JP6116335B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to an insulating structure of a stator coil of a rotating electric machine, particularly a high voltage rotating machine represented by a generator.

  In a high-voltage rotating machine, the stator coil used by being housed in a slot of the stator core is a predetermined number of mica tapes with excellent corona discharge resistance on the outer periphery of the coil conductor formed by bundling a plurality of wire conductors. After being wound only, a thermosetting resin such as an epoxy resin is impregnated by vacuum pressurization, and heat treatment is performed to cure, thereby forming a ground insulating layer.

  Further, in the outermost peripheral portion of the ground-main insulating layer, the portion housed inside the slot of the stator core, and the portion extended to the outside of the slot are connected to the stator core that is at the ground potential. A low resistance corona shield layer is provided in order to suppress the discharge between the two. In addition, a high resistance corona shield layer is provided so as to overlap a part of the outer end portion of the low resistance corona shield layer and reduce the creeping electric field on the surface of the stator coil to suppress the occurrence of creeping discharge.

  Of the single stator coil, the portion extending from the slot of the stator core to the outside is generally called a coil end portion. An electric field generated between adjacent coil end portions may cause a discharge between the coil end portions. On the other hand, since the mica tape for forming the ground main insulating layer is generally expensive, it is preferable that the total amount of use of the mica tape can be reduced as much as possible.

  Therefore, in the prior art, while the coil end portion forms the ground main insulating layer only with mica tape having excellent corona discharge resistance, the inside of the slot where there is no possibility of discharge between the stator coils is A stator winding of an AC rotating electrical machine that uses both mica tape and non-mica tape to form a ground-main insulating layer, thereby maintaining the insulation performance of the ground-main insulating layer and reducing the total amount of mica tape used. A line is disclosed (for example, see Patent Document 1 below).

  In another conventional technique, the stator coil is housed in the slot, and the part is wound with a normal mica tape around the outer periphery of the coil conductor to form the ground main insulating layer, while the coil end portion outside the slot is An insulation method for rotating machine coils that reduces the total amount of mica tape used and shortens the taping operation by forming a main ground insulating layer by coating the outer periphery of the coil conductor with a thermosetting resin. It is disclosed (for example, see Patent Document 2 below).

JP 62-104448 A JP 59-111346 A

  In a stator coil of a high-voltage rotating electrical machine, the electric field generated in the ground insulating layer during rated operation is higher inside the slot than in the outside of the stator core slot. In the prior art described in Patent Document 1 above, the amount of mica tape used to form the ground main insulating layer inside the slot is reduced, so that the dielectric strength inside the slot may be lowered in the long run. Furthermore, compared to the electric field generated in the ground main insulating layer inside the slot as described above, the electric field generated in the ground main insulating layer in the coil end portion outside the slot is low, and the ground main insulating layer in the coil end portion is made only of mica tape. In the case where it is formed, the insulation performance may be excessively more than necessary. Therefore, the intention of reducing the amount of mica tape used while maintaining the insulating performance of the ground insulating layer is not sufficiently achieved. In addition, since the thickness of the ground insulating layer is ensured more than necessary, there is a concern about a decrease in cooling performance.

  On the other hand, in the prior art described in the above-mentioned Patent Document 2, it is necessary to use a thermosetting resin which is a separate member in addition to the normal mica tape at the time of forming the ground insulating layer. Will increase significantly. In addition, the insulating main ground layer has a uniform insulation thickness between the housing portion in the slot around which the mica tape is wound and the coil end portion using the thermosetting resin. The cooling performance of the coil end portion using the resin is lowered.

  The present invention has been made to solve the above-mentioned problems, and effectively reduces the amount of mica tape used while maintaining good insulation performance of the main ground insulating layer of the stator coil during rated operation. Another object of the present invention is to provide a rotating electrical machine with improved stator coil cooling performance.

  A rotating electrical machine according to the present invention includes a stator coil that is housed in a slot formed in a stator iron core and a part of which is extended to the outside of the slot, and the stator coil includes an outer periphery of a coil conductor. A ground resistance insulating layer is formed by winding mica tape around the portion, and a low resistance corona is formed on a portion of the outer periphery of the ground resistance insulating layer that is housed inside the slot and a part of the outside of the slot. In the case where the shield layer is formed and the high resistance corona shield layer is formed by partially overlapping the end portion of the low resistance corona shield layer, the following configuration is adopted.

That is, in this invention, the mica tape, among the stator coils of the extending out portions from the inside to the outside of the slot, the same winding as the winding number inside the predetermined length fraction from the exit of the slot is slot The number of turns is reduced toward the extension side of the stator coil excluding the predetermined length, the cross-sectional area is reduced, and the mica tape is placed inside the slot. The predetermined length that is uniformly wound at the same number of turns as the number of turns in the coil is the length from the outlet of the slot to the position where the surface potential of the stator coil reaches the maximum potential during rated operation. It is characterized by.

According to the present invention, the coil end portion of the coil end portion where the electric field applied to the ground main insulating layer is low while maintaining the long-term reliability of the ground main insulating layer of the stator coil inside the slot of the stator core during rated operation is well maintained. by reducing the number of turns of the mica tape, suppresses the mica tape usage by reducing the insulation thickness of a portion insulation performance becomes excessive beyond necessity, have Rukoto improve the cooling performance to the heating of the coil conductor it can. In particular, the place where the mica tape is uniformly wound with the same number of turns as the inside of the slot is the length from the slot outlet to the position where the stator coil surface potential reaches the maximum potential during rated operation. Therefore, the long-term reliability can be more satisfactorily maintained without deteriorating the insulation performance of the main ground insulating layer up to the position where the coil surface potential becomes the highest potential.

It is sectional drawing which shows the structure of the rotary electric machine (turbine generator) which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the insulation structure in the slot exit vicinity of the stator coil of the rotary electric machine which concerns on Embodiment 1 of this invention. FIG. 3 is a cross-sectional view taken along line A-A ′ and line B-B ′ of FIG. 2. It is a top view which shows arrangement | positioning of the mutually adjacent two stator coils extended outside from the slot of the stator core of the rotary electric machine which concerns on Embodiment 1 of this invention. FIG. 5A shows a state near the slot outlet of a stator coil of a rotating electrical machine according to Embodiment 2 of the present invention, FIG. 5A is a characteristic diagram showing the surface potential distribution, and FIG. 5B shows an insulating structure. It is sectional drawing shown. It is sectional drawing which shows the insulation structure in the slot exit vicinity of the stator coil of the rotary electric machine which concerns on Embodiment 3 of this invention. It is sectional drawing about the insulation structure in the slot exit vicinity of the stator coil of the rotary electric machine which concerns on Embodiment 4 of this invention. It is a top view which shows arrangement | positioning of two mutually adjacent stator coils extended outside from the slot of the stator core of the rotary electric machine which concerns on Embodiment 4 of this invention. It is a perspective view which shows the principal part structure of the insulation structure in the slot exit vicinity of the stator coil of the rotary electric machine as a reference example. It is sectional drawing which shows the insulation structure in the slot exit vicinity of the stator coil of the rotary electric machine as a reference example.

  Before explaining the rotating electrical machine according to the embodiment of the present invention, in order to facilitate understanding of the present invention, as a reference example, an insulating structure in the vicinity of the slot outlet of the stator coil of the rotating electrical machine will be described with reference to FIGS. explain.

  FIG. 9 is a perspective view showing the main structure of the insulating structure in the vicinity of the slot outlet of the stator coil of the rotating electrical machine, and FIG. 10 is a cross-sectional view showing the insulating structure in the vicinity of the slot outlet of the stator coil.

  In a high voltage rotating machine, a stator coil 7 housed and used in a slot 5 of a stator core 4 is a mica having excellent corona discharge resistance on the outer periphery of a coil conductor 9 in which a plurality of strand conductors are bundled. After the tape 11 is wound a predetermined number of times, a thermosetting resin such as an epoxy resin is impregnated by vacuum pressurization and cured by heat treatment to form the ground insulating layer 12.

  Further, a portion of the outermost peripheral portion of the ground-main insulating layer 12 that is housed inside the slot 5 of the stator core 4 and a portion that extends outside the slot 5 are fixed at the ground potential. A low resistance corona shield layer 13 is provided to suppress discharge between the core 4 and the core. In addition, a high resistance corona shield layer 14 is provided so as to overlap a part of the outer end portion of the low resistance corona shield layer 13 and reduce the creeping electric field on the surface of the stator coil 7 to suppress the occurrence of creeping discharge. It is done.

  Of the single stator coil 7, a portion extending from the slot 5 of the stator core 4 to the outside is generally called a coil end portion 8. There is a possibility that electric discharge is generated between the coil end portions 8 due to the electric field generated between the coil end portions 8 adjacent to each other. Therefore, in the reference example, the ground-end insulating layer is formed only by the mica tape 11 having excellent resistance to corona discharge in the coil end portion 8.

  Next, a rotating electrical machine according to an embodiment of the present invention will be described with reference to the drawings. In each of the following embodiments, a turbine generator is illustrated as an example of a rotating electrical machine. However, the present invention is not limited to a turbine generator, and widely includes, for example, the concept of a generator and an electric motor. .

Embodiment 1 FIG.
1 is a cross-sectional view showing a configuration of a turbine generator that is a rotating electrical machine according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view showing an insulating structure in the vicinity of a slot outlet of a stator coil, and FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. 2, and FIG. 3B is a cross-sectional view taken along the line BB ′ in FIG. In addition, the same code | symbol is attached | subjected to the component corresponding to or the reference example shown in FIG. 9 and FIG.

  A turbine generator 1 according to Embodiment 1 of the present invention includes a stator 2 and a rotor 3. The stator 2 includes a stator core 4, and a plurality of slots 5 are formed in the stator core 4 along the circumferential direction. A stator coil 7 is accommodated in each slot 5. A portion of the stator coil 7 housed in each slot 5 extends outside the slot 5 and is formed as a coil end portion 8.

  Also in the first embodiment, the ground main insulating layer 12 formed by winding the mica tape 11 around the outer periphery of the coil conductor 9, and the ground main insulating layer 12, as in the case shown in FIGS. 9 and 10. A low resistance corona shield layer 13 formed on a portion housed inside the slot 5 and a part outside the slot 5 in the outer peripheral portion, and a part of the low resistance corona shield layer 13 are overlapped on the end portion. And a high resistance corona shield layer 14 formed.

  The feature of the first embodiment is that when the mica tape 11 is wound around the outer periphery of the coil conductor 9 to form the ground main insulating layer 12, the stator coil 7 is arranged so that the stator coil 7 extends from the inside of the slot 5 to the outside. Of the extended coil end portion 8, a predetermined length L from the outlet of the slot 5 is uniformly wound at the same number of turns as the number of turns in the slot 5, and the coil end portion excluding the predetermined length L The number of windings is reduced toward the extending side of 8, and the cross-sectional area is reduced.

  In the first embodiment, the ground main insulating layer 12 is formed by winding mica tape 11 around the outer circumference of the coil conductor 9 a predetermined number of times and then impregnating a thermosetting resin such as epoxy resin by vacuum pressurization. However, the present invention is not limited to this. For example, after winding a so-called prepreg mica tape, which is preliminarily impregnated with a resin and applied in a mica tape 11, around the outer periphery of the coil conductor 9. There is also a method of molding and heat curing.

Next, the electric field generated in the ground main insulating layer 12 of the stator coil 7 will be described.
For example, in the turbine generator 1, during normal operation, the stator core 4 is at ground potential, while a high voltage of 10 kV to 20 kV or higher is applied to the coil conductor 9. Therefore, a high electric field, which is a value obtained by dividing the applied voltage by the thickness of the ground main insulating layer 12 on average, is always applied to the ground main insulating layer 12 inside the slot 5. 12 requires long-term insulation reliability. Further, the potential of the low-resistance corona shield layer 13 provided for the purpose of suppressing the discharge between the stator core 4 and the stator core 4 can be regarded as the same ground potential. Therefore, the same electric field is applied to the ground insulating layer 12 from the exit of the slot 5 to the portion where the low resistance corona shield layer 13 is provided. Long-term insulation reliability is required.

  On the other hand, the surface potential of the ground main insulating layer 12 from the outer end of the low resistance corona shield layer 13 toward the extending side of the coil end portion 8 has a potential distribution that increases from the ground potential toward the voltage applied to the coil conductor 9. . In addition, the electric field generated in the main ground insulating layer 12 has a distribution that decreases from the outer end portion of the low resistance corona shield layer 13 toward the extending side of the coil end portion 8.

  As can be seen from the above, in Embodiment 1, the mica tape 11 is uniformly wound at the same number of turns as the number of turns in the slot 5 for a predetermined length L from the outlet of the slot 5 in the coil end portion 8. Since the electric field generated toward the extending side of the coil end portion 8 excluding the predetermined length L is lower than that in the slot 5 during rated operation, the number of windings of the mica tape 11 is reduced. The thickness of the landowner insulating layer 12 is reduced. For this reason, the cooling performance with respect to the heat_generation | fever of the coil conductor 9 in the coil end part 8 can be improved, maintaining the insulation performance at the time of rated operation. Further, since the number of turns of the mica tape 11 in the coil end portion 8 is reduced, the total amount of use of the expensive mica tape 11 is reduced, which can contribute to the cost reduction of the entire rotating electrical machine. .

  FIG. 4 is a plan view showing the arrangement of two adjacent stator coils extending outward from the slots of the stator core in the turbine generator according to the first embodiment.

  The stator coil 7 housed in the slot 5 of the stator core 4 has a part of the coil end portion 8 extending from the inside of the slot 5 and the slot 5 in a linear shape. The coil end portion 8 extending outward is curved in a certain direction. When the withstand voltage test of the turbine generator 1 is performed, a voltage more than twice the rated voltage is applied with the stator coil 7 in the slot 5. When a high voltage is applied in this way, a potential difference is generated between the coil end portions 8 of the stator coils 7 adjacent to each other, and a discharge such as a surface flash may occur. In addition, during the withstand voltage test, a current higher than that during normal rated operation flows through the stator coil 7, so that heat generation at the coil end portion 8 becomes a problem.

  However, in the first embodiment, since the number of turns of the mica tape 11 is reduced and the thickness of the ground insulating layer 12 is reduced for a part of the coil end portion 8 of the stator coil 7, the coil end portion The cooling performance of 8 is improved. Moreover, since the cross-sectional area of the coil end portion 8 is reduced, the distance W necessary for insulation between the adjacent stator coils 7 can be easily ensured. For this reason, it becomes difficult to generate discharge between the coil end portions 8 adjacent to each other, and the reliability can be improved.

  Further, as a method for cooling the stator coil 7 through a medium around the coil, there is a method using air or hydrogen. When the thickness of the ground insulating layer 12 of the coil end portion 8 of the stator coil 7 is reduced as in the first embodiment, the distance W between the adjacent stator coils 7 is as shown in FIG. Since it becomes large, the influence of the heat radiation received from the surface of each stator coil 7 can be reduced, and the amount of the cooling medium flowing between the stator coils 7 is increased, so that the cooling performance of the surface of the stator coil 7 is increased. Can be increased.

  Moreover, the relative dielectric constant of the ground main insulating layer 12 formed by impregnating the mica tape 11 with an epoxy resin is generally about 5.0 to 6.0. Like this Embodiment 1, the cross-sectional area of the earth main insulating layer 12 of the coil end part 8 was reduced, and thereby the gap (air, relative dielectric constant: 1) between the coil end parts 8 was increased as compared with the prior art. In this case, the electric field between the coil end portions 8 can be relaxed, and the reliability against discharge generated between the coil end portions 8 can be further improved.

  When the method of forming the ground insulating layer 12 is to adopt a method in which the mica tape 11 is wound around the coil conductor 9 a predetermined number of times and then cured by vacuum pressure impregnation with a thermosetting resin. When the resin is impregnated with a vacuum under pressure, it is molded by pressing around the coil with an iron plate or the like. At that time, as shown in FIG. 4, the portion of the stator coil 7 housed in the slot 5 and the portion slightly extended from the slot 5 are in a linear shape, so that press molding is easy. is there. On the other hand, the coil end portion 8 extending further outward from the linear portion is curved in a certain direction, so that press molding is difficult.

  For this reason, in the prior art, a portion where the coil end portion 8 is curved cannot be sufficiently formed, and there is a possibility that a so-called winding thickening in which the coil cross-sectional area becomes larger than the design dimension may occur. On the other hand, in the first embodiment, since the thickness of the ground main insulating layer 12 on the extension side of the coil end portion 8 is reduced, the effect of reducing the winding thickness that makes the coil cross section larger than the design dimension is reduced. Can also be obtained.

Embodiment 2. FIG.
FIG. 5 shows a state near the slot outlet of a stator coil of a turbine generator that is a rotating electrical machine according to Embodiment 2 of the present invention, and FIG. 5 (A) is a characteristic diagram showing the surface potential distribution, FIG. FIG. 5B is a cross-sectional view showing an insulating structure. In addition, the same code | symbol is attached | subjected to the component corresponding or equivalent to Embodiment 1 shown in FIGS. 1-4, and detailed description of a structure is abbreviate | omitted.

  The feature of this second embodiment is that the position of the mica tape 11 for reducing the number of turns of the mica tape 11 for forming the ground main insulating layer 12 with respect to the ground main insulating layer 12 formed on the coil end portion 8 of the stator coil 7. It is to prescribe. That is, from the position p0 at the outlet of the slot 5 to the position p2 at which the surface potential of the stator coil 7 reaches the maximum potential during rated operation, the mica tape 11 is uniformly wound on the coil conductor 9 with the same number of turns as in the slot 5. That is, the number of turns is reduced from the position p2 toward the extension side of the coil end portion 8, and the cross-sectional area is reduced.

  The high-resistance corona shield layer 14 is made of, for example, a paint containing carbon powder or a non-linear resistance characteristic containing silicon carbide particles, that is, a paint having a characteristic that the surface resistivity decreases as the generated electric field increases. It is formed by applying to the outermost peripheral part of the insulating layer 12 or winding it around the outermost peripheral part using a tape coated with these paints.

  Here, the surface potential along the extending direction of the coil end portion 8 of the stator coil 7 is a position p1 from the inside of the slot 5 to the end portion of the low resistance corona shield layer 13 as shown in FIG. Is the ground potential, and at the location where the high resistance corona shield layer 14 is formed, the potential distribution gradually increases until reaching the potential applied to the coil conductor 9 along the extending direction of the coil end portion 8. Therefore, the position where the distribution of the surface potential along the extending direction of the coil end portion 8 becomes the highest during rated operation, that is, on the extending side of the coil end portion 8 further than the position p2 where the potential is the same as that of the coil conductor 9, The electric field generated in the earth-main insulating layer 12 during normal operation is slight.

  As described above, in the second embodiment, the number of turns of the mica tape 11 from the outlet of the slot 5 is the same as that in the slot 5 with respect to the ground main insulating layer 12 formed in the coil end portion 8 of the stator coil 7. Since the range L to be performed is from the exit position p0 of the slot 5 to the position p2 where the coil surface potential reaches the maximum potential during rated operation, the inside of the slot 5 where the high electric field is generated during the rated operation and the position where the coil surface potential becomes the maximum potential The insulation performance of the main ground insulating layer 12 up to p2 is not deteriorated. Further, since the number of turns is further reduced and the cross-sectional area is reduced on the extending side of the coil end portion 8 from the position p2 at which the coil surface potential becomes the highest potential, the mica tape used for forming the ground insulating layer 12 can be reduced. 11 can be effectively reduced.

  Also in the second embodiment, since the thickness of the ground main insulating layer 12 of the coil end portion 8 is reduced, the cooling performance against the heat generated from the coil conductor 9 can be improved.

Embodiment 3 FIG.
6 is a cross-sectional view showing an insulating structure near the slot outlet of a stator coil of a turbine generator that is a rotating electrical machine according to Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the component corresponding or equivalent to Embodiment 1 shown in FIGS. 1-4, and detailed description of a structure is abbreviate | omitted.

  A feature of the third embodiment is that a method for reducing the number of turns of the mica tape 11 from the inside of the slot 5 toward the extending side of the coil end portion 8 is defined. That is, as a winding method of the mica tape 11, for example, the next tape of the second volume is overlapped on half of the tape width of the first volume, and the next third volume is wound on the half of the tape width of the second volume. There is a half lap that wraps and winds the tape. When the mica tape 11 is wound in this way, the number of turns of the mica tape 11 is gradually reduced from the inside of the slot 5 toward the extending side of the coil end portion 8 by one turn. In this way, a step due to a change in the cross-sectional area does not occur on the outermost periphery of the ground-side insulating layer 12.

  As described in the first embodiment, when the ground main insulating layer 12 is formed by winding the mica tape 11 around the coil conductor 9 and vacuum curing and impregnating the thermosetting resin, the iron plate or the like is formed. Press around the coil to form. By this press molding, the stator coil 7 can be adjusted to a necessary size, and at the same time, the amount of voids remaining at the interface between the tapes when the mica tape 11 is wound can be reduced.

  When the ground main insulating layer 12 is formed by winding the mica tape 11 as in the third embodiment, there is no step due to the change in the cross-sectional area on the outermost periphery of the ground main insulating layer 12, so that the coil conductor 9 When the mica tape 11 is wound around and thermosetting resin is impregnated with vacuum pressure to be cured, press molding becomes easy and workability can be improved. Moreover, since press molding becomes easy, the voids remaining at the interface between the mica tapes 11 can be reduced. At the same time, since press molding is easy, it is possible to suppress winding thickness due to insufficient press.

  Further, also in the turbine generator 1 according to the third embodiment, since the thickness of the ground main insulating layer 12 of the coil end portion 8 is reduced, the coil conductor 9 is similar to the first and second embodiments described above. Cooling performance against heat generation can be improved.

Embodiment 4 FIG.
FIG. 7 is a cross-sectional view of the insulating structure in the vicinity of the slot outlet of the stator coil of a turbine generator that is a rotating electrical machine according to Embodiment 4 of the present invention, and corresponds to Embodiment 1 shown in FIGS. Alternatively, corresponding components are denoted by the same reference numerals, and detailed description of the configuration is omitted.

  The feature of the fourth embodiment is that, in the coil end portion 8, the ground main insulating layer is provided at the outermost peripheral portion of the ground main insulating layer 12 where the number of turns of the mica tape 11 is reduced and the cross-sectional area thereof is reduced. That is, it is coated with a thermosetting resin 15 having a relative dielectric constant smaller than 12.

  In general, the relative dielectric constant of a composite insulating system in which an epoxy resin is impregnated with mica tape 11 which is a constituent member of the ground-main insulating layer 12 of the stator coil 7 is about 5.0 to 6.0. Examples of the thermosetting resin 15 having a relative dielectric constant smaller than that of the insulating layer 12 include polyester resin, silicon resin, and epoxy resin.

Next, the operation of the configuration of the fourth embodiment will be described.
FIG. 8 is a plan view showing the arrangement of two adjacent stator coils extending from the slots of the stator core in the turbine generator according to the fourth embodiment.

  As described in the first embodiment, there is a possibility that electric discharge is generated between the coil end portions 8 due to a potential difference generated between the coil end portions 8 of the adjacent stator coils 7 in the conventional withstand voltage test. is there. On the other hand, according to the configuration of the fourth embodiment, in the coil end portion 8, the outermost periphery of the portion of the ground main insulating layer 12 where the number of turns of the mica tape 11 is reduced and the cross-sectional area thereof is reduced. Since the portion is coated with the thermosetting resin 15 having a relative dielectric constant smaller than that of the ground insulating layer 12, the coated portion is reinforced to improve the mechanical strength and increase the relative dielectric constant. By covering the main insulating layer 12 with a low rate with the thermosetting resin 15 as well, the electric field between the coil end portions 8 can be relaxed, and the reliability against the discharge generated between the coil end portions 8 is further improved. be able to.

  In addition, the said Embodiment 1-4 disclosed this time is an illustration in all the points, Comprising: It does not become the basis of the limited interpretation of this invention. Therefore, the technical scope of the present invention is not interpreted only by the configurations of the first to fourth embodiments described above, but is defined based on the claims. Moreover, the meaning of a claim is equal, and the range of all the structures within the range is included.

1 Turbine generator (rotary electric machine), 2 stator, 3 rotor, 4 stator core,
5 slots, 7 stator coils, 8 coil ends, 9 coil conductors,
11 Mica tape, 12 Ground-main insulating layer, 13 Low resistance corona shield layer,
14 high resistance corona shield layer, 15 thermosetting resin.

Claims (3)

Part while being accommodated in a slot formed in the stator core comprises a stator coil which extends outside of the slot, the stator coil is wound mica tape on an outer peripheral portion of the coil conductor A ground resistance insulating layer is formed by turning, and a low resistance corona shield layer is formed on a part of the outer periphery of the ground resistance insulating layer, a portion housed in the slot, and a part of the outside of the slot, In the rotating electrical machine in which a high resistance corona shield layer is formed by overlapping a part on the end of the low resistance corona shield layer,
The mica tape is uniformly wound with the same number of turns as the number of turns inside the slot for a predetermined length from the outlet of the slot in the portion where the stator coil extends from the inside of the slot. The number of turns is reduced toward the extension side of the stator coil excluding the predetermined length to reduce the cross-sectional area, and the mica tape has the same number of turns as the number of turns inside the slot. The predetermined length that is uniformly wound by the number of times is a length from the outlet of the slot to a position where the surface potential of the stator coil reaches the maximum potential during rated operation. . 2. The rotating electrical machine according to claim 1, wherein the reduction in the number of windings of the mica tape is formed by sequentially reducing the number of half laps. The outermost peripheral portion of the ground main insulating layer portion whose cross-sectional area is reduced by reducing the number of turns of the mica tape is thermosetting having a relative dielectric constant smaller than that of the ground main insulating layer. The rotating electrical machine according to claim 1 or 2, wherein the rotating electrical machine is coated with a conductive resin.

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