JPS609110A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To alleviate electric field with a simple structure and reduce a loss of eddy current by providing a shield made of a flexible semi-conductive material can be expanded or compressed to the end part of high voltage winding made of foil wound coil. CONSTITUTION:A semi-conductive shield 12, like a rubber including carbon, which can be expanded or compressed is attached to the outside of final end part of foil which will become the line end part of high voltage winding 3. An internal diameter of shield 12 is smaller than the outer diameter of foil wound high voltage winding 3 before mounting but is expanded for loading from the outside of foil wound high voltage winding 3. After it is loaded, the end part of foil wound high voltage winding 3 is compressed. Since the shield 12 is expanded and compressed, it is attached closely to the winding by attaching it to the foil wound winding by widening it. Thereby it can be loaded in such a way as tightening the end part of winding. Accordingly, structure is simplified and a reliable foil wound transformer which realizes alleviation of electrical field and reduction of loss can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to foil-wound transformers, and particularly to loss reduction and electric field mitigation techniques.

[Technical background of the invention and its problems] Sheet-shaped foil windings have traditionally been used mainly for low-voltage windings, but recently they have been used as high-voltage windings in high-voltage, large-capacity transformers. There was a demand to use it. When a foil coil is used as a high-voltage winding of a high-voltage transformer, the thickness of the sheet-like conductor is generally very thin, ranging from several tens of micrometers to several hundred micrometers. An example of a foil-wound transformer is shown in the first example.
As shown in the figure. In FIG. 1, the low-voltage winding 2 and the high-voltage winding 3 wound around the iron core 1 are both sheet-like foil windings, and each has a cooling duct 5a extending in the stack direction inside.
5b to prevent temperature rise within the winding. The entire winding and core are housed in a tank 10, which is filled with an insulating medium 35 such as SF, gas, or insulating oil.

When increasing high voltage and capacity in a foil-wound transformer configured as shown in Figure 1, eddy current losses due to ringing of the electric field and magnetic flux at the ends of the foil of the high-voltage winding 3 may increase. It is necessary to prevent it from coming off.

By attaching a high-voltage shield, which is used for conventional multiplex cylindrical winding, to the end of the foil to alleviate the electric field,
Electric field relaxation and eddy current loss are reduced. In addition, this type of shield requires a lot of time and effort to manufacture, as it involves wrapping a thin metal tape around the insulating core that serves as the shield so as not to form a single turn, and applying insulation over that. However, since the weight of the shield itself is large, it is necessary to strengthen the supporting structure of the shield when applying it to a coiled foil wire. Furthermore, in order to reduce the effect of the edges of the tape in order to wind the tape-shaped metal, the insulation must be thick to a certain extent, which means that the shield metal surface is separated from the foil winding wire, and the electric field There is a risk that the relaxation effect will be impaired, and in order to produce the electric field relaxation effect, it is necessary to make the shield itself large, resulting in an increase in the size of the device.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and aims to provide a highly reliable foil-wound transformer that can reduce the eddy current loss and alleviate the electric field with a simple structure such as the ends of the foil-wound wire. There is.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized in that a shield made of a stretchable and flexible semiconductive material is attached to the end of a high voltage winding made of a foil wound wire.

[Embodiments of the invention]

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

A semiconductive shield 12 made of stretchable material such as carbon-containing rubber is attached to the outside of the final end of the foil serving as the line end of the high-voltage winding 3 at both ends of the stack.

Before installation, the inner diameter of this shield 12 is smaller than the outer diameter of the foil-wrapped high-voltage winding 3. When installing it, it is stretched and inserted from the outside of the foil-wrapped high-voltage winding 3, and after installation, the end of the foil-wrapped high-voltage winding 3 is inserted. It is in a compressed form.

According to the present invention shown in the second factor, since the shield 12 is elastic, when it is attached to the foil winding wire, it is pushed out and attached so that it comes into close contact with the winding wire and tightens the ends of the winding wire. It becomes a state. Therefore, compared to conventional shields,
The shield itself can be easily fixed, and since the sheet winding itself can be tightened, it also prevents the turns from shifting, thereby preventing deformation of the winding. Furthermore, since the shield is made of a semiconducting material, the electric field at the end of the winding can be relaxed, and the shield itself does not suffer from eddy current loss due to magnetic flux, and eddy current loss at the end of the coil can also be reduced.

In all of the above explanations, two shields 12 are attached to the high voltage winding 3 at the ends in the stacking direction.
A similar effect can be obtained by using a strained and tightened structure.

Further, the shape of the cross section of the shield 12 is not particularly limited as long as it has a structure that can alleviate the electric field.

However, the shield 12 itself does not have to be annular; for example, even if it is a dead-end type with a high-voltage lead coming out from the gap, the same effect can be obtained as long as the shield itself is stretchable. It will be done.

The shield material is not limited to rubber containing carbon, as long as it is stretchable and semiconductive. Furthermore, a semiconductive layer may be applied and adhered to the surface of a stretchable insulating material. Further, the shield material can be molded by fixing it to the high-voltage winding as a stretchable rubber tube and then enclosing a polymeric phase material such as Styrofoam inside the tube. At this time, the material to be encapsulated is not particularly limited as long as it hardens after being encapsulated, since it is a conductive material.

〔Effect of the invention〕

As explained above, 1. According to the present invention, the structure is simple,
A highly reliable foil-wound transformer capable of alleviating the electric field and reducing rectangular loss can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional foil-wound transformer, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1... Iron core 2... Low voltage winding 3... High voltage winding 4... Main insulation 5a+5b... Cooling duct 1o... Tank 30.
31... Insulating cylinder 12... Shield 35... Insulating medium agent Patent attorney Noriyuki Chika (1 person) Figure 1 Figure 2

Claims (1)

[Claims] In foil-wound transformers, which have high-voltage and low-voltage windings made by layering and winding sheet-like conductors and sheet-like insulators around an iron core, the whole is housed in a tank filled with an insulating medium such as insulating oil, SF, or gas. A foil-wound transformer characterized by having a shield made of a stretchable and flexible semiconductor material attached to the end of the high-voltage winding.