JPH0510898B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an electric machine winding, for example, a stator winding of a generator or a motor, etc., in particular an electric machine winding in which a corona shield layer is formed at the end of the winding located outside the slot of a stator core. and its manufacturing method. [Technical background of the invention and its problems] Conventionally, in rotating electric machines such as turbine generators and water turbine generators, it has been necessary to prevent corona at the end of the stator winding located outside the slot of the stator core, especially in high voltage models. Countermeasures have become an important issue. FIG. 1 shows a partial longitudinal sectional view of an end portion of an electric machine winding provided with an end corona shield layer. In FIG. 1, a conductive layer 4 for preventing corona inside the stator core is formed on the outer periphery of an insulating layer 2 applied to the outer periphery of the conductor 1 from the insertion part of the stator core 3 to the outside. The end corona shield layer 5 of the winding is electrically connected to the end of the conductive layer 4, and the corona shield layer 5 is connected from the end of the conductive layer 4 to the end of the winding (in the direction of the arrow shown in the figure).
The conductive layer 4 is formed over the entire length of the conductive layer 4 to alleviate the concentration of electric field at the end portions of the conductive layer 4 and prevent corona. Here, the conductive layer 4 is generally formed by coating a paint containing carbon or graphite powder, or by impregnating and coating a sheet (cloth) or tape-like fiber with a paint containing carbon or graphite powder. It is formed by winding a conductive material. The end corona shield layer 5 of the winding is generally coated with a paint (hereinafter referred to as SiC-containing paint) containing carbon black, graphite, or silicon carbide powder (hereinafter referred to as SiC) in resin. Alternatively, it can be formed by winding a corona shield material made by impregnating and coating a sheet or tape-like fiber with this coating material, iron-containing asbestos, or the like. In particular, as the end corona shield layer 5 of the winding in high voltage models, a corona shield material mainly composed of a SiC-containing paint having non-linear voltage resistance characteristics is used. In general, the characteristics of corona shield materials having this voltage non-linear resistance characteristic are as follows:
When the electric field is E and the current at that time is I, it is expressed as I=KE ⁿ . Here, when n=1, it is called linearity, and when n>1, it is called nonlinearity. By the way, the conventional treatment of the end corona shield layer 5 of the winding with a SiC-containing paint is carried out by directly applying it to the insulating layer 2 with a brush and drying and solidifying it. However, in order to provide the desired voltage nonlinear resistance characteristics, it is not only necessary to repeat brush coating and drying 2 to 4 times to thicken the coating layer of the SiC-containing paint, but also to cause uneven coating. Therefore, there is a large variation in the above characteristics. Therefore, recently, SiC coatings have been developed that are easier to work with, have a more homogeneous SiC coating layer, and have less variation in properties.
A corona shield material (hereinafter referred to as SiC prepreg material), which is prepared by impregnating a sheet or tape-like fiber with SiC-containing paint and drying it into a prepreg shape, is wound around the outer periphery of the insulating layer 2. A method of forming the end corona shield layer 5 simultaneously with the formation of the insulating layer 2 by impregnating it with an epoxy-based insulating varnish and curing it by heating is used. However, conventional SiC-containing paints are based on epoxy ester resins, bisphenol epoxy resins, epoxy novolac resins, or alkyd resins.
This type of SiC prepreg material, which contains SiC and is made by impregnating sheet or tape-like fibers with the SiC-containing paint, dissolves in the epoxy-based insulating varnish used for impregnating windings. ,
The end corona shield layer 5 could not be formed. Additionally, the varnish used for impregnation treatment was contaminated with dissolved SiC. Therefore, in order to form the end corona shield layer 5 using the above-mentioned SiC prepreg material, after performing an impregnation treatment and a heat curing treatment with an epoxy-based insulating varnish to form the insulating layer 2, the outer periphery of the insulating layer 2 is to SiC
The prepreg material was wound and the SiC prepreg material was heat-cured. That is, the insulating layer 2 of the winding and the SiC prepreg material must be heated separately, which poses a problem that not only the working time becomes longer but also the working cost increases. Therefore, in recent years, a material made by sufficiently drying and hardening the SiC prepreg material (hereinafter referred to as SiC dry tape) has been developed as a material that does not dissolve in the insulating varnish. However, after this SiC dry tape is wound around the outer periphery of the insulating layer 2 of the winding wire, it is impregnated with insulating varnish to form the insulating layer 2 and cured by heating. Since the insulating varnish is cured while remaining in the mutually overlapping seams, the end corona shield layer 5 has a SiC dry tape layer and an insulating varnish layer, and the distribution of SiC, which is effective for corona prevention, is not uniform. This is SiC
Prepreg material has adhesive strength because it is in a semi-hardened state, but SiC dry tape that has been sufficiently dried and cured has no adhesive strength, so it cannot seal the insulating varnish during the impregnation process. There is a problem that the preventive effect is not sufficient. [Objective of the Invention] An object of the present invention is to form a homogeneous end corona shield layer that does not dissolve in the insulating varnish, sufficiently seals the insulating varnish, and ensures good voltage non-linear resistance characteristics. It is an object of the present invention to provide an electric machine winding wire that has an extremely excellent corona prevention effect even for voltage models, and that can shorten working time and reduce working costs, and a method for manufacturing the same. [Summary of the invention] In order to achieve the above object, first, in the first invention, a conductive layer is formed on the outer periphery of an insulating layer provided on the outer periphery of a conductor, and electrically connected to the conductive layer. In an electric machine winding in which an end corona shield layer of the winding wire is formed from the end of the conductive layer to the end of the winding wire, the end corona shield layer of the winding wire is made of acrylic modified polybutadiene resin and silicon carbide powder. It is formed by winding a prepreg-like corona shield material made by impregnating and coating sheet or tape-like fibers with the main material. Further, in the second invention, a conductive layer is formed on the outer periphery of an insulating layer using an impregnated insulation method applied to the outer periphery of a conductor, and then the conductive layer is electrically connected and wound from the end of the conductive layer. A prepreg-like corona shield material made by impregnating sheet or tape-like fibers with a material mainly composed of acrylic modified polybutadiene resin and silicon carbide powder is wound around the wire ends to create a corona shield layer at the end of the winding wire. After that, the insulating layer is impregnated with an insulating varnish and heat-cured. Furthermore, in the third invention, a conductive layer is formed on the outer periphery of an insulating layer using a resin rich insulation method applied to the outer periphery of the conductor, and then the conductive layer is electrically connected and wound from the end of the conductive layer. A prepreg-like corona shield material made by impregnating sheet or tape-like fibers with a material mainly composed of acrylic modified polybutadiene resin and silicon carbide powder is wound around the wire ends to create a corona shield layer at the end of the winding wire. After that, the insulating layer is heated and hardened. [Embodiment of the Invention] Hereinafter, an embodiment of the present invention shown in the drawings will be described. In the present invention, the end corona shield layer 5 of the winding shown in FIG. The corona shield material is formed by winding the corona shield material, and then the insulating layer is impregnated with insulation varnish and heat hardened using the impregnation insulation method, or the insulation layer is heat hardened using the resin rich insulation method. This point will be discussed in detail below. First, as the acrylic modified polybutadiene resin used for the end corona shield layer 5, TE2000 (polybutadiene acrylate manufactured by Nippon Soda), E-1000 (polybutadiene acrylate manufactured by Showa Kobunshi), etc. having the basic structural formula () are used. . Also,
As the epoxy-modified polybutadiene resin, EPR-12B (polybutadiene epoxy manufactured by Nippon Soda) having the basic structural formula () is used. In addition, "poly"
indicates that there is a large amount of butadiene (indicated by n in the basic structural formula). Normally, in the present invention, an acrylic-modified polybutadiene resin is used as the resin material, but in order to set the heat drying time to an appropriate time to semi-cure the material and make it into a prepreg state, epoxy-modified polybutadiene resin is used as the resin material. A portion of the polybutadiene resin may be added as necessary. Further, as the SiC particles used for the end corona shield layer 5 of the electric machine winding, ordinary commercially available products can be used, and there is no particular restriction on the particle size, and various types can be used depending on the purpose. For example, there are Nitso Random (SiC manufactured by Taiheiyo Metal Co., Ltd.), Carborundum (SiC manufactured by Carborundum, USA), and SiC manufactured by Shinano Electric Refining Co., Ltd. Furthermore, the end corona shield layer 5 of this electric machine winding
As the sheet or tape-shaped fibers used for this purpose, porous substrates such as glass fibers, organic fibers, glass nonwoven fabrics, and organic fiber nonwoven fabrics, plastic films, and the like are used. On the other hand, the end corona shield layer 5 of the electric machine winding is
In paints made mainly of acrylic-modified polybutadiene resin and SiC powder, we use amine curing agents and reaction initiators (radical polymerization initiators) to give them a pregregg-like effect, and solvents to adjust viscosity. It may be added as necessary. Next, Table 1 shows composition examples of SiC-containing paints. The paint obtained with this composition is
0.13mm, width 25mm Kagarasu cloth tape, 0.4
It is applied through a mm slitter and dried at 100°C for 10 minutes to obtain a SiC pregreg material. Further, Table 2 shows the workability and solubility of these materials for the end corona shield layer 5. In addition, Comparative Example 1 and Comparative Example 2 are as follows:
Made of SiC prepreg material and epoxy novolak resin.
The main material is SiC, and the main material is applied to polyester cloth tape and semi-cured (for example,
217.01 prepreg tape, 217.02 prepreg tape manufactured by ISOLA), Comparative Example 3, and Comparative Example 4 are SiC
A dry tape whose main materials are epoxy ester resin and SiC, which are applied to polyester cloth tape and cured (for example, ISOLA
217.11 dry tape, 217.12 dry tape)
It is. From the table, it can be seen that because the material of the present invention uses an acrylic modified polybutadiene resin, it does not dissolve in the insulating varnish even though it is prepreg-like. In addition, in Comparative Example 1 and Comparative Example 2, “02”
indicates that the particle diameter is larger than "01", and in Comparative Examples 3 and 4, "12" indicates that the particle diameter is larger than "11".

【table】

[Table] Next, Figure 2 shows that the material of the present invention and the conventional comparative example material described above are wound around an electrical winding for testing, and then subjected to insulation varnish impregnation treatment and heat hardening treatment using an impregnation insulation method. , or an end corona shield layer (subscript a) that has been heat-cured using a resin-rich insulation method (hereinafter referred to as varnish-treated), and an electrical winding for testing that has already been impregnated with insulation varnish and heat-cured. The surface resistance of the end corona shield layer (subscript b) obtained by winding the material of the present invention and the material of the conventional comparative example and then heating and curing these materials alone (hereinafter referred to as "no varnish treatment") is They are shown below. In FIG. 2, Comparative Example 3 with varnish treatment 6a
And Comparative Example 4 with varnish treatment 7a is higher than the values of 6b and 7b without varnish treatment, and voltage nonlinearity also tends to be impaired. Further, the varnish treated 8a of Example 3 is the same as the varnished untreated 8a.
Although the value is a little higher than b, voltage nonlinearity is not impaired. Further, as shown in Table 2, Examples 1 and 2 have surface resistances that are almost the same as Example 3, although their workability is inferior to Example 3. Note that Comparative Example 1 and Comparative Example 2 are not shown in FIG. 2 because they are dissolved after the varnish treatment and the surface resistance cannot be measured. As explained above with reference to Fig. 2, the material used in the present invention is prepreg-like and has sufficient adhesive strength, so when the material is wound, it sticks to each other, exerting a sealing effect and creating a varnish. Homogeneous edge corona shield layer 5 that prevents penetration during processing
can be formed. Next, Table 3 shows the visible corona onset voltage as an index for evaluating the edge corona prevention effect. From the table, the materials used in the present invention have a high visible corona onset voltage even during varnish treatment. This is because the SiC prepreg material of the present invention used to form the edge corona shield layer 5 does not dissolve in the insulating varnish and exhibits a sealing effect due to the adhesive strength of the prepreg material, resulting in an extremely excellent edge corona shield layer 5. It can be seen that the anti-coronavirus effect is maintained.

[Table] *1: Measurement is not possible because the coating film dissolves in the varnish [Effects of the invention] As explained above, the electrical winding wire and the manufacturing method thereof of the present invention are made by using acrylic polybutadiene resin and
A prepreg-like corona shield material made by impregnating and coating a sheet or tape-like fiber with a material mainly composed of SiC is wound to form a corona shield layer at the end of the winding, and then an impregnation insulation method is applied. The insulating layer is impregnated with an insulating varnish and heat hardened, or the insulating layer is heat hardened using a resin rich insulation method. Therefore, since the corona shield material uses acrylic modified polybutadiene resin, it does not dissolve in the insulating varnish and sticks in the form of a prepreg, making it possible to seal the insulating varnish and form a homogeneous edge corona shield layer. . As a result, the end corona shield layer can ensure good voltage non-linear resistance characteristics, and has an extremely excellent corona prevention effect even for high voltage models, as well as shortening work time and reducing work costs. It becomes possible to achieve this goal.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view of a winding end provided with a corona shield layer, and FIG. 2 is a characteristic diagram showing the relationship between electric field and surface resistance depending on the materials of the corona shield layer of the present invention and a conventional example. DESCRIPTION OF SYMBOLS 1... Conductor, 2... Insulating layer, 3... Stator core, 4... Conductive layer, 5... End corona shield layer, 6a... Comparative example 3 (with varnish treatment), 6b...
Comparative Example 3 (without varnish treatment), 7a... Comparative Example 4 (with varnish treatment), 7b... Comparative Example 4 (without varnish treatment),
8a...Example 3 (with varnish treatment), 8b...Example 3 (without varnish treatment).

Claims (1)

[Scope of Claims] 1. A conductive layer is formed on the outer periphery of an insulating layer provided on the outer periphery of a conductor, and is electrically connected to the conductive layer so that a wire is wound from the end of the conductive layer to the end of the winding wire. In an electric machine winding having an end corona shield layer formed thereon, the end corona shield layer of the winding is made of a sheet or tape-shaped fiber made of a material mainly composed of acrylic modified polybutadiene resin and silicon carbide powder. An electrical winding wire characterized in that it is formed by winding a prepreg-like corona shield material coated with impregnation. 2. A conductive layer is formed on the outer periphery of an insulating layer using the impregnated insulation method applied to the outer periphery of the conductor, and then an acrylic layer is electrically connected to the conductive layer from the end of the conductive layer to the end of the winding. A prepreg-like corona shield material made by impregnating and coating a sheet or tape-like fiber with a material mainly composed of modified polybutadiene resin and silicon carbide powder is wound to form a corona shield layer at the end of the winding. A method for producing an electrical winding wire, characterized in that the insulating layer is then subjected to an insulating varnish impregnation treatment and a heat curing treatment. 3. A conductive layer is formed on the outer periphery of an insulating layer using a resin-rich insulation method applied to the outer periphery of the conductor, and then an acrylic layer is electrically connected to the conductive layer from the end of the conductive layer to the end of the winding. A prepreg-like corona shield material made by impregnating and coating a sheet or tape-like fiber with a material mainly composed of modified polybutadiene resin and silicon carbide powder is wound to form a corona shield layer at the end of the winding. A method for manufacturing an electrical winding wire, characterized in that the insulating layer is then subjected to a heat curing treatment.