JPS6015305Y2 - dry transformer winding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry type transformer winding, and particularly to one in which the insulation structure of the ends of the winding is improved.

Conventionally, a type H insulation structure has been adopted for dry type transformer windings in order to reduce the size and weight of the equipment.

Therefore, as the insulating material, inorganic materials such as glass, mica, and asbestos, or materials with excellent heat resistance such as polyimide film, polyamide paper, and silicone are used.

By the way, in dry type transformer windings having a multi-winding structure, end insulators are added at the time of winding formation to improve electrical characteristics or to protect the transformer from electrical and mechanical vibrations. The required thickness is applied to both ends of the winding.

FIG. 1 is a configuration diagram of a conventional dry-type transformer winding, in which a plurality of duct rails 2 are fixed on the outer periphery of an insulating tube 1.
A plurality of cylindrical winding layers 3 are concentrically wound thereon with interlayer insulators 4 interposed therebetween.

As shown in FIG. 2, end insulators 5 are disposed at both ends of each winding layer in the axial direction.

As the material constituting the end insulator 5, for example, asbestos paper, heat-resistant polyamide paper (trade name: Nomex), prepreg glass cloth, etc. are used.

However, the conventional dry type transformer winding constructed in this manner has the following drawbacks.

That is, (1) Asbestos paper absorbs a large amount of moisture, so even after it has been treated with silicone varnish, its insulation resistance may decrease due to moisture absorption, and its mechanical strength may be weak due to its low resin content. In terms of workability, it also has the disadvantage of being easily broken when bent.

In addition, in terms of safety and health, asbestos paper fibers are suspected of being carcinogenic, so they are designated as specified chemical substances, so it is necessary to pay close attention to the working environment.

(2) Heat-resistant polyamide paper is highly hygroscopic, and even after it is attached to a winding, it absorbs moisture and deforms, creating a wavy phenomenon that obstructs the airways.

Furthermore, since the heat-resistant polyamide paper is thin, it must be wound many times when forming the end insulator.

For this reason, the installation of end insulators takes up a relatively large amount of time in the winding manufacturing process, and is also very expensive, which is economically disadvantageous.

(3) So-called prepreg glass cloths, in which a glass cloth base material is impregnated with an adhesive resin to bring it into a B-stage state, have difficulty adhering between the prepregs without pressure.

Therefore, it is difficult to form an integrated structure, and when the prepreg is attached as an end insulator, it is difficult to wrap it tightly due to poor slippage of the prepreg, and furthermore, it is difficult to align the coil stack.

As described above, although asbestos paper is inexpensive, it has problems in terms of moisture absorption properties and mechanical strength, while prepreg glass cloths have good mechanical strength but poor workability.

In addition, heat-resistant polyamide paper has both advantages and disadvantages, such as poor dimensional stability due to moisture absorption and high price.

Therefore, the purpose of the present invention is to improve the mechanical strength required for the ends of the winding, improve moisture resistance, and improve the ease of manufacturing the winding by using an inexpensive material with a high resin content. It is an object of the present invention to provide a dry type transformer winding having an end insulator structure that shortens working time and facilitates workability.

The feature of the end insulation structure of the dry transformer winding according to the present invention is that the slag from the blast furnace is melted, turned into inorganic fibers using centrifugal force and wind pressure, and then inorganic or organic binder (
Mineral fiber insulators, such as Mineral Fiber Board (trade name, W Sheet) manufactured by Chiyoda Kagaku Sangyo Co., Ltd., are produced in sheet form by adding a binder (bonding agent) and are generally used as heat insulating materials. Taking note of its extremely high and excellent holding power, it was used as an end insulator in combination with other insulating materials.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is an enlarged sectional view of an end insulation structure of a dry transformer winding according to an embodiment of the present invention.

Reference numeral 11 denotes an insulating cylinder, and a duct rail 12 is fixed on the outer periphery of this insulating cylinder 11.

A plurality of winding layers 13 are concentrically wound thereon with interlayer insulators 14 interposed therebetween.

End insulators 15 are provided at both ends in the axial direction of each layer during the formation of the winding layer.

In the process of winding the winding layer 13, the end insulator 15 is formed by winding, for example, resin-impregnated prepreg glass cloth 15b multiple times for each layer, and then placing a band-shaped mineral fiber insulator 15a on top of it. It is formed by winding it to a predetermined thickness, and then winding the resin-impregnated prepreg glass cloth 15b a plurality of times thereon.

Thereafter, although not shown, a separate impregnation treatment is performed with a suitable resin to form the end insulator 1 containing the mineral fiber insulator 15a.
A dry type transformer winding is formed by impregnating the end insulator 15 and the winding layer 13 with a resin and heat-curing the resin to firmly form the end insulator 15 and the winding layer 13 together.

In the end insulating structure of the dry transformer winding constructed as described above, the end insulator 15 is formed by the mineral fiber insulator 15a.
In this case, the resin-impregnated prepreg glass cloth 15b plays an auxiliary role as a reinforcing material for the purpose of improving the mechanical strength of the end insulator 15.

Furthermore, the resin-impregnated prepreg glass cloth 15b is effective in preventing the resin impregnated into the mineral fiber insulator from leaking due to the resin impregnation treatment.

Incidentally, the mineral fiber insulator 15a has a thickness of 1 depending on the dimensions of the winding conductor.
The thickness can be freely selected within the range of 107m, and depending on the type of binder, it can be made from flexible to hard, so workability can be adjusted to match the quality and performance required for the winding end. It is only necessary to select the best one as appropriate.

In this way, by using a combination of the mineral fiber insulator 15a and the resin-impregnated prepreg glass cloth 15a as the end insulator of the dry type transformer winding, it is possible to replace the conventional asbestos paper, heat-resistant polyamide paper, etc. The following advantages can be obtained in comparison:

(1) Mineral fiber insulation has a varnish and resin impregnation rate 4 to 5 times higher than asbestos paper, so it has excellent adhesion to prepreg glass cloth and is easy to form edge insulation. A solid product is obtained.

Furthermore, the compressive strength can be improved by several steps higher than that of the conventional method.

(2) Very good moisture absorption properties.

That is, in FIG. 4, the moisture absorption conditions 91 of the mineral fiber insulator 15a and the asbestos paper 5 when impregnated with silicone varnish are shown.
As shown by the moisture absorption Meg characteristics under ~95%RH,
Mineral fiber insulation has much higher surface resistance and better moisture absorption properties.

(3) The thickness and flexibility of the insulator can be freely selected depending on the use of the end insulator, making installation of the end insulator easier and reducing work time. Significant shortening is possible.

(4) It is inexpensive and non-polluting.

In addition to the above-mentioned examples, the material constituting the end insulator may be a combination of mineral fiber insulator and heat-resistant polyamide paper in accordance with the requirements of the transformer. Effects can be obtained.

As described above, according to the present invention, a mineral fiber insulator with excellent resin impregnation and retention power, and an insulator such as prepreg glass cloth and heat-resistant polyamide paper, which have higher mechanical strength than this insulator, are used. When used in combination, it is possible to obtain a dry transformer winding that is inexpensive and easy to manufacture, while improving the functionally necessary mechanical strength and moisture resistance of the end insulator.

[Brief explanation of drawings]

Figure 1 is a side view of a conventional dry transformer winding, and Figure 2 is a side view of a conventional dry transformer winding.
3 is an enlarged sectional view of the end insulation structure of a dry transformer winding showing an embodiment of the present invention; FIG. 4 is a partial cross-sectional view taken along line A-A in the figure; FIG. FIG. 3 is a characteristic diagram showing changes in surface resistance over time due to moisture absorption of fiber insulators and asbestos paper. 11... Insulation tube, 12... Duct rail, 13... Coil, 14... Interlayer insulation, 15... End insulation Thing, 15a...
・Mineral fiber insulation 15b...Prepreg glass cloth.

Claims (1)

[Scope of utility model registration request] In a dry transformer winding in which end insulators are provided at both ends in the axial direction of the winding wire and impregnated with resin, the end insulators are replaced with a band-shaped insulator made of mineral fibers and A dry transformer winding characterized by being composed of a strip-shaped insulator with high mechanical strength.