JPS62210850A - Insulating treatment for electric coil - Google Patents

Abstract

PURPOSE:To obtain an impregnated insulation with no void in a slot gap by winding a flocked tape around the outer layer of an insulated coil. CONSTITUTION:A bonding resin is applied to a base material of film, cloth or paper to make a tape dried to a semi-hardened state. Then, a flocked tape 2 prepared by flocking short fibers to said tape is wound around an insulated coil 1 so that the flocked face is placed outside. After this insulated coil 1 has been inserted into a core slot and secured by a wedge, epoxy resin is vacuum-pressurized and impregnated into said coil which is then hardened by a heating furnace while rotated by a rotating apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a rotating electric machine, and particularly to an insulation treatment suitable for a stator coil of an AC motor.

[Technical background of the invention and its problems]

Methods for insulating electrical coils include the prepreg method, in which resin-rich tape is wound around the insulator, and dry tape, which is bonded together with a small amount of adhesive (for example, bonding glass cloth and mica paper).

There is a method in which the amount of adhesive (used to bond film and mica paper, etc.) is limited to a few to 10-odd percent by weight) is wound and impregnated with resin.

Impregnation methods include a single coil immersion method, in which a coil with main insulation is impregnated, and a total impregnation method, in which the coil is incorporated into the core and then impregnated with resin. Of these, the latter allows the stator, including the coil connections, to be impregnated in one piece, so it has excellent resistance to environments such as moisture and dust, and contributes to maintenance-free operation. In order to take advantage of this advantage, the main insulation material can also be impregnated by using the dry tape mentioned above, and either wrapping heat shrink tape around the outermost layer of the main insulation material or applying sealing varnish to the insulation layer. Prevents resin leakage. This manufacturing method is becoming mainstream.

However, this total impregnation method also has the problem that the film used for slot insulation cannot retain the resin.

Furthermore, due to the heat capacity of the stator, it takes time to heat the resin to the temperature required for the curing reaction, so the impregnated resin is required to have a long pot life, and in many cases,
Since it contains a latent curing agent that exhibits a catalytic effect at high temperatures, the viscosity of the impregnated resin decreases before the curing reaction occurs. As a result, the resin flows out and creates voids, which obstructs the heat dissipation of the conductor and weakens the adhesion with the iron core in the slot, allowing moisture and dust to enter, causing corona discharge in the voids. Therefore, it is necessary to perform the impregnation treatment again.

FIG. 5 is a cross section of an AC motor stator coil made by the most common conventional method, in which an insulating coil 1 is wrapped with a film slot insulation 6, inserted into a slot of an iron core 3, and fixed with a wedge 5.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for insulating a coil by which impregnated insulation without voids in the slot gap can be obtained.

[Summary of the invention]

The present invention is characterized in that, in order to prevent the resin filling the slot gap from flowing out, a flocked tape having flocked on one side of a film or the like is wound around the outermost layer of the insulated coil. That is, an adhesive resin 2b is applied to a base material 2a of film, cloth, or paper.
A tape is prepared by coating and drying into a semi-cured state, and a flocked tape 2 in which short fibers 2c are flocked to this tape is wound around an insulating coil 1 so that the flocked surface faces outside. In this case, the thinner the base material 2a is, the better in terms of space factor.
When the thickness is less than 0.125n+l, the tensile strength decreases and the winding workability decreases, and on the other hand, when it is 0.25mm or more, it becomes difficult to fit the insulated coil and flocked tape when the insulated coil is wound.

As for the short fibers 2c, the thinner the diameter and the longer the fibers, the better the resin retention properties, but the worse the flocking properties. The reason is that when the fiber length is longer than the fiber diameter, the fibers become entangled with each other and cannot be loosened by sieving. It is desirable that the short fibers for flocking be dry like dry sand, and those with poor fiber dispersibility cannot be flocked.The length of the short fibers should be about 1.2 to 2 times the slot gap. I'm getting good results.

In addition, the adhesive 2b is mainly composed of polyester, acrylic, epoxy, resin, etc., and the thinner the adhesive is applied to the base material, the better, 0.01 mm to 0.03 mm.
Approximately 111m is desirable. When the length is less than 0.01111 m, the adhesive strength of the fibers is low and it is easy to remove the fibers.

Short fibers are made of organic fibers such as acrylic, nylon, polyester, and aramid, and inorganic fibers such as rock wool, asbestos, and glass, and the better the heat resistance, the less heat deterioration occurs.

Various methods of flocking the short fibers 3c can be used, such as a spray flocking method using a spray gun, an ultrasonic vibration flocking method, a mechanical vibration flocking method, and an electrostatic flocking method.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the stator coil, in which a flocked tape 2 is wound around the straight portion of the insulated coil 1. FIG. 2 is a sectional view of a stator coil, in which a flocked tape 2 is wound around an insulated coil 1, placed in a slot of an iron core 3, and held down by a wedge 5.

FIG. 3 is a sectional view of the flocked tape 2. The material composition of the flocked tape 2 is a polyimide film with a thickness of 0.025 mm as the base material 2a.

TVB'2024 varnish (Toshiba Chemical) for adhesive 2b
A coating film with a thickness of about 0.03 mm was selected for the short fibers 2c, and a heat-resistant fiber Aviere (Unitika) made of i-aromatic polyamide was selected as the short fiber 2c, with a length of 2 denier and a length of 0.3 mm. A flocked tape 2 is obtained from the short fibers 2c by an electrostatic flocking method. Such flocked tape 2 is subjected to catalytic treatment with a resin composition for impregnation.

An appropriate brand of contact is selected based on the type of leveling resin, workability, reaction temperature, etc. Impregnated resin is Epicoat #828
(shell specific gravity) and D EN431 (Dow Chemical) and an acid anhydride curing agent HN-2200 (Hitachi Chemical). r
The goal was rr. As shown in Fig. 1, the flocked tape 2 with the flocked side facing outward is wound around the straight part of the insulated coil 1, inserted into the slot of the iron core 3, and fixed with the stem 5, and then impregnated with the epoxy resin under vacuum pressure. Then, it is solidified in a heating furnace while being rotated by a rotating device. Then, the impregnated resin is held by the short fibers 3c in the flocked tape 2, the slot gap 4, and the sub-wedge gap, and is hardened from the outside of the insulated coil 1 by the curing catalyst. Therefore, there was no leakage of the resin from the inside of the insulated coil 1 and the slot gap 4, and a stator coil with good characteristics was obtained. FIG. 4 shows a dielectric loss tangent-voltage characteristic 7b of a 140 KV AC motor in comparison with a conventional example 7a.

〔Effect of the invention〕

In the present invention, since the flocked tape is wound around the outer layer of the insulated coil as described above, the impregnated resin filled in the slot gap of the iron core is improved in retention due to the short fibers and becomes an integral structure.

Therefore, the cooling of the coil by heat transfer from the insulated coil to the iron core is improved (for example, the stator coil temperature after one hour of rated operation of a 140 KW AC motor is reduced by 6 degrees Celsius using the resistance method), and the electrical characteristics are also significantly superior. A rotating electric machine can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a stator coil of a rotating electric machine obtained by the method of the present invention, FIG. 2 is a sectional view showing a part of the stator, and FIG. 3 is a structure of the flocked tape used in the present invention. FIG. 4 is a diagram showing dielectric loss tangent-voltage characteristics, and FIG. 5 is a cross-sectional view showing a part of a stator coil of a rotating electric machine obtained by a conventional method. 1... Insulating coil 2... Flocked tape 2a... Base material 2b... Adhesive 2c... Short fiber 3... Iron core 4... Slot gap 5... Wedge 6... Slot insulation 7a... Conventional dielectric loss tangent-voltage characteristics 7b... Dielectric loss tangent-voltage characteristics according to the present invention Agent Patent attorney Noriyuki Chika Hirofumi Mitsumata = 8- Figure 3 mark jUI voltage (kv) No. 4 Figure S 5

Claims (1)

[Claims] A method for insulating a voltage coil that is impregnated with an insulating resin and cured, which is incorporated into a groove of an electric device, characterized in that a flocked tape is wrapped around the electric coil incorporated in the groove with the flocked side facing outward. A method for insulating electrical coils.