JPH06197502A - Insulation of rotating electric machine - Google Patents

Abstract

PURPOSE:To obtain only one kind of solventless epoxy resin for impregnation to realize partial discharge proof characteristic similar to that of the prior art by previously soaking a startor coil into a solution mixing scale-pieces of inorganic filler and binder into a low boiling point solvent so that the scale- pieces of inorganic filler are adhered to the stator coil. CONSTITUTION:A coil 1 as a sample is formed by winding in parallel two enamel wires of 1mm diameter for 5 turns and then binding these wires at four points with a thread 2. Here, the coil 1 is soaked into a solution obtained by mixing 20 pts.wt. of the mica powder in the average grain size of 150 mesh and 2 pts.wt. of varnish to 100 pts.wt. of methanol. Thereafter, the coil 1 is dried up and is then impregnated with a thermosetting type solventless epoxy resin. Since mica power is adhered in the pre-processing stage as explained above, it is no longer necessary, unlike the impregnation resin previously mixing the mica powder, to prepare extra impregnation resin for temperature adjustment due to rise of viscosity and impregnation, and moreover sufficient partial discharge proof characteristic can be realized at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for insulating a stator coil of a rotary electric machine, and more particularly to insulating a stator coil of a low-voltage rotary electric machine.

[0002]

2. Description of the Related Art In the conventional insulation method, in order to prevent deterioration due to partial discharge, a stator coil of a low-voltage rotating electric machine is dipped in a solution obtained by mixing a predetermined amount of a scale-like inorganic filler into a solventless epoxy resin for impregnation, It had been heat-dried.

However, when a scale-like inorganic filler is mixed in advance with the solventless epoxy resin for impregnation,
As a matter of course, since the viscosity of the liquid increases, it is necessary to raise the temperature of the liquid to the same level as the viscosity of the resin containing no filler. Further, for an insulation system that does not require a filler, it is necessary to prepare another type of solventless epoxy resin for impregnation, which requires extra space and extra labor for management.

[0003]

The present invention was made in view of the above-mentioned drawbacks, and an object thereof is to fill 100 to 2000 parts by weight of a low boiling solvent with a scale-like inorganic filler of 100 to 2000 mesh. The stator coil of the low-voltage rotating electric machine is dipped in a liquid in which 20 to 40 parts by weight of the agent and 2 to 8 parts by weight of the binder are mixed, pulled up, and then dried. In this state, the scale-like inorganic filler is adhered to the enamel electric wire to such an extent that it cannot be removed by hitting, and then the stator coil is dipped in a solventless epoxy resin for impregnation and heat-dried.
The low boiling point solvent used in the present invention includes methanol, ethanol, acetone, methyl ethyl ketone, chloroform and the like. Further, examples of the scale-like inorganic filler include powders of mica, talc, kaolin and the like, and among them, mica is preferable. The blending number is preferably 20 to 40 parts by weight of 100 to 2000 mesh per 100 parts by weight of the low boiling point solvent, and when 40 parts by weight or more is mixed, the amount of the scale-like inorganic filler attached increases, but the impregnability is become worse. Further, when the amount is 20 parts by weight or less, the amount of the scale-like inorganic filler attached is very small, and the effect of adding the scale-like inorganic filler is not effective. When the average particle size of the scale-like inorganic filler is larger than 150 mesh, the uniformity of the adhered mica is lost, and the average particle size of the scale-like inorganic filler is 2000.
When it is finer than the mesh, it becomes difficult to handle. As the binder, solid epoxy such as oil-based shell epoxy No. 1000 series (Epicoat 1001 to 101) is used.
0), alcohol solvent type varnishes such as Hitachi Chemical's WB-2340 (synthetic resin) and W51 (shellac), but solid epoxy is preferable from the viewpoint of heat resistance. The compounding number is 2 with respect to 100 parts by weight of the low boiling point solvent.
-8 parts by weight, especially 2 to 4 parts by weight, which has little influence on the properties of the solventless epoxy resin for impregnation, is desirable. It should be noted that the mica powder can be attached to the coil without mixing the binder, but it may fall off by a small impact, so it is preferable to use the binder.

[0004]

[Function] The effect is that by applying a scale-like inorganic filler to the insulating coil beforehand, only one type of solventless epoxy resin for impregnation is required. Space and extra management effort are eliminated.

[0005]

Embodiments of the present invention will be described in detail below with reference to the drawings. In this example, methanol was used as the low boiling point solvent, mica powder was used as the scale-like inorganic filler, and shellac varnish was used as the binder. In order to objectively see the amount of mica powder adhered, FIG. 1 shows a solution in which methanol, 150 to 2000 mesh mica powder (change the number of blended parts), and shellac varnish are combined to form a solution of about 40 × 75 mm with a thickness of 0.3 m. It is a data obtained by dipping an iron plate and examining the amount of mica powder attached.
The horizontal axis shows the number of parts of mica powder mixed, the vertical axis shows the amount of mica powder attached,
The parameter represents the particle size of mica flour. Shellac varnish was mixed in 2 parts for all. FIG. 2 shows the number of copies of the mica powder of the material of FIG. 1 as a parameter. FIG. 3 shows the shape of a coil as a sample. In this coil, two enamel electric wires having a wire diameter of 1 mm are wound in parallel five times and bound at four points with a thread.

Based on the materials shown in FIGS. 1 and 2, Example 1 is
20 parts of mica powder having an average particle size of 150 mesh (manufactured by Japan Mica Mfg. Co .: A100) per 100 parts by weight of methanol
The coil was dipped in a liquid obtained by mixing 2 parts by weight of shellac varnish with 1 part by weight, dried, and impregnated with a thermosetting type solventless epoxy resin. Example 2 is methanol 10
The coil was dipped in a liquid obtained by mixing 20 parts by weight of mica powder having an average particle diameter of 2000 mesh (A2000 manufactured by Mica Japan Co., Ltd.) and 2 parts by weight of shellac varnish with respect to 0 part by weight, and dried. The above coil and 100 parts by weight of the conventional thermosetting type solventless epoxy resin were previously added with an average particle size of 20.
A comparison of the life characteristics with a coil treated by mixing 20 parts by weight of 00 mesh mica powder was carried out. FIG. 4 shows 180
Comparative examples of breakdown time when 50 Hz and 1350 V (peak value) were applied at 0 ° C.
The breaking time of both the conventional coil and the conventional coil is 1
Within the range of 400 to 4130h, the average value is 2410, 2
There was no big difference with 660 and 2420h. In addition, no cracks or cracks were formed in the resin in any of the coils, and there was no difference between the present invention and the conventional method. In Example 1 and Example 2, the amount of the mica powder mixed was set to 20 parts by weight, because an effect equivalent to 20 parts by weight can be expected for a larger amount. Further, in the examples, the thermosetting type epoxy resin was used as the impregnating solventless resin, but the present invention is not limited to this, and the same effect can be obtained with an epoxy resin that is cured by ultraviolet rays or the like.

[0007]

As described above, by attaching the mica powder in the pretreatment, it is possible to adjust the temperature by increasing the viscosity and impregnate without using the mica powder like the impregnating resin mixed with the mica powder in advance. There is no need to prepare an extra impregnating resin in the same way as in the conventional method, an inorganic layer is formed on the coating of the enamel wire, the partial discharge resistance characteristics are improved, and the resin layer also contains mica powder. Therefore, it is possible to provide an insulation method that is resistant to the stress of the heating / cooling heat cycle and can sufficiently cope with the surge voltage due to the cable constant of the inverter power supply at low cost.

[0008]

[Brief description of drawings]

FIG. 1 is a characteristic diagram in which the amount of mica powder adhering to an iron plate was measured by the method of the present invention.

FIG. 2 is a characteristic diagram in which the amount of mica powder attached to an iron plate was measured by the method of the present invention.

FIG. 3 is an explanatory diagram showing the shape of a coil used for a life test.

FIG. 4 is a comparison diagram comparing the lives of the coils of the present invention and the conventional system.

[0009]

[Explanation of symbols]

 1 coil 1'coil 2 binding thread

Claims (1)

[Claims] 1. An insulating coil for a low-voltage rotating electric machine obtained by treating a coil formed of an enamel electric wire inserted into a slot through a slot liner with a solventless epoxy resin for impregnation and a scale-like inorganic filler. In, in which the scale-like inorganic filler and binder are dispersed in a low boiling point solvent, the coil is previously dipped, dried, and then immersed in a solventless epoxy resin for impregnation of a rotating electric machine. Insulation method.