but also medical technology systems (e.g. computer tomographs) and / or cable systems for electromobility , The electrical field control is necessary to distribute the load on the electrically non-conductive insulating materials as evenly as possible and not to overload the insulation locally.

In the case of AC voltage, the field conditions generally result as a capacitive displacement field, which is largely determined by the permittivities or dielectric constants of the materials. In contrast, with DC voltage there is usually a resistive or conductive flow field for which the conductivities are responsible. In the case of mixed fields and / or transient loads, more complex field conditions can also occur. In any case, an exact knowledge of the electrical and dielectric material properties is advantageous. If interfaces from an electric field are normal or orthogonal, i.e. perpendicular to the interface, a simplified view can be made, which is limited to the loads of the adjacent insulating materials. However, if tangential loads, i.e. If loads occur parallel to the interface, the generally lower electrical strength along the interface has a disadvantageous effect. In this context, it can often be determined that the interface has a lower electrical strength than would be expected on the basis of the properties of the media which adjoin one another. It has also often been found that the structure of a typical insulation structure favors the very early ignition of discharges and the spread of high-current, far-reaching and eroding sliding discharges. In this case one speaks of a so-called “sliding arrangement”.

A typical example of such a sliding arrangement is the end of a cable as shown in 1a is illustrated, in which the high voltage conductor 6 surrounding cable insulation 7 is exposed and on which the grounded outer conductive layer (cable sheath 8th ) ends with sharp edges. Without field control measures, extremely high local field strengths result. The corresponding field lines 5 (Equipotential lines) are in 1a indicated.

• - In 1b ist beispielhaft und schematisch eine geometrische Feldsteuerung durch die geometrische Gestaltung von Elektrodenkonturen veranschaulicht. Für die geometrische Feldsteuerung wird hier ein ggf. mit dem Erdpotential des Kabelmantels gebildeter und in einem Steuerkonus 9 angeordneter Deflektor 19 genutzt.
• - In 1c ist beispielhaft und schematisch eine kapazitive Feldsteuerung durch leitfähige Steuerbeläge 10 mit kapazitiv bestimmter Spannungsaufteilung bei Wechsel- bzw. Stoßspannung veranschaulicht.
• - In 1d ist beispielhaft und schematisch eine refraktive Feldsteuerung durch hoch permittives Material 11, insbesondere hochpermittive Isolierstoffe mit dielektrisch (bzw. kapazitiv) verzerrter Feldverteilung bei Wechsel- und Stoßspannung veranschaulicht.
• - In 1e ist beispielhaft und schematisch eine resistive Feldsteuerung durch halbleitendes Material 12, beispielsweise gebildet mit restleitfähigen Steuerbelägen oder halbleitenden Leitschichtaufträgen, mit resistiv bestimmter Spannungsaufteilung veranschaulicht.
• - In 1f ist beispielhaft und schematisch eine nichtlineare resistive Feldsteuerung durch Materialien, die sich in Bereichen mit hoher Feldstärke durch Leitfähigkeitszunahme selbst entlasten, veranschaulicht. Hierzu wird nichtlineares Material 13 verwendet, das bei niedrigen Feldstärken isolierende Eigenschaften aufweist und bei höheren Feldstärken in einen wesentlich besser leitfähigen Zustand übergeht.

Various field control methods are available to avoid or defuse sliding arrangements:

• - In 1b A geometrical field control is exemplarily and schematically illustrated by the geometrical design of electrode contours. For the geometric field control, a cone, possibly formed with the earth potential of the cable sheath, is used here 9 arranged deflector 19 used.
• - In 1c is an example and schematic of a capacitive field control by conductive control pads 10 illustrated with capacitively determined voltage distribution for AC or surge voltage.
• - In 1d is an example and schematic of a refractive field control using highly permittive material 11 , in particular highly permeable insulating materials with a dielectric (or capacitive) distorted field distribution with AC and surge voltage.
• - In 1e is an example and schematic of a resistive field control through semiconducting material 12 , for example formed with residual conductive control coatings or semiconducting guide layer applications, illustrated with resistively determined voltage distribution.
• - In 1f is exemplarily and schematically illustrated a nonlinear resistive field control by materials that relieve themselves in areas with high field strength by increasing conductivity. This is done using nonlinear material 13 used, which has insulating properties at low field strengths and changes into a much better conductive state at higher field strengths.

In these five technical approaches to electrical field control (geometric, capacitive, refractive, resistive, non-linear), the last three are based on the properties of the insulating materials used. The material properties can be adjusted by introducing powdered fillers and modified evenly in all directions due to the lack of order of the fillers. None of these three approaches, or none of the technologies associated with them, has so far allowed the material properties to be adjusted depending on the direction.

The fillers mentioned are generally kneaded in the form of powders into an uncrosslinked polymer matrix and then poured or injected. Due to the resulting disordered structure of the mostly spherical or flat fillers, the electrical conductivity is influenced uniformly regardless of the direction of the current flow. Differences only arise due to concentration differences of the fillers or the partial presence and absence of so-called “filler bridges”, in which filler particles are arranged in a long chain and touch each other. However, this effect has so far not been able to be set in a targeted manner depending on the direction; rather, these filler bridges are created more by chance, which can even be disadvantageous for targeted influencing of the electrical field.

Proceeding from this, it is an object of the present invention to at least partially solve the problems described with reference to the prior art. In particular, a material for controlling an electrical field, a component for controlling an electrical field, a method for producing a material for controlling an electrical field and the use of textile fibers are to be specified, each of which at least contribute to enabling direction-dependent field control. In addition, the simplest possible and cost-effective production and / or free design of component shapes should also be possible.

These objects are achieved by the features of the independent claims. Further advantageous refinements of the solution proposed here are specified in the dependent claims. It should be pointed out that the features listed individually in the dependent patent claims can be combined with one another in any desired, technologically sensible manner and define further refinements of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, further preferred embodiments of the invention being illustrated.

A material for controlling an electrical field contributes to this, comprising a matrix material and textile fibers which are held in the matrix material, at least some of the fibers being arranged in the matrix material with a predetermined orientation. As a result, the electrical conductivity in the fiber direction can advantageously be increased compared to one or more transverse directions (based on the fiber direction).

The solution proposed here advantageously contributes to specifying an electrical field control for, for example, DC voltage applications, in which the distribution of the electrical field is direction-dependent, by means of a particularly homogeneous introduction of (thin) preferably electrically conductive textile bevels into a matrix material or an insulating material can be influenced or is influenced. In other words, this means in particular that the solution presented here (for the first time) permits direction-dependent field control. It has surprisingly been found that by introducing textile fibers with preferably adjusted or adjusted electrical properties (such as a predetermined electrical conductivity) into a matrix material, in particular a surrounding insulating material (with a low electrical conductivity), the material properties of which are changed in the direction of the fibers can. For an electrical field control, the electrical conductivity of the resulting composite material can be influenced. With the help of the aligned textile fibers, it is particularly advantageously possible to (only) modify the material properties relevant for electrical field control in one or two spatial directions. This advantageously enables the design and construction of completely new component shapes that could not previously be realized.

The material for controlling an electrical field is in particular a material for field control or a field control material (or a field control material). In other words, this means in particular that the material is set up in such a way that it can at least influence or control, in particular smooth, the course of equipotential lines or field lines of an electrical field and / or reduce their slope or maximum density. In other words, the latter means in particular that the maximum of the electric field strength can be reduced. In this context, a lower density results in particular from a greater distance between the corresponding field or equipotential lines and indicates a lower field strength.

It has surprisingly been shown that the field lines can be guided in the thread direction (course of the textile fiber). In particular, the electrical conductivity in the fiber direction can be increased compared to one or more transverse directions (based on the fiber direction). This can be used advantageously to influence the field lines in order to enable direction-dependent field control. In particular, this effect can also depend on a temperature and / or possibly field strength-dependent ratio of the electrical conductivity of the fibers and the surrounding matrix. However, the directional dependency of the field control presented here with the aligned fibers can in principle also be observed independently of the temperature and / or possibly field strength-dependent ratio of the electrical conductivity of the fibers and the surrounding matrix or without special consideration of the temperature and / or possibly field strength-dependent ratio the electrical conductivity of the fibers and the surrounding matrix.

The matrix material is in particular an electrically insulating (matrix) material. In other words, this means in particular that the matrix material has electrically insulating material properties. The matrix material preferably has an electrical conductivity of less than or equal to 10 ^-10 S / m [Siemens per meter], preferably less than or equal to 10 ^-13 S / m or even less than or equal to 10 ^-16 S / m. In this context, an electrical conductivity of less than or equal to 10 ^-16 S / m is particularly preferred.

The matrix material is preferably at least partially formed with an electrical insulating material. At least one of the following materials or a combination thereof can be considered as the insulating material: ethylene-propylene-diene rubber (EPDM / EPR), silicone rubber, silicone resin, epoxy resin, unsaturated polyester resins, glass fiber reinforced plastic (GRP), polyurethane (PU), polyethylene ( PE), cross-linked polyethylene (VPE), ceramics, glass, soaked insulating tapes (fiberglass, paper, mica, aramid), polyamides (PA), polytetrafluoroethylene (PTFE).

The (textile) fibers are usually elongated. In other words, this means in particular that the longitudinal extension of the fiber is many times greater than its thickness or its diameter. The orientation of a fiber here relates in particular to the direction from one fiber end to the other fiber end of the (elongated) fiber. The fibers are, in particular, textile (melt-spun) filaments with a finite length. The fibers preferably have a (predetermined) minimum length of 10 mm, preferably 15 mm, particularly preferably 20 mm or even 30 mm [millimeters]. The minimum lengths specified here can advantageously contribute to the fibers in a component being able to extend from one (end) side to an opposite (and facing away from) the (end) side of the component. It is further preferred if a maximum length of the fibers corresponds to a (maximum) component length.

The fibers are preferably (compared to the matrix material) electrically conductive fibers. In other words, this means in particular that the fibers have electrically conductive material properties, in particular have better electrically conductive material properties than the matrix. The fibers preferably have an electrical conductivity (possibly dependent on temperature and / or field strength) of less than or equal to 10 ^-9 S / m [Siemens per meter], particularly preferably less than or equal to 10 ^-12 S / m or even less than or equal to 10 ^-15 S / m on. To increase the electrical conductivity of textile bevels in this z. B. (linear or non-linear) conductive particles can be integrated.

The fibers preferably have an electrical conductivity of less than or equal to 10 ^-9 S / m if the matrix material has an electrical conductivity of less than or equal to 10 ^-10 S / m. Furthermore, the fibers preferably have an electrical conductivity of less than or equal to 10 ^-12 S / m if the matrix material has an electrical conductivity of less than or equal to 10 ^-13 S / m. The fibers particularly preferably have an electrical conductivity of less than or equal to 10 ^-15 S / m if the matrix material has an electrical conductivity of less than or equal to 10 ^-16 S / m. In other words, this means in particular that the difference in the conductivities should preferably be one to two orders of magnitude.

Electrically conductive (melt-spun) fibers are special for field control advantageous, which have an electrical conductivity of less than or equal to 10 ^-9 S / m [ten to the minus nine Siemens per meter]. Corresponding electrical conductivities in (melt-spun) fibers can be achieved, for example, by introducing nanoscale carbon nanoparticles (and / or microvaristors) into a thermoplastic, which is spun out as a thread and then further processed. In this connection, the thread thickness is preferably 0.5 mm to 1 mm [millimeter]. The field lines can be guided particularly advantageously in the thread direction by such filaments. The further processing of the filaments or threads includes, in particular, cutting into fibers (certain length). The thread thickness (then fiber thickness) usually does not change.

The fibers are held in the matrix material. In other words, this means in particular that the arrangement and alignment of the fibers can be fixed or fixed by means of the matrix material. In addition, the fibers are usually firmly (chemically or physically) bound to the matrix material.

At least some of the fibers are arranged in the matrix material with a predetermined orientation. Preferably at least 50% or even all of the fibers present are arranged in the matrix material with a predetermined orientation. Alternatively or cumulatively, a maximum of 80% of the fibers present are arranged in the matrix material with a predetermined orientation. Fibers with a predetermined orientation differ in particular from fibers which are only used as fillers and are therefore non-directional. However, it can be provided that in addition to the fibers with a predetermined orientation, (non-directional) filler fibers and / or other fillers, such as powder, are also held or contained in the matrix material.

Furthermore, the fibers are preferably introduced homogeneously in at least a partial area of the material or in a body produced by means of the material, in particular arranged homogeneously (equidistantly) and / or aligned homogeneously (parallel). A homogeneous introduction of the fibers advantageously contributes to a distribution of the electric field that is as homogeneous as possible. In addition, the homogeneous introduction can also help to at least reduce the risk of thermal overloading of the fibers or electrical overloading of the matrix.

At least part of the fibers is preferably aligned parallel to an interface and / or an outer surface of a body formed at least partially or even completely with the material. Since the field lines can be guided in particular in the thread direction, this can advantageously contribute to a more uniform distribution of the field lines. Alternatively or cumulatively, at least some of the fibers with an interface and / or an outer surface of a body formed at least partially or even completely with the material enclose an angle greater than 0 ° [zero degrees] and less than or equal to 90 °. In the latter case in particular, it is particularly preferred if at least some fibers extend to the interface and / or the outer surface.

At least some of the fibers are preferably oriented as a function of an expected field line course or equipotential line course and / or an expected field distribution or potential distribution. For example, for a large number of applications, such as the sliding arrangement described at the outset, it is known which courses and / or distribution (at least in idealized form) are to be expected. Alternatively or cumulatively, for example, a simulation of a possible application of the material can help to determine the courses and / or distributions to be expected.

It is particularly preferred for at least some of the fibers to be oriented in such a way that the material properties relevant for electrical field control are (only) modified in one or two spatial directions. These material properties are in particular the electrical conductivity and / or the thermal conductivity. In particular, in order to modify the material properties that are decisive for an electrical field control (only) in one spatial direction, it is advantageously possible to use individual (aligned) fibers which may be aligned parallel to one another. In particular, in order to (only) modify the material properties relevant for an electrical field control in two spatial directions, an (aligned) fiber braid can be used, for example. In other words, this means in particular that the fiber braid is arranged in the matrix material with a predetermined orientation. The fiber braid can advantageously contribute to two-dimensional field control.

At least some of the fibers preferably run straight. Alternatively or cumulatively, it can be provided that at least some of the fibers describe curves and / or kinks.

According to an advantageous embodiment, it is proposed that the electrical conductivity of the fibers, in particular at least a factor of five (5), is higher than the electrical conductivity of the matrix material. The electrical conductivity of the fibers is preferably at least ten times (10) as large as the electrical conductivity of the matrix material. The electrical one is particularly preferred Conductivity of the fibers at least a hundred times (100) as large as the electrical conductivity of the matrix material. It was found that the introduction of (finite) threads or chamfers, which have a higher electrical conductivity than the surrounding (insulating) material, can advantageously influence the distribution of the electrical field. In order to increase the electrical conductivity of the chamfers, for example, corresponding particles may have been introduced therein, in particular during a melt spinning process.

According to an advantageous embodiment, it is proposed that the fibers contain carbon particles. By introducing carbon particles or carbon particles into a thread base material (for example thermoplastic), linear-ohmic behavior can advantageously be achieved (for DC voltage applications). In this context, the carbon particles in particular produce a change in the basic electrical conductivity of the resulting composite material (ohmic behavior). It is particularly preferred that the fibers contain nanoscale carbon nanoparticles.

According to an advantageous embodiment, it is proposed that the fibers contain microvaristors. The microvaristors are in particular microvaristor particles. For this purpose, nonlinear materials such as zinc oxide (ZnO), silicon carbide (SiC) and / or iron oxide (FeO), in particular in the form of (nano) particles, can be embedded in a thread base material (e.g. thermoplastic) and form the so-called microvaristors therein. The microvaristors generate (in particular with a sufficient degree of filling) in particular an electrical conductivity which is dependent on the electrical field load (non-linear ohmic behavior). As a result, it can be achieved in an advantageous manner that the electric field can be displaced and lowered at points of maximum field strength by locally increased electrical conductivity. The non-linear behavior is achieved in particular through tunnel effects at the grain boundaries of the particles.

Thus, on the one hand, fibers can be used which, for example, have a linear-ohmic behavior with carbon particles and, on the other hand, fibers filled with microvaristors, which have a non-linear-ohmic behavior. The five existing possibilities for electrical field control are advantageously supplemented by the use of linear resistively controlling or non-linear resistively controlling fibers by two further options. This results, for example, in application potential in the increasingly high-voltage direct current transmission systems (HVDC) and other direct current applications, for example in medical technology or electromobility.

The fibers preferably form a predetermined (minimum) portion of the total volume of the partial area of the material in at least one partial area of the material or in a body produced using the material. The predetermined (minimum) proportion can advantageously contribute to adjusting the electrical conductivity of the composite material. If the conductivity of the composite material is too high, for example, the material heats up too much and can be thermally destroyed. For example, the (minimum) proportion can be predetermined in such a way that the field control is achieved to the desired extent and / or locally inadmissible heating is avoided as far as possible.

In addition, it should preferably be taken into account that the electrical conductivity increases sharply in the area of the so-called percolation threshold. This applies in particular to any fillers that may be present, such as carbon particles and / or microvaristors, in the fibers. The (weight) proportion of fillers in the fibers is also referred to here as the degree of filling. The fibers preferably have a predetermined degree of filling in at least a partial area of the material or in a body produced by means of the material. If a desired electrical conductivity with fillers is to be adjustable, it is particularly advantageous that the fillers in the fibers observe the percolation threshold so that the desired electrical conductivity can be set particularly advantageously. It is therefore particularly advantageous if the degree of filling is set as precisely as possible. A degree of filling in the range from 0.5 to 2% by weight is particularly preferred here.

According to a further aspect, a component for controlling an electrical field is proposed, the component being formed at least partially with a material proposed here for controlling an electrical field.

The component can be a body that is at least partially or even completely formed with the material proposed here. The component itself can be dimensionally stable. For example, the component can have the shape of a sleeve.

The component can still be one of the following components: high-voltage bushing, high-voltage insulator, cable termination, cable sleeve.

The component is preferably an electrical component High-voltage apparatus, such as a transformer, a high-voltage cable, a conductor cable, a (gas-insulated) switchgear (disconnector, circuit breaker, current transformer, voltage transformer) or a power capacitor. In addition, the component can be one for a medical technology apparatus or for an electrically drivable vehicle (automobile).

A plurality of zones with different fiber orientations are preferably formed in the component. In other words, this means in particular that the fibers in a first zone of the component have a different (predetermined) orientation than the fibers in a second zone of the component. This advantageously means that different material properties can be set for the field control in different zones of the component. The zones can be arranged (directly or spaced apart) next to one another (and preferably not one above the other). Alternatively or cumulatively, the component can also be formed with at least one zone with (aligned) fibers and at least one zone without (aligned) fibers (zone with normal insulation).

The fibers are preferably introduced homogeneously in at least one partial area of the component, in particular arranged homogeneously (equidistantly) and / or aligned homogeneously (parallel). Furthermore, at least some of the fibers are preferably aligned parallel to an interface and / or an (outer) surface of the component. Alternatively or cumulatively, at least some of the fibers with an interface and / or an (outer) surface of the component enclose an angle greater than 0 ° [zero degrees] and less than or equal to 90 °. In the latter case in particular, it is particularly preferred if at least some fibers extend to the interface and / or the (outer) surface.

Furthermore, at least some of the (aligned) fibers in the component preferably extend from an end region of the component to an opposite (and facing away from) the (end) side region of the component. In this connection, the fibers particularly preferably extend from one (end) side to an opposite (and away from this) (end) side of the component. In other words, this means in particular that the fibers are continuous from one (end) side to an opposite (and facing away from) the (end) side of the component.

1. a) Bereitstellen eines Matrixmaterials,
2. b) Bereitstellen textiler Fasern,
3. c) Anordnen zumindest eines Teils der Fasern mit einer vorbestimmten Ausrichtung in dem Matrixmaterial.

According to a further aspect, a method for producing a material for controlling an electrical field is proposed, comprising at least the following steps:

1. a) providing a matrix material,
2. b) providing textile fibers,
3. c) placing at least a portion of the fibers with a predetermined orientation in the matrix material.

The specified sequence of process steps a), b) and c) generally results from a regular operating sequence. Process steps a), b) and c) can, however, also be carried out at least partially in parallel or even simultaneously. The method is used in particular to produce a material proposed here for controlling an electrical field.

In step a), a matrix material is made available. An electrically insulating material or an insulating material is preferably provided as the matrix material. In other words, this means in particular that the matrix material has electrically insulating material properties. In step a), the matrix material can, for example, be filled into a mold, in particular cast and / or injected.

In step b), textile fibers are made available. The fibers are preferably provided by means of a melt spinning process. In this context, a polymer mass, in particular a thermoplastic, can first be melted. Thereafter, particles for increasing the electrical conductivity, such as carbon particles and / or microvaristors, can be introduced therein. The polymer mass can then be extruded into endless threads or (endless) filaments. After the filaments have cooled, they can be cut into fibers (predetermined length). In addition, the fibers can in principle also be provided with another spinning process, such as a wet spinning process. Alternatively or cumulatively, coated textile fibers can also be provided in step b).

In step c) at least some of the fibers are arranged with a predetermined orientation in the matrix material. For this purpose, the fibers can be placed with a predetermined orientation on a layer of the matrix material and / or a floor (for example a shape) and then covered with a (further) layer of the matrix material. This process can be repeated several times. Alternatively or cumulatively, at least some of the fibers with the predetermined orientation can be stretched in two or three dimensions and then cast with the matrix material. In this context, the fibers can be draped (stretched) in two or three dimensions and then, for example, by a fixation (e.g. outer holder, textile structure) are encapsulated with the matrix material. Alternatively or cumulatively, at least some of the fibers can each be (one-dimensionally) pierced into the matrix. Furthermore, individual fibers or a fiber braid can be arranged in step c).

According to an advantageous embodiment, it is proposed that in step b) carbon particles are introduced into a polymer melt which is then spun out as a thread. The polymer melt is in particular a thermoplastic melt. The carbon particles are, in particular, nanoscale carbon nanoparticles.

According to an advantageous embodiment, it is proposed that in step b) microvaristors are introduced into a polymer melt which is then spun out as a thread. Microvaristor particles are preferably introduced into the polymer melt. The polymer melt is in particular a thermoplastic melt.

Basically, in step b) (any) electrically conductive particles, which in particular have a higher electrical conductivity than the matrix material, can be introduced into a polymer melt. For example, the electrically conductive particles can be metallic particles. These electrically conductive particles are particularly preferably (nanoscale) carbon particles and / or microvaristor particles.

Alternatively or cumulatively to the use of electrically conductive particles, intrinsically conductive polymers can preferably be used to provide the textile fibers. At least one of the following materials or a combination thereof can be considered as an intrinsically conductive polymer: chlorofluoroethylene, chloropropylene, chlorosulfone, polyamide, polychloroprene, polyethylene, PE terephthalate, polyfluorovinylidene.

According to an advantageous embodiment, it is proposed that in step c) the material properties of the material which are relevant for an electrical field control are set in a direction-dependent manner. In step c) in particular, the material properties relevant to electrical field control (due to the orientation of fibers) were modified in one or two spatial directions. A (local) electrical conductivity of the resulting composite (made of matrix material and fibers) is preferably modified or influenced in at least one spatial direction. In this context, the field lines in particular are guided or deflected in the thread direction.

In step c), at least some of the fibers are preferably aligned as a function of an expected field line course or equipotential line course and / or an expected field distribution or potential distribution. The expected courses can be determined (previously) for example (once or for a large number of manufacturing processes) by measurements on a prototype and / or by one or more simulations.

According to a further aspect, the use of textile fibers, which are arranged with a predetermined orientation in a matrix material, for controlling an electric field is proposed. This can advantageously contribute to enabling more compact and lighter designs than were previously possible with conventional field control materials. The electric field is preferably controlled in the fiber direction, in particular by guiding and / or deflecting field lines in the fiber direction (or thread direction).

The textile fibers are preferably used for direction-dependent field control. The textile fibers are particularly preferably used for direction-dependent field control in a high-voltage component, in particular high-voltage direct current transmission system (HVDC) component, a medical technology component and / or an electrically drivable vehicle, such as an electrically drivable automobile.

The field of application of the solution presented here is particularly not only limited to the field of energy technology, but rather includes all areas in which DC voltage with higher voltages or field strengths are used. Possible further fields of application are, for example, medical technology and / or electromobility. In the field of energy technology, the solution presented here is particularly advantageous for HVDC cables.

The details, features and advantageous configurations discussed in connection with the material can accordingly also occur in the component presented here, the method and / or the use, and vice versa. In this respect, full reference is made to the explanations given there for the more detailed characterization of the features.

• 1a-f: aus dem Stand der Technik bekannte Ansätze zur Feldsteuerung,
• 2: eine beispielhafte Ausgestaltung eines hier vorgeschlagenen Bauteils in einer Schnittdarstellung,
• 3: eine beispielhafte Verwendung eines hier vorgeschlagenen Werkstoffs,
• 4: eine Kabelmuffe, in einer teilweise geschnittenen Darstellung,
• 5: eine Detailansicht der Kabelmuffe aus 4,
• 6: einen Äquipotentialverlauf, der sich in einer Kabelmuffe einstellen kann,
• 7: einen weiteren Äquipotentialverlauf, der sich in einer Kabelmuffe einstellen kann,
• 8: einen Äquipotentialverlauf, der sich in der Kabelmuffe gemäß 4 einstellen kann,
• 9: eine elektrische Feldverteilung, die sich in der Kabelmuffe gemäß 4 einstellen kann, und
• 10: einen beispielhaften Ablauf eines hier vorgeschlagenen Verfahrens.

The solution presented here and its technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and / or knowledge from other figures and / or the present description. They show schematically:

• 1a-f : approaches to field control known from the prior art,
• 2 an exemplary embodiment of a component proposed here in a sectional view,
• 3 : an exemplary use of a material proposed here,
• 4 : a cable sleeve, in a partially sectioned representation,
• 5 : a detailed view of the cable sleeve 4 .
• 6 : an equipotential curve that can occur in a cable sleeve,
• 7 : another equipotential curve that can occur in a cable sleeve,
• 8th : an equipotential curve, which is in the cable sleeve according to 4 can adjust
• 9 : an electrical field distribution, which is in the cable sleeve according to 4 can adjust, and
• 10 : an exemplary sequence of a method proposed here.

1a to 1f schematically show field controls known from the prior art. For a more detailed explanation, the introductory part of the description is also referred to.

2 schematically shows an exemplary embodiment of a component proposed here 4 in a sectional view. The component 4 is set up to control an electrical field. This is the component 4 with a material proposed here 1 formed to control an electrical field. The material 1 exhibits a matrix material 2 and textile fibers 3 on that in the matrix material 2 are held, the fibers 3 with a predetermined orientation in the matrix material 2 is arranged. The component 4 is here exemplarily formed in the form of a (rotationally symmetrical) sleeve. The (elongated) fibers 3 are also aligned, for example, parallel to the center or symmetry axis of the cuff.

3 shows schematically an exemplary use of a material proposed here 1 , 3 illustrates an equipotential distribution of a slide assembly. The electric field is indicated here by means of three equipotential curves (at 25%, 50% and 75%).

If one compares the equipotential curves according to 3 with those from 1a , it can be seen that the material 1 A control of the electrical field enables, for example, a direction-dependent field control in the horizontal direction. The material points to this 1 an insulating material as a matrix material, for example 2 and electrically conductive textile fibers 3 on that in the matrix material 2 are held. This is an example of the electrical conductivity of the fibers 3 is preferably higher than the electrical conductivity of the matrix material 2 , The equipotential lines are steep to vertical on the fibers due to the higher conductivity and then follow the course of the fibers a bit the fibers 3 along before they exit. Therefore, a "step-like" course of the equipotential lines usually arises.

Here are the fibers 3 with a predetermined orientation, namely here horizontally (and continuously) as an example, in the matrix material 2 arranged. With the help of textile fibers, it is possible, for example, to modify the material properties that are relevant for electrical field control (only) in one or two spatial directions. This enables the design and construction of completely new component shapes that could not previously be realized.

4 shows schematically a cable sleeve 14 , in a partially sectioned representation. The cable sleeve 14 connects two high voltage cables 15 together. The cable sleeve 14 includes a conductor connection 16 , a shield electrode 17 , an insulating body 18 , two deflectors 19 , an external, mechanical protection 20 , a moisture barrier 21 and filler 22 on. The insulating body 18 is exemplary with a material presented here 1 to control an electric field, which is related to the 5 is illustrated in more detail. Thus, the insulating body 18 also an exemplary embodiment of a component proposed here 4 represents.

5 shows schematically a detailed view of the cable sleeve 4 , The detailed view is in 4 with the Roman numeral 5 marked and marked with a dashed frame. The reference numerals are used uniformly, so that on previous statements (in particular for 4 ) can be referred to in full.

6 shows schematically an equipotential curve that can occur in a cable sleeve. 6 illustrates a simplified electrical field distribution in an HVDC cable sleeve (HVDC stands for high-voltage direct current transmission systems) for the case when only a geometric field control is used. Thus illustrated 6 an equipotential curve of the voltage without additional field control (no fibers). It shows that the critical boundary layer between cable and sleeve, which is critical for breakdown, is not equally loaded (dashed circles).

7 shows schematically another equipotential curve that can be set in a cable sleeve. 7 in this context illustrates the field distribution when using a possible embodiment of the solution proposed here with fibers which are arranged with a predetermined orientation in the matrix material. For example, comparatively coarse, cylindrical structures for resistive field control are used in this context. Thus illustrated 7 an equipotential curve of the voltage with (additional, ie in addition to the geometric field control provided) directional field control with aligned fibers (for example formed by multi-layer fiber braids). Across from 6 shows that the full length of the (critical for breakdown) boundary layer between cable and sleeve can be used (evenly) to reduce the electrical potential.

8th shows schematically an equipotential curve, which is in the cable sleeve according to 4 can adjust. 8th in this context illustrates a field distribution that can arise when using an exemplary embodiment of the solution presented here. The field distribution according to 8th could be achieved by using microscopic (only in the upper material or sleeve body) (quasi) homogeneously distributed fibers for resistive field control. Thus illustrated 8th an equipotential curve with (quasi) homogeneous, directed field control in the sleeve. For (directional or direction-dependent) field control, fibers were used here with one compared to the insulation material of the sleeve 10 -fold increased electrical conductivity used.

Across from 6 shows that the full length of the boundary layer (critical for breakdown) between the cable and the sleeve can be used. In addition, the location of the highest electrical field load can be shifted significantly (see also 9 , dashed circle).

9 shows schematically an electrical field distribution, which is in the cable sleeve according to 4 can adjust. Here we become fibers at 8th used. Thus illustrated 9 a field distribution with (quasi) homogeneous, directed field control (in the upper material or sleeve body). 9 illustrates in particular that when using an exemplary embodiment of the solution presented here, the location of the highest electrical field load can be significantly shifted.

The result deviates greatly from the electrical field distributions that usually occur with such geometries and was a great surprise. The design of high-voltage components will in many cases be able to be changed significantly by the solution presented here.

10 shows schematically an exemplary sequence of a method proposed here. The method is used to manufacture a material for controlling an electrical field. The sequence of process steps a), b) and c) shown with the blocks 110 . 120 and 130 usually results from a regular operating procedure. In block 110 a matrix material is provided. In block 120 textile fibers are provided. In block 130 there is an arrangement of at least some of the fibers with a predetermined orientation in the matrix material.

LIST OF REFERENCE NUMBERS

1

material

2

matrix material

3

fibers

4

component

5

field lines

6

High voltage conductor

7

cable insulation

8th

cable sheath

9

control cone

10

control surfaces

11

permittive material

12

semiconducting material

13

nonlinear material

14

cable sleeve

15

High voltage cables

16

conductor connection

17

shield grid

18

insulator

19

deflector

20

protection

21

moisture barrier

22

filling material

Claims (10)

Material (1) for controlling an electric field, comprising a matrix material (2) and textile fibers (3) which are held in the matrix material (2), at least some of the fibers (3) having a predetermined orientation in the matrix material ( 2) is arranged. Material after Claim 1 , wherein the electrical conductivity of the fibers (3) is higher than the electrical conductivity of the matrix material (2). Material according to one of the preceding claims, wherein the fibers (3) contain carbon particles. Material according to one of the preceding claims, wherein the fibers (3) contain microvaristors. Component (4) for controlling an electrical field, the component (4) being formed at least partially with a material (1) according to one of the preceding claims. Method for producing a material (1) for controlling an electrical field, comprising at least the following steps: a) providing a matrix material (2), b) providing textile fibers (3), c) arranging at least part of the fibers (3) with a predetermined orientation in the matrix material (2). Procedure according to Claim 6 , wherein in step b) carbon particles are introduced into a polymer melt, which is then spun out as a thread. Procedure according to Claim 6 or 7 , wherein in step b) microvaristors are introduced into a polymer melt, which is then spun out as a thread. Procedure according to one of the Claims 6 to 8th In step c), the material properties of the material (1) which are relevant for an electrical field control are set in a direction-dependent manner. Use of textile fibers (3), which are arranged with a predetermined orientation in a matrix material (2), for controlling an electric field.

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