CA3189007A1

CA3189007A1 - Hvdc air-core reactor

Info

Publication number: CA3189007A1
Application number: CA3189007A
Authority: CA
Inventors: Josef Eder; Bernhard Frohlich; Rainer Schuster
Original assignee: Coil Holding GmbH
Current assignee: Coil Holding GmbH
Priority date: 2020-07-07
Filing date: 2021-07-07
Publication date: 2022-01-13
Also published as: EP4179555A1; BR112022026678A2; WO2022006610A1; AT523998B1; AT523998A1

Abstract

The invention relates to an HVDC air-core reactor (1) having at least two electric terminals. Said air-core reactor (1) comprises at least one hollow-cylindrical winding layer (2 - 2"), the electrical conductor wire (17) of which, together with its lateral-surface insulation layer (18), is wound helically around a reactor axis (14), and a charge dissipation layer (20) with a predefined electrical conductivity, which charge dissipation layer (20) is applied at least to an outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2 - 2") and is electrically conductively connected to at least one of the electrical terminals of the air-core reactor (1). The charge dissipation layer (20) comprises at least one first strip element (23) consisting of electrically conductive material, which runs helically around the reactor axis (14) and bears against the outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2 - 2"). The invention also relates to a method for producing such an HVDC air-core reactor (1). An HVDC air-core reactor is thus created with which undesired, field-strength-induced particle deposits can be avoided during active operation and which HVDC air-core reactor can still be constructed as cost-effectively and as functionally reliably as possible.

Description

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HVDC AIR-CORE REACTOR
The invention relates to a HVDC reactor, in particular an air-core reactor for the medium, high. and maximum voltage range in energy supply networks, with measures for suppressing particle depositions on the surface of the HVDC reactor due to field strength, as well as a method for producing a corresponding HVDC reactor.
Especially in the case of reactors installed outdoors and implemented in maximum or high voltage DC ranges (HVDC ranges), or also in direct current medium voltage sections of elec-trical energy supply networks, undesirable, permanent particle accumulations and/or a gradual accumulation of dirt particles on the surface of said reactors may occur due to the high electri-cal DC field of such reactors. This is typically amplified when the reactors are installed in an environment with a high degree of pollution. This causes so-called "black spots" on the sur-faces of such reactors. This gradual pollution process on maximum or high voltage reactors, or also on medium voltage reactors, is also referred to as "black spot phenomenon" among ex-perts.
As standard, the surface layer of these reactors has the highest possible electrical insulation capacity. With an increasing surface density and layer thickness of the aforementioned con-taminations, which typically form in a punctiform manner, an initially purely optical impair-ment of the electrically highly insulating surface of such reactors may also become a technical and/or electrical impairment. In the worst case, the insulating effect of the insulation layer, in particular the plastic insulation at the winding surface of the reactor, may be impaired and thus, the electrical behavior of the reactor may be adversely affected. This may lead to unde-sirable and/or undefined leakage currents and, in an extreme case, even an insulation failure and short circuits inside the reactor.
In order to impede such charge-induced contaminations of the reactor, it is necessary from a physical point of view, to optimally avoid or reduce the build-up of electrical charges during the operation of the reactor in or on the at least one insulation layer on the winding surface of the reactor. For this purpose, the electrical insulation layer of the reactor is to be provided at

- 2 -least partially with a charge dissipating layer, which charge dissipating layer consists of elec-trically dissipative material. This electrically dissipative material has a predetermined electri-cal conductivity, in order to thus impede the build-up of high electrical charges, in particular of increased electrostatic charges, at the insulation surface of the reactor.
The electrical con-ductivity of the charge dissipating layer and/or it electrically dissipative material is selected such that the maximally occurring charge intensities at the winding surface of the reactor re-main below a predetermined value.
In the context of reducing electrostatically induced contaminations of HVDC
air-core reac-tors, W02009/126977A1 suggests applying an electrostatic shielding at the outer lateral sur-face of the reactor. This electrostatic shielding is formed by a hollow-cylindrical jacket for the reactor, which hollow-cylindrical jacket is provided, at at least one of its axial ends, with a separate, annular collector electrode extending essentially across the circumference of the hol-low-cylindrical jacket, which collector electrode is provided for connecting to one of the elec-trical connections of the air-core reactor. The hollow-cylindrical jacket is formed of a film of electrostatically dissipative material with a surface resistivity in the range of 109 to 1014 ohm/square. This structure is satisfactory only to a limited extend as it is difficult to produce and/or because it requires individually custom-built shieldings for different geometries or di-mensions of reactors. Due to complex production procedures, increased production costs oc-cur for such HVDC air-core reactors.
Consequently, W02017/182577A1 has suggested an HVDC air-core reactor, in which the electrostatic shielding also contains a layer of electrostatically dissipative material, and which layer is provided, at at least one end, with an annular collector electrode extending essentially across the circumference of the air-core reactor for connecting to one of the connections of the air-core reactor. Here, however, this layer is formed as a spray coating, which spray coating is applied to a lateral surface of an outer winding layer of the air-core reactor. Such spray coat-ings require an increased technical effort with respect to environmental compatibility and/or low processing emissions. Additionally, it is difficult to produce as even and gap-free and/or sufficiently thick a layer thickness as possible when applying such a spray coating.
When the abbreviated designation HVDC air-core reactor or air-core reactor is used in the fol-lowing, this is to be understood to mean air-core reactors for DC voltages in the maximum, high, and medium voltage range.

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- 3 -The object of the present invention was to overcome the shortcomings of the prior art and to provide an HVDC air-core reactor, on which undesirable particle depositions due to field strength during the active operation can be reduced and which HVDC air-core reactor can still be designed as economically and functionally reliable as possible while also being produced in a process-stable manner.
This object is achieved by means of an HVDC air-core reactor and by means of a production method according to the claims.
The HVDC air-core reactor according to the invention comprises an essentially hollow-cylin-drical winding body with at least one hollow-cylindrical winding layer and has a central coil axis and at least two electrical connections. The at least one hollow-cylindrical winding layer of the air-core reactor comprises an electrical conductor wire, which electrical conductor wire is wound helically about the coil axis along with its jacket-side insulation layer, i.e. along with its jacket insulation. Preferably, the individual windings of the at least one winding layer are directly on top of one another and/or above one another with respect to the axial direction of the at least one hollow-cylindrical winding layer and thus form radially inner and outer lat-eral surfaces, each self-contained, of the at least one hollow-cylindrical winding layer. Addi-tionally, a charge dissipating layer with a predetermined electrical conductivity is formed, which charge dissipating layer is applied at least on the radially outer lateral surface of the at least one hollow-cylindrical winding layer and is connected to at least one of the electrical connections of the air-core reactor in an electrically conductive manner, preferably connected electrically parallel to the at least one hollow-cylindrical winding layer. In this regard, the charge dissipating layer comprises at least one first tape element of electrically conductive material, which at least one first tape element extends helically about the coil axis and con-tacts the outer lateral surface of the at least one hollow-cylindrical winding layer, in particular is wound helically about a radially outer winding insulation of the at least one hollow-cylin-drical winding layer and contacts this directly and/or without any gaps.
An advantage of the HVDC according to the invention according to the invention consists in that an optimal charge dissipation to at least one of the two axial end faces of the winding layer can be achieved, and thus, a gradual formation of operation-induced, punctiform con-taminations of the winding surfaces can be impeded. In particular, thereby, a charge dissipat-

- 4 -ing layer according to plan with a reliable functionality can be ensured. Due to a reliably re-producible high accuracy and functional reliability of this construction, an improved robust-ness and long-term high quality level of the charge dissipating layer can also be achieved.
Furthermore, such a design of the HVDC air-core reactor allows for a cost-efficient and/or swift producibility. In particular, a relatively process-safe production process can be created, which supports the production of high-quality HVDC reactors.
In addition, it may be useful if the charge dissipating layer comprises at least one second tape element of electrically conductive material, which at least one second tape element extends in the axial direction of the air-core reactor at least one the outer lateral surface and/or in the im-mediate vicinity of the outer lateral surface of the at least one winding layer, wherein the at least one first tape element and the at least one second tape element extend so as to cross over at multiple crossover points and contact one another at these crossover points, in particular are connected to one another in an electrically conductive manner. In this regard, it is useful if at least two, preferably three or more, second tape elements distributed across the circumference of the winding layer and extending axially are provided. Axial direction is to be understood as a course parallel to the coil axis. Thereby, electrical charges can be transported over a short distance in the direction towards the at least one second tape element and can be dissipated, via the at least one second tape element, to one of the electrical connections of the air-core re-actor, in particular to star arms of a possible winding star of the air-core reactor. In particular, this allows creating dissipation paths that are defined and/or as reliable as possible for avoid-ing or reducing electrostatic charges of the reactor lateral surface and/or the winding layer in-sulation. In this regard, the corresponding construction is particularly functionally reliable and failsafe as individual contact points with an increased transition resistance, for example due to temperature changes and/or compensation movements due to the temperature, cannot lead to a failure and/or can barely cause an impairment of the orderly function of the charge dissipating layer.
The air-core reactor may furthermore comprise a first electrically conductive winding star, which is arranged at a first axial end face of the at least one hollow-cylindrical winding layer, and a second electrically conductive winding star, which is arranged at a second axial end face of the at least one hollow-cylindrical winding layer. In this regard, it may be provided that the at least one second tape element of the electrically conductive material, extending axi-ally to the air-core reactor, connects the first to the second winding star with a predetermined k , 1 t ,

- 5 -electrical conductivity. The same applies when, instead of such winding stars, first and/or sec-ond star arm elements, each being structurally independent and radially comparatively shorter, are formed on each of the axial end faces of the air-core reactor. An advantage of this struc-tural measure consists in that no separate connecting wires and/or wire bridges or connecting straps between the charge dissipating layer and the at least one winding star and/or star arm element are necessary. This facilitates achieving low overall costs as well as the robustness and long-term reliability of the reactor. Furthermore, thereby, a multifunctionality of the tape elements is created. In particular, this allows achieving a small component variety, a robust structure, and a long-term reliable function of the charge dissipating layer.
Moreover, it may be provided that the first and second electrically conductive winding star and/or first and second star arm elements are clamped together in the axial direction at the ax-ial end faces of the air-core reactor by means of the at least one second tape element, in partic-ular are held together at least during the production phase of the reactor and/or the at least one hollow-cylindrical winding layer and/or are secured relative to one another at the desired axial distance with the interposition of the at least one hollow-cylindrical winding layer. Thereby, the at least one hollow-cylindrical winding layer can be held together in the axial direction at least proportionally or also primarily by the at least one second tape element. In this regard, the second tape elements also have the function of mechanical traction elements in addition to their function as electrical dissipation paths. Especially in smaller dimensions of air-core reac-tors, this may allow for so-called gap and/or connecting strips between the first and second winding star and/or between star arm elements axially distanced from one another to be omit-ted completely, whereby the material costs and also the production efforts for such reactors can be reduced significantly.
An embodiment, according to which it may be provided that the at least one second, axially extending tape element is arranged closer to the at least one winding layer in the radial direc-tion than the at least one helically extending first tape element, is also advantageous. Accord-ingly, it may be provided that the helically extending first tape element is wound onto the axi-ally extending second tape element in a directly contacting manner.
Advantageously, this caused the second tape element to be urged and/or pressed, by means of the first tape element, in the radial direction, against the outer lateral surface and/or against the winding insulation of the at least one hollow-cylindrical winding layer. A gradual detaching and/or lifting off of the at least second tape element from the lateral surface and/or from the winding insulation can ,..

- 6 -thereby be reliably impeded and/or precluded. It is also possible that thereby, the axial ten-sioning force and/or tensile force of the at least one second tape element can be easily in-creased and/or regulated.
According to an advantageous embodiment, it may be provided that the at least one first and the at least one second tape element are formed by identical tape materials.
This sameness can, in this regard, be defined by the material and/or the geometry of the tape materials.
Thereby, a simple structure that is as cost-effective as possible can be achieved, in which as few different components and/or elements as possible are used. Such a common parts concept also facilitates the corresponding production process of such reactors.
Furthermore, it may be useful if the electrically semiconducting and/or partially conducting material of the charge dissipating layer and/or the first and/or second tape element has a sur-face resistivity in the range of 107 to 1012 ohm/square, in particular in the range of 108 to 1010 ohm/square. Thereby, an optimized resistance range is provided. In particular, disad-vantages may set in when outside this electrical resistance range. In case of too high of a re-sistance of the charge dissipating layer, the charge carriers can no longer dissipate quickly enough, and the desired function is no longer given. A resistance that is too low, may lead to an increase of leakage currents and an associated damage to the reactor.
Moreover, it may be provided that at least one star arm of the winding stars or a holding pro-jection on at least one of the winding stars is at least partially entangled by the at least one second tape element. The same applies when, instead of such winding stars, first and/or sec-ond star arm elements, each being structurally independent and radially comparatively shorter, are formed on each of the axial end faces of the air-core reactor. Thereby, a high-strength, break-proof connection that can be established quickly between the at least one second tape element and at least one of the winding stars and/or between at least two star arm elements ax-ially distanced from one another, can be obtained. Such an electrical connection is addition-ally mechanically robust. In particular, this way, delicate transition wires and/or connecting bridges can be spared.
Furthermore, it may be provided that the at least one first tape element is wound in an over-lapping manner, at least in partial sections of the axial height of the at least one winding layer.
Thereby, a practicable design of a full-surface and/or gap-free charge dissipating layer is cre-ated. This allows the creation of a mostly homogenous charge dissipating layer and causes an k, . 1 I

- 7 -even dissipation of electrostatic charges. In this regard, the corresponding attachment is easily possible both when using relative narrow and when using relatively wide tape elements.
According to an alternative or combinatorial embodiment for the structure of the charge dissi-pating layer, it is possible that the at least one first tape element is wound in an axially dis-tanced manner, in particular in a helical manner, at least in partial sections of the axial height of the at least one winding layer. Thereby, tape material can be saved, and depending on the predominant parameters, such as voltage range, particle load, or conductivity of the tape ma-terial, a sufficient dissipation of electrical charges can still be ensured.
According to an advantageous embodiment, it may be provided that the at least one first and/or second tape element comprises a woven fabric or knitted fabric of textile fibers, glass fibers, and/or plastic fibers, which woven fabric or knitted fabric is provided with synthetic resin and conductive particles dispersed therein. Thereby, the predetermined and/or desired partial conductivity of the tape material can be selected and/or adjusted in a practicable and reliable manner. Additionally, a high robustness and/or an easily sufficient tensile strength of the at least one tape element can be achieved. The elastic stretchability of the at least one tape element can thereby easily be preadjusted and/or adapted within defined limits.
Additionally, it may be advantageous if the at least one first and/or second tape element has a thickness of between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.3 mm.
This al-lows for easy processing of the at least one tape element, and additionally, a relatively small layer thickness of the charge dissipating layer can be ensured thereby.
Moreover, it can be achieved thereby that the at least one tape element can be shaped and/or adapted well to the lateral surface and/or to the surface structures of hollow-cylindrical winding layer bearing the charge dissipating layer. In particular, this may facilitate as gap-free and/or void-free an appli-cation as possible of the charge dissipating layer on the outer lateral surface of the at least hol-low-cylindrical winding layer.
The object of the invention is also achieved by means of the method according to the claims.
This method for producing an HVDC air-core reactor comprises the following method steps:
- providing at least one hollow-cylindrical winding layer, the electrical conductor wire of which is wound helically about a coil axis along with its jacket-side insulation layer, - coating the at least one hollow-cylindrical winding layer on its outer lateral surface, which lateral surface is defined by a winding insulation with a high electrical insulation strength, L

- 8 -which winding insulation comprises the insulation layer of the conductor wire, with a charge dissipating layer, wherein the charge dissipating layer is formed or defined by winding at least one first tape element around the at least one hollow-cylindrical winding layer in a helical manner with respect to the coil axis, wherein this at least one first tape element is selected with a predetermined electrical conductivity, which predetermined electrical conductivity is lower, particularly lower by a factor of 1015 bis 1020, than an electrical conductivity of the electrical conductor wire, which predetermined electrical conductivity of the at least one first tape element is higher, however, in particular higher by a factor of 102 bis 107 than an electri-cal conductivity of the jacket-side insulation layer of the conductor wire or of the jacket-side winding insulation of the hollow-cylindrical winding layer comprising the insulation layer of the conductor wire.
In particular, an attachment of a charge dissipating layer on the outer lateral surface of the at least one hollow-cylindrical winding layer takes place by means of winding at least one first tape element around the at least one hollow-cylindrical winding layer in a helical manner with respect to the coil axis. In this process, at least the outer lateral surface of the radially outer-most hollow-cylindrical winding layer is provided with the helically applied charge dissipat-ing layer.
By means of the measures according to the invention, a cost-effective producibility can be achieved for HVDC reactors with structural measures for suppressing field strength induced particle depositions. This particularly enables a reliable dissipation of electrical surface charges, secured under typical operating conditions, to the connections and/or end faces of the HVDC air-core reactor, in particular to at least one of the electrical connections of the HVDC
air-core reactor. Simultaneously, the production process according to the invention can be re-alized in a relatively process-stable manner, so that orderly, high-quality HVDC air-core reac-tor can be produced by means of this production process. A particular advantage of the method according to the invention also consists in that the respective electrical effect of the charge dissipating layer can be easily adapted to the respective requirements and/or frame-work conditions. Furthermore, a charge dissipating layer produced and/or designed according to the claims can be adapted to a plurality of different geometries and/or dimensions of HVDC air-core reactor easily and without particular preparations or provisions. For this, only the number of windings, the overlap width, and/or the width of the tape element is to be adapted to the structural conditions of the HVDC air-core reactor. In particular, a particular a , 1 t

- 9 -type of a semiconducting and/or partially conducting tape element can cover the creation of charge dissipating layers for a plurality of geometrically or structurally different reactors.
According to a useful, further measure, applying at least one second tape element of electri-cally conducting material, the tape element extending axially to the at least one hollow-cylin-drical winding layer, to the outer lateral surface of the at least one hollow-cylindrical winding layer may be provided. Preferably, multiple, in particular three to eight, second tape elements distributed across the circumference of the hollow-cylindrical winding layer, extending axi-ally, are provided. Preferably, the second tape elements extend over the entire axial height and/or length of the respective hollow-cylindrical winding layer. Thereby, defined, axial dissi-pation paths for electrical surface charges are created, which dissipation paths can be designed efficiently in order to ensure a secured dissipation of electrostatic charges in the direction to-wards at least one of the axial end faces of the air-core reactor.
In this regard, it may be useful if the application of the at least one second tape element takes place chronologically before the at least one first tape element is wound around the at least one hollow-cylindrical winding layer, wherein the at least one first tape element and the at least one second tape element is applied so as to directly cross over one another at multiple crossover points and are thereby made to electrically contact one another.
Thereby, the at least one second, axially extending tape element is urged against the outer lateral surface of the hollow-cylindrical winding layer and/or against its winding insulation by the at least one first, helically extending tape element, and thereby, a stable structure is created and/or a process-safe, high-quality production is achieved.
A provision and implementation of the at least one first and/or second tape element with a width of between 1 cm and 40 cm, preferably between 2 cm and 10 cm, and a thickness of be-tween 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.3 mm, is advantageous. This ensures a good and/or as uncomplicated a processability as possible of the at least one tape el-ement and simultaneously, an efficient structure of the charge dissipating layer is made possi-ble.
Furthermore, it may be useful if the at least one first and/or second tape element is provided in the form of a woven fabric or knitted fabric impregnated or coated with synthetic resin, which woven fabric or knitted fabric functions as a carrier material for the synthetic resin. In this re-gard, the synthetic resin of the tape element is to have a partially crosslinked state that is pasty k.
. r

- 10 -to solid, not fluid at room temperature. In particular, the synthetic resin is to be cured and/or or hardened only partially in the processing state of the at least one tape element. This allows for an efficient, process-safe and high-quality production of the charge dissipating layer.
According to a particular embodiment, it is possible that on each of the axial end faces of the at least one hollow-cylindrical winding layer one winding star is mounted, and that the at least one second, axially extending tape element is electrically contacted with at least one of the two winding stars, preferably with both winding stars, in particular with at least one of the star arms extending radially to the coil axis. Thereby, a reliable and/or as direct a dissipation as possible of surface charges on the winding insulation of the at least one hollow-cylindrical winding layer to the winding stars and/or to the connections of the and/or on a defined voltage potential.
According to an advantageous method measure, it may also be provided that the at least one hollow-cylindrical winding layer and/or the at least one first and/or second tape element is/are heated and/or warmed up after the winding operation or application on the at least one hot-low-cylindrical winding layer, so that the synthetic resin chemically reacts on or in the at least one first and/or second tape element and in this process, the at least one first and the at least one second tape element are adhered together and/or to the outer lateral surface and/or to the winding insulation of the winding layer. This enables the creation of a robust charge dissipat-ing layer, in which detachment tendencies from the hollow-cylindrical winding layer and/or from its winding insulation, which is typically also based on synthetic resin and/or contains synthetic resin, can be virtually precluded.
According to an advantageous design, it may be provided that the at least one first tape ele-ment is wound in an overlapping manner, at least in partial sections of an axial height of the at least one hollow-cylindrical winding layer. Thereby, a full-surface and/or gap-free overlap of the winding insulation with the charge dissipating layer is made possible.
This method meas-ure also facilitates the formation of as smooth and/or as stepless a surface of the air-core reac-tor as possible, whereby the adherence of dirt and/or dust particles contained in the surround-ing air can be further minimized. This applies especially when the overlap between the axially adjacent, helically extending tape sections is formed in a scale-like and/or shingle-like man-..
. , =

ner, in particular when the at least one first tape element is wound such that it extends heli-cally upwards in the vertical direction with respect to a vertically aligned coil axis, starting from a lower initial position.
Alternatively or in combination to an overlapping attaching of the at least one first tape ele-ment, it may be provided that the at least one first tape element is wound so as to be spaced apart from one another in the axial direction, at least in partial sections of an axial height of the at least one hollow-cylindrical winding layer. Thereby, a low material requirement is at-tainable and/or the required length of tape material can be reduced thereby. A
low material re-quirement can, in this regard, reduce the expenditure, whereby a cost-effective production is attainable while maintaining sufficient dissipation of surface charges.
Moreover, an application of a stabilizing resin, which is fluid in its processing state and can subsequently be hardened and/or cured, may be provided. Preferably, such a stabilizing resin is applied only to an inner lateral surface of the at least one hollow-cylindrical winding layer, so that the jacket-side insulation layer of the electrical conductor wire is impregnated with the stabilizing resin for the at least one hollow-cylindrical winding layer only originating from the inner lateral surface of the at least one hollow-cylindrical winding layer.
Thereby, it can relia-bly and easily be ensured that no electrically insulating stabilizing resin reaches the outside of the dissipative shell and/or the charge dissipating layer, or only a minimal, insignificantly small amount of stabilizing resin adheres to said outside. This way, the orderly functionality of the charge dissipating layer on the outside and/or outer lateral surface of the at least one hollow-cylindrical winding layer can be ensured in a technically simple yet reliable manner.
According to a practicable method measure, the method step of mutual adhering and/or join-ing the at least one first and/or second tape element is performed chronologically before the method step of applying liquid stabilizing resin to the inner lateral surface of the at least one hollow-cylindrical winding layer. Thereby, it can reliably and easily be ensured that, upon ap-plication and/or introduction of the liquid stabilizing resin for the at least one hollow-cylindri-cal winding layer, the electrical contact between the at least one first and second tape element and/or the electrical contact between the windings, overlapping one another in the axial direc-tion, of the at least one second tape element is maintained, and thus, a high effectiveness of the charge dissipating layer can be ensured.

, CA 03189007 2023-01-05 , According to an advantageous measure, it may be provided that helically winding up the elec-trical conductor wire is carried out by means of a rotatable, in particular an actively driven, coil-like winding body for forming the at least one hollow-cylindrical winding layer. In this regard, it is useful if the at least one first tape element is wound onto the at least one hollow-cylindrical winding layer, before said hollow-cylindrical winding layer is taken off and/or re-moved from the coil-like winding body. This makes an efficient production possible and also, as true to size and high-quality a production process as possible is attainable thereby. This is true particularly because thereby, separate, time-sensitive and quality-critical equipping and/or modification steps related to the attaching of the charge dissipating layer can be omit-ted.
For the purpose of better understanding of the invention, it will be elucidated in more detail by means of the figures below.
These show in a respectively very simplified, schematic and exemplary representation:
Fig. I an embodiment of an air-core reactor in a perspective oblique view from above;
Fig. 2 the air-core reactor according to Fig. 1 in a perspective oblique view from below;
Fig. 3 the air-core reactor according to Fig. 1 in a sectional view with a vertical section plane;
Fig. 4 a diagram of an air-core reactor with two concentrically arranged, hollow-cylin-drical winding layers and a charge dissipating layer on the radially outermost winding layer;
Fig. 5 a section of an air-core reactor in an oblique top view with a charge dissipating layer on the outer lateral surface of the radially outermost, hollow-cylindrical winding layer;
Fig. 6 a schematic detailed view of an air-core reactor with a charge dissipating layer on the radially outermost lateral surface;
Fig. 7 a semi-finished product of an air-core reactor during a production phase of a charge dissipating layer in combination with an exemplary winding device;

= CA 03189007 2023-01-05 , Fig. 8 a further exemplary embodiment of an air-core reactor with a charge dissipating layer on the outer lateral surface of the air-core reactor.
First of all, it is to be noted that in the different embodiments described, equal parts are pro-vided with equal reference numbers and/or equal component designations, where the disclo-sures contained in the entire description may be analogously transferred to equal parts with equal reference numbers and/or equal component designations. Moreover, the specifications of location, such as at the top, at the bottom, at the side, chosen in the description refer to the directly described and depicted figure and in case of a change of position, these specifications of location are to be analogously transferred to the new position.
Figs. 1 to 3 show an exemplary illustration of an embodiment of an HVDC air-core reactor 1.
This electrical coil is referred to in short as air-core reactor 1. It does not have an iron core and is therefore considered a so-called air-core reactor. It is intended for the electrical me-dium, high, and maximum voltage range. Typical operating voltage values are above 10 kV
and may go up to the maximum voltage region of 700 kV or more. In this regard, the respec-tive air-core reactors 1 are designed for high voltage DC sections in electrical energy supply and/or energy distribution systems, in particular intended for high voltage DC
transmission (HVDC). Such HVDC air-core reactors may also be used in the context of industrial plants with a higher electrical energy demand.
The air-core reactor 1 illustrated by way of example has four essentially hollow-cylindrical winding layers 2, 2', 2", 2" ' which are arranged concentrically to one another. Typically, two to ten of such winding layers may be formed. In individual cases, it is possible for signifi-cantly more than ten hollow-cylindrical, concentrically arranged winding layers to be pro-vided. In the simplest embodiment, it is also possible for just a single hollow-cylindrical winding layer 2 to be provided. In the operating state of the air-core reactor 1, its central axis and/or coil axis 14 is vertically aligned.
When forming at least two hollow-cylindrical, coaxially positioned winding layers 2, 2', 2", 2", they are preferably arranged so as to form air gaps 3, 3', 3" between one another. In par-ticular, the individual winding layers 2, 2', 2", 2" have different outer diameters, so that es-sentially hollow-cylindrical cooling air gaps 3, 3', 3" are formed between radially distanced limiting walls of the individual, hollow-cylindrical winding layers 2, 2', 2", 2".

For a radial, mutual support between the concentrically positioned, hollow-cylindrical wind-ing layers 2, 2', 2", 2', multiple gap slats 4 arranged so as to be distributed across the cir-cumference may be provided in the cooling air gaps 3, 3', 3". However, an embodiment, which can do entirely without such gap slats 4, or which has no radially supporting gap slats 4 in at least one cooling air gap 4, is also possible.
Optionally and by way of example, winding stars 5, 6, in particular a lower winding star 5 and an upper winding star 6, are formed on each of the axial end faces 12, 13 of the hollow-cylin-drical winding layers 2, 2', 2", 2". These winding stars 5, 6 each have essentially radial star arms 7, 8 originating from one central point. However, embodiments, in which only one front side winding star 5 or 6 is provided, or in which no front side winding star is provided, are also conceivable. Alternatively, it is also possible to provide only short star arm elements in-stead of star arms 7, 8 reaching far into the center of the hollow-cylindrical winding layers 2, 2', 2", 2", which star arm elements extend in the radial direction essentially only across the thickness of the winding package defined by the hollow-cylindrical winding layers 2, 2', 2", 2', therefore extending in the radial direction essentially only across the respectively pro-vided winding layers 2, 2', 2", 2".
According to the embodiment shown, a supporting structure 9 comprising multiple insula-tors 10 is provided, by means of which the air-core reactor 1 is supported on an essentially horizontal supporting plane 11, in a load-dissipating manner, relative to a base section. Such a supporting structure 9 typically comprises multiple dot-like and/or columnar supports, so that multiple supporting points relative to the supporting plane 11 are formed. The supporting structure 9 preferably bears the star arms 7 of the lower winding star 5 and/or the relatively short and/or stump-like, radially aligned star arm elements.
The first and/or lower electrically conductive winding star 5 is, in this regard, arranged on a first and/or lower axial end face 12 of the at least one hollow-cylindrical winding layer 2-2".
The exemplary second and/or upper electrically conductive winding star 6 is assigned nearest to the second and/or upper axial end face 13 of the at least one hollow-cylindrical winding layer 2-2".

, CA 03189007 2023-01-05 , , A coil axis 14 of the air-core reactor 1 is defined by the central axis of the at least one hollow-cylindrical winding layer 2-2" and extends in the vertical direction with respect to the oper-ating state of the air-core reactor 1. Thus, the coil axis 14 of the air-core reactor 1 extends be-tween its first and second axial end face 12, 13.
For electrically connecting and/or integrating the and/or 1, it has at least two electrical con-nections 15, 16. Typically, these are assigned to the respective winding stars 5, 6 and/or indi-vidual star arms 7, 8 and/or are formed thereon. As can best be seen in Fig.
2, the first electri-cal connection 15 may be formed on a star arm 7 of the lower winding star 5, and the second electrical connection 16 of the air-core reactor 1 may be formed on a star arm 8 of the upper winding star 6. Between the connections 15, 16, the defined electrical inductivity of the air-core reactor 1 is given. Moreover, different coil taps may be formed on other points of the air-core reactor 1, in particular on points and/or positions of the air-core reactor 1 that are electri-cally insulated from the star arms 7, 8.
Fig. 4 shows a heavily schematic representation of the electrical basic structure of an air-core reactor 1. From it, it can be seen, among other things, that the individual winding layers 2, 2', 2", which are arranged concentrically to the coil axis 14, are electrically connected in paral-lel, in particular are electrically interconnected in parallel via the upper and lower winding star 5, 6. The radial width of the respective air gaps 3 formed between the individual winding layers 2, 2', 2" is dependent, in each case, on the diameters of the individual winding lay-ers 2, 2', 2".
As is known per se, each of the hollow-cylindrical winding layers 2, 2', 2" is defined by con-ductor wire 17 helically wound about the coil axis 14. Typically, the conductor wire 17 has an essentially rectangular or oval cross-section, formed from a solid conductor or from a conduc-tor bundle. The latter may also be formed like a rope or as a stranded wire cable.
The lateral surfaces of the helically wound conductor wire 17 have an electrical insulation layer 18 which may be embodied as a plastic sheathing. Typically, this jacket-side insulation layer 18 of the conductor wire 17 is formed by insulation material wound around the lateral surface of the conductor wire 17 like a bandage. This insulation material may, for example, be defined by a synthetic resin-impregnated, curable woven fabric material. The insulation layer 18 is formed such that the individual windings and/or line sections of conductor , CA 03189007 2023-01-05 . , , wires 17 of the hollow-cylindrical winding layers 2, 2', 2", the conductor wires 17 being lo-cated axially above one another, are electrically insulated from one another.
Further details and elaborations on the basic structure of such air-core reactors 1 can be gathered, for exam-ple, from AT501074A1, which traces back to the applicant. In this regard, the conductor wire 17 with its jacket-side, electrical insulation layer 18 is helically wound about the coil axis 14 such that the individual windings of the hollow-cylindrical winding layers 2, 2', 2"
are preferably arranged above one another in an uninterrupted and/or gap-free manner, mean-ing they are positioned so as to lie directly on top of one another without an axial distance, as it is schematically illustrated in Fig. 4 and additionally, is illustratively shown in Fig. 5.
Fig. 5 shows the upper end face of an air-core reactor 1 in an enlarged representation in ex-tracts. Here, four winding layers 2, 2', 2", 2" electrically connected in parallel are provided and electrically connected in parallel. Air gaps 3 between the individual winding layers serve to cool the air-core reactor 1 during its operating state. Gap slats 4 arranged by way of exam-ple keep the individual winding layers 2, 2', 2", 2' at their intended radial mutual distance.
Accordingly, the gap slats 4 are arranged at least in individual ones of the hollow-cylindrical air gaps 3. By way of example, coil ends 19 of the winding layers 2, 2', 2"
are connected to the star arm 8 of the upper winding star 6 in an electrically conductive manner. This star arm 8 also defined the upper electrical connection 16 of the air-core reactor 1.
In order to reduce or avoid electrostatic charges in and/or on at least one of the surfaces of the hollow-cylindrical winding layers 2-2', at least one charge dissipating layer 20 is formed on at least one of the lateral surfaces 21 of the hollow-cylindrical winding layers 2-2". As shown in Fig. 5, it is preferred if a charge dissipating layer 20 is formed only on the outer lat-eral surface 21 of the radially outermost winding layer 2. This charge dissipating layer 20 preferably covers the entire outer cylindrical lateral surface 21 of the hollow-cylindrical wind-ing layer 2. Additionally, it is possible to also provide the winding layer 2¨
closest to the coil axis 14, in particular the radially innermost one, with a charge dissipating layer 20 on its inner lateral surface 22. Typically, a charge dissipating layer 20 with a predetermined, electrical conductivity is formed at least on the outer lateral surface 21 of the radially outermost, hol-low-cylindrical winding layer 2, in order to thus impede excessive electrostatic charges of the outer lateral surface 21 of the hollow-cylindrical winding layer 2 and/or of the winding insula-tion of the hollow-cylindrical winding layer 2 and, in further consequence, to impede the for-mation of gradual, punctiform contaminations on the surface of the air-core reactor 1.

, CA 03189007 2023-01-05 , , The at least one charge dissipating layer 20 of the air-core reactor 1 is, in this regard, con-nected to at least one of the electrical connections 15, 16 in an electrically conducting manner.
Preferably, the at least one charge dissipating layer 20 is connected, on each of its two axial end sections, with one of the two electrical connections 15, 16 of the air-core reactor 1 in an electrically conductive manner. Accordingly, the charge dissipating layer 20, which is ar-ranged directly on the electrically insulating lateral surface 21 of the radially outermost hol-low-cylindrical winding layer 2, forms an electrical parallel connection to the hollow-cylindri-cal winding layers 2-2". In particular, the respective axial end sections of the charge dissi-pating layer 20 are polarized in a defined manner and/or applied to a defined electrical poten-tial by the electrical connection to the electrical connections 15, 16 of the air-core reactor 1.
Accordingly, surface charges, which gradually accumulate in and/or on the winding insula-tion, are dissipated in the direction towards at least one of the two electrical connec-tions 15, 16 of the air-core reactor 1, which connections 15, 16 are at a defined electrical volt-age potential during the operation of the air-core reactor 1. Consequentially, the charge dissi-pating layer 20 with its predetermined electrical conductivity forms an electrical parallel re-sistance to the at least one hollow-cylindrical winding layer 2-2".
According to the invention, the charge dissipating layer 20 comprises at least a first tape ele-ment 23 of electrically conductive and/or partially conductive material. This at least one first tape element 23 extends helically and/or spirally about the coil axis 14 and in doing so, abuts the electrically insulating, outer lateral surface 21 of the at least one hollow-cylindrical wind-ing layer 2-2'. Preferably, the at least one first tape element 23 is wound up at least on the radially outer lateral surface 21 of the radially outermost hollow-cylindrical winding layer 2.
This wrapping of the outer winding layer 2 is preferably carried out with a consistent gradient, helically with respect to the coil axis 14. Accordingly, the entire axial height 24 or also only a partial section of the axial height 24 of the at least one hollow-cylindrical winding layer 2-2"
can thus be provided with the charge dissipating layer 20.
The at least one first tape element 23 may be wound up in the same winding direction com-pared to the conductor wire 17 of the hollow-cylindrical winding layer 2 on the lateral sur-face 21 of the latter. In particular, the conductor wire 17 and the at least one first tape ele-ment 23 may each be wound up clockwise or counterclockwise with respect to the coil axis 14.

, CA 03189007 2023-01-05 , According to an advantageous embodiment, the conductor wire 17 and the at least one first tape element 23 extend around the coil axis 14 in opposite directions to one another. For ex-ample, the conductor wire 17 may be wound up clockwise, and the at least one first tape ele-ment 23 may be wound up counterclockwise and/or left-turning, so that these winding direc-tions are opposite. Thereby, a relatively planar and/or as flat an outer dissipation surface 25 of the charge dissipating layer 20 as possible may be created in an advantageous manner. Due to the planar course of this dissipation surface 25, the adherence of dirt or of liquid particles can be further impeded. A winding progression in opposite direction may be useful particularly when the at least one first tape element 23 has a relatively narrow design, in particular has an axial height and/or a tape width 27 in a range of about 50 % to 200 % of an axial height and/or axial thickness of the conductor wire 17. Especially then, an opposite winding direc-tion may effect a relatively planar and/or smooth dissipation surface 25.
The at least one first tape element 23 is preferably wound to be mutually overlapping at least in partial sections of the axial height 24 of the at least one winding layer 2-2". Accordingly, winding sections of the at least one first tape element 23 that are adjacent in the axial direction ¨ arrow 29 ¨ are placed in partial overlap relative to one another. An overlap width 26 in the at least one first tape element 21 may be minor, in particular amount to 1 %
to 10 %, or amount to up to 50 % of a tape width 27 of the at least one first tape element 23. The at least one first tape element 23 is, in this regard, fixedly joined with, in particular adhered together with, the lateral surface 21 and/or with the winding insulation of the hollow-cylindrical wind-ing layer 2-2" carrying the charge dissipating layer 20. Preferably, a resin-based adhesive connection between the at least one first tape element 23 for the charge dissipating layer 20 and the lateral surface 21 of the winding layer 2-2' is provided. Preferably, a resin-coupled and/or resin-impregnated, firmly bonded connection is established between the jacket-side in-sulation layer 18 of the conductor wire 17 and the at least one first tape element 23 for the charge dissipating layer 20. For this purpose, the at least one first tape element 23 and the in-sulation layer 18 of the conductor wires 17 are each impregnated with resin and/or coated with synthetic resin 35. The corresponding synthetic resin 35 ensures in its cured state a pro-found connection between the windings of the at least one first tape element 23 and the insu-lation layer 18, which is formed on the individual lateral surfaces of the conductor wire 17 and ultimately defines the actual lateral surface 21 of the hollow-cylindrical winding layer 2-, CA 03189007 2023-01-05 , , 2"'. Fig. 5 schematically visualizes the layer structure of the winding layer 2 with its outer lateral surface 21 and the charge dissipating layer 20 applied thereto.
In the design according to Fig. 5, the axial height of a conductor wire 17 is only a fraction, in particular less than 50 %, preferably less than 40 %, of the tape width 27 of the tape ele-ment 23. It is useful if the tape width 27 of the at least one first tape element 23 amounts to between 1 % and a maximum of 20 % of the axial height 24 of the winding layer 2-2". Pref-erably, at least five windings of the tape element 23 extending around the entire circumfer-ence are provided. In this regard, these at least five windings of the at least one first tape ele-ment 23 create a preferably full-surface coverage of the lateral surface 21 and a self-contained charge dissipating layer 20. Typically, between five to about 100 windings of the at least one first tape element 23 are useful in order to cover the entire axial height 24 with the at least one first tape element 23.
It may be useful if, with respect to an air-core reactor 1 with a vertically extending coil axis 14, the tape sections of the at least one first tape element 23 overlapping in the axial di-rection ¨ arrow 29 ¨ are designed such that a tape section positioned axially higher is located partially above the tape section that is positioned axially lower. In other words, in this regard, the at least one first tape element 23 is wound onto the outer lateral surface 21 of the radially outer hollow-cylindrical winding layer 2 helically from the bottom to the top.
This particu-larly results in a shingle-like and/or scale-like, axial overlap of the tape sections of the at least one first tape element 23. Thereby, an admission of water is made difficult, and the possibili-ties for dirt deposits are reduced.
With respect to the radial direction ¨ arrow 31 ¨ of the reactor 1, preferably, only a single layer of the at least one first tape element 23 is provided for constructing the charge dissipat-ing layer 20. Alternatively, it is also conceivable to form multiple layers radially on top of one another with the at least one first tape element 23, in order to form the charge dissipating layer 20. The individual layers of the at least one first tape element 23 may be wound in the same direction, or preferably in opposite directions, meaning they may comprise windings of the at least one first tape element 23 that cross over one another. The at least one first tape ele-ment 23 may extend continuously over the entire axial height 24 of the hollow-cylindrical winding layer 2-2" or be formed by multiple first tape elements 23, each of which being wound helically onto the lateral surface 21 of the hollow-cylindrical winding layer 2-2".

, CA 03189007 2023-01-05 , , The electrically conductive material of the at least one first tape element 23 and/or the ulti-mately created charge dissipating layer 20 preferably has a surface resistivity in the range of 107 to 1012 ohm/square, in particular in the range of 108 bis 101 ohm/square.
Thus, a good compromise between a functional conductivity and a good and/or sufficient electrical insula-tion resistance of the charge dissipating layer 20 is given.
As can be seen best from a combination of Figs. 5, 6, the charge dissipating layer 20 may comprise at least one second tape element 28 of electrically conductive material. This at least one axially extending, second tape element 28 forms, together with the at least one first, heli-cally extending tape element 23, the charge dissipating layer 20. The at least one second tape element 28 is particularly provided for ensuring a good and/or long-term stable electrical con-tacting between the at least one first tape element 23 and the at least one winding star 5, 6 and/or the at least one electrical connection 15, 16 of the air-core reactor 1. The at least one second tape element 28 extends in the axial direction ¨ arrow 29 ¨ of the air-core reactor 1 and in doing so, preferably abuts the outer lateral surface 21 of the at least one hollow-cylin-drical winding layer 2-2". As can be seen best from Fig. 5, but also from Fig.
6, this ensures that the at least one first tape element 23 and the at least one second tape element 28 extends so as to cross one another at multiple crossover points 30 and/or are arranged so as to cross.
Preferably, the at least one first electrically conductive tape element 23 and the at least one second electrically conductive tape element 28 are contacted with one another in an electri-cally conductive manner at least at individual ones of these crossover points 30. This ensures a charge dissipating layer 20 that electrically functions well.
The at least one second electrically conductive tape element 28 is contacted with at least one of the winding stars 5 or 6, preferably with both electrical winding stars 5, 6, in an electrically conductive manner. In particular, it is provided that the first electrically conductive winding star 5, which is arranged at the first axial end face 12 of the at least one winding layer 2-2", and the second electrically conductive winding star 6, which is arranged at the second axial end face 13 of this at least one winding layer 2-2", are connected in an electrically conduc-tive manner by means of the at least one second tape element 28. In particular, the at least one second tape element 28 extending axially to the air-core reactor 1 is an electrically conductive connecting element between the first and the second winding star 5, 6. The at least one axially extending second tape element 28 thus connects the first and the second winding star 5, 6 with a predetermined electrical conductivity. The same applies also when, instead of winding . CA 03189007 2023-01-05 , , stars 5, 6 and/or star arms 7, 8, star arm elements that are relatively short in the radial direc-tion ¨ arrow 31 ¨ are provided.
It is useful if the first and second electrically conductive winding star 5, 6 are clamped to-gether by means of the at least one second tape element 28 with a predetermined tensile stress in the axial direction ¨ arrow 29. This tensile stress may, in this regard, amount to a few new-tons up to several hundreds of newtons. This tensile stress may, in particular, be made de-pendent on the tensile strength and/or the stretching behavior of the at least one second tape element 28. It is useful if the at least one second tape element 28 has a high tensile strength, in order to thus press the first and second winding stars 5, 6 against the end faces of the hollow-cylindrical winding layers 2-2'. The same applies also when, instead of winding stars 5, 6 and/or star arms 7, 8, star arm elements that are relatively short in the radial direction ¨ ar-row 31 ¨ are provided.
Accordingly, the individual windings of the hollow-cylindrical winding layers 2-2" can be impeded from axially drifting apart by means of the at least one second tape element 28, among other things. The prestressing force of the at least one second tape element 28 may, in this regard, also amount to only a fraction of the total prestress required, which halts a drifting apart of the individual windings. In particular, a resin coating and/or a resin impregnation of the insulation layer 18 of the conductor wires 17 may counteract an undesired drifting apart of the individual windings. Additionally, the gap slats 4 may assume a relevant function if they are ¨ as adumbrated in Fig. 5 ¨ connected to, in particular screwed to, the two winding stars 5, 6 at least at individual locations. Preferably, multiple second tape elements 28 ar-ranged to be distributed across the circumference of the air-core reactor 1 are provided. The axial extensions of the at least one second tape element 28 are preferably at those circumfer-ential positions at which individual star arms 7, 8 of the winding stars 5, 6 span over and/or radially cross over the hollow-cylindrical winding layers 2-2". The at least one second tape element 28 may extend along the radially outer lateral surface 21 and optionally also on the radially inner lateral surface 22 of the at least one hollow-cylindrical winding layer 2-2".
Instead of the winding stars 5, 6, shown by way of example in Figs. 1-3, 5, and 8, with star arms 7, 8 extending up to the coil axis 14 and/or close to the coil axis 14, it is also possible to embody the air-core reactor 1 on one of the axial end faces 12, 13 or on both axial end faces 12, 13 with stump-like, radially extending star arm elements. Such stump-like star arm . , , elements extend in the radial direction essentially only across the radial thickness of the wind-ing package of hollow-cylindrical winding layers 2-2'.
As can further be gathered from Figs. 5, 6, it may be useful if the at least one second axially extending tape element 28 is arranged closer to the at least one hollow-cylindrical winding layer 2-2" in the radial direction ¨ arrow 31 ¨than the at least one helically extending first tape element 23. Accordingly, it is preferably provided that the at least one second tape ele-ment 28 is wrapped and/or wound over by the at least one first tape element 23 and is thus urged and/or pressed against the lateral surface 21 of the respective winding layer 2-2'.
The at least one first and the at least one second tape element 23, 28 may, in this regard, be formed by technically and/or structurally identical tape materials. The respective tape widths 27, however, may vary. Additionally, it may be provided that the at least one second tape element 28 has a greater strain strength than the at least one first tape element 23.
At least one star arm 7 or 8, preferably multiple star arms 7, 8 of the winding stars 5, 6 in each case, may be at least partially entangled by the at least one second tape element 28, in order to be able to achieve a reliable contact and an optimized application of tensile forces. Alterna-tively or in combination therewith, it is possible that in each case, at least one holding projec-tion 32 is formed on at least one star arm 7, 8 of at least one of the winding stars 5, 6, which holding projection 32 is at least partially wrapped by the at least one second tape element 28.
In particular, holding projections 32 may be provided on the star arms 7, 8 of the winding stars 5, 6, which holding projections 32 enable a firm connection and/or anchoring with re-spect to the at least one second tape element 28. These holding projections 32 may, in this re-gard, be designed in a pin-like manner and pass through the distal ends of at least individual star arms 7, 8 via bores. According to an advancement, the holding projections 32 may also be designed as a clamping and/or winding device, in order to be able to exert a tensile force on the at least one second tape element 28 during the production of the air-core reactor I.
It is useful if, in each case, pairs of second tape elements are formed, which pairs are mounted on directly opposite flat sides of the respective star arm 7 and/or 8 with respect to the circum-ferential direction of the hollow-cylindrical winding layer 2-2'. In particular, pairs of second tape elements 28 extending in parallel to one another are provided, the distance of which es-sentially corresponds with the thickness 33 of the star arms 7, 8 extending in the circumferen-tial direction of the air-core reactor 1, as this can be seen in Fig. 6.

, , , As can further be seen in Fig. 6 but also in Fig. 7 and 8, it may also be provided that the at least one first tape element 23 is wound at a mutual axial distance in the axial direction ¨ ar-row 29 ¨ at least in partial sections of the axial height 24 of the at least one winding layer 2-2". Accordingly, in each case, clearances are provided between the individual windings of the first tape element 23, in which clearances the insulating lateral surface 21 and/or the wind-ing insulation of the respecting winding layer 2-2" appears and/or is accessible. Thereby, es-pecially the required amount of the first tape material 23 can be reduced while a sufficient dis-sipation of surface charges can still be achieved, in particular in cooperation with the at least one second, axially extending tape element 28. Accordingly, the lateral surface 21 of the air-core reactor 1 may also be provided and/or coated with a grid-like structure of first and sec-ond tape elements 23, 28.
As can be seen best in Fig. 7, the at least one first and/or second tape element 23, 28 may comprise a woven fabric 34 or a knitted fabric of textile, glass, and/or plastic fibers. This wo-ven fabric 34 and/or knitted fabric is provided with synthetic resin 35 and conductive parti-cies 36 dispersed therein. Especially due to the proportion of synthetic resin 35 and conduc-tive particles 36 dispersed therein, the electrical conductivity of the first and/or second tape element 23, 28 can be adapted to the respective requirements. In this regard, it is useful if the at least one first and/or second tape element 23, 28 has a thickness 37 of between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.3 mm. Thereby, a sufficient robustness and tensile strength and/or strain strength of the first and/or second tape element 23, 28 can be ensured.
Yet, an excessive thickness of the charge dissipating layer 20 is avoided thereby.
Figs. 7, 8 illustrate a useful production process for creating an air-core reactor 1 and/or a rele-vant semi-finished product. In this process, at least one hollow-cylindrical winding layer 2, 2' is provided and/or produced by means of a winding device 38, which comprises a rotatably borne winding body 39. The example shown shows two hollow-cylindrical winding layers 2, 2', between which axially extending gap slats 4 are arranged.
The winding body 39 of the winding device 38 is rotatable about a horizontally extending ro-tation axis 40 by way of example. The winding body 39 can be driven in a controlled manner in terms of control technology. The winding body 39 comprises a plurality of support ele-ments 41 that extend parallel to its rotation axis 40, are distanced at a predetermined radial distance from the rotation axis 40, and arranged so as to be distributed on a circumference.

, , By means of the winding device 38 and/or the rotatably borne winding body 39, at least one hollow-cylindrical winding layer 2, 2' is produced, wherein the electrical conductor wire 17 of this at least one hollow-cylindrical winding layer 2, 2' is wound, along with its jacket-side insulation layer 18, helically about the conductor wire 14 of the air-core reactor 1 to be pro-duced, which conductor wire 14 corresponds with the rotation axis 40. The respective winding and production process for such air-core reactors 1 is known, for example, from AT501074A1, which traces back to the applicant.
In the production phase shown in Fig. 7, the electrical core components, in particular the hol-low-cylindrical winding layers 2, 2' are already produced by means of the winding device 38.
In the production step shown in solid lines, the radially outer hollow-cylindrical winding layer 2 is provided and/or coated with the charge dissipating layer 20 on its outer lateral sur-face 21. Additionally, a later and/or subsequent production step is illustrated in dashed lines, namely the application and/or introduction of a stabilizing resin 42 for stabilizing the at least one hollow-cylindrical winding layer 2, 2'. After a certain hardening or curing of the stabiliz-ing resin 42, an inherently dimensionally stable winding package is present, and the hollow-cylindrical winding layers 2, 2' can be taken off the winding device 38 and/or off the winding body 39.
In this regard, the charge dissipating layer 20 is produced by wrapping the lateral surface 21 of the at least one and/or outer hollow-cylindrical winding layer 2 in a helical manner with re-spect to the coil axis 14 and/or with respect to the rotation axis 40 of the winding body 39. For this purpose, a first tape element 23 is used, which at least one first tape element 23 has a pre-determined electrical conductivity. The predetermined electrical conductivity of this at least one first tape element 23 is, in this regard, significantly lower, in particular lower by a factor of 1015 to 1020, than the electrical conductivity of the helically wound electrical conductor wire 17. The predetermined electrical conductivity of the at least one first tape element 23 is, however, significantly higher, in particular higher by a factor of 102 to 107, than the electrical conductivity of the jacket-side insulation layer 18 of the conductor wire 17.
In particular, a de-fined charge dissipating layer 20 is constructed and/or defined by winding an electrically par-tially and/or restrictedly conductive tape element 23 around the previously provided, radially outer winding layer 2 on the outer lateral surface 21 of this winding layer 2.
In this regard, . CA 03,189007 2023-01-05 , , , this charge dissipating layer 20 may be designed to be full-surface and/or partial or also com-prise a combination of a full-surface and a partial coverage of the at least one hollow-cylindri-cal winding layer 2, 2', as this is illustrated by way of example in Figs. 7 and 8.
Before applying the at least one first tape element 23, it may also be provided according to a useful method step that at least one second tape element 28 is applied at least to the outer hol-low-cylindrical winding layer 2. By way of example, this at least one second tape element 28 is provided on the outer lateral surface 21 of the radially outer winding layer 2 and also on the inner lateral surface of the inner and/or innermost winding layer 2'. In this regard, in each case, multiple axially extending second tape elements 28 arranged so as to be distributed across the circumference of the winding layer 2, 2' are provided, as can be seen best in Fig. 8.
The at least one second tape element 28 extends between the first winding star 5 and the sec-ond winding star 6 in an electrically connecting manner. At least individual star arms 7, 8, for example all star arms 7, 8 of the winding stars 5, 6, are clamped together and/or held together in the axial direction ¨ arrow 29 ¨ in each case via a pair of second tape elements 28. Thus, the at least one second tape element 28 constitutes electrical connecting elements between the first and/or lower winding star 5 and the second and/or upper winding star 6 at multiple posi-tions mutually distanced in the circumferential direction of the reactor 1. In this regard, it is useful if pairs of second tape elements 28 are anchored and/or mounted at sides of the star arms 7, 8 of the winding stars 5, 6 that are opposite one another in the circumferential direc-tion. In this regard, the second tape elements 28 preferably abut and/or lie directly on the outer lateral surface 21 and/or on the inner lateral surface 43 of the winding layers 2, 2'.
A second tape element 28 applied to the at least one hollow-cylindrical winding layer 2 before the first tape element 23 is subsequently at least partially wrapped and/or urged against the lateral surface 21 by the helically applied first tape element 23. In particular, the first, heli-cally extending tape element 23 and the second tape element 28, which extends axially and essentially straight, are made to cross over one another at multiple positions running in the ax-ial direction. In particular, a plurality of mutual contacting and/or crossover points 30 between the at least one first tape element 23 and the at least one second tape element 28 are created.
This results in a reliable electrical contacting between the mentioned tape elements 23, 28 and in further consequence, due to the coupling of the at least one second tape element 28 to the , CA 03189007 2023-01-05 , .

winding stars 5, 6 and/or its star arms 7, 8, in a reliable electrical connection. The helically ex-tending first and/or the axially extending second tape element 23, 28 may have dimensions and/or material properties according to the preceding parts of the description.
In order to create an air-core reactor 1 that is compact in itself, a method is useful in which the at least one hollow-cylindrical winding layer 2, 2' and/or the at least one first and/or second tape element 23, 28 are heated and brought to a predetermined temperature level after being wound up and/or applied to the winding layer 2, 2'. This achieves that the synthetic resin 35 on or in the at least one first and/or second tape element 23, 28 reacts chemically and/or phys-ically and in this process, the first and/or the second tape element 23 is adhered to one another and/or to the outer lateral surface 21, or to the winding insulation and/or to the insulation layer 18 of the conductor wire 17. Thereby, an inherently stable and compact compound of the tape elements 23, 28, of the insulation layer 18 in the jacket region of the conductor wires 17 and of the conductor wires 17 is created.
As can also be seen from Figs. 7, 8, the at least one first tape element 23 may be wound so as to mutually overlap at least in axially extending partial sections of an axial height 24 of the at least one hollow-cylindrical winding layer 2, 2'. Likewise, a gapless and/or gap-free helical winding of the hollow-cylindrical winding layer 2 with the at least one first tape element 23 is conceivable. This results in a particularly smooth application, in particular one that is either completely step-free or approximately step-free in the axial direction, of the at least one first helically extending tape element 23. Alternatively or in combination therewith, it is also pos-sible to wind the at least one first tape element 23 at a mutual distance in the axial direction ¨
arrow 29 ¨ at least in axial partial sections of an axial height 24 of the at least one hollow-cy-lindrical winding layer 2. A combination of both winding schemes is illustrated by way of ex-ample in Fig. 8. A step-free application of the at least one first tape element 23 is achievable if the individual windings of the at least one first tape element 23 neither overlap nor are dis-tanced from one another in the axial direction ¨ arrow 29.
For stabilizing and/or stabilization of the air-core reactor 1, it may be useful if it is provided with a stabilizing resin 42, as has already been stated above. This stabilizing resin 42 is pref-erably applied after the application of the first and/or second tape element 23, 28. In this pro-cess, the stabilizing resin 42 is preferably applied to, in particular sprayed on, only an inner lateral surface 43 of the at least one hollow-cylindrical winding layer 2, 2'.
For this purpose, a CA 03,189007 2023-01-05 , , spray lance 44 may be used. The application and/or the spraying on of this stabilizing resin 42 is carried out such that it is applied only starting from the inner lateral surface 43 of the at least one hollow-cylindrical winding layer 2, 2'. In this process, the at least one hollow-cylin-drical winding layer 2, 2', in particular its insulation layer 18, is impregnated with the stabiliz-ing resin 42. This ensures that the predetermined electrical conductivity of the charge dissipat-ing layer 20 is maintained in that no stabilizing resin 42 or only a marginal amount of stabiliz-ing resin 42 hits the charge dissipating layer 20 and/or the tape elements 23 and/or 28.
In particular, the at least one winding layer 2, 2' is saturated, effectively starting from the in-side, with the stabilizing resin 42, and the stabilizing resin 42 can subsequently cure and/or solidify by means of temperature influence and/or by waiting for the respective curing time.
It is useful if the process of adhering the first and/or second tape element 23, 28 together via the synthetic resin 35 is carried out chronologically before the method step of applying the liquid stabilizing resin 42 to the inner lateral surface 43 of the at least one hollow-cylindrical winding layer 2, 2'. This ensures that the first and/or second tape element 23, 28 can remain in electrical contact while still being able to adhere well to the outer lateral surface 21.
It is particularly useful if the helical winding of the electrical conductor wire 17 with its jacket-side insulation layer 18 is carried out by means of the rotatable, coil-like winding body 39, and subsequently, preferably before the at least one hollow-cylindrical winding layer 2, 2' is taken off the coil-like winding body 39, the at least one first and/or second tape element 23, 28 is/are applied. In particular, the winding device 38 and/or the winding body 39 can also be used efficiently for applying, above all, the at least one first tape element 23, pos-sibly also the at least one second tape element 28, to the at least one hollow-cylindrical wind-ing layer 2, 2'. This results in substantial productional and economical advantages as well as qualitative effects.
The at least one first tape element 23 may, in this regard, also be designed with multiple lay-ers and/or be wound on the at least one hollow-cylindrical winding layer 2, 2' in multiple lay-ers. Likewise, a two-ply layer of the at least one first tape element 23 that runs counter to the winding direction is also conceivable as the charge dissipating layer 20. In particular, oppos-ing, assembled and/or integral first tape elements 23 may be provided, with which the charge dissipating layer 20 is constructed.

, CA 03189007 2023-01-05 , The exemplary embodiments show possible embodiment variants, and it should be noted in this respect that the invention is not restricted to these particular illustrated embodiment vari-ants of it, but that rather also various combinations of the individual embodiment variants are possible and that this possibility of variation owing to the technical teaching provided by the present invention lies within the ability of the person skilled in the art in this technical field.
The scope of protection is determined by the claims. Nevertheless, the description and draw-ings are to be used for construing the claims. Individual features or feature combinations from the different exemplary embodiments shown and described may represent independent in-ventive solutions. The object underlying the independent inventive solutions may be gathered from the description.
All indications regarding ranges of values in the present description are to be understood such that these also comprise random and all partial ranges from it, for example, the indication Ito 10 is to be understood such that it comprises all partial ranges based on the lower limit 1 and the upper limit 10, i.e. all partial ranges start with a lower limit of 1 or larger and end with an upper limit of 10 or less, for example 1 through 1.7, or 3.2 through 8.1, or 5.5 through 10.
Finally, as a matter of form, it should be noted that for ease of understanding of the structure, elements are partially not depicted to scale and/or are enlarged and/or are reduced in size.

, CA 03189007 2023-01-05 , , List of reference numbers 30 Crossover point 1 Air-core reactor 31 Radial direction - arrow 2 Winding layer 32 Holding projection 3 Air gap 33 Thickness 4 Gap slat 34 Woven fabric Winding star 35 Synthetic resin 6 Winding star 36 Particle 7 Star arm 37 Thickness 8 Star arm 38 Winding device 9 Supporting structure 39 Winding body Insulator 40 Rotation axis

11 Supporting plane 41 Support element

12 End face 42 Stabilizing resin

13 End face 43 Lateral surface (inner)

14 Coil axis 44 Spray lance Connection 16 Connection 17 Conductor wire 18 Insulation layer 19 Coil end Charge dissipating layer 21 Lateral surface (outer) 22 Lateral surface (inner) 23 Tape element 24 Axial height Dissipation surface 26 Overlap width 27 Tape width 28 Tape element 29 Axial direction - arrow

Claims

1. An HVDC air-core reactor (1) with at least two electrical connections (15, 16), comprising:
- at least one hollow-cylindrical winding layer (2-2"), the conductor wire (17) of which is helically wound about a coil axis (14) along with its jacket-side insulation layer (18), - a charge dissipating layer (20) with a predetermined electrical conductivity, which charge dissipating layer (20) is applied at least to an outer lateral surface (21) of the at least one hol-low-cylindrical winding layer (2-2') and is connected in an electrically conductive manner to at least one of the electrical connections (15, 16) of the air-core reactor (1), characterized in that - the charge dissipating layer (20) comprises at least one first tape element (23) of electrically conductive material, which extends helically around the coil axis (14) and abuts on the outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2-2').

2. The air-core reactor according to claim 1, characterized in that the charge dissipat-ing layer (20) comprises at least one second tape element (28) of electrically conductive mate-rial, which at least one second tape element (28) extends in the axial direction ¨ arrow (29) ¨
of the air-core reactor (1) at least on the outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2-2"), and that the at least one first tape element (23) and the at least one second tape element (28) extend so as to cross over one another at multiple crossover points (30) and are contacted to one another in an electrically conductive manner at these crossover points (30).

3. The air-core reactor according to claim 2, characterized by a first electrically con-ductive winding star (5) or by multiple first star arm elements, which is/are arranged on a first axial end face (12) of the at least one hollow-cylindrical winding layer (2-2"), and a second electrically conductive winding star (6) or multiple second star arm elements which is/are ar-ranged on a second axial end face (13) of the at least one hollow-cylindrical winding layer (2-2"), wherein the at least one second tape element (28) made of the electrically conductive material and extending axially to the air-core reactor (1) connects the first and second winding star (5, 6) or at least individual ones of the first and second star arm elements with a predeter-mined electrical conductivity.

,

4. The air-core reactor according to claim 3, characterized in that the first and second electrically conductive winding star (5, 6) or at least individual ones of the first and second star arm elements are clamped together in the axial direction ¨ arrow (29) ¨
by means of the at least one second tape element (28).

5. The air-core reactor according to one of claims 2 to 4, characterized in that the at least one second axially extending tape element (28) is arranged closer to the at least one hol-low-cylindrical winding layer (2-2") in the radial direction ¨ arrow (31) ¨
than the at least one helically extending first tape element (23).

6. The air-core reactor according to one of claims 2 to 5, characterized in that the at least one first and the at least one second tape element (23, 28) are formed by identical tape materials.

7. The air-core reactor according to one of the preceding claims, characterized in that the electrically conductive material of the characterized in that (20) has a surface resistivity in the range of 107to 1012 ohm/square, in particular in the range of 108 to 1010 ohm/square.

8. The air-core reactor according to one of claims 3 to 7, characterized in that at least one star arm (7, 8) of the first and/or second winding star (5, 6), or at least one holding projec-tion (32) on at least one of the winding stars (5, 6), or at least one holding projection (32) on at least one of the first and second star arm elements is at least partially wrapped by the at least one second tape element (28).

9. The air-core reactor according to one of the preceding claims, characterized in that the at least one first tape element (23) is wound so as to overlap in the axial direction ¨ ar-row (29) ¨ at least in partial sections of an axial height (24) of the at least one hollow-cylin-drical winding layer (2-2").

10. The air-core reactor according to one of the preceding claims, characterized in that the at least one first tape element (23) is wound so as to be distanced in the axial direction ¨

, , , arrow (29) ¨ at least in partial sections of an axial height (24) of the at least one hollow-cylin-drical winding layer (2-2').

11. The air-core reactor according to one of the preceding claims, characterized in that the at least one first and/or second tape element (23, 28) comprises a woven fabric (34) or knitted fabric of textile fibers, glass fibers, and/or plastic fibers, which woven fabric (34) or knitted fabric is provided with synthetic resin (35) and conductive particles (36) dispersed therein.

12. The air-core reactor according to one of the preceding claims, characterized in that the at least one first and/or second tape element has a thickness (37) of between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.3 mm.

13. A method for producing an HVDC air-core reactor (1), in particular formed ac-cording to one of the preceding claims, comprising the method steps:
- providing at least one hollow-cylindrical winding layer (2-2"), the electrical conductor wire (17) of which is helically wound about a coil axis (14) along with its jacket-side insula-tion layer (18), - applying a charge dissipating layer (20) to the outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2-2"), which charge dissipating layer (20) is formed or de-fined by winding at least one first tape element (23) around the at least one hollow-cylindrical winding layer (2-2') in a helical manner with respect to the coil axis (14), which at least one first tape element (23) has a predetermined electrical conductivity, which predetermined elec-trical conductivity of the at least one first tape element (23) is lower than an electrical conduc-tivity of the electrical conductor wire (17) while still being higher than an electrical conduc-tivity of the jacket-side insulation layer (18) of the conductor wire (17).

14. The method according to claim 13, characterized by applying at least one second tape element (28) made of electrically conductive material and extending axially ¨ arrow (29) ¨ to the at least one hollow-cylindrical winding layer (2-2') to the outer lateral surface (21) of the at least one hollow-cylindrical winding layer (2-2').

, CA 03189007 2023-01-05 ,

15. The method according to claim 14, characterized by applying the at least one sec-ond tape element (28) chronologically before the at least one first tape element (23) is wound around the at least one hollow-cylindrical winding layer (2-2"), wherein the at least one first tape element (23) and the at least one second tape element (28) is applied so as to directly cross over one another at multiple crossover points (30) and are thereby made to electrically contact one another.

16. The method according to one of claims 13 to 15, characterized by providing the at least one first and/or second tape element (23, 28) with a width (27) of between 1 cm and 40 cm, preferably between 2 cm and 10 cm, and a thickness (37) of between 0.1 mm and 1.0 mm, preferably between 0.2 mm and 0.3 mm.

17. The method according to one of claims 13 to 16, characterized by providing the at least one first and/or second tape element (23, 28) in the form of a woven fabric (34) or knit-ted fabric impregnated with synthetic resin (35), in which the synthetic resin (35) has a par-tially crosslinked state that is pasty to solid, not fluid at room temperature.

18. The method according to one of claims 14 to 17, characterized by applying one winding star (5, 6) or multiple star arm elements at each axial end face (12, 13) of the at least one hollow-cylindrical winding layer (2-2') and by electrically contacting the at least one second axially extending tape element (28) with at least one of the two winding stars (5, 6) or with axially distanced star arm elements.

19. The method according to one of claims 13 to 18, characterized by heating the at least one hollow-cylindrical winding layer (2-2') and/or the at least one first and/or second tape element after it has been wound on or applied to the at least one hollow-cylindrical wind-ing layer (2-2"), so that synthetic resin (35) on or in the at least one first and/or second tape element (23, 28) reacts and, in this process, the first and/or the second tape element (23, 28) are adhered to one another and/or to the outer lateral surface 821) or to a winding insulation of the at least one hollow-cylindrical winding layer (2-2").

, CA 03189007 2023-01-05

20. The method according to one of claims 13 to 19, characterized in that the at least one first tape element (23) is wound so as to overlap in the axial direction ¨
arrow (29) ¨ at least in partial sections of an axial height (24) of the at least one hollow-cylindrical winding layer (2-2').

21. The method according to one of claims 13 to 20, characterized in that the at least one first tape element (23) is wound so as to be mutually distanced in the axial direction ¨ ar-row (29) ¨ at least in partial sections of an axial height (24) of the at least one hollow-cylin-drical winding layer (2-2').

22. The method according to one of claims 13 to 21, characterized by applying a sta-bilizing resin (42) that, in its processing state, is fluid and can subsequently be cured, only to an inner lateral surface (22, 43) of the at least one hollow-cylindrical winding layer (2-2"), so that the jacket-side insulation layer (18) of the electrical conductor wire (17) is impreg-nated with the stabilizing resin (42) for the at least one hollow-cylindrical winding layer (2-2") only originating from the inner lateral surface (22, 43) of the at least one hollow-cylin-drical winding layer (2-2').

23. The method according to claim 19 and 22, characterized in that the method step of adhering the first and/or second tape element (22, 28) is carried out chronologically before the method step of applying the liquid stabilizing resin (42) to the inner lateral surface (22, 43) of the at least one hollow-cylindrical winding layer (2- 2').

24. The method according to one of claims 13 to 23, characterized by helically winding the electrical conductor wire (17) onto a rotatable, coil-like winding body (39) for forming the at least one hollow-cylindrical winding layer (2-2') and by helically winding the at least one first tape element (23) onto the at least one hollow-cylindrical winding layer (2-2") even before it is taken off the winding body (39).