JPH06153434A - Stator coil for rotary electric machine - Google Patents

Abstract

PURPOSE:To improve reliability by preventing generation of a creeping corona discharge due to a wrinkle of an electric field-relaxation layer. CONSTITUTION:A stator coil 1a for a rotary electric machine has a coil insulating layer 2 formed of a prepreg insulator on a conductor, a low resistance corona shielding layer 3, and an electric field-relaxation layer 5 which are thermally pressure molded together, and comprises a buffer layer 7 in contact at one side end with an end of the layer 3 between the layers 5 and 2. Thus, a dimensional change at the time of thermally pressure molding the coil insulating layer is absorbed by the buffer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator coil of a rotary electric machine.

[0002]

2. Description of the Related Art Currently, high voltage equipment, for example, rated voltage 3k
As a manufacturing method of the coil insulation layer of the AC generator of V or more,
The prepreg method and vacuum pressure impregnation method are the mainstream.

In the prepreg method, a prepreg tape containing a semi-cured thermosetting resin is wound around a conductor and then heat-pressed to produce the prepreg tape, whereas in the vacuum pressure impregnation method, a dry tape is wound around the conductor. After that, inject thermosetting resin,
Since heat and pressure molding is performed, one extra step is required. In addition, the electric field strength of the insulating layer of the prepreg method is stronger than that of the vacuum pressure impregnation method, the thickness of the insulating layer is thin, and the size of the device can be made compact.

When the stator coil thus just insulated is inserted and fixed in the slot of the stator iron core, when a high voltage is applied to the stator coil, the surface of the portion inserted in the slot is removed. Corona is generated toward the slot. Therefore, as shown in FIG. 6, a semiconductive layer (low resistance corona shield layer) 3 is provided on the surface of the coil insulating layer 2 of the stator coil 1 in the slot insertion portion.
The surface of the stator coil 1 near the slot outlet (hereinafter referred to as the coil end portion) has the same potential as the conductor 4, and the potential gradient of the creeping surface with the end portion of the low-resistance corona shield layer 3. The electric field is likely to concentrate at the end of the low resistance corona shield layer 3, and corona discharge occurs when the potential rises sharply. Therefore, the coil insulating layer 2 from the end of the low resistance corona shield layer 3 to the coil end part is formed. The electric field relaxation layer 5 is provided on a portion of the surface where the creeping potential gradient increases.
In the figure, 6 is an insulating cover layer.

The method for treating the electric field relaxation layer 5 includes the following. (1) A method of winding and fixing a semi-conductive tape having a high resistance value on the coil insulating layer 2 which has been preheated and pressed by using an adhesive. (2) Silicon carbide particles have non-linear characteristics and are often used as an electric field relaxation material. A resin containing the silicon carbide particles is applied by brushing onto the coil insulating layer 2 which has been preheated and pressed. And then how to handle. (3) An electric field relaxation tape obtained by applying a semi-cured thermosetting resin containing silicon carbide particles to a reinforcing cloth is wound around the coil insulating layer 2 and at the same time the coil insulating layer 2 is heated and pressed. How to handle.

[0006] As for this, Japanese Patent Laid-Open No. 54-
116603, JP-A-62-68031,
JP-A-62-123936, JP-A-62-132
There is 650 publication.

[0007]

By the way, a conventional method for treating an electric field relaxation layer is applied with a fixing agent on a coil insulating layer obtained by preheating and pressurizing the high-resistance semiconductive tape described in (1) above. In the method of winding and treating, there is a concern that the adhesive may penetrate into the lap surface of the semi-conductive tape and the resistance value of the semi-conductive tape may become unsuitable, resulting in failure to withstand high electric field specifications. As a result, there is a method of applying the resin containing the silicon carbide particles of the above (2) by brushing on the coil insulating layer which has been preheated and pressed, and treating it. Since it is necessary to perform brushing, the workability is not good, and the characteristic value fluctuates depending on the operator, so that it is difficult to stabilize the nonlinear resistance characteristic to an ideal value. There is also a problem that the step of forming the coil insulating layer and the step of treating the electric field relaxation layer are separate.

Since the prepreg method tends to be adopted as the method for manufacturing the coil insulating layer, as a method for forming the electric field relaxation layer at the same time as the heating / pressurizing molding of the coil insulating layer, the reinforcing cloth described in (3) above is used. There is a method of forming an electric field relaxation layer by applying an electric field relaxation tape obtained by coating a semi-curable thermosetting resin containing silicon carbide particles on the surface. The non-linear resistance characteristic is due to the contact between the silicon carbide particles, and the characteristic value largely changes depending on the curing conditions of the thermosetting resin. Therefore, when the electric field relaxation tape is formed by simply applying a semi-cured thermosetting resin containing silicon carbide particles to the reinforcing cloth, the electric field relaxation is performed so that the nonlinear resistance characteristic becomes a stable and ideal value. The layers are difficult to form.

In addition, there is also a problem that the semiconducting silicon carbide particles flow together with the thermosetting resin during the heat and pressure molding and flow into the coil insulating layer, resulting in deterioration of the insulating property. As a countermeasure for this, there is a method of providing a separate material between the electric field relaxation layer and the coil insulating layer so as to prevent the flow of the thermosetting resin, but a material having a different resistance value is used between the electric field relaxation layer and the coil insulating layer. It is not desirable to provide it on the coil insulation layer, and if the separate material deteriorates due to long-term operation, a void or the like will be generated between the electric field relaxation layer and the coil insulation layer, and the electric field relaxation characteristics will become unstable, which may adversely affect the coil insulation layer. is there.

In order to form the electric field relaxation layer in this way,
It is optimum to heat and press-mold at the same time as the prepreg type coil insulating layer, and various studies have been made.

That is, a semi-cured thermosetting resin is applied to the electric field relaxation tape as a resin containing silicon carbide particles, and the flow of the silicon carbide particles due to heat and pressure molding has been a problem. Therefore, a resin containing silicon carbide particles is applied to a reinforcing cloth, and an electric field relaxation tape prepared by drying in advance is wound around the coil insulating layer to form an electric field relaxing layer at the same time as heating and pressurizing the coil insulating layer. By doing so, the problem that the silicon carbide particles do not flow and impair the insulating property is solved.

However, the coil insulating layer is formed by heat-pressing a prepreg tape containing a semi-cured thermosetting resin, so that the resin in the prepreg tape remains as much as necessary to form the insulating layer, and the surplus resin remains. As the component is pushed out of the insulating layer, the thickness of the coil insulating layer is reduced by heat and pressure molding. And while the outer circumference of the coil insulation layer also decreases, the electric field relaxation tape wound on the coil insulation layer has been dried in advance, so there is no dimensional change during heat and pressure molding, and the outer circumference of the electric field relaxation layer is small. Since this does not change, the electric field relaxation layer is overhanged, and when pressure is applied in such a state, wrinkles are generated in the electric field relaxation layer. The generation of such wrinkles causes wrinkles in the electric field relaxation layer. The wrinkle causes the contact state of the lap surface of the electric field relaxation tape to become sparse, the non-linear resistance characteristic becomes unstable, the electric field is not relaxed, and a creeping corona discharge occurs to create an electrical weak point. .

Further, the electric field relaxation tape is hard because it has been dried in advance, and it has a drawback that it bites into the coil insulating layer by heat and pressure molding, peels off and forms voids in the coil insulating layer, and significantly deteriorates the coil insulating property. .

When a rotating electric machine is operated for a long period of time using the stator coil thus manufactured, a creeping corona discharge is constantly generated at the end of the low-resistance corona shield layer where the electric field is concentrated, and the coil insulation It may erode the layer, reduce the withstand voltage performance, and accelerate the deterioration.

Therefore, the conventional electric field relaxation layer of the stator coil has a problem that wrinkles are generated in the electric field relaxation layer when the electric field relaxation layer is formed simultaneously with the heating and pressurizing of the coil insulating layer.

The present invention has been made in view of the above points, and provides a stator coil for a rotating electric machine that prevents creeping corona discharge from occurring due to wrinkles in the electric field relaxation layer and enables improvement in reliability. The purpose is.

[0017]

The above object is to provide a buffer layer between the electric field relaxation layer and the coil insulating layer, one end of which is in contact with the end of the low resistance corona shield layer. This will be achieved.

[0018]

Since the above-mentioned means is provided, the buffer layer absorbs the dimensional change of the coil insulating layer during the heat and pressure molding.

That is, when the electric field relaxation layer is formed at the same time when the coil insulation layer is heated and pressed, a buffer layer is provided between the coil insulation layer and the electric field relaxation layer so that the coil insulation layer can be formed by heating and pressurization. Although the excess resin is discharged and the thickness of the coil insulating layer is reduced, the buffer layer compensates for the thickness reduction, and the outer peripheral dimension of the coil insulating layer does not change from that before the heating and pressurizing. As a result, wrinkles of the electric field relaxation layer due to heat and pressure molding can be prevented, and excess resin in the coil insulating layer can be prevented from flowing out to the electric field relaxation layer.

[0020]

EXAMPLES Next, the present invention will be specifically described by way of examples.

[Embodiment 1] FIGS. 1 and 2 show an embodiment of the present invention. Since the same parts as those of the prior art are designated by the same reference numerals, the description thereof will be omitted. In this embodiment, a buffer layer 7 is provided between the electric field relaxation layer 5 and the coil insulating layer 2, one end of which is in contact with the end of the low resistance corona shield layer 3. By doing so, the buffer layer 7 absorbs the dimensional change of the coil insulating layer 2 during the heat and pressure molding, and the electric field relaxation layer 5 is prevented from being loosened, and the creeping corona due to the wrinkles of the electric field relaxation layer 5 is eliminated. It is possible to obtain the stator coil 1a of the rotating electric machine that prevents the occurrence of discharge and improves reliability.

That is, on the outer periphery of the coil end portion of the coil insulation layer 2 formed by winding the prepreg insulating tape around the outer periphery of the conductor 4, from the end portion of the low resistance corona shield layer 3 to the range where the electric field relaxation layer 5 is formed, a buffer layer. 7, the buffer layer 7
An electrolytic relaxation layer 5 was provided on the outer periphery of the above in contact with the low resistance corona shield layer 2. Then, an insulating cover layer 6 for protecting the electric field relaxation layer 5 was provided on the outer periphery of the electric field relaxation layer 5 to form the stator coil 1a (see FIG. 1).

This stator coil 1a is provided with the coil insulating layer 2, the low resistance corona shield layer 3, the electric field relaxation layer 5, the insulating cover layer 6 and the buffer layer 7 on the conductor 4 and then heat and pressure molding. To do. The buffer layer 7 is the same base material as the coil insulating layer 2, and this base material is formed by winding any one tape or sheet of dry laminated mica containing no uncured resin, non-resin film, non-resin non-woven fabric, or non-resin woven fabric. Form.

The electric field relaxation layer 5 is formed by applying a resin containing silicon carbide particles to a reinforcing cloth as described above, and winding a previously dried electric field relaxation tape.

The low resistance corona shield layer 3 is formed by winding a semi-conductive tape around the portion of the coil insulating layer 2 which is to be inserted into the slot.

The cover insulating layer 6 is formed by winding a prepreg insulating tape around the electric field relaxation layer 5.

By forming the stator coil 1a by providing the buffer layer 7 in this manner, the excess resin in the coil insulating layer 2 is discharged by the heat and pressure molding, and the thickness of the coil insulating layer 2 is reduced. Since the buffer layer 7 compensates for the reduction in thickness, the outer peripheral dimension of the coil insulating layer 2 is the same as that before the heat and pressure molding, so that the electric field relaxation layer 5 does not sag and the electric field relaxation layer 5 by the heat and pressure molding is eliminated. It is possible to prevent the generation of wrinkles. Further, the buffer layer 7 can prevent the electric field relaxation layer 5 from being bitten into the coil insulating layer 2 due to the heat and pressure molding. Since the buffer layer 7 is the same base material as the coil insulating layer 2, even if it is provided between the coil insulating layer 2 and the electric field relaxation layer 5, the electric field relaxation characteristic is not impaired, and the buffer layer 7 Since 7 is a non-resin material containing no uncured resin, it is possible to absorb the excess resin in the coil insulating layer 2 and prevent it from flowing out to the electric field relaxation layer 5.

The electric field relaxation tape 8 forming this electric field relaxation layer 5 is carbonized so that the electric field relaxation material 9 in which a resin containing silicon carbide particles is applied to a reinforcing cloth and the porous fabric 10b are kept contractible. The electric field relaxation material 10 is formed by impregnating an appropriate amount of a resin 10a containing silicon particles (see FIG. 2).

An electric field relaxation layer 5 is formed by winding the electric field relaxation tape 8.
Is installed and the pressure of the coil insulating layer 2 is reduced by heating and pressurizing, the electric field relaxation tape 8 itself shrinks following the pressurizing by heating and pressurizing. As a result, the dimensional change of the electric field relaxation layer 5 following the dimensional change of the outer periphery of the coil insulating layer 2 can prevent the generation of wrinkles. The electric field relaxation tape 8 does not impair the electric field relaxation characteristics because the porous fabric 10b is impregnated with the resin 10a containing silicon carbide particles. When the electric field relaxation tape 8 is wound to form the electric field relaxation layer 5, the buffer layer 7 prevents the electric field relaxation layer 5 from digging into the coil insulating layer 2 and absorbs excess resin in the coil insulating layer 2 to form the electric field relaxing layer. Needless to say, it is more effective to install it because it has the effect of preventing the outflow to No. 5.

The results of examining the effect of using such a buffer layer 7 will be described below.

On the outer circumference of the coil end portion of the coil insulating layer 2 made of mica epoxy prepreg, the electric field relaxation layer 5 is formed from the end portion of the low resistance corona shield layer 3 made of carbon as a base material.
The buffer layer 7 was provided by winding the dry-assembled mica tape in a predetermined number of times up to a predetermined range for forming the film. This buffer layer 7
The epoxy resin containing silicon carbide particles is applied to the polyester fiber in contact with the low resistance corona shield layer 3 on the outer periphery of the electric field relaxation tape 8 wound in a predetermined length with a half length to relax the electric field. A layer 5 was provided, and a prepreg glass tape was wound around the outer circumference of the electric field relaxation layer 5 in half to provide a cover insulating layer 6, and then heat press molding was performed to obtain a stator coil 1a. The outer appearance of the coil end portion of the stator coil 1a molded in this manner is good because it has no wrinkles on the surface and forms a uniform surface.

Further, FIG. 5 shows the stator coil 1 of this embodiment.
The result of the comparison of the electrical characteristics between a and the conventional stator coil 1 (see FIG. 6) is shown. In this figure, the visible corona generation voltage and flashover voltage are plotted on the vertical axis, and the visible corona and flashover are plotted on the horizontal axis, showing the visible corona generation voltage and flashover voltage characteristics. As is clear from the figure, the characteristic of this embodiment is excellent in both the visible corona generation voltage and the flashover voltage by about 30% as compared with the characteristic straight line B of the conventional example, as shown by the straight line A. This is because the coil of the present example was provided with the buffer layer, so that the electric field relaxation layer did not cause wrinkles and could sufficiently exhibit its function.

As described above, according to the present embodiment, the electric field relaxation for preventing the creeping corona discharge at the coil end portion of the stator coil having the high voltage and high electric field specifications is accompanied by the increase in the capacity of the rotating electric machine and the downsizing of the equipment. When forming a layer, the wrinkle of the electric field relaxation layer is prevented at the same time when the coil insulating layer is heated and pressed, so that the contact state of the lap surface of the electric field relaxation tape becomes dense and the nonlinear resistance characteristic is stabilized. Ideal value, no creeping corona discharge, excellent coil insulation performance,
It is possible to obtain a stator coil of a rotating electric machine with improved reliability.

Example 2 FIGS. 3 and 4 show another example of the electric field relaxation tape applied to the electric field relaxation layer. The electric field relaxation tape 11 is obtained by applying a resin 11a containing silicon carbide particles to a heat shrinkable woven fabric 11b in a mottled manner so as to keep the heat shrinkability.

The electric field relaxation tape 11 is wound to form an electric field relaxation layer, which is heated and pressed to form the electric field relaxation tape 1.
Since No. 1 shrinks, as described in the electric field relaxation tape 8 (see FIG. 2), the dimensional change of the electric field relaxation layer can prevent the generation of wrinkles. An example of mottled application of the resin 11a containing silicon carbide particles so as to maintain the heat shrinkability on the heat shrinkable fabric 11b is shown in FIG. The resin 11a containing silicon carbide particles is used in the heat shrinkable woven fabric 11b in a predetermined range of about 70% or more, and in a predetermined range of about 3%.
By applying so as to form a dense portion and a sparse portion such as 0% or less, heat shrinkage can be performed in the sparse portion during heat and pressure molding.

Also in this case, when the electric field relaxation tape 11 is wound to form an electric field relaxation layer, the buffer layer is used to prevent the electric field relaxation layer from digging into the coil insulating layer and to prevent excess resin in the coil insulating layer, as in the case described above. Needless to say, it is more effective to install it, because it has the effect of absorbing the water and preventing it from flowing out to the electric field relaxation layer.

In this case as well, the same operational effects as the above-mentioned case can be obtained.

[0038]

As described above, according to the present invention, the buffer layer whose one end is in contact with the end of the low resistance corona shield layer is provided between the electric field relaxation layer and the coil insulating layer. The buffer layer absorbs the dimensional change of the coil insulation layer during heating and pressurization, eliminating the slack of the electric field relaxation layer and preventing the occurrence of creeping corona discharge due to the wrinkles of the electric field relaxation layer. It is possible to obtain a stator coil of a rotating electric machine that can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of a coil main part of an embodiment of a stator coil of a rotary electric machine according to the present invention.

FIG. 2 is a sectional view of an electric field relaxation tape of the same embodiment.

FIG. 3 is a sectional view of an electric field relaxation tape of another embodiment of the stator coil of the rotating electric machine of the present invention.

4 is a sectional view taken along the line AA of FIG.

FIG. 5 is a characteristic diagram of visible corona generation voltage and flashover voltage between a coil according to an embodiment of the stator coil of the rotating electric machine of the present invention and a conventional coil.

FIG. 6 is a vertical sectional side view of a coil main part of a stator coil of a conventional rotating electric machine.

[Explanation of symbols]

1a ... Stator coil, 2 ... Coil insulation layer, 3 ... Low resistance corona shield layer, 4 ... Conductor, 5 ... Electric field relaxation layer, 7 ... Buffer layer, 8 ... Electric field relaxation tape, 11 ... Electric field relaxation tape.

Claims (4)

[Claims] 1. A coil insulating layer wound on a conductor and made of a prepreg insulating material, a low resistance corona shield layer formed on a surface of a portion of the coil insulating layer to be inserted into a slot, and An electric field relaxation layer formed over a predetermined range of the coil end portion protruding from the low resistance corona shield layer to the outside of the slot, and covering the end portion side of the low resistance corona shield layer and the coil insulating layer. In a stator coil of a rotating electric machine comprising the coil insulation layer, the low-resistance corona shield layer, and the electric field relaxation layer, which are heat-pressed together, between the electric field relaxation layer and the coil insulation layer, one of them is provided. A stator coil for a rotating electric machine, wherein a buffer layer whose side end is in contact with an end of the low resistance corona shield layer is provided. 2. The buffer layer is formed of any one of dry laminated mica, non-resin film, non-resin non-woven fabric, and non-resin fabric of the same base material as the base material of the coil insulating layer, and the coil insulating layer. The stator coil for a rotating electric machine according to claim 1, wherein the stator coil is heat-pressed together with the low-resistance corona shield layer and the electric field relaxation layer. 3. The electric field relaxation layer comprises an electric field relaxation material in which a resin containing silicon carbide particles is applied to a reinforcing cloth, and a resin containing silicon carbide particles so as to maintain the shrinkability of a porous woven fabric. 2. The stator coil for a rotating electric machine according to claim 1, wherein the stator coil is formed of an electric field relaxation material impregnated in a fixed amount and is wound around an electric field relaxation tape having a predetermined non-linear resistance characteristic. 4. An electric field relaxation tape having a predetermined non-linear resistance characteristic, wherein the electric field relaxation layer is formed by applying a resin containing silicon carbide particles to a heat shrinkable woven fabric in a mottled manner so as to maintain the heat shrinkability. The stator coil for a rotating electric machine according to claim 1, which is formed by winding.