Electric machine with an insulation material sensitive to partial discharges

Abstract

The invention relates to a stator (8) and / or rotor (9) of an electric machine (1) having a, in particular multiphase, winding system (13) arranged in a slot (16) of an electromagnetic conductor (10), which forms a winding head (7) on an end face of the respective electromagnetic conductor (10), wherein at least sectionally in the slot (16) and / or in the winding head (7) an insulating material is provided, wherein the insulating material has a conductor track carrier (27) which is equipped in a predefinable section with a composite material (28) having a frequency-dependent resistance characteristic in order to be able to detect voltage overloads, in particular partial discharges, in the winding system, in particular in the slot and / or winding head region.

Description

Technical Field

[0001] The present invention relates to a stator and / or rotor of an electric machine having a partial discharge sensitive insulating material as a slot liner or phase separator, and also to a method for determining partial discharge. Background Technology

[0002] In particular, the winding systems of low-voltage motors (up to 1000 V DOL (Direct on line) or 690 V VSD (Variable speed drive) in the stator and / or rotor are equipped with a partial discharge-free electrical insulation system according to current IEC standards. This insulation system consists of a wire varnish pre-coated by the manufacturer onto copper wire (approximately 200 µm) using a multi-layer structure made of materials such as PAI (polyamide-imide), and a so-called slotted box, which is a standard U-shaped folded paper serving as the main insulation. This slotted box is often made of commercially available laminated material, with an inner layer of PET film (200 µm; polyethylene terephthalate) and coated on both sides with aramid fibers (aramid felt).

[0003] In the manufacturing process of stators for electric machines, for example, slot liner is first inserted into the slots of the laminated iron core, and then pre-wound copper wire windings are mechanically embedded into the slots.

[0004] Subsequently, in the winding head area of ​​the stator end face, the phases are further insulated from each other by insulating inserts, also known as phase isolators.

[0005] After the winding heads are formed and bound, an impregnation process (cold impregnation, hot impregnation, or drip impregnation) is applied to at least partially fill the conductor gaps, the spaces before and after the slot liner, and the geometric angle areas of the winding heads with impregnating resin (PEI, polyetherimide, or epoxy resin). This impregnating resin should primarily ensure the mechanical fixation and heat dissipation of the copper wires, and under normal circumstances, it should only be conditionally suitable as primary electrical insulation.

[0006] In other words, viewed from the direction of (high) voltage to ground, the insulation system of the stator of an electric machine is basically composed of varnish, impregnation layer (with many holes), slot liner, and impregnation layer (with many holes) in cross-section.

[0007] In this case, the insulation system can be simplified to a capacitor made of different dielectric materials, where electric field lines are always repelled to low ε. r These areas, when in doubt, always refer to pores or areas of incompletely cured resin in the insulation system.

[0008] This type of insulation system is generally sufficient to meet the operating voltage requirements of electric machinery in terms of breakdown strength, insulation resistance, and loss factor.

[0009] However, the increasing use of frequency converters (VDCs) in end-customer motors, particularly electric motors, leads to significant voltage overshoot during the continuous switching process (square wave voltage) of the VDC, due to rise times as short as 150 ns or even less. This is because, from an electrical engineering perspective, this steep edge is generated by the superposition of very high frequencies (1 kHz to megahertz range). The amplitude of this type of voltage overshoot can be several times the actual voltage setpoint and propagates through the motor windings with a specific pulse propagation time (traveling wave effect). In these traveling wave effects, the pulse attenuates within the coil due to ohmic resistance and inductance, creating a voltage difference several times the operating voltage between the first and last turns of a coil in a slot, separated only by the enamel coating and, in some cases, a low-quality impregnation layer. The shorter this rise time, the higher the load on the motor's insulation system.

[0010] According to the principle of "split-embedded winding", during the manufacturing process of stator winding, there may be situations where low-turn-count turns and high-turn-count turns (i.e., turns at the coil inlet and coil outlet) come into direct contact and cross each other.

[0011] This is usually unavoidable, or can only be avoided or corrected with extremely high human intervention. The same problem also occurs between phases and laminated cores (ground potential), or between two different phases, but its impact is significantly smaller when the interphase insulation in the slot liners or winding heads is installed correctly.

[0012] However, common manufacturing problems caused by displacement of the surface insulation material (e.g., in the slot or winding head) can have a particularly adverse effect.

[0013] In the above configuration, the overvoltage often exceeds the initiation voltage (TE) of partial discharge in the insulation system (typically wire-to-wire), which exists due to variations in porosity, cavities, and materials (different ε). r The weak points formed by this.

[0014] Overvoltage between insulated electrical conductors can in particular damage the insulation of the conductors.

[0015] Therefore, insulation systems often have manufacturing defects, manifested as pores and gaps ranging in size from micrometers to millimeters. Overvoltages can thus induce partial discharges in the insulation. Because these defective sites typically have low dielectric constants, partial discharges are triggered by the avalanche effect of charge carriers, especially when the electric field reaches a certain strength, according to Paschen's law. These partial discharges cause the insulation, particularly in the defective regions, to gradually deteriorate until the insulation fails.

[0016] Therefore, the Paschen minimum value will be exceeded, triggering partial discharge. These partial discharges will then be continuously triggered during inverter operation and further aggravated by the continuous "erosion" of the insulation material, which may even lead to insulation system failure in a relatively short period of time, resulting in motor failure.

[0017] In automatic winding machines that embed random windings into slots, wire crossings are unavoidable. Similarly, especially in cost-optimized impregnation systems, various weak points are difficult to avoid.

[0018] The only remaining possibility is to perform a partial discharge test, but this often fails when there is doubt, so the motor must be sorted out as a defective product. However, this only applies to motors that already have obvious weaknesses before delivery.

[0019] However, this is usually a "gradual degradation" process, and significant changes only occur after the electric machine has been running for a period of time. Therefore, it will be judged as good in the factory's quality control (initially).

[0020] The quality and condition of the insulation of the winding system of electric machines cannot usually be quantitatively determined from the outside. Therefore, the complete failure of electric machines caused by electrical breakdown due to insulation damage caused by partial discharge (such as electrical breakdown between two different phase turns of the machine or between a turn and the grounded laminated iron core) is currently unpredictable.

[0021] Other winding methods used to avoid the resulting partial discharge (such as pin windings) are significantly more expensive to purchase, significantly limit the flexibility of motors in terms of variant management, and also have longer cycle times, which ultimately increases the cost of the manufacturing process, making the production of standard motors, in particular, often less economical.

[0022] Very high-quality impregnation, which nearly 100% fills the gap between the conductor and the channel liner, will displace the electric field from the critical region (ε). r This causes a shift in the Paschen minimum. Therefore, the TE starting voltage increases, and the probability of TE problems occurring on the inverter decreases. However, such impregnation is difficult to achieve in practice (economically) because methods such as VPI (vacuum pressure impregnation) and full potting have significantly higher manufacturing and material costs, and complete resin filling cannot be guaranteed.

[0023] Therefore, the resulting “TE problem” exists, which is particularly evident in the winding head between two critical conductors in contact, or in the slot between the conductor and the grounded laminated core.

[0024] These so-called partial discharges (TEs) occur when the TE initiation voltage, determined by the wire insulation, impregnation resin, insulating paper (slot box or phase separator) of the two conductors, and any air bubbles that may be present, is exceeded.

[0025] Due to the frequent occurrence of these discharges (in the worst-case scenario, they occur with every voltage pulse of the inverter), the conductor insulation and the entire insulation system gradually degrade until complete discharge, i.e., breakdown, occurs. Now, a short circuit occurs between the affected coil or conductor and the laminated iron core (grounded). This causes a significant increase in temperature at that point due to the short-circuit current, until the affected conductor "burns out."

[0026] If the motor current becomes unbalanced, the windings may burn out completely, or the inverter may detect the imbalance and shut down. In both cases, the motor will fail and is usually beyond repair.

[0027] Therefore, it is only possible to identify the defective part and the resulting partial discharge when the motor has already failed.

[0028] Therefore, there are currently two methods for preventing faults on the motor side: Using the significantly more expensive manufacturing process described above, or The insulation system is significantly enhanced by either undergoing factory inspection and accepting a correspondingly high scrap rate, or at the cost of increased costs and the resulting reduction in copper filler in the tank.

[0029] Customers can also use filters, which increase the rise time of the inverter voltage edge, thereby reducing overshoot. However, this is an expensive expense for customers, and because these filters are connected in series, they can negatively impact the overall efficiency of the motor-inverter system.

[0030] European Patent EP 3 505 943 A1 discloses a detection device that measures overvoltages occurring in a power grid, which can cause partial discharges when there are defects in the motor insulation system. Therefore, this is an indirect assessment of potentially damaged insulation systems. The detection device is installed between the input and output terminals of each phase, between individual phases, and between each phase and the ground potential. Summary of the Invention

[0031] Based on this, the object of the present invention is to provide a stator and / or rotor of an electric machine that can directly perform position-related detection of partial discharges that occur independently of the electrical load within the insulation.

[0032] The technical problem raised is solved by the features of the independent claims.

[0033] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0034] The stator and / or rotor of the electric machine according to the invention are based on having a winding system, particularly multiphase, formed of electrical conductors arranged in slots of an electromagnetic conductor, particularly a laminated iron core. The winding system forms winding heads at the end faces of the respective electromagnetic conductors and is provided with insulating material arranged at least in segments in the slots and / or winding heads. This insulating material has a conductor line carrier, which is provided with a composite material having frequency-dependent resistance characteristics in predetermined sections to detect voltage overloads, particularly partial discharges, in the winding system, particularly in this region (slots / winding heads, etc.).

[0035] The insulating material has a granular, partially conductive layer composed of microparticles (e.g., SnO2, doped with Sb, I, F or SiC if necessary, in sheet or spherical form, with or without a substrate, with a particle size of 1 µm to 50 µm) and any plastic matrix. The particles are introduced into the plastic matrix by over-permeation to form a conductive network.

[0036] In this process, the composite material is made into a slurry using a suitable matrix. The slurry is then coated onto an insulating material using conventional “printable electronics” processes such as screen printing or dispensing, i.e., onto the aforementioned slot and / or phase isolator serving as the substrate, thereby forming a conductor circuit structure. The insulating material is directly positioned in the electromechanical system (e.g., in the slot and / or winding head).

[0037] In other words, the insulation system itself is a voltage overload sensor. Therefore, the insulation system is an insulating material designed to be surface insulated and integrates the sensor.

[0038] That is, for example, there exists a conductor circuit structure composed of the aforementioned particles combined with any plastic matrix, which allows for printing and curing (by thermal baking and / or UV crosslinking), such as polysiloxane, polyester, or epoxy resin. The conductor circuit structure particularly features a layer thickness of 10 µm to 200 µm and an edge and radius accuracy of 50 µm. The width of the conductor circuit itself ranges from 100 µm to 2000 µm.

[0039] The composite material according to the invention has a resistance of about 100 ohms to 100,000 ohms (surface resistance, i.e., a specific ohmic resistance of about 1 ohm-cm to 100 ohm-cm) at low frequencies (up to 1000 Hz), thus obtaining an easily readable total resistance in a structure with fine wires. However, this partially conductive structure has no measurable effect on the electromagnetic field in the region between the laminated iron core and the copper conductor because its resistance is significantly too high at relatively low frequencies (up to 1 kHz).

[0040] This design takes into account the use of solvents in the fabrication of conductor circuits (e.g., printing conductor circuit carriers), which are then evaporated after coating the conductor circuits. When the conductor circuit thickness is too large, solvent evaporation can cause cracks or pores within the conductor circuit, affecting its quality. A typical thickness is approximately 100 μm, at which the conductor circuit exhibits sufficient conductivity and is unaffected by solvent evaporation.

[0041] The surface resistance (also known as surface impedance) of a conductive layer refers to its specific resistivity given a defined layer thickness. When the conductor line thickness is approximately 100 µm, it is advantageous for the surface resistance to not exceed 100 kΩ; otherwise, a significant portion of the overvoltage would be absorbed within the conductor line.

[0042] The conductor lines, for example, each have a thickness of approximately 100 µm and a surface resistance of up to 100 kΩ before partial discharge. The conductor lines are coated onto a conductor line carrier, for example, by screen printing or dispensing printing processes.

[0043] Since the structure involved is a granular structure with many particle contact transition regions and grain boundaries, each of these regions and grain boundaries has high impedance and constitutes a capacitance. Therefore, there is a frequency-dependent decrease in resistance, which can be measured by impedance spectroscopy.

[0044] The structure on the insulating material itself can consist of straight conductor lines, crossed conductor lines, or serpentine conductor lines laid out on the slot or phase isolator, and signal extraction can be performed at the edges of the insulating material (e.g., via contact pads). Therefore, resistance changes caused by partial discharge can be detected (e.g., at the flange of the slot, which is axially located outside the laminated core).

[0045] In one design, by laying out conductor lines corresponding to the antenna structure, signals can be captured or electrically influenced on signals modulated on the motor phases, thereby altering the resonant characteristics when the conductor line structure becomes partially high impedance due to partial discharge. Thus, an electromagnetic resonant circuit is formed between the motor phases and the conductor line structure, which changes its resonant frequency through a "TE load" and consequently, by increasing the impedance of the conductor line structure. This can be measured, in particular, through contact pads and evaluated using appropriate evaluation tools.

[0046] During inverter switching operations, oscillating overshoots with extremely high frequencies (>1 kHz) occur, with voltages reaching several times the actual voltage. Therefore, the composite material layer constituting the printed conductor circuitry exhibits significantly higher conductivity than the low-frequency, low-voltage components due to the high-frequency resistance reduction effect. Consequently, a polarization effect also occurs in the conductor circuitry layer, preferentially guiding TE (transient current) to the layer described in this invention, thus enabling it to be read as previously stated.

[0047] Partial discharge in electric motors mainly occurs in the slots between the copper wire and the ground potential (i.e., through the slot box towards the grounded laminated iron core of the stator or rotor), or at the contact position between small and large turns or different phases at the winding head.

[0048] Therefore, it can be ensured that the partial discharge that occurs is always generated in close proximity to the (surface) insulating material coated according to the invention, and usually also directly interacts with the conductor circuit structure, so that the released energy and oxidation potential (temperature, UV light, ozone) will irreversibly change the conductor circuit according to the invention to a high-resistance state, so that it can be read by resistance offset.

[0049] By cleverly arranging and designing the conductor circuit structure, such as laying it in parallel, meandering, or dense mesh patterns, it is possible to achieve adjustable and precise location identification of the resulting partial discharge and thus the weak points in the insulation system.

[0050] The solution shown in EP 3 505 943 A1 is only an indirect method for detecting overvoltages that can cause partial discharge in motors when the insulation system may be defective or damaged.

[0051] The solution disclosed in this paper produces an electrically readable sensing mechanism that can directly detect partial discharges occurring in the slots or winding heads of a motor, unaffected by voltage or load peaks present on the motor.

[0052] That is, according to the present invention, the reduction in insulation strength caused by partial discharge (TE) is detected by the increase in the impedance of the conductor line.

[0053] That is, it can be used, for example, for quality control at the end of the manufacturing process, or as a predictive maintenance sensing mechanism for electric machinery at the customer's location. Attached Figure Description

[0054] The present invention and other advantageous technical solutions of the present invention will be further described below with reference to the embodiments shown in the principle diagram, wherein: Figure 1 A longitudinal section of the electric motor is shown. Figure 2 The cross-section of the stator slot is shown. Figure 3 The arrangement of slot boxes in the stator laminated iron core is shown. Figures 4 to 7 Different slot box design schemes are shown. Figure 8 , Figure 9 Different winding heads are shown. Figure 10 A schematic diagram showing two filler particles embedded in a plastic matrix and the energy band of the filler is presented. Detailed Implementation

[0055] It should be noted that terms such as "axial," "radial," and "tangential" refer to the axis 6 used in the corresponding figures or described embodiments. In other words, the axial, radial, and tangential directions always refer to the axis 6 of the rotor 9, and thus also to the corresponding axis of symmetry of the stator 8. "Axial" describes a direction parallel to the axis 6, "radial" describes a direction orthogonal to, towards, or away from the axis 6, and "tangential" refers to a circular direction around the axis 6 when the radial distance from the axis 6 is constant and the axial position is constant. The expression "circumferentially" is equivalent to "tangential."

[0056] The terms “axial,” “radial,” “tangential,” etc., relative to a surface, such as a cross-section, describe the orientation of the normal vector of that surface, that is, the vector perpendicular to the relevant surface.

[0057] Here, the expression "coaxial components" (e.g., coaxial assemblies such as rotor 9 and stator 8) refers to components having the same normal vector, that is, the planes defined by these coaxial components are parallel to each other. Furthermore, this expression should include the fact that the midpoints of the coaxial components lie on the same axis of rotation or axis of symmetry. However, these midpoints may be located at different axial positions on that axis, that is, the distance between the mentioned planes is greater than 0. This expression does not necessarily require that the coaxial components have the same radius.

[0058] In the context of two complementary components, the term "complementary" means that their shapes are designed such that one component can preferably be fully arranged within its complementary component, so that the inner surface of one component and the outer surface of the other component ideally make full or seamless contact. Therefore, in the case of two complementary objects, the shape of one object is determined by the shape of the other. The term "complementary" can be replaced by the term "inverse."

[0059] For clarity, in the accompanying drawings, where a component appears multiple times, not all of the components shown are usually labeled with reference numerals.

[0060] The described embodiments can be combined arbitrarily. Similarly, individual features of the corresponding embodiments can also be combined with each other without departing from the spirit of the invention.

[0061] Figure 1 A schematic longitudinal section of the electric machine 1 is shown. In this example, a stator 8 with a winding system 7 arranged in substantially axially extending slots 16 is arranged in a housing 2. The housing 2 is supported on a shaft 5 by means of bearing end caps 3 and bearings 4. A rotor 9 is arranged spaced apart from the stator 8 by an air gap 25, the rotor having permanent magnets in substantially axially extending recesses. The rotor 9 can also be constructed as an aluminum / copper / hybrid die-cast rotor, or as a reluctance rotor.

[0062] The laminated iron cores 10 and 11 of the stator 8 and rotor 9 may optionally have axially extending cooling channels, thereby enabling a closed internal cooling circuit within the housing 2. When the winding system 7 of the stator 8 is energized, the shaft 5 rotates about the axis 6 through electromagnetic interaction with the rotor 9. This rotation drives working machinery (not shown) and a self-ventilated fan 15 located in or on the housing 2.

[0063] Figure 2 The slot liner, specifically the slot box 14 made of insulating material, is shown in the cross-section of the slot 16 of the stator 8. The slot box 14 is either inserted axially into the slot 16 or positioned within the slot via the slot opening 22. Figure 3 As shown, the slot box 14 extends axially from the end face of the laminated iron core 10 of the stator 8 by an axial length 24, and a flange 17 is formed there.

[0064] according to Figure 4 The slot 14 has a preset bending area 23 to facilitate installation in the slot 16.

[0065] according to Figures 5 to 7 A contact pad 19 is provided on the flange 17 so that resistance changes can be detected by measuring the arrangement.

[0066] The routing of conductor line 18 on conductor line carrier 27 of slot 14 is shown in the figure. Figures 5 to 7 The diagram shows both parallel conductor lines 18 each equipped with contact pads 19 and conductor lines 18 meandering in various ways.

[0067] The material of these conductor line carriers 27 can also be used as phase separators in the winding heads of two different phases or coil groups that are close to each other. These phase separators can be used in winding systems 13 composed of toothed coils. Figure 8 The winding head 7 of the winding can also be used in the short-pitch winding system 13. Figure 9 ) winding head 7.

[0068] For example, the conductor line 18 is made of a composite material 28, which includes a non-conductive plastic matrix 32 and a filler 29 embedded therein, through which the filler makes the composite material 28 conductive.

[0069] Figure 10 The structure of one embodiment of this composite material 28 is schematically shown. The plastic matrix 32 is made of a chemically cross-linked thermosetting or thermoplastic plastic. For example, the plastic matrix 32 is made of epoxy resin, silicone, polyurethane, or polyetherimide.

[0070] The filler 29 has conductive filler particles 30 that occupy grid positions in the network formed by the plastic matrix 32 with a probability greater than a permeation threshold, above which the composite material 28 is conductive. That is, the filler particles 30 form a continuous particle network in the plastic matrix 32, and the composite material 28 is conductive through this particle network.

[0071] For example, filler 29 is an n-type conductive metal oxide doped with a chemical element whose atomic number in the periodic table is one greater than that of the metal in the oxide. For example, filler 29 is antimony-doped tin dioxide, manganese-doped chromium oxide, cobalt-doped iron oxide, or nickel-doped cobalt oxide.

[0072] These fillers 29 spontaneously generate oxygen vacancies during their preparation. These oxygen vacancies act as charge carrier donors and contribute to the good conductivity of the filler 29. Partial discharge caused by overvoltage can locally heat the filler 29, leading to localized ozone generation. Due to the increased temperature and the generated ozone, the surface edge layer 33 of the filler particles 30 with oxygen vacancies oxidizes. Consequently, the number of oxygen vacancies in the filler 29 decreases, and the conductivity of the composite material 28 decreases, i.e., the resistance of the composite material 28 increases.

[0073] Figure 10 A cross-sectional view of two contacting filler particles 30 is shown in an exemplary and schematic manner. These filler particles are composed of antimony-doped tin dioxide as filler 29 and have an oxidized surface edge layer 33 due to partial discharge. Furthermore, Figure 10 The upper edge E of the valence band of filler 29 is also shown. V E, lower edge of the conductor band L and Fermi level E F Along the orientation of filler particles 30. Oxidation of filler particles 30 causes the upper edge E of the valence band to... V and the lower edge of the conductor band E L The resistance of the composite material 28 increases in the contact region 34, where the surface edge layers 33 of the filler particles 30 are adjacent to each other. Therefore, a potential barrier for electrons 35 is formed in the conduction band in the contact region 34, thereby increasing the resistance of the composite material 28.

[0074] However, filler 29 may not be any of the materials mentioned above, but other materials, such as undoped n-type conductive metal oxides, fluorine-doped or indium-doped n-type conductive metal oxides, coated or uncoated mica, quartz powder, carbon black, graphite, and / or metals, such as copper. When filler 29 is copper, filler particles 30 are, for example, copper flakes. Filler particles 30 made of carbon black, graphite, or metal do not form the surface edge layer 33 of the type described above during partial discharge, but instead oxidize and thus lose their conductivity, thereby increasing the resistance of the composite material 28.

[0075] Alternatively, conductor line 18 may not use the aforementioned composite material 28, but may be made of conductive plastic, such as polyaniline (PANI) or poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), whose conductivity may be reduced or destroyed by partial discharge.

[0076] The conductor lines 18 of the slot liners, especially the slot box 14 and / or phase isolators, are constructed and arranged such that a predetermined overvoltage generated between different potentials due to, for example, partial discharge, will change the resistance of the conductor lines 18 to a resistance value corresponding to that overvoltage. These different potentials may exist between conductors of different phases, between different turns of a coil, or between a live conductor and a grounding component of the motor 1 (e.g., the laminated core 10 of the stator 8). To detect overvoltage, the resistance of the conductor lines 18 is measured, and the overvoltage is inferred from the change in resistance.

[0077] This invention can also be used in other motors, such as transformers, or in other places where partial electrical discharges that need to be detected may occur.

[0078] Although the present invention has been illustrated and described in more detail through preferred embodiments, the present invention is not limited to the disclosed examples; those skilled in the art can derive other variations therefrom without departing from the scope of protection of the present invention.

[0079] Therefore, TE overvoltage can be identified in a timely manner during motor operation, which may lead to insulation damage to the winding system and ultimately complete motor failure.

[0080] Specifically, the conductor line 18 on the conductor line carrier 27 is explicitly not electrically connected to the potential (i.e., the coil of the winding system 13 or the grounded laminated iron core 10 of the stator 8). That is, the measurement is performed at a floating potential.

Claims

1. A stator (8) and / or rotor (9) of an electric machine (1), the stator and / or rotor having, in particular, a multiphase winding system (13) arranged in slots (16) of an electromagnetic conductor (10), the winding system forming winding heads (7) on the end faces of the respective electromagnetic conductors (10), wherein, An insulation system with insulating material is provided at least in sections in the slot (16) and / or in the winding head (7), wherein the insulating material has a conductor line carrier (27), which is equipped with a composite material (28) with frequency-varying resistance characteristics in a preset section to detect voltage overload, particularly partial discharge, in the winding system (13), especially in the slot and / or winding head region.

2. The stator (8) and / or rotor (9) of the electric machine (1) according to claim 1, characterized in that, The insulating material is used as the slot liner of the slot (16) and / or the phase separator in the winding head (7).

3. The stator (8) and / or rotor (9) of the electric machine (1) according to claim 1 or 2, characterized in that, The preset section is designed as a conductor line (18), which forms an uninterrupted connection between at least two contact pads (19).

4. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, In particular, at the axial edge of the pre-defined region of the conductor line carrier (27), especially in the region of at least one end face, the resistance change can be detected by the contact pad (19).

5. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, The conductor lines (18) on the conductor line carrier (27) have a preset conductor line structure, which in particular extends in a straight line or in a meandering manner.

6. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, The conductor line (18) is made of a composite material (28) having a non-conductive plastic matrix (32) and a filler (29) embedded in the plastic matrix, through which the composite material (28) becomes conductive.

7. The stator (8) and / or rotor (9) of the electric machine (1) according to claim 6, characterized in that, The filler (29) has conductive filler particles (30) that occupy grid positions in the grid formed by the plastic matrix (32) with a probability greater than the permeation threshold, and the composite material (28) is conductive above the permeation threshold, wherein the conductivity of the filler particles (30) is reduced by partial discharge acting on the filler particles (30).

8. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of claims 6 or 7, characterized in that, The filler (29) contains n-type conductive metal oxides, coated or uncoated mica, quartz powder, carbon black, graphite and / or metals.

9. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of claims 6 to 8, characterized in that, The filler (29) contains antimony-doped tin dioxide and / or fluorine-doped or indium-doped tin oxide.

10. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of claims 6 to 9, characterized in that, The plastic matrix (32) is made of chemically cross-linked thermosetting plastic or thermoplastic plastic.

11. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, The conductor line (18) is made of conductive plastic.

12. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, The conductor line (18) is made of polyaniline or poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate.

13. The stator (8) and / or rotor (9) of the electric machine (1) according to any one of the preceding claims, characterized in that, Each of the conductor lines (18) has a thickness of about 100 μm and a surface resistance of no more than 100 kΩ before partial discharge.

14. A method for measuring partial discharge in the stator (8) and / or rotor (9) of an electric machine (1), the stator and / or rotor of the electric machine having, in particular, a multiphase winding system (13) arranged in slots (16) of electromagnetic conductors (10), the winding system forming winding heads (7) on the end faces of the respective electromagnetic conductors (10), wherein, An insulation system with insulating material is provided at least in sections in the slot (16) and / or the winding head (7), wherein the insulating material has a conductor line carrier (27), the conductor line carrier is equipped with a composite material (28) with frequency-varying resistance characteristics in a preset section to detect voltage overload, especially partial discharge, in the winding system in the (slot / winding head) region.

15. The method for measuring partial discharge in the stator (8) and / or rotor (9) of an electric machine (1) according to claim 14, characterized in that, During the operation of the electric motor (1), a modulation signal is applied to at least one phase of the motor at a preset time interval, wherein, due to the conductor line structure becoming locally high impedance through partial discharge and being detected by the partial discharge, the antenna structure preset by the conductor line structure undergoes a resonant change during the partial discharge.

16. The method for measuring partial discharge in the stator (8) and / or rotor (9) of an electric machine (1) according to claim 14 or 15, characterized in that, The measurement is performed on a floating potential.

Images