Semiconductive member, stator coil, and rotating electrical machine

Abstract

A semiconductive member according to one embodiment of the present disclosure comprises: semiconductive resin layers in which conductive particles are dispersed and mixed in a resin part; and a fibrous insulating substrate on which the semiconductive resin layers are disposed. The conductive particles are expanded graphite particles.

Description

Semiconductive member, stator coil and rotating electric machine

[0001] The present disclosure relates to a semiconductive member, a stator coil, and a rotating electric machine.

[0002] In stator coils used in stators of high-power rotating electric machines, in order to suppress corona discharges that occur in the small space between the iron core and the main insulating layer, a semiconductive layer made of semiconductive tape wound around the main insulating layer, which covers the conductor portion made of bundled strands of conductors, is placed on top of the main insulating layer. This semiconductive tape serves to reduce the potential gradient between the iron core and the main insulating layer, thereby lowering the voltage shared in the small space on the iron core surface. The semiconductive tape is manufactured by placing a semiconductive resin layer, in which conductive particles such as carbon black are added to the resin, on a fibrous insulating substrate such as glass cloth or nonwoven fabric.

[0003] In recent years, as rotating electrical machines have become smaller and more powerful, the electrical, thermal, and mechanical stresses during operation have tended to increase, causing the semiconductive layer to deteriorate over time. Furthermore, since it is difficult to manufacture a machine without voids at the interface between the main insulating layer and the semiconductive layer, a relatively high level of partial discharges occurs from the voids, accelerating the deterioration of the semiconductive layer and making it difficult to suppress corona discharges occurring in the space between the iron core and the main insulating layer over the long term.

[0004] Therefore, a semiconductive tape has been disclosed in which a semiconductive resin layer is applied to a fibrous insulating substrate, the semiconductive resin layer being made by adding inorganic particles of at least one type selected from layered clay mineral particles, oxide particles, and nitride particles in addition to conductive particles (see, for example, Patent Document 1). Also, a semiconductive tape has been disclosed in which a mixture of conductive particles and nonconductive nanoparticles added to a high molecular weight polymer is disposed on a fibrous insulating substrate (see, for example, Patent Document 2).

[0005] JP 2006-246599 A International Publication No. 2018 / 002974

[0006] The degradation caused by partial discharge can be roughly divided into impact action by charged particles, thermal decomposition action due to local temperature rise, and chemical action by activated gas generated by discharge, and these actions act synergistically to cause the degradation to progress. Among these, the inventors have focused on ozone (O ３ The inventors have newly discovered that the influence of the oxidizing action of activated gases such as ozone and atomic oxygen (O) is extremely large and is the dominant factor in the deterioration of the semiconductive layer. Therefore, in this respect, although the semiconductive tapes disclosed in Patent Documents 1 and 2 as mentioned above can be expected to improve initial corona resistance, the organic resins and high molecular weight polymers are quickly deteriorated by the oxidizing action of the ozone and atomic oxygen generated by the partial discharge as mentioned above and are decomposed into low-molecular-weight volatile products, making it difficult to maintain the initial corona resistance over the long term.

[0007] The present disclosure has been made in view of the above problems, and one of its objects is to provide a semiconductive member, a stator coil, and a rotating electric machine that can exhibit stable corona resistance over a long period of time.

[0008] One aspect of the semiconductive member of the present disclosure comprises: a semiconductive resin layer having conductive particles dispersed and mixed in a resin portion; and a fibrous insulating substrate on which the semiconductive resin layer is disposed, wherein the conductive particles are particles of expanded graphite.

[0009] One aspect of the stator coil of the present disclosure includes a winding and a thermosetting resin impregnated into the winding, and the winding includes a conductor portion formed by bundling strand conductors, an insulating layer formed by winding a mica member around the outer periphery of the conductor portion, and a semiconductive layer formed by winding the semiconductive member described above around the outer periphery of the insulating layer.

[0010] One aspect of a rotating electric machine according to the present disclosure includes the above-described stator coil.

[0011] The semiconductive member, stator coil, and rotating electric machine of the present disclosure can exhibit stable corona resistance over a long period of time.

[0012] Fig. 1 is a cross-sectional view schematically illustrating a configuration of a semiconductive tape according to embodiment 1. Fig. 2 is a flow chart illustrating a manufacturing process of the semiconductive tape according to embodiment 1. Fig. 3 is a cross-sectional view schematically illustrating a configuration of a stator coil using the semiconductive tape according to embodiment 1. Fig. 4 is a cross-sectional view schematically illustrating another configuration of the semiconductive tape according to embodiment 1. Fig. 5 is a cross-sectional view schematically illustrating another configuration of the semiconductive tape according to embodiment 1.

[0013] Hereinafter, embodiments to which the present disclosure is applied will be described in detail with reference to the drawings. Note that the drawings used in the following description are for explaining the configuration of the embodiments of the present disclosure, and the size, thickness, dimensions, etc. of each part shown in the drawings may differ from the actual dimensional relationships.

[0014] (Embodiment 1) [Semiconductive Member] Fig. 1 is a cross-sectional schematic diagram showing the configuration of a semiconductive tape 1 according to this embodiment 1. As shown in Fig. 1, the semiconductive tape 1 as a semiconductive member includes semiconductive resin layers 10a and 10b and a fibrous insulating substrate 4. The fibrous insulating substrate 4 holds the semiconductive resin layers 10a and 10b on both sides in the thickness direction. The fibrous insulating substrate 4 holds the semiconductive resin layer 10a on one side (upper surface) in the thickness direction and holds the semiconductive resin layer 10b on the other side (lower surface) in the thickness direction.

[0015] The semiconductive resin layer 10a has a resin portion 11a in which conductive particles are dispersed and mixed. The resin portion 11a has a thermosetting resin 3a. Particles of expanded graphite 2 serving as conductive particles are dispersed and mixed inside the thermosetting resin 3a. That is, the semiconductive resin layer 10a has a thermosetting resin 3a in which particles of expanded graphite 2 serving as conductive particles are dispersed and mixed inside.

[0016] The semiconductive resin layer 10b has a resin portion 11b in which conductive particles are dispersed and mixed. The resin portion 11b has a thermosetting resin 3b. Particles of expanded graphite 2 are dispersed and mixed inside the thermosetting resin 3b as conductive particles. In other words, the semiconductive resin layer 10b has a thermosetting resin 3b in which particles of expanded graphite 2 are dispersed and mixed inside as conductive particles. In the following description, the particles of expanded graphite 2 will be simply referred to as expanded graphite 2.

[0017] [Method for manufacturing semiconductive member] Next, a method for manufacturing the semiconductive tape 1 according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a flowchart showing manufacturing steps in the method for manufacturing the semiconductive tape 1 according to the first embodiment.

[0018] First, the thermosetting resins 3a and 3b are kneaded with the expanded graphite 2 (step S501). The kneading step of the expanded graphite 2 into the thermosetting resins 3a and 3b is preferably performed by applying shear mixing, which applies shear force. By applying shear force, the expanded graphite 2 can be uniformly dispersed in the thermosetting resins 3a and 3b.

[0019] The mixer for shear mixing is not particularly limited, and any suitable mixer can be used as long as it is capable of mixing while applying shear force. Specific examples include a bead mill mixer, a three-roll mill mixer, a homogenizer mixer, and a Laboplastomill mixer.

[0020] Next, a curing agent is added and mixed into the mixture of the thermosetting resins 3a, 3b and the expanded graphite 2 (step S502). After mixing, the mixture is applied to the fibrous insulating substrate 4 (step S503) and cured by heating (step S504), thereby obtaining the desired semiconductive tape 1.

[0021] In addition, a coupling agent or a surface treatment agent, which will be described later, is added or mixed as needed in the above-described manufacturing process of the semiconductive tape 1. By modifying the surface of the expanded graphite 2 with the coupling agent or the surface treatment agent, it is possible to firmly bond the interfaces between the thermosetting resins 3a, 3b and the expanded graphite 2.

[0022] A feature of the semiconductive tape 1 according to the first embodiment is the use of expanded graphite 2 whose expansion start temperature is higher than the curing temperature of the thermosetting resin used for the impregnation treatment. Due to this feature, when a local temperature rise occurs due to partial discharge, the expandable graphite 2 present near the voids expands and spreads inside the voids, connecting the neighboring pieces of expanded graphite together. This forms a conductive path inside the voids. As a result, the inside of the voids and the semiconductive tape 1 have the same potential, and partial discharge inside the voids is stopped, thereby improving the corona resistance of the thermosetting resin.

[0023] Hereinafter, a detailed description will be given using an example in which the semiconductive tape 1 is applied to a stator coil.

[0024] [Stator Coil] Fig. 3 is a cross-sectional schematic diagram showing the configuration of a stator coil 6 using semiconductive tape 1 according to embodiment 1. As shown in Fig. 3, the stator coil 6 has a winding 12 and a thermosetting resin 13 impregnated into the winding 12.

[0025] The winding 12 has a conductor portion 7 formed by bundling strand conductors, a main insulating layer (insulating layer) 8 formed by winding mica tape as a mica member around the outer periphery of the conductor portion 7, and a semiconductive layer 9 on the outside of the main insulating layer 8. The semiconductive layer 9 is formed by winding semiconductive tape 1. One example of the thermosetting resin 13 is an electrical insulating varnish. The stator coil 6 is manufactured by pressure-impregnating the winding 12 with the electrical insulating varnish, followed by a thermal curing process.

[0026] 3 is applied to a rotating electric machine such as a motor. The application examples of the semiconductive tape 1 of the first embodiment are not limited to the semiconductive layer of the stator coil in the stator of the rotating machine described above, but can also be used for various purposes such as a generator coil, a circuit breaker rod, and a cable covering material.

[0027] In the semiconductive tape 1 according to the first embodiment, the expanded graphite 2 is uniformly dispersed in the thermosetting resins 3 a and 3 b, but this is not limiting. Fig. 4 is a schematic cross-sectional view showing another configuration of the semiconductive tape 1 according to the first embodiment of the present invention, and is an enlarged view of region A in Fig. 3.

[0028] 4, as another configuration of the semiconductive tape 1, the expanded graphite 2 may be locally distributed unevenly in the thermosetting resin 3b in the semiconductive resin layer 10b arranged on the main insulating layer 8 side. The semiconductive layer 9 made of this semiconductive tape 1 deteriorates due to partial discharges that originate from voids present at the interface between the main insulating layer 8 and the semiconductive layer 9. Therefore, in the semiconductive resin layer 10b of the semiconductive tape 1 wound in contact with the main insulating layer 8, the expanded graphite 2 is unevenly distributed on the interface side with the main insulating layer 8.

[0029] In this case, when a discharge occurs inside a void present at the interface between the main insulating layer 8 and the semiconductive layer 9, the expandable graphite 2 can expand and connect with nearby particles, making it easier to form a conductive path inside the void, thereby improving the corona resistance of the thermosetting resin contained in the main insulating layer 8.

[0030] 5 is a cross-sectional schematic view showing another configuration of the semiconductive tape 1 according to embodiment 1, and is an enlarged view of region A in Fig. 2. As shown in Fig. 5, another configuration of the semiconductive tape 1 may be a semiconductive resin layer composed of a semiconductive resin layer 10c in which expanded graphite 2 is dispersed and mixed in a thermosetting resin 3c, and semiconductive resin layers 10a and 10b in which other conductive particles 5 are dispersed and mixed in thermosetting resins 3a and 3b.

[0031] The semiconductive layer 9 made of this semiconductive tape 1 deteriorates due to partial discharges that originate from voids present at the interface between the main insulating layer 8 and the semiconductive layer 9, so in the semiconductive resin layer of the semiconductive tape 1 that is wound in contact with the main insulating layer 8, the expanded graphite 2 is unevenly dispersed in the semiconductive resin layer 10c on the interface side with the main insulating layer 8. In this case as well, when a discharge occurs inside the voids present at the interface between the main insulating layer 8 and the semiconductive layer 9, the expanded graphite 2 can melt and connect with nearby particles, making it easier to form conductive paths inside the voids and improving the corona resistance of the thermosetting resin.

[0032] In any of the above semiconductive tapes 1, the surface resistance is preferably in the range of 100 Ω or more and 100 kΩ or less. A surface resistance of less than 100 Ω is not preferable because eddy currents will be generated on the surface of the semiconductive layer during actual operation. In any of the above semiconductive tapes, the tape thickness is preferably in the range of 50 to 200 μm.

[0033] Each component constituting the semiconductive tape 1 according to the first embodiment will be described in detail below.

[0034] <Expanded Graphite> Expanded graphite 2 is used that has a curing temperature higher than that of the thermosetting resin 13 that is impregnated in the manufacturing process of the stator coil 6. This allows the expandable graphite 2 to expand due to a local temperature rise caused by partial discharge.

[0035] Expanded graphite 2 is a graphite intercalation compound formed when a substance other than graphite penetrates between the layers of graphite, and is a material in which the spaces between layers in the graphite crystal structure are expanded. Expanded graphite 2 can be obtained, for example, by immersing a graphite material in acid (sulfuric acid, nitric acid, etc.). Expanded graphite 2 refers to expandable graphite obtained by acid treatment, and is distinguished from expanded graphite obtained by heat treatment.

[0036] The expanded graphite 2 used in the present disclosure is preferably one in which an acid is intercalated between the graphite layers of flake graphite. The acid intercalated between the graphite layers is characterized by being converted from a liquid to a gas by the application of heat. At this time, the acid expands to widen the gap between the layers, increasing in volume by 200 times or more.

[0037] The temperature at which the expandable graphite 2 starts to expand (thermal expansion onset temperature) is preferably 180°C or higher, and more preferably 250°C or higher. There is no particular upper limit to the expansion onset temperature of the expandable graphite 2, but it is usually 400°C or lower. If the temperature is less than 200°C, it is lower than the curing temperature (100 to 190°C) of the thermosetting resin used in a typical impregnation treatment, and therefore the expandable graphite 2 will be mixed into the electrical insulating varnish as foreign matter during the impregnation treatment process, and the desired electrical insulating properties of the stator coil 6 will not be obtained. The expansion onset temperature is the temperature at which acid vaporizes, and is therefore defined as the temperature at which a sudden mass loss can be confirmed under continuous heating in thermogravimetric analysis (TGA).

[0038] The expanded graphite 2 can be used alone or as a mixture of two or more types including other conductive particles. The conductive particles can be any particles that are conductive, and the type is not particularly limited, but examples include conductive carbon materials such as carbon black, graphite, conductive diamond, carbon fiber, and carbon nanotubes, as well as conductive metal oxides and metals such as indium oxide, cadmium oxide, triiron oxide, zinc oxide, tin oxide, and titanium oxide.

[0039] The expanded graphite 2 can be used alone or as a mixture of two or more types including other inorganic particles. The inorganic particles are filled with inorganic particles consisting of at least one type selected from layered clay mineral particles, oxide particles, and nitride particles.

[0040] Examples of inorganic particles include the following: Layered clay mineral particles include at least one selected from mineral groups such as smectite, mica, vermiculite, and mica. Examples of layered clay mineral particles belonging to the smectite group include montmorillonite, hectorite, saponite, sauconite, beidellite, stevensite, and nontronite. Examples of layered clay mineral particles belonging to the mica group include chlorite, phlogopite, lepidolite, muscovite, biotite, paragonite, margarite, taeniolite, and tetrasilicic mica. Examples of layered clay mineral particles belonging to the vermiculite group include trioctahedral vermiculite and dioctahedral vermiculite. Examples of layered clay mineral particles belonging to the mica group include muscovite, biotite, paragonite, levitolite, margarite, clintite, and anandite. Among these, layered clay mineral particles belonging to the smectite group are preferred in terms of dispersibility in the thermosetting resins 3a and 3b. These layered clay mineral particles can be used alone or in a mixture of two or more. Examples of oxide particles include titanium oxide, silica, alumina, bismuth trioxide, cerium dioxide, cobalt monoxide, copper oxide, iron trioxide, holmium oxide, indium oxide, manganese oxide, tin oxide, yttrium oxide, and zinc oxide. Examples of nitride particles include titanium nitride, tantalum nitride, niobium nitride, molybdenum nitride, cobalt nitride, iron nitride, chromium nitride, vanadium nitride, aluminum nitride, and silicon nitride. These can be used alone or in a mixture of two or more.

[0041] The expanded graphite 2 used is one that begins to expand in a temperature range higher than the curing temperature of the thermosetting resin 13 used for the impregnation treatment. Even when expanded graphite 2 within this expansion-starting temperature range is dispersed in the thermosetting resins 3a and 3b, if partial discharge occurs starting from the voids, the thermosetting resins 3a and 3b are oxidized and decomposed into low-volatility products due to the deteriorating effects of the partial discharge (oxidizing effects of ozone and atomic oxygen). However, the local temperature rise caused by the partial discharge causes the expanded graphite 2 near the voids to expand, and the nearby expanded graphite 2 connects to each other, forming a conductive path within the voids. As a result, the inside of the voids and the semiconductive tape 1 become at the same potential, stopping the partial discharge within the voids and suppressing the thermal decomposition of the surrounding thermosetting resins 3a and 3b while also providing corona resistance.

[0042] Here, if inorganic particles having corona resistance, such as those disclosed in Patent Document 1, are used instead of expanded graphite, initial corona resistance can be expected to improve due to their physical barrier effect. However, unless the inorganic particles thicken and completely cover the front of the deterioration progression, the resin and high molecular weight polymer present between the inorganic particles will be oxidized and decomposed by the oxidizing action of ozone, making it difficult to maintain initial corona resistance over the long term. Furthermore, adding inorganic particles having electrical insulation properties to the semiconductive resin layer reduces the initial resistance value of the semiconductive tape.

[0043] However, by using the expandable graphite 2 that expands due to a local temperature rise caused by partial discharge as in the first embodiment, the corona resistance of the thermosetting resins 3 a, 3 b can be improved. As a result, stable corona resistance can be exhibited over a long period of time, and the initial resistance value of the semiconductive tape 1 can be maintained.

[0044] The average particle size of the expanded graphite 2 is preferably 1 nm or more and 100 μm or less, more preferably 10 nm or more and 50 μm or less, in terms of median diameter (50% diameter, D50). When the above range is specified, a method for measuring the average particle size can be, for example, a laser diffraction / scattering particle size distribution analyzer (Microtrac (registered trademark) MT3300). If the average particle size of the expanded graphite 2 is smaller than 1 nm, the volume that expands when the temperature rises locally due to partial discharge becomes small, and the desired ozone resistance described above cannot be exhibited. On the other hand, if the average particle size of the expanded graphite 2 is larger than 100 μm, the interparticle distance increases proportionally, making it difficult for adjacent particles to connect when expanding due to discharge, and the desired corona resistance described above cannot be exhibited.

[0045] The expanded graphite 2 is dispersed in the thermosetting resins 3a and 3b, and the amount of the expanded graphite 2 is preferably in the range of 1 vol % to 50 vol % relative to the thermosetting resins 3a and 3b. If the amount of the expanded graphite 2 is less than 1 vol % relative to the thermosetting resins 3a and 3b, the desired corona resistance cannot be achieved. On the other hand, if the amount of the expanded graphite 2 is more than 50 vol % relative to the thermosetting resins 3a and 3b, the viscosity of the thermosetting resins 3a and 3b increases, making it difficult to uniformly disperse the expanded graphite 2. Furthermore, the thermosetting resins 3a and 3b become brittle, making it difficult to use them as a tape.

[0046] In order for partial discharge to occur originating from voids present at the interface between the main insulating layer 8 and the semiconductive layer 9, it is desirable that the expanded graphite 2 be locally distributed in the vicinity of one surface of the semiconductive tape 1 and that the average interparticle distance between the expanded graphite 2 be less than 1 μm. If the average interparticle distance of the expanded graphite 2 exceeds 1 μm, it becomes difficult for the expanded graphite 2 to join with neighboring particles when it expands due to discharge, and the desired corona resistance described above cannot be exhibited.

[0047] The surface of the expanded graphite 2 may be modified or coated with a coupling agent or surface treatment agent for the purposes of improving adhesion to the thermosetting resins 3a and 3b or improving dispersibility in the thermosetting resins 3a and 3b. Examples of such coupling agents include silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane, titanate-based coupling agents, and aluminum-based coupling agents. Examples of surface treatment agents include aluminum laurate, aluminum stearate, alumina iron stearate, silica, zirconia, and silicone. These coupling agents or surface treatment agents may be used alone or in combination.

[0048] <Thermosetting Resin> As the thermosetting resins 3a and 3b, any thermosetting resin that remains flexible even after being applied to the fibrous insulating substrate 4 can be used as appropriate, and the type is not particularly limited. Examples of thermosetting resins 3a and 3b having such properties include phenolic resins, imide resins, alkyd resins, unsaturated polyester resins, polyesterimide resins, and epoxy resins. Two or more of these resins may be used in combination depending on the intended use and the mechanical properties required of the resin composition.

[0049] <Fibrous insulating substrate> Any suitable material can be used as the fibrous insulating substrate 4 as long as it has insulating properties and can be coated with a thermosetting resin, and the type is not particularly limited. Examples of fibrous insulating substrates 4 having such properties include glass cloth, polyester cloth, Tetron cloth, and mica sheet. In any of the above fibrous insulating substrates, the thickness of the substrate is preferably in the range of 1 to 100 μm.

[0050] In addition to the components described above, additives may be blended as needed into the materials constituting the semiconductive tape 1 according to embodiment 1, provided that the effects of the present disclosure are not impaired. Examples of other additives that may be blended into the materials for the semiconductive tape 1 include reactive diluents, viscosity modifiers such as toluene and xylene, curing accelerators, anti-sagging agents, anti-settling agents, anti-foaming agents, leveling agents, slip agents, dispersants, and substrate wetting agents.

[0051] As described above, according to the semiconductive tape 1 of embodiment 1, the semiconductive resin layers 10a, 10b in which the expanded graphite 2 is dispersed and mixed in the resin portions 11a, 11b are disposed on the fibrous insulating substrate 4. Therefore, when a local temperature rise due to partial discharge occurs, the expandable graphite 2 present near the voids expands, forming a conductive path connecting the expandable graphite particles together, thereby stopping the partial discharge inside the voids.

[0052] Therefore, the semiconductive tape 1 according to the first embodiment can exhibit stable corona resistance for a long period of time.

[0053] Furthermore, according to the semiconductive tape 1 of embodiment 1, the thermal expansion initiation temperature of the expanded graphite 2 is higher than the thermal curing initiation temperature of the thermosetting resins 3 a, 3 b, and 13, and therefore it is possible to prevent the thermosetting resins 3 a, 3 b, and 13 from being consumed and losing their semiconductivity due to the effects of heat generation, discharge, and the like.

[0054] Furthermore, the stator coil 6 according to the first embodiment has windings 12 formed from a main insulating layer 8 formed by winding mica tape around the outer periphery of the conductor portion 7 and a semiconductive layer 9 formed by winding the semiconductive tape 1 around the outer periphery of the main insulating layer 8, and thermosetting resin 13 impregnated into the windings 12. The rotating electric machine according to the first embodiment is equipped with the stator coil 6 described above.

[0055] Therefore, the stator coil 6 and rotating electric machine according to the first embodiment can suppress the effects of heat generation and discharge during operation of the rotating electric machine, which can cause the thermosetting resin to wear out and lose its semiconductivity. Furthermore, the first embodiment can effectively suppress corona discharge occurring in the minute space between the iron core and the main insulating material for a long period of time, thereby providing the semiconductive tape 1, stator coil 6, and rotating electric machine that have high reliability over a long period of time. That is, the semiconductive tape 1, stator coil 6, and rotating electric machine according to the first embodiment exhibit the effect of stopping partial discharge occurring inside the voids, suppressing deterioration of the thermosetting resins 3 a, 3 b, and 13 over time, thereby exhibiting stable corona resistance over a long period of time.

[0056] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with other components.

[0057] 1 Semiconductive tape (semiconductive member), 2 Expanded graphite, 3a, 3b Thermosetting resin, 4 Fibrous insulating substrate, 5 Conductive particles, 6 Stator coil, 7 Conductor portion, 8 Main insulating layer (insulating layer), 9 Semiconductive layer, 10a, 10b, 10c Semiconductive resin layer, 12 Winding, 13 Thermosetting resin (impregnating thermosetting resin)

Claims

1. A semiconductive member comprising: a semiconductive resin layer having conductive particles dispersed and mixed in the resin portion; and a fibrous insulating substrate on which the semiconductive resin layer is disposed, wherein the conductive particles are particles of expanded graphite.

2. The semiconductive member according to claim 1, wherein the resin portion comprises a thermosetting resin, and the thermal expansion initiation temperature of the expanded graphite particles is higher than the thermal hardening initiation temperature of the thermosetting resin.

3. The semiconductive member according to claim 2, wherein the thermal expansion starting temperature of the expanded graphite particles is 180°C or higher.

4. The semiconductive member according to any one of claims 1 to 3, wherein the expanded graphite has an acid intercalated between layers of the expanded graphite particles.

5. A semiconductive member according to any one of claims 1 to 4, wherein the expanded graphite is blended in an amount ranging from 1 vol % to 50 vol % of the resin portion.

6. A semiconductive member according to any one of claims 1 to 5, wherein the expanded graphite particles have an average particle size in the range of 1 nm or more and 100 μm or less.

7. A semiconductive member according to any one of claims 1 to 6, characterized in that the expanded graphite particles have a coupling agent or a surface treatment agent interposed at the interface with the resin portion.

8. A semiconductive member according to any one of claims 1 to 7, wherein the resin portion is filled with inorganic particles consisting of at least one type selected from layered clay mineral particles, oxide particles, and nitride particles.

9. A stator coil comprising: a winding; and a thermosetting resin impregnated into the winding, wherein the winding comprises: a conductor portion formed by bundling strand conductors; an insulating layer having a mica member wound around the outer periphery of the conductor portion; and a semiconductive layer having a semiconductive member according to any one of claims 1 to 8 wound around the outer periphery of the insulating layer.

10. A stator coil according to claim 9, wherein the semiconductive layer has the expanded graphite unevenly distributed on the side of the interface with the insulating layer in the semiconductive member that contacts the interface with the insulating layer.

11. A stator coil according to claim 9 or 10, wherein the semiconductive layer has conductive particles other than the expanded graphite dispersed and mixed in the semiconductive member not in contact with the interface with the insulating layer.

12. A stator coil according to claim 10 or 11, wherein in the semiconductive member in contact with the interface with the insulating layer, the average interparticle distance between the expanded graphite particles is less than 1 μm.

13. A rotating electric machine comprising a stator coil according to any one of claims 9 to 12.

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