JPH0440845B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention provides a material with excellent electrical, thermal, and mechanical properties.
The present invention particularly relates to electrically insulated wire wheels suitable for use in high-voltage rotating machines. [Technical Background of the Invention and Problems Therein] High-voltage AC motors, industrial DC machines, water turbine generators, turbine generators, and the like are increasing in unit capacity, resulting in high voltage and large capacity. Along with this, efforts have been made to increase the operating temperature, increase the operating electric field, and reduce the size of machines. To this end, it is essential that the electrically insulated coils used in these machines have improved thermal, electrical, and mechanical properties such as heat resistance and voltage resistance. Insulation for these machines has traditionally been achieved by wrapping mica tape, which is made by adhesively bonding reinforcing materials such as paper, film, glass woven fabric, or polyester nonwoven fabric, to peelable mica or laminated mica, and filling the voids in these base materials with epoxy, polyester, This was done by filling it with a resin such as polyimide and curing it. There are two ways to fill the resin: wrapping a mica tape containing a small amount of adhesive and then impregnating it with resin under vacuum pressure (vacuum pressure impregnation method), and adding an appropriate amount of adhesive into the mica tape in advance. There are two methods (prepreg method or resin rich method). Generally, in order to obtain electrically insulating wire with excellent thermal, electrical, and mechanical properties, it is necessary to increase the mica content in the insulating layer, improve the formation of mica, use adhesives, impregnated resins, and It is necessary to have good compatibility between the reinforcements. However, with conventional mica tape, the adhesive between the mica is only due to the weak adhesive force of crystallized water, so the density is low and the mica layer easily peels, and when the mica tape is wound around a coil, mica pieces scatter. Therefore, the mica tape had to contain more adhesive than necessary. For this reason, it has been difficult to increase the mica content in the insulating layer, to improve the impregnating property in the case of a vacuum pressure impregnation method, and to improve the compatibility between the adhesive and the impregnated resin. Furthermore, in conventional mica tapes, when the insulating layer is heated and cured by applying pressure, flow of the mica layer occurs, causing a decrease in edge coverage and worsening the formation of the mica. Furthermore, conventional mica tape tends to be thick because the mica and reinforcing material are bonded together with adhesive.
In addition, since the adhesive interposed between the reinforcing material and the mica moves toward the mica and the reinforcing material during storage of the mica tape, the mica may separate from the reinforcing material during taping, causing problems. [Purpose of the Invention] The present invention was made to solve these conventional problems, and by using a mica tape in which reinforcing material and mica are bonded together without using an adhesive, it is possible to eliminate the problems caused by the adhesive. There are no problems with impregnation or compatibility, and the mica is less likely to scatter and fall off during taping, has excellent winding workability, and is less likely to cause laminar flow, so it has a high mica content and good mica formation. The purpose is to provide electrically insulated coils with excellent thermal, electrical, and mechanical properties. [Summary of the Invention] Aramid fibrids have an extremely large mica trapping effect (Japanese Patent Publication No. 43-20241). The present invention utilizes this fact to heat-fuse aramid-mixed mica paper, which is wet-formed by mixing a very small amount (several weight percent) of fibrids with mica, and aramid paper using a thermal calendar without using an adhesive. The mica sheet or mica tape is wrapped around a wire ring, impregnated with thermosetting resin, and cured to create an electrically insulating wire ring. [Embodiments of the Invention] Next, embodiments of the present invention will be described. Example 1 As epoxy resins, alicyclic epoxy resin Chitsonox 221 (trade name, Chitsuso Co., Ltd.), Syodyne 540 (trade name, Showa Denko Co., Ltd.), and bisphenol F type epoxy resin Epicron 830 (trade name, Dainippon Ink) were used. A resin composition a prepared by mixing bisphenol A type epoxy resin DER332 (trade name, Dow Chemical Company), and Epiclon B570 (trade name, Dainippon Ink Company) as an acid anhydride in the proportions shown in Table 1.
~d is prepared as an impregnating resin.

[Table] These resin compositions a to d are all characterized by low viscosity and long pot life. Separately, a mica sheet made by heat-sealing 160 g/m ² aramid-mixed mica paper and 25 μm thick aramid paper was prepared in advance using a siloxane compound SH6018 containing hydroxyl groups to accelerate the hardening of the impregnated resin. After immersing in a diluted solution of (trade name, Toray Silicone Co., Ltd.) and aluminum triacetylacetonate dissolved in methyl ethyl ketone,
Dried, SH6018 and aluminum triacetylacetonate are included in the mica sheet at 0.2% and 0.1% by weight, respectively. This is cut into tape shapes to obtain mica tape, which is an insulating base material. Although this tape contained almost no adhesive, there was no scattering of mica when the tape was wound, and because it was mixed with fibrid, the mica paper had strength and elongation, and it had excellent winding workability. Then wrap this mica tape 1/2 layer around the wire13
Turn it, put it in a simulated iron core (not shown), put it together with the iron core in an impregnation tank, and after reducing the pressure at 0.1 mmHg for 5 hours, feed the resin compositions a to d of Table 1 under reduced pressure,
After pressurizing at 5Kg/cm ² (gauge pressure) for 10 hours, it was taken out from the impregnation tank and placed in an oven at 150℃.
After heating and curing for 15 hours, an electrically insulating wire ring was obtained. The resulting insulated wire ring had no problems with mica laminar flow or cut-through at corners, and the mica had good formation. Table 2 shows the results of measuring the tan δ (dielectric loss tangent) of these electrically insulated coils at 155° C. and a voltage of 1 KV/mm.

〔Effect of the invention〕

As described above, the electrical insulating wire ring of the present invention is made of an insulating sheet or insulating tape made by heat-sealing aramid-containing mica paper and aramid paper, which have excellent winding workability, impregnation properties, cut-through resistance, etc. Because it is wound around a ring, impregnated with thermosetting resin, and cured, it has excellent thermal, electrical, and mechanical properties, and can be supplied at a lower cost than conventional wire rings, making it ideal for rotating machines. This can greatly contribute to higher electric fields and higher temperature operation.

Claims (1)

[Claims] 1. An electrically insulated wire ring characterized in that an insulating sheet or insulating tape made by heat-sealing aramid-mixed macaque paper and aramid paper is wound around a wire ring, impregnated with a thermosetting resin, and cured.