JP2002125339A - Coil of high-voltage dynamoelectric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax concentration of electric field at the corners of an element conductor bundle in the insulator for the ground surrounding the element conductor bundle of a coil used, in a high voltage dynamo-electric machine. SOLUTION: Concentration of potential at the corners can be relaxed through almost equalization of potential around the element conductor bundle, by providing a floating potential conductor layer near the element conductor, in a manner as surrounding the same conductor, within the insulator for the ground surrounding the periphery of the element conductor bundle of the coil used in the high voltage dynamo-electric machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for alleviating electric field concentration inside a ground insulating layer on the outer periphery of a high-voltage rotating electric machine coil.

[0002]

2. Description of the Related Art FIG. 3 is a longitudinal sectional view showing a main part of a coil of a conventional high-voltage rotating electric machine.

In FIG. 3, reference numeral 1 denotes a wire conductor of a coil, the outer periphery of which is covered with a wire insulator (not shown).
A plurality of the wire conductors 1 wound in a plurality of rows are stacked in a plurality of layers and bundled, and the outer periphery thereof is covered with a ground insulating layer 2 to form a coil of a high-voltage rotating electric machine.

The coil is inserted and arranged in a slot of a stator core of a high-voltage rotating electric machine (not shown). In order to prevent a partial discharge from occurring between the core and the coil, the coil has a ground insulating layer 2. The surface is covered with a semiconductive paint or a semiconductive tape 3 to form a semiconductive layer 3 so that the potential of the coil surface becomes the same ground potential as the iron core.

The reason why the semiconductive layer 3 is provided on the outer periphery of the insulating layer 2 is to suppress the flow of eddy current in the conductive layer due to a change in magnetic flux. For the ground insulating layer 2, a mica tape having excellent partial discharge resistance is used, and a polymer insulating material such as an epoxy resin is impregnated and hardened to secure its mechanical strength. The cross-sectional shape of the wire conductor is rectangular to increase the conductor space factor in the coil cross section.

[0006]

With such a conventional coil structure, as shown in FIG. 4, electric field concentration occurs at the four corners of the wire conductor bundle forming the coil, and the equipotential lines 4 are formed. Are narrowed toward the conductor 1 side. The degree increases as the radius of curvature of the corner of the conductor bundle decreases. The thickness of the ground insulating layer was governed by the electric field at the corner.

The electric field concentration at the corners of the conductor bundle can be alleviated by increasing the curvature of the corners of the conductor by changing the cross-sectional shape of the wire conductor, but this reduces the space factor of the conductor. Therefore, there is a disadvantage that the size of the apparatus is increased.

The electric field concentration can be reduced by changing the shape of only the wire conductor located at the corner, but it is not preferable because the manufacturing process of the coil becomes complicated and the manufacturing cost increases.

It is an object of the present invention to provide a coil for a high-voltage rotating electric machine which can reduce the concentration of an electric field at the corners of a wire conductor bundle of a coil without causing such a drawback and can make a ground insulating layer thin. Is what you do.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a plurality of rows of insulated wire conductors are wound and laminated in a plurality of stages to form a wire conductor bundle. In a coil of a high-voltage rotating electrical machine in which an insulating tape and an insulating resin are coated on the outer side of a wire conductor bundle to form a ground insulating layer, a floating potential conductor is formed by surrounding the element conductor in the ground insulating layer in the vicinity of the element conductor. It is characterized by having a body layer.

It is more effective to divide the floating potential conductor layer into a plurality of layers in the axial direction of the wire conductor or to divide the floating potential conductor layer into a plurality of layers in the radial direction of the wire conductor.

Further, it is preferable that the floating potential conductor layer is formed of a conductive material having a relatively high resistance.

[0013]

Embodiments of the present invention will be described below. Embodiment 1 FIG. 1 shows a first embodiment of the present invention. (A) in this figure is a longitudinal sectional view of a main part of the coil. (B) is a sectional view taken along line BB of (A).

In FIG. 1, reference numeral 10 denotes a wire conductor covered with a wire insulator, which is wound in a plurality of rows and a plurality of stages to form a wire conductor bundle serving as a coil. The outer periphery of the wire conductor bundle is surrounded by an insulating tape such as a mica tape and a ground insulating layer 20 made of a polymer insulating resin or the like, and the surface of the ground insulating layer 20 is covered with a semiconductive layer 30 as in the conventional case. In addition, a floating potential conductor layer 40 is provided near the element conductor in the ground insulating layer 20 so as to surround the element conductor bundle. The floating potential conductor layer 40 has no electrical connection to a member to which another voltage is applied or to a grounded member, and is in a state of being electrically floating from these members.

The potential of the floating potential conductor layer 40 depends on the capacitance between the conductor layer 40 and the wire conductor 10 and the potential difference between the conductor layer 40 and the semiconductor layer 30 on the surface of the insulating layer 20. It is a value obtained by dividing the potential between the ground and the wire conductor according to the capacitance between them. The facing surface between the floating potential conductor layer 40 and the wire conductor bundle and the semiconductive layer 30 on the surface occupies most of the area of the parallel portion as apparent from FIG. It is approximately the reciprocal ratio of the facing distance of the parallel portion. Therefore, the voltage sharing ratio is the parallel portion facing distance ratio. The voltage shared by the floating potential conductor layer 40 is maintained at the corners because it is a conductor. As a result, the potential at the corners is substantially equal to the potential at the linear portion, and the electric field concentration at this portion is reduced. Will be done.

The material forming the floating potential conductor layer 40 is preferably a conductive material having a higher resistance than a conductive material having a lower resistance in order to reduce Joule loss due to eddy current generated by a change in magnetic flux in this portion. Embodiment 2 FIG. 2 shows a second embodiment of the present invention. In this figure,
(A) is a longitudinal cross-sectional view of a main part of the coil, (B) is a section of (A) B
FIG. 4 is a cross-sectional view taken along line B.

In the embodiment 2 of FIG. 2, the floating potential conductor layer 40 provided in the ground insulating layer 20 in the embodiment 1 of FIG.
As shown by 40a to 40n, a plurality of wires are mechanically and electrically divided and arranged in the axial direction of the wire conductor 1.
The other points are the same as the first embodiment of FIG. 1 except for the difference from the first embodiment of FIG.

Since a mica tape having excellent partial discharge resistance is used in the ground insulating layer 20, the generation of a low level partial discharge as an insulation system is allowed. By dividing the floating potential conductor layer into a plurality of parts, the area of the floating potential conductor layer is reduced, so that the capacitance between the floating potential conductor layer and the wire conductor 10 and the semiconductive layer 30 on the surface is reduced. Therefore, the amount of charge stored here becomes small, and the discharge energy can be reduced to the extent that partial discharge occurs. Therefore, even if a partial discharge occurs, damage to the ground insulating layer is reduced, and a decrease in the life of the coil insulation can be reduced.

Further, when the floating potential conductor layer is divided into a plurality of parts, there is also an effect of suppressing eddy current due to magnetic change, so that a normal conductive material can be used instead of a semiconductive material. . In this case, using a material having high resistance as the conductive material is effective in reducing Joule loss.

Although the above-mentioned divided floating potential conductor layers 40a and the like have a rectangular cross-sectional shape, there is no difference in their functions regardless of whether they are circular, elliptical, or polygonal.

Incidentally, In the first or second embodiment, if the floating potential conductor layers 40 are arranged at intervals of a plurality of layers in the radial direction of the strand conductor 10, the effect of alleviating the electric field concentration is further increased.

[0022]

As described above, according to the present invention, a plurality of rows of insulated wire conductors are wound and laminated in a plurality of stages to form a wire conductor bundle. In a coil of a high-voltage rotating electrical machine in which a ground insulating layer is formed by covering an insulating tape and an insulating resin in multiple layers, a floating potential conductor layer is provided in the circumferential direction in the ground insulating layer in the vicinity of the elementary wire conductor. Thereby, the potential in the circumferential direction of the wire conductor inside the ground insulating layer is kept substantially constant, so that the electric field concentration at the corners of the wire conductor bundle is alleviated, so that the effect of making the ground insulating layer thin can be obtained.

[Brief description of the drawings]

1A and 1B show a configuration of a coil according to a first embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of a main part thereof, and FIG.
It is a BB sectional view taken on the line of (A).

2A and 2B show a configuration of a coil according to another embodiment of the present invention, wherein FIG. 2A is a longitudinal sectional view of a main part thereof, and FIG.
FIG. 7 is a sectional view taken along line BB of FIG.

3A and 3B show a configuration of a conventional coil, in which FIG. 3A is a longitudinal sectional view of a main part thereof, and FIG. 3B is a sectional view taken along line BB of FIG. 3A.

FIG. 4 is a diagram illustrating a potential distribution of a conventional coil.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 element conductor 20 ground insulating layer 30 conductor layer 40 floating potential conductor layer 40 a to 40 b divided floating potential conductor layer

Claims (4)

[Claims] An insulated wire conductor is wound in a plurality of rows and laminated in a plurality of stages to form a wire conductor bundle. The outside of the wire conductor bundle is coated with multiple insulating tapes and insulating resin. A coil for a high-voltage rotating electrical machine, wherein a floating potential conductor layer is provided in the ground insulating layer in the vicinity of the elementary wire conductor so as to surround the element conductor. 2. The coil for a high-voltage rotating electric machine according to claim 1, wherein the floating potential conductor layer is divided into a plurality of portions in an axial direction of a wire of the coil. 3. The coil for a high-voltage rotating electric machine according to claim 1, wherein the floating potential conductor layers are arranged at intervals of a plurality of layers in the radial direction of the coil wire. 4. A coil for a high-voltage rotating electric machine according to claim 1, wherein the floating potential conductor layer is formed of a conductive material having high resistance.