Electrical wire and electrical cable for suppressing high-frequency interference currents

Abstract

An electrical wire comprising at least one first electrical conductor, wherein the at least one first electrical conductor comprises at least one first conductor core and at least one first conductive layer directly surrounding the first conductor core, and wherein the first conductor core has a first electrical conductivity, and the first conductive layer has a second electrical conductivity, and wherein the second electrical conductivity is lower than the first electrical conductivity, and at least one first insulation surrounding the first electrical conductor.

Description

[0001] Lapp Engineering AG - 1 - 30A-168 749

[0002] Electrical conductor and electrical cable for suppressing high-frequency interference currents

[0003] This disclosure relates to an electrical conductor for suppressing high-frequency interference currents and an electrical cable with at least three electrical conductors for suppressing high-frequency interference currents. The disclosure relates in particular to electrical conductors and cables for operating electrical machines such as turbines, fans, pumps, and industrial drives.

[0004] In industrial plants using frequency converter-controlled motors, unwanted currents increasingly occur on the equipotential bonding conductors (PA) or protective earth conductors (PE). In particular, the pulsed control generates interference currents in the range of approximately 3 kHz to 1 MHz, which flow towards earth potential via housing components, PA / PE conductors, and, in the worst case, via the shielding of data cables. This can result in high-frequency equalizing currents with an amplitude of 10 A in the time domain.

[0005] These interference currents on the protective earthing conductors often exceed the legally required maximum value of <30 mA, which can lead to false tripping of, for example, residual current devices (RCDs). RCDs with special characteristics or complex sine wave filters must be installed to ensure system availability and comply with legal requirements.

[0006] Furthermore, interference can occur in data lines or in electronically sensitive devices, impairing data communication. These faults are very difficult to detect because they do not follow a systematic pattern (sporadic protocol errors). Additionally, damage can occur due to spark erosion if high PA / PE equalizing currents flow, for example, via the drive shaft and ball bearings of motors. Generally, the fire protection of the system is reduced because high thermal outputs can occur at poorly connected ground connections.

[0007] Furthermore, amplitude overshoot and traveling wave reflection shortly after the frequency converter's switching moment place a heavy load on the motor winding's insulation system. The insulation systems of motor windings are often only designed for up to one and a half times the maximum operating voltage, so that under unfavorable conditions, damage to the motor winding can occur. Lapp Engineering AG - 2 - 30A-168 749

[0008] Due to cable-specific capacitances and asymmetries in conventional designs, high levels of electrical and magnetic coupling result. These negatively impact the efficiency of the entire drivetrain and promote the coupling and propagation of electromagnetic interference.

[0009] Especially in the case of motor connection / servo lines, capacitance-optimized lines are therefore often prescribed for installation and / or the maximum line length is limited in order to limit the propagation of these common-mode currents on PE / PA compensating lines as a result of the use of frequency converters.

[0010] Especially with high connection capacities (> 30 kW), and the resulting large cross-sections, conventional cables, such as types of the 2YSLCY, 2XSLCY or 9YSLCY family, are required, which are expensive and heavy due to the high copper content.

[0011] EP 3 279 901 Al describes in this context a power transmission device comprising at least one three-phase cable with a central protective conductor around which the phase conductors are stranded. Each phase has at least two identical phase conductors, which together form a two- or multi-part phase conductor, for which purpose they are electrically connected to each other at at least two connection points.

[0012] EP 2 027 589 Bl describes a high-voltage power cable for 50 / 60 Hz TN-S networks, preferably featuring a central earth conductor around which three phase conductors and a neutral conductor are stranded. The earth conductor can have a smaller cross-section than the phase conductors and the neutral conductor and can be straight. This high-voltage power cable is characterized by a defined cable reactance, a uniform current distribution across the phase conductors, and the avoidance of any induced currents. Furthermore, virtually no interference coupling occurs on parallel instrumentation and control (I&C) lines. There is only minimal non-ionizing radiation and no short-circuit forces. Finally, installation time is saved.

[0013] DE 10 2021 1 16 629 Al relates to a cable, in particular a cable for at least partial transmission of electrical energy, comprising several, in particular three, phase conductors and at least one further conductor, in particular a protective conductor, proposed, wherein the several phase conductors are stranded to form at least one phase bundle Lapp Engineering AG - 3 - 30A-168 749 and which includes at least one further conductor that runs outside the at least one phase bundle in the cable.

[0014] Based on this, an improved electrical conductor and an improved electrical cable are to be provided to reduce interference currents and harmonic overtones.

[0015] The problem is solved by the subject matter of the attached independent patent claims.

[0016] According to a first aspect, an electrical conductor is provided. The electrical conductor has at least one first electrical conductor. The first electrical conductor comprises at least one first conductor core. The first conductor core has a first electrical conductivity. The first electrical conductor further comprises at least one first conductive layer. The first conductive layer directly surrounds the first conductor core. The first conductive layer has a second electrical conductivity. The second electrical conductivity is lower than the first electrical conductivity. The electrical conductor further comprises at least one first insulation. The first insulation surrounds the first electrical conductor.

[0017] The design of the electrical conductor with a first conductor core and a first conductive layer, wherein the first conductive layer directly surrounds the first conductor core and the second conductivity is lower than the first conductivity, offers in particular the advantage that high-frequency interference currents and harmonic overtones and their reflection components are reduced and converted into heat over the conductor length.

[0018] This reduction is achieved by amplifying the effects of the skin effect. The skin effect describes the displacement of current from the interior of the conductor to the outside, or the diffusion of the electric field from the outside into the conductor at high frequencies. As the frequency increases, the current flows increasingly along the surface of the conductor, while the core of the conductor experiences less current flow. This is primarily due to the induction of opposing currents within the conductor by changes in magnetic flux density. The skin effect can negatively affect the conductivity of conductors and is taken into account, particularly in high-frequency applications such as telecommunications and electronics, where design measures are implemented to reduce the skin effect. Lapp Engineering AG - 4 - 30A-168 749

[0019] The equivalent penetration depth <5 of a current into the conductor as a function of the

[0020] Frequency a> can be described by the equation > to be determined, whereby

[0021] <5 represents the equivalent penetration depth of the current into the conductor, o) the angular frequency of the current, li the magnetic permeability of the conductor and K the electrical conductivity of the conductor.

[0022] It turns out that the penetration depth decreases with increasing angular frequency of the current and that the current flows mainly in the outer layer of the electrical conductor.

[0023] The AC resistance Z of the conductor or the current-carrying layer of the conductor can be calculated by:

[0024] Z = Z / ( * K) * (1 + J)

[0025] Here, l defines the length of the conductor.

[0026] A the cross-sectional area of ​​the current-carrying layer, depending on a radius of the conductor and the penetration depth <5

[0027] K is the electrical conductivity of the current-carrying layer.

[0028] The complex AC resistance Z has a real part and an imaginary part, which can be described as internal inductance. The AC resistance is inversely proportional to the electrical conductivity K of the current-carrying layer. This means that the lower the electrical conductivity K, the greater the complex AC resistance Z, and the better high-frequency interference currents and harmonic overtones are attenuated. However, the electrical conductivity K must not be so low that the material acts as an insulator, otherwise no current will flow in this layer, and thus the desired high-frequency attenuation or amplification of the skin effect will not occur.

[0029] In applications with an operating, load, or working current in the low-frequency range, e.g., from 0 Hz to 800 Hz, the working current penetrates the entire electrical conductor due to the low frequency. This means it flows across the entire cross-sectional area of ​​the conductor and is only very slightly, if at all, affected by the first conductive layer, which has a lower secondary electrical conductivity than the first conductor core. Interference currents, electromagnetic interference, or harmonic overtones and their reflection components with frequencies between 3 kHz and 1 MHz or higher penetrate the electrical conductor, and thus especially the first conductor core, only very weakly. Therefore, they mainly travel through the first conductive layer, where they are more strongly attenuated by the low secondary electrical conductivity.Furthermore, the AC resistance increases with the length of the electrical conductor, so that high-frequency interference currents are dampened more strongly the longer the electrical conductor is.

[0030] In one variant, the electrical conductor can have a cross-sectional area larger than approximately 25 mm². 2 exhibit.

[0031] The penetration depth of the current depends solely on the frequency and the material properties (magnetic permeability and electrical conductivity), not on the cross-sectional area of ​​the electrical conductor itself. Therefore, a larger cross-sectional area of ​​the electrical conductor leads to a decrease in the frequency at which the current achieves a penetration depth corresponding to complete penetration of the conductor. Consequently, even interference currents with lower frequencies can no longer completely penetrate the electrical conductor and flow primarily within the first conductive layer, where they are attenuated due to the low electrical conductivity of the second layer.

[0032] In one variant, the first conductive layer can completely surround the first conductor core. Alternatively, in another variant, the first conductive layer can partially surround the first conductor core in a longitudinally striped or helical pattern. In another variant, the first conductor core and the surrounding first conductive layer can be electrically connected to each other.

[0033] The first conductive layer can be configured as a braided shield containing at least two shielding wires. These two shielding wires can be made of aluminum, nickel, steel, iron, or graphite. The diameter of these two shielding wires can range from approximately 0.04 mm to approximately 0.2 mm, and in particular from approximately 0.08 mm to 0.12 mm.

[0034] The first conductive layer can be configured in one variant as a layer containing at least one single wire. This single wire can, in one variant, contain aluminum, nickel, steel, iron, or graphite. The single wire in the Lapp Engineering AG - 6 - 30A-168 749 variant can have a diameter of approximately 0.04 mm to approximately 0.2 mm, and in particular approximately 0.08 mm to approximately 0.12 mm.

[0035] The first conductive layer can be configured in one variant as a helical, self-overlapping bandage. Alternatively, the first conductive layer can be configured as a longitudinally striated, self-overlapping bandage.

[0036] The bandage can be designed with a metal foil. The bandage can be designed with a conductive foil. The bandage can be designed with a metallized fleece, fabric, or braid.

[0037] In one variant, the first conductive layer can have an effective thickness of approximately 0.02 mm to approximately 0.6 mm, and in particular approximately 0.04 mm to 0.06 mm. The effective thickness here represents the radial extent of the first conductive layer.

[0038] The first conductive layer can be a coating of an iron-containing material. In one variant, the first conductive layer can be a coating of nickel. In another variant, the first conductive layer can be a coating of steel. The coating can be applied by electrolysis or a chemical process.

[0039] The first conductive layer can be a plastic layer with embedded stainless steel particles. Alternatively or additionally, other metal particles, graphene, carbon nanotubes, carbon black, conductive carbon black, or any combination thereof can be embedded in the plastic layer. The plastic layer can have a thickness of approximately 0.1 mm to approximately 1 mm. In one variant, the plastic layer can be applied using an extrusion process.

[0040] In one variant, the first conductive layer can still be configured as a surface roughness on a surface of the first conductor core. This surface roughness can range from approximately 20 pm to approximately 100 pm.

[0041] The first conductive layer can be made of a material with a specific resistance of approximately 2.5 * 10-8 n * m 2 / m to about 2.5 * 10 -7 n * m 2 / m, especially of about 4 * 10 -8 n * m 2 / m to about 1.2 * 10 -7 n * m 2 / m trained. Lapp Engineering AG - 7 - 30A-168 749

[0042] The first conductive layer can, in one variant, contain a diamagnetic material. In another variant, the first conductive layer can contain a ferromagnetic material. The first conductive layer can have a relative permeability of approximately 10 to approximately 1000, particularly approximately 350 to approximately 650.

[0043] The first conductor core can be made of aluminum in one variant. The first conductor core can be made of tinned aluminum in one variant. The first conductor core can be made of copper in one variant. The first conductor core can be made of tinned copper in one variant. The first conductor core can be made of a material with a specific resistance of approximately 1.5 * 10 -8 n * m 2 / m to about 2.8 * 10 -8 n * m 2 / m be trained.

[0044] By using aluminum for the first conductor core, the electrical conductor can be manufactured significantly more cost-effectively than, for example, an electrical conductor with a copper first core. However, using copper offers the advantage of higher transmission efficiency compared to an aluminum first core, as copper has a lower resistivity than aluminum.

[0045] The first conductor core can be configured as a Class 5 conductor in one variant. Alternatively, the first conductor core can be configured as a Class 6 conductor. Configuring the first conductor core as a Class 5 or 6 conductor significantly increases the flexibility of the electrical conductor, which in turn expands its range of applications.

[0046] The first conductor core can also have a non-circular cross-sectional area. In one variant, the first conductor core can have a rectangular cross-sectional area. In another variant, the first conductor core can have a square cross-sectional area.

[0047] The electrical conductor can have a non-circular cross-sectional area. In one variant, the electrical conductor can have a rectangular cross-sectional area. In another variant, the electrical conductor can have a square cross-sectional area. Lapp Engineering AG - 8 - 30A-168 749

[0048] The first insulation layer can have a relative permittivity of approximately 1.5 to approximately 2.5 in one variant. The first insulation layer can, in one variant, contain at least a portion of a plastic. Specifically, the first insulation layer can contain at least a portion of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), cross-linked polyethylene (XLPE), or a combination of these plastics.

[0049] According to a second aspect, an electrical cable is provided. The electrical cable has at least three electrical conductors, as described in the first aspect. These three conductors are twisted together in the first stranding direction to form a conductor bundle. The electrical cable has at least one shielding layer. The shielding layer surrounds the conductor bundle. The electrical cable also has a jacket. The jacket surrounds the shielding layer.

[0050] The first shielding layer can, in one variant, be designed as a winding with at least three individual conductors. The winding direction of these at least three individual conductors can, in one variant, be opposite to the stranding direction of the electrical conductors. The at least three individual conductors can, in one variant, be made of copper. The at least three individual conductors can, in one variant, be multi-stranded conductors of class 2. The at least three individual conductors can, in one variant, form the protective earth conductor of the electrical cable.

[0051] A winding direction for the at least three individual conductors that is opposite to the stranding direction of the electrical conductors offers the particular advantage of reducing the number of points where the at least three individual conductors come close to the at least three electrical conductors. Specifically, this means that no single conductor runs at a constant distance from a single electrical conductor, but rather crosses all three electrical conductors symmetrically and alternately. This symmetrical arrangement of the at least three individual conductors, resulting from the opposing winding direction, reduces or at least approximately eliminates inductive interference, since interference from the individual electrical conductors would otherwise interfere destructively.

[0052] In conjunction with the increased attenuation of high-frequency interference currents by the electrical conductors themselves, this means that, firstly, longer cables can be used in systems, and secondly, special sine wave filters and special residual current circuit breakers can be dispensed with. The interference currents are continuously attenuated along the entire length of the electrical cable; that is, they are converted into heat instead of being reflected at the discontinuities of a sine wave filter, as is the case with a sine wave filter.

[0053] In one version, the electrical cable can have at least three dummy wires.

[0054] In one variant, the at least three dummy wires can be stranded together with the electrical wires to form the wire bundle.

[0055] Stranding three dummy conductors with at least three electrical conductors offers the advantage that the cable bundle acquires an approximately circular cross-sectional geometry, which in particular also determines and simplifies the geometry and shape of the surrounding first shielding layer. This geometry, i.e., the cross-sectional shape of the first shielding layer, also defines the distance of the shielding layer to the electrical conductors and thus both the capacitive and inductive coupling between the first shielding layer and the electrical conductors.

[0056] The electrical cable can, in one variant, have at least one inner sheath. In one variant, this inner sheath can be positioned between the conductor bundle and at least one first shielding layer.

[0057] The inner jacket can, in one variant, contain at least some plastic. Specifically, the inner jacket can contain at least some polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), cross-linked polyethylene (XLPE), or a combination of these plastics. In another variant, the inner jacket can contain a halogen-free and flame-resistant material (HFFR).

[0058] The formation of an inner sheath serves to increase the electrical separation between the electrical conductors and the first shielding layer. Here, electrical separation is defined not solely as a distance, but rather as electrical attenuation. The greater this attenuation, the lower the inductive and capacitive interference coupling into the first shielding layer. Capacitive interference coupling, in particular, causes a frequency converter to operate against a capacitive short circuit during switching, forcing it to supply a higher current than would actually be required for the operation of the connected machine. This higher current typically leads to increased interference coupling. Lapp Engineering AG - 10 - 30A-168 749

[0059] In one variant, the inner jacket may contain air inclusions. These air inclusions can be introduced into the inner jacket by foaming it during manufacturing. In another variant, a radially outer surface of the inner jacket, facing the first shielding layer, may have a ribbed geometry. In this context, a ribbed geometry means that the radially outer surface of the inner jacket does not correspond to the surface of a smooth cylinder. The surface may, for example, have a star geometry, a sawtooth geometry, a wave geometry, or an external toothed ring geometry.

[0060] This corrugated geometry of the radially outer surface of the inner sheath offers the advantage that a particularly large amount of air can be introduced as an insulating medium between the conductor bundle and the first shielding layer. This increases the electrical distance between the conductor bundle and the first shielding layer and simultaneously reduces the capacitive and inductive coupling between the conductor bundle and the first shielding layer.

[0061] In one variant, the electrical cable may have a second shielding layer. In another variant, the second shielding layer may be positioned between the first shielding layer and the outer jacket. In yet another variant, the second shielding layer may contain a copper foil. In yet another variant, the second shielding layer may be helically shaped and overlapping the first shielding layer. In yet another variant, the winding direction of the helical second shielding layer may be opposite to that of the first shielding layer.

[0062] This particularly reduces the stray capacitances between the individual electrical conductors and between the electrical conductors and the first shielding layer.

[0063] The casing can, in one variant, contain at least some plastic. Specifically, the casing can contain at least some polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), cross-linked polyethylene (XLPE), or a combination of these plastics. In another variant, the casing can contain a halogen-free and flame-resistant material (HFFR).

[0064] Further details, features, advantages, and effects of the electrical conductor and electrical cable described herein will become apparent from the following description of currently preferred variants and from the drawings, as detailed in Lapp Engineering AG - 11 - 30A-168 749. These drawings show:

[0065] Fig. 1 shows a schematic representation of a cross-section of the electrical conductor according to the first aspect;

[0066] Fig. 2a is a schematic representation of a cross-section of the electrical conductor according to Fig. 1 with a current distribution at low frequencies;

[0067] Fig. 2b is a schematic representation of a cross-section of the electrical conductor according to Fig. 1 with a current distribution at high frequencies;

[0068] Fig. 3a is a schematic representation of the electrical conductor according to Fig. 1 with a first conductive layer as a helical bandage;

[0069] Fig. 3b is a schematic representation of the electrical conductor according to Fig. 1 with a first conductive layer as a shielding braid;

[0070] Fig. 4a shows a schematic representation of a cross-section of an electrical cable according to a first embodiment;

[0071] Fig. 4b shows a schematic representation of a cross-section of an electrical cable according to a second embodiment;

[0072] Fig. 4c shows a schematic representation of a cross-section of an electrical cable according to a third embodiment;

[0073] Fig. 4d shows a schematic representation of a cross-section of an electrical cable according to a fourth embodiment;

[0074] Fig. 5 shows a schematic equivalent circuit diagram of the electrical cable;

[0075] Fig. 6 shows the resistance of the electrical conductor in various embodiments as a function of frequency.

[0076] Figure 1 schematically shows a cross-section of an electrical conductor 100 according to the first aspect. The electrical conductor 100 has an electrical conductor 110, which in turn has a first conductor core 111 and a first conductive layer 112. Lapp Engineering AG - 12 - 30A-168 749

[0077] The electrical conductor 110 has a cross-sectional area greater than 25 mm². 2 is.

[0078] The first conductor core 111 is designed as a class 5 or class 6 conductor containing aluminum or copper. Alternatively, the first conductor core 111 is made of a material with a specific resistance of approximately 1.5 * 10 -8 n * m 2 / m to about 2.8 * 10 -8 n * m 2 trained / m.

[0079] The first conductive layer 112 is applied directly to the first conductor core 111 and electrically connected to it. The first conductive layer 112 is made of a material with a specific resistance of approximately 2.5 * 10⁻⁵ Ω. -8 n * m 2 / m to about 2.5 * 10 -7 n * m 2 / m formed. The structure of the first conductive layer 112 is described in more detail for two variants in the description accompanying Figures 3a and 3b.

[0080] The first conductor core 111 has a first electrical conductivity that is greater than a second electrical conductivity of the first conductive layer 112.

[0081] The electrical conductor 100 further comprises a first insulation 120 that surrounds the electrical conductor 110. In the embodiment shown here, the first insulation 120 comprises a plastic, in particular a cross-linked polyethylene (XLPE). However, the first insulation 120 is not limited to this embodiment.

[0082] Fig. 2a schematically shows the current distribution (hatched background) within the electrical conductor 110 of the electrical wire 100 according to Fig. 1 when subjected to a low-frequency operating, load, or working current. The working current has, for example, a frequency of 0 Hz to approximately 800 Hz.

[0083] Due to the low frequency, the operating current penetrates almost the entire electrical conductor 110. Consequently, the majority of the operating current flows in the first conductor core 111 and is almost unaffected by the lower electrical conductivity of the first conductive layer 112, so that the electrical conductor 110 exhibits low electrical resistance and high transmission efficiency for low-frequency operating currents. Lapp Engineering AG - 13 - 30A-168 749

[0084] Fig. 2b, in contrast, shows a current distribution of high-frequency currents, such as induced interference currents or harmonic overtones. Due to the skin effect, at high frequencies the current penetrates the electrical conductor 110 from the outside to a certain depth, with the penetration depth decreasing further with increasing frequency. In the embodiment shown here, the high-frequency current flows almost entirely within the first conductive layer 112. Due to the lower second electrical conductivity of the first conductive layer 112 compared to the first electrical conductivity of the first conductor core 111, the high-frequency interference current is attenuated significantly more than the low-frequency current according to Fig. 2a. The electrical conductor 110 thus exhibits a high electrical resistance and low transmission efficiency for high-frequency interference currents.

[0085] Figure 3a shows an electrical conductor 100 according to Figure 1 with a first conductive layer 112 in a first embodiment. The electrical conductive layer 112 is designed as a self-overlapping bandage 113 with a metal foil. The first conductive layer 112 has a second electrical conductivity that is lower than the first electrical conductivity of the first conductor core 111. In this case, the first conductive layer 112 is wound helically directly around the first conductor core 111 and completely surrounds it.

[0086] Fig. 3b shows an electrical conductor 100 according to Fig. 1 with a first conductive layer 112 in a second variant. In this variant, the first conductive layer 112 is designed as a braided shield with at least two shield wires 114. In the embodiment shown here, the first conductor core 111 contains copper, and the at least two shield wires 114 are aluminum-containing shield wires 114 with a diameter of 0.1 mm. The braided shield is not limited to a specific lay length and a specific lay angle of the at least two shield wires.

[0087] Figure 4a shows an electrical cable 1000 according to the second aspect. The electrical cable comprises at least three electrical conductors 100 according to the first aspect. In the embodiment shown here, the at least three electrical conductors 100 have a first conductor core 111, which is designed as a Class 5 conductor containing aluminum. The electrical conductors 100 also have a first conductive layer 112, which is designed as a nickel coating. The first insulation 120 is designed to contain an XLPE plastic. Lapp Engineering AG - 14 - 30A-168 749

[0088] The electrical cable 1000 also includes three dummy conductors 400. The at least three electrical conductors 100 and the three dummy conductors 400 are twisted together in a first stranding direction to form a conductor bundle. The dummy conductors 400 have a diameter that is smaller than the diameter of the electrical conductors 100. This results in the conductor bundle having an approximately circular cross-sectional geometry, which in particular also determines and simplifies the geometry and shape of the surrounding first shielding layer 200. The geometry, i.e., the cross-sectional shape of the first shielding layer 200, also defines the distance of the shielding layer 200 to the electrical conductors 100 and thus both the capacitive and inductive coupling between the first shielding layer 200 and the electrical conductors 100.

[0089] The first shielding layer 200 is formed from at least three individual conductors 210 and, in particular, forms a protective earthing conductor for the electrical cable 1000. The at least three individual conductors 210 are wound spirally around the core bundle, with the winding direction of the at least three individual conductors 210 being opposite to the stranding direction of the electrical cores 100. This results, in particular, in an electrically symmetrical arrangement of the at least three individual conductors 210 relative to the electrical cores 100, which advantageously reduces, in particular, inductive interference coupling from the electrical cores 100 to the individual conductors 210, since, in particular, the interference effects caused by destructive interference are reduced or even at least approximately eliminated.

[0090] The electrical cable 1000 further comprises a sheath 300, which in the embodiment shown here is designed to contain a halogen-free and flame-resistant material (HFFR) and directly surrounds the first shielding layer 200.

[0091] Fig. 4b shows an electrical cable 1000 according to a second embodiment. The electrical cable 1000 differs from the electrical cable 1000 of the first embodiment in that only the at least three electrical conductors 100 are stranded together to form the conductor bundle. The electrical cable 1000 of the second embodiment does not have any dummy conductors 400. Instead, the electrical cable 1000 has an inner sheath 500, which is arranged between the conductor bundle and the first shielding layer 200.

[0092] The inner sheath 500, like the sheath 300, is made of a halogen-free and flame-resistant material (HFFR). The inner sheath 500 increases the electrical distance between the conductor bundle and the first Lapp Engineering AG - 15 - 30A-168 749

[0093] Shielding layer 200, which leads to a reduction in the line capacitances between the electrical conductors 100 and between the electrical conductors 100 and the first shielding layer 200, and thus to a reduction in high-frequency interference currents on the shielding layer 200 and thus on the protective earth conductor.

[0094] Figures 4c and 4d show further embodiments of the electrical cable 1000 with an inner sheath 500 analogous to the second embodiment according to Figure 4b, wherein the inner sheath in the embodiment shown in Figure 4c has air inclusions 501 distributed over the entire cross-sectional area of ​​the inner sheath. In the embodiment shown in Figure 4d, the inner sheath 500 has a corrugated geometry in the form of a sawtooth pattern on its radially outer surface. Both the air inclusions 501 and the sawtooth geometry of the inner sheath 500 make it possible to introduce as much air as possible into the area between the conductor bundle and the first shielding layer 200, thereby reducing the relative permittivity of the inner sheath 500 and of the area between the conductor bundle and the first shielding layer 200. This, in turn, leads to a reduction in interference coupling into the shielding layer 200.Furthermore, by forming the inner sheath 500 with air inclusions 501 and / or a corrugated geometry, material is saved during the manufacture of the electrical cable 1000.

[0095] The grooved geometry on the radially outer surface of the inner jacket 500 is created by extrusion through a special die.

[0096] Fig. 5 schematically shows an equivalent circuit diagram of an electrical cable 1000 with three electrical conductors 100-1, 100-2, 100-3 and a first shielding layer 200 as shown in the embodiments in Figs. 4a to 4d. Both the electrical conductors 100-1, 100-2, 100-3 and the first shielding layer 200 have an inherent complex AC resistance, each comprising a real part, represented by the resistances 101-1, 101-2, 101-3 and 201, and an imaginary part, represented by the inductances 102-1, 102-2, 103-2 and 202. Since the complex AC resistance of the electrical conductors 100-1, 100-2, 100-3 depends in particular on the frequency of the current, the low-pass blocks 105-1, 105-2, 105-3 are additionally shown in Fig. 5, which illustrate the low-pass characteristic of the electrical conductors 100-1, 100-2, 100-3 for various frequencies.The low-pass blocks 105-1, 105-2, 105-3 thus describe the functioning of the first conductive layer 112 of the electrical conductors 100-1, 100-2, 100-3. For the consideration of the inductive and capacitive couplings of the individual electrical conductors, see Lapp Engineering AG - 16 - 30A-168 749.

[0097] The low-pass blocks 105-1, 105-2, 105-3 are initially neglected between the conductors 100-1, 100-2, 100-3 and the first shielding layer 200.

[0098] The inductances 102-1, 102-2, 103-2, and 202 represent, in particular, the inductive coupling between the conductors 100-1, 100-2, 100-3 and between the conductors 100-1, 100-2, 100-3 and the first shielding layer 200. Since the individual wires 210 of the first shielding layer 200 in the electrical cable 1000 are wound around the conductor bundle with a winding direction opposite to the stranding direction of the individual conductors 100-1, 100-2, 100-3 relative to the conductor bundle, an electrically symmetrical arrangement is achieved, and, in particular, the inductive interference coupling of the electrical conductors 100-1, 100-2, 100-3 to the individual wires 210 of the first shielding layer 200 is at least reduced, since, in particular, the interference influences from Destructive interference is reduced or even almost eliminated.

[0099] The capacitive couplings 104 between the electrical conductors 100-1, 100-2, 100-3 are approximately equal due to the identical structure of the individual electrical conductors 100-1, 100-2, 100-3 and their symmetrical arrangement within the conductor bundle. Because of the electrically symmetrical arrangement of the first shielding layer 200 relative to the electrical conductors 100-1, 100-2, 100-3, the capacitive couplings 103 between the individual conductors 100-1, 100-2, 100-3 and the first shielding layer 200 are also approximately equal.

[0100] The low-pass filters 105-1, 105-2, 105-3 shown in Fig. 5 represent, in particular, the low-pass characteristics of the electrical conductors 100-1, 100-2, 100-3 at different frequencies. This will be explained in more detail below using the example of the low-pass filter 105-1 of the first electrical conductor 100-1.

[0101] In the embodiment shown here, the low-pass filter 105-1 comprises two low-pass filters. The first low-pass filter is formed by the resistor 107-1 and the inductor 109-1. This first low-pass filter has a cutoff frequency of, for example, 10 Hz, so that only currents with a frequency of 10 Hz and below flow through the resistor 107-1. The second low-pass filter is formed by the resistor 106-1 and the inductor 108-1 and has a cutoff frequency of, for example, 100 kHz.

[0102] The first low-pass filter is connected in parallel to the resistor 106-1 of the second low-pass filter, and the second low-pass filter is connected in parallel to the resistor 101-1, Lapp Engineering AG - 17 - 30A-168 749, which in conjunction with the inductor 102-1 forms a third low-pass filter with an exemplary cutoff frequency of 1MHz.

[0103] Figure 5 thus shows a cascade circuit of three low-pass filters with different cutoff frequencies, which exemplify the frequency-dependent behavior of the electrical conductors 100-1, 100-2, 100-3. In particular, the low-pass filters thus represent individual sections of the electrical conductor 110 of the electrical conductors 100-1, 100-2,

[0104] 100-3. Thus, the first low-pass filter consisting of resistor 107-1 and inductor 109-1 represents the electrical conductor core 111, since it is only fully penetrated by low-frequency currents. The electrical conductor core therefore represents a low-pass filter with a low cutoff frequency, in this embodiment 10 Hz.

[0105] The second low-pass filter, consisting of resistor 106-1 and inductor 108-1, represents, for example, a radially inner section of the first conductive layer 112, on which the high-frequency interference currents flow. The third low-pass filter, consisting of resistor

[0106] In contrast to the second low-pass filter, the 101-1 and the inductor 102-1 represent a radially outer section of the first conductive layer 112, on which the currents flow at an even higher frequency, in this embodiment up to 1 MHz.

[0107] The low-pass filters thus exemplify the low-pass characteristics of the individual sections of the electrical conductor 110. As can be seen in particular from the frequency dependence of the penetration depth of the current distribution in the electrical conductor 110, a real electrical conductor 110 does not only have three cascading low-pass filters with different cutoff frequencies, but rather represents a low-pass filter with a cutoff frequency that increases from the center of the electrical conductor 110 to the radially outermost surface of the electrical conductor 110.

[0108] Fig. 6 schematically shows the magnitude |Z| of the AC resistance Z of an electrical conductor 110 as a function of the frequency f over a frequency range from 50 Hz to about 500,000 Hz for various embodiments LI to L5 of the electrical conductor 110.

[0109] The magnitude |Z| of the AC resistance Z of an electrical conductor 110 is, as described above, dependent on the length l, the cross-sectional area A of the current-carrying layer, and the electrical conductivity K. The cross-sectional area A depends on the equivalent penetration depth <5 of the current into the electrical conductor. Lapp Engineering AG - 18 - 30A-168 749

[0110] conductor 110 and thus in particular of the angular frequency a> of the current and the magnetic permeability / z.

[0111] The magnitude \Z\ of the AC resistance Z is thus also determined in particular by the layer thickness of the first conductive layer 112, since the layer thickness of the first conductive layer 112, depending on the equivalent penetration depth <5, determines the proportion of the current that flows through the first conductive layer 112 and thus through the material with the lower second electrical conductivity.

[0112] In the following, the magnitude \Z\ of the AC resistance Z of the electrical conductor 110 of embodiments LI to L6 will be referred to as conductor resistance Z. Furthermore, the respective electrical conductors 110 of the embodiments will be referred to below as electrical conductors 110-L1 to 110-L6.

[0113] Furthermore, the electrical conductors 110 of embodiments LI to L6 all have an identical radius in their respective configurations.

[0114] The first frequency range Bl, marked in Fig. 6, represents the operating frequency range, i.e., the frequency range in which the operating, load, or working current lies. In the example shown here, the first frequency range Bl covers a range from 50 Hz to approximately 800 Hz. Frequencies from 0 Hz to 50 Hz also fall within the first frequency range Bl, but are not shown due to the chosen frequency division. Within the operating frequency range, the lowest possible conductor resistance Z, and thus high transmission efficiency, is desired.

[0115] The second frequency range B2, labelled in Fig. 6, represents the frequency range of the high-frequency interference currents. This second frequency range B2 covers a frequency range from approximately 3 kHz to over 500 kHz. In this second frequency range B2, the highest possible conductor resistance Z, and thus a low transmission efficiency of the electrical conductor 110, is desired.

[0116] In particular, the electrical conductors 110 according to the illustrated embodiments LI, L2, L4 and L6 are merely exemplary embodiments serving for explanation and comparison.

[0117] The electrical conductor 110-L1 according to the first embodiment LI has a copper-containing first conductor core 111, but no first conductive layer 112, and thus represents a commercially available electrical conductor. Lapp Engineering AG - 19 - 30A-168 749

[0118] The conductor resistance Z of the electrical conductor 110-L1 exhibits a nearly constant value of approximately 0.7 mΩ / m in the first frequency range Bl, thus demonstrating high transmission efficiency in the operating current frequency range. From a frequency of approximately 800 Hz, the conductor resistance Z increases almost linearly due to the onset of the skin effect, reaching a value of approximately 10 mΩ / m at 500 kHz. This linear increase is primarily attributable to the homogeneous material of the electrical conductor 110-L1, as only the decreasing current-carrying cross-sectional area with increasing frequency causes a change in the conductor resistance Z.

[0119] The electrical conductor 110-L1 therefore has a higher conductor resistance Z in the second frequency range B2 than in the first frequency range Bl, but this increase is so small that high-frequency interference currents along the length of the conductor cannot be converted into heat and thus sufficiently dampened.

[0120] The electrical conductor 110-L2 according to the second illustrated embodiment L2 has a copper-containing first conductor core 111 and a first conductive layer 112 with a layer thickness of approximately 0.01 mm.

[0121] The electrical conductor 110-L2 thus represents an electrical conductor with a first conductive layer 112, which, however, with a layer thickness of about 0.01 mm, is too thin to provide sufficient amplification of the effects of the skin effect.

[0122] The conductor resistance Z of the electrical conductor 110-L2, as shown in Fig. 6, only rises above the value of the conductor resistance ZI of the electrical conductor 110-L1 at a frequency of approximately 50 kHz. This is primarily due to the fact that, because of the small thickness of the first conductive layer 112, the first conductive layer 112 constitutes only a small fraction of the current-carrying cross-sectional area A at these frequencies, since the equivalent penetration depth <5 of the current is still many times greater than the layer thickness, so that the lower second conductivity of the first conductive layer 112 has only a very small effect, or none at all, on the conductor resistance Z.

[0123] The electrical conductor 110-L4 according to the fourth illustrated embodiment L4 has a copper-containing first conductor core 111 and a first conductive layer 112, wherein the first conductive layer 112 has a relative permeability greater than 4000. Lapp Engineering AG - 20 - 30A-168 749

[0124] The electrical conductor 110-L4, like the electrical conductors 110-L1 and 110-L2, also represents an electrical conductor that serves only for explanation and comparison.

[0125] The equivalent penetration depth <5 of the current in the electrical conductor 110-L4 depends in particular on the magnetic permeability / z and thus also on the relative permeability of the first conductive layer 112. A high relative permeability, such as that of the electrical conductor 110-L4, reduces the equivalent penetration depth <5 of the current, so that the conductor resistance Z increases sharply even at frequencies in the first frequency range Bl. For example, the electrical conductor 110-L4 has a conductor resistance Z of approximately 100 mQ / m at a frequency of about 500 Hz, so that the electrical conductor 110-L4 does not have a high transmission efficiency, especially in the first frequency range Bl and thus for operating currents.

[0126] The electrical conductor 110-L6 according to the sixth embodiment L6 has a copper-containing first conductor core 111 and, in this embodiment, a copper-containing first conductive layer 112. The electrical conductor 110-L6 is therefore an electrical conductor in which the conductivity of the first conductive layer 112 is too high.

[0127] Like the electrical conductors 110-L1, 110-L2 and 110-L4, the electrical conductor 110-L6 is also an electrical conductor that serves only for explanation and comparison.

[0128] As shown in Fig. 6, the conductor resistance Z of the electrical conductor 110-L6 is always lower than the conductor resistance ZI of the electrical conductor 110-L1. This is primarily due to the fact that, because of the high conductivity of the first conductive layer 112, there is little or no attenuation or blocking effect at high frequencies. Using a first conductive layer 112 with high conductivity can counteract the skin effect, but in return results in a low conductor resistance.

[0129] The electrical conductor 110-L3 according to the third illustrated embodiment L3 has a copper-containing first conductor core 111 and a first conductive layer 112 with a layer thickness of about 0.05 mm, wherein the first conductive layer 112 is formed with a diamagnetic material.

[0130] The electrical conductor 110-L5 according to the fifth embodiment L5 has a copper-containing first conductor core 111 and a first conductive layer 112 with a layer thickness of approximately 0.05 mm and a relative permeability of approximately 500. Lapp Engineering AG - 21 - 30A-168 749

[0131] The conductor resistances Z of the electrical conductors 110-L3 and 110-L5 shown in Fig. 6 exhibit a high transmission efficiency in the first frequency range Bl of the operating currents and a low transmission efficiency for high-frequency disturbance currents in the second frequency range B2 due to the greater layer thickness of the first conductive layer 112 compared to the first conductive layer 112 of the electrical conductor 110-L2, due to the lower relative permeability compared to the electrical conductor 110-L4, and due to the lower conductivity of the first conductive layer 112 compared to the electrical conductor 110-L6.

[0132] The previously described variants of the electrical conductor and the electrical cable, as well as their construction and operational aspects, serve only to improve understanding of the structure, function, and properties; they do not limit the disclosure to the exemplary embodiments. Some of the figures are schematic. In some cases, essential properties and effects are shown significantly enlarged to clarify the functions, operating principles, technical designs, and features. Each function, principle, technical design, and feature disclosed in the figures or in the text may be further defined by all claims, features in the text, and in the other figures.Other functionalities, principles, technical configurations, and features contained in or arising from this disclosure may be freely and arbitrarily combined, such that all conceivable combinations of the described procedure are included. This also encompasses combinations between all individual embodiments in the text, i.e., in every section of the description, in the claims, and also combinations between different variants in the text, in the claims, and in the figures. The claims do not limit the disclosure and thus the possible combinations of all the features shown. All disclosed features are explicitly disclosed here, both individually and in combination with all other features.

Claims

Lapp Engineering AG - 22 - 30A-168 749 Patent claims 1. Having an electrical conductor (100), - at least one first electrical conductor (110), wherein the at least one first electrical conductor (110) at least - a first conductor core (111) and at least - a first conductive layer immediately surrounding the first conductor core (111) (112) includes, and wherein - the first conductor core (111) exhibits a first electrical conductivity, and - the first conductive layer (112) has a second electrical conductivity, and wherein - the second electrical conductivity is lower than the first electrical conductivity, and - at least a first insulation (120) surrounds the first electrical conductor (110).

2. The electrical conductor (100) according to claim 1, wherein - the electrical conductor (110) has a cross-sectional area greater than approximately 25 mm 2exhibits, and / or - the first conductive layer (112) completely surrounds the first conductor core (111) or - the first conductive layer (112) partially surrounds the first conductor core (111) in a longitudinally striped or helical manner, and / or - the first conductor core (111) and the surrounding first conductive layer (112) are electrically connected to each other.

3. The electrical conductor (100) according to one of the preceding claims, wherein the first conductive layer (112) - is formed as a shielding mesh with at least two shielding wires (114), or - is designed as a rerouting with at least one single wire, or - is designed as a helical, self-overlapping bandage (113) with a metal foil, a conductive film or a metallized fleece, fabric or mesh, or - is formed as an electrolytic or chemical coating with an iron-containing material, nickel or steel, or Lapp Engineering AG - 23 - 30A-168 749 - is formed as an extruded plastic layer with embedded stainless steel particles, metal particles, graphene, carbon nanotubes, industrial carbon black and / or conductive carbon black, or - is formed as a surface roughness of about 20 pm to about 100 pm on a surface of the first conductor core (111).

4. The electrical conductor (100) according to claim 3, wherein the at least two shield wires (114) of the shield braid or the at least one single wire of the wrapping have a diameter of about 0.04 mm to about 0.2 mm, in particular about 0.08 mm to 0.12 mm.

5. The electrical conductor (100) according to one of the preceding claims, wherein the first conductive layer (112) has a specific resistance of about 2.5 * 10 -8 n * m 2 / m to about 2.5 * 10 -7 n * m 2 / m, especially of about 4 * 10 -8 n * m 2 / m to about 1.2 * 10 -7 n * m 2 / m 6. The electrical conductor (100) according to one of the preceding claims, wherein the first conductive layer (112) has an effective layer thickness of about 0.02 mm to about 0.6 mm, in particular about 0.04 mm to about 0.06 mm.

7. The electrical conductor (100) according to one of the preceding claims, wherein the first conductive layer (112) - is designed to contain a diamagnetic material, or - comprising a ferromagnetic material with a relative permeability of about 10 to about 1000, in particular about 350 to about 650.

8. The electrical conductor (100) according to one of the preceding claims, wherein the first conductor core (111) is configured to contain aluminium, tinned aluminium, copper or tinned copper.

9. The electrical conductor (100) according to one of the preceding claims, wherein the first conductor core (111) is designed as a Class 5 or Class 6 conductor.

10. The electrical conductor (100) according to one of the preceding claims, wherein the first insulation (120) has a relative permittivity of about 1.5 to about 2.

5. Lapp Engineering AG - 24 - 30A-168 749 11. The electrical conductor (100) according to one of the preceding claims, wherein the at least one first electrical conductor (110) has a non-circular or rectangular or square cross-sectional area.

12. The electrical conductor (100) according to one of the preceding claims, wherein the material of the conductor core (111) and the material of the first conductive layer (112) are not the same material.

13. Having an electrical cable (1000): - at least three electrical conductors (100) according to one of claims 1 to 12, wherein the at least three electrical conductors (100) are stranded in a first stranding direction to form a conductor bundle, - at least a first shielding layer surrounding the bundle of veins (200), and - a mantle (300) surrounding the first shielding layer (200).

14. The electrical cable (1000) according to claim 13, wherein the first shielding layer (200) is formed as a winding with at least three individual conductors (210) and a winding direction of the individual conductors (210) opposes the stranding direction of the electrical conductors (100).

15. The electrical cable (1000) according to one of the preceding claims, wherein the electrical cable (1000) has at least three dummy wires (400) which are stranded with the electrical wires (100) to form the wire bundle.

16. The electrical cable (1000) according to one of the preceding claims, wherein the electrical cable (1000) has at least one inner sheath (500) arranged between the conductor bundle and the at least one first shielding layer (200).

17. The electrical cable (1000) according to claim 15, wherein the inner sheath (500) has air inclusions and / or a radially outer surface of the inner sheath (500) facing the first shielding layer (200) has a corrugated surface, and wherein the corrugated surface has a star geometry, a sawtooth geometry, a wave geometry or an outer toothed ring geometry.

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