JPS5820132B2 - Coil manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a manufacturing method that replaces varnish impregnation and resin casting for dry transformer coils, for example, by producing a film with good electrical, mechanical, and physical properties in a mold. The present invention relates to a coil characterized in that it can be formed efficiently without using.

Conventional dry-type transformer coils require characteristics such as moisture absorption prevention, so they are produced using a manufacturing method that involves impregnating the surface and inside with liquid varnish and curing it, and a method that involves pouring resin around the coil using a mold. There were two types of hardening, the so-called coil mold method.

When manufactured by such a method, the former requires time and effort such as sloppy varnish and air-drying time, and the latter requires time and effort such as installation and removal of the mold.

In addition, the molds had to be kept in place until the resin hardened, and if the coil dimensions changed, the mold dimensions would also change, so a large number of molds and shapes were required.

The object of the present invention is to obtain a coil that improves these manufacturing defects.

This invention will be explained below with reference to FIGS. 1 and 2.

FIG. 1 shows a cross-sectional view of a coil formed according to the present invention, where 1 is a coil, 3 is a powder mixture composition, and 2 is an insulator having heat resistance equal to or higher than that of the powder mixture composition 3. It is.

That is, in this invention, one or a plurality of coils 1 covered with an insulator 2 are heated in advance to raise the surface temperature to 80°C to 220°C, and then the powder is heated before the surface temperature drops. Mixed compositions, e.g. epoxy powder for powder coating V
It is passed through a filter with a mesh size of about 10 to 100 microns and placed in a container in which it is diffused and suspended using compressed air, held for 0.5 to 5 minutes to fuse the powder mixture composition to the coil surface, and then removed from the container. The coil is taken out and heated again for a required period of time to harden the powder mixture composition and surround the coil.

Repeat this until the desired thickness is achieved.

Conventionally, this method has already been applied to bare conductors such as busbars for the purpose of insulation, but this method can also be applied to coils such as transformers that have been covered with an insulator with heat resistance equivalent to or higher than that of the powder mixture composition. By using the powder mixture composition, it not only provides insulation but also increases mechanical strength and moisture absorption resistance, and the surface temperature of the coil can be raised more than when the powder mixture composition alone is used for insulation.

Increasing the coil surface temperature will be explained with reference to FIG. 2.

In Fig. 2, To is the surface temperature of the coil 1 when the coil is energized, and the temperature decreases to T1 due to the temperature gradient of the insulator 2, which has a heat resistance equal to or higher than that of the powder mixture composition, and then the temperature decreases to T1. Due to the temperature gradient of object 3, the temperature decreases at T2ma.

Therefore, the applicability of the powder mixed composition insulation is determined by the maximum temperature T1.

Here, T1 is the maximum temperature to which the powder mixture composition can be applied, and if the entire surface of the coil is covered with it, the coil surface temperature can only be raised up to T1.

As in the present invention, if the powder mixture composition is covered in advance with an insulating material having heat resistance equal to or higher than that of the powder mixture composition, the coil surface can be You can raise the temperature.

However, if this method is used alone, the powder mixture composition will not get inside the coil, so if higher mechanical strength and void-free properties are desired, prepreg paper can be used for conductor wire insulation, coil-to-coil insulation, and ground-to-ground insulation. A coil is manufactured using it as insulation, etc., and the surface temperature of this coil is set to 80℃ to 220℃.
The prepreg paper is cured by heating, and the same treatment as above is performed to embed the coil before the surface temperature drops.

Another method is to pre-dip the coil in varnish or vacuum impregnation using the same method as before, reducing the number of treatments, and then perform the same treatment as above before the coil surface temperature drops after the final baking. and embed the coil.

In this latter method, by using a heat-resistant varnish, for example a silicone varnish, the heat resistance can be improved compared to the case of using only a powder mixture composition.

Although the above method describes a method of heating the powder mixture composition outside the container, the coil surface is placed in the container at room temperature, and electricity is applied to raise the coil surface temperature, resulting in fusion and curing. You can get the same effect by doing this.

As described above, the present invention allows coils to be embedded without using a mold, reducing working time, and providing coils having characteristics similar to those obtained by varnish impregnation and resin casting.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the coil around which a powder mixture composition and an insulator with heat resistance equal to or higher than the above are attached. The temperature gradient in each insulator is shown. In the figure, 1 is a coil, 2 is an insulator with heat resistance equal to or higher than that of the powder mixture composition, 3 is a powder mixture composition, and tl is an insulator with heat resistance equal to or higher than that of the powder mixture composition. thickness,
t2 is the total thickness of the insulator, to is the coil surface temperature, T1
．． T2 is the temperature at each position j1+j2 away from the coil surface.

Claims (1)

[Claims] 1 A powder mixture composition containing a hardening agent is diffused and suspended in a container, and an insulation having heat resistance equal to or higher than that of the above powder mixture composition formed by pre-immersion in varnish or vacuum impregnation treatment is placed in the container. A method for manufacturing a coil, in which a coil covered with a material is inserted, a powder mixture composition is fused to the surface, and the coil is heated to harden the powder mixture composition fused to the surface.