JPS59197110A - Foil-winding transformer - Google Patents

Abstract

PURPOSE:To cool insulating medium efficiently without using a cooling duct and the like by a method wherein openings, through which the insulating medium flows, are provided to shields attached between windings and a core. CONSTITUTION:A plurality of (at least two) circular openings 19 are provided to shields 16 attached between windings and a core 1. Insulating pipes, through which coolant flows, are inserted into some of the openings 19 provided to the shields 16. With this constitution, the flow of the insulating medium cooled at a waveguide part is improved so that the insulating medium is cooled efficiently without using a cooling duct which is necessary for conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foil-wound transformer using a foil-like winding formed by overlapping and winding a metal sheet such as copper or aluminum foil and an insulating sheet.

[Technical Background of the Invention] Foil-wound transformers are characterized by good winding space and can be made smaller and lighter. It has already been put to practical use in small capacity transformers with relatively low voltages of several KV and several hundred KVA. In recent years, in view of its excellent advantages, research has been conducted to expand its application to higher voltage, larger capacity transformers, such as 275KV and 300MVA class transformers. The two issues are whether the winding has sufficient capacity μ and whether it can withstand 1q of radial mechanical force in the event of a short circuit accident. . Such high-voltage, large-capacity transformers have not yet been put to practical use, but as shown in Figure 1, a cooling duct is built into the winding, and a refrigerant with excellent insulation properties is fed into this cooling duct. The foil-wound transformer on the right is a so-called heat-vib type foil-wound transformer that uses the latent heat of vaporization of the refrigerant to cool the heat generated from winding loss.

That is, in this foil-wound transformer, a low-voltage winding 4 and a high-voltage winding 5, which are made by overlapping metal sheets 2 and 3, are wound around a leg 1 of an iron core. (J) A hollow cooling duct 6 is built-in.

In the thin gap in the hollow part of the cooling duct 6, Freon R-1
A refrigerant such as 13 or Fluorinert FC75 is sealed in the refrigerant, and is circulated by a pump 7, and the heat generated in the winding is absorbed by the refrigerant's exothermic latent heat, and the vapor is sent to the condenser 8, cooled by a cooling water pipe, and condensed. It has become. The liquefied refrigerant is
A cooling system is constructed in which the refrigerant is stored in a refrigerant tank 10 and further fed into the windings by a pump 7.

The liquid guide pipe 11 constituting the cooling system is made of metal such as stainless steel, and the S liquid @11 and the cold duct 6 are connected via an insulating pipe 1°2 made of Teflon resin or the like. The liquid guide pipe 11 is also connected to the ground potential of the tank 13 and the like. On the other hand, since the cooling duct 6 is built into the winding, it is electrically connected to the same potential as the adjacent winding. Furthermore, the insulation of each part of the winding is
This is ensured by an insulating gas such as SF6 gas sealed in the inside of 3. In addition, on the outer periphery of the upper and lower ends of the high voltage winding 5,
A shield 14 is provided to prevent dielectric breakdown from the end (
is being pulled.

This cooling type transformer is called a Sebaret 1 type foil-wound transformer because the circulation circuit through which the refrigerant flows for cooling and the insulating medium for insulation are completely separated. ing.

[Problems with the background technology] Transformers using this cooling method utilize the latent heat of evaporation of the refrigerant and are able to send the refrigerant inside the windings to remove heat, so they can be expected to have excellent cooling characteristics. .

However, in high-voltage, large-capacity transformers, the heat generated by the windings is large and is transferred to the insulating medium that insulates between the windings, resulting in a considerable amount of heat during winter.
1 needs to be given sufficient consideration.

Therefore, since the cooling duct 6 is not exposed outside the windings, such as between the windings and the tank 13 or between the windings and the shield 14, the insulating medium such as SF6 gas or oil may leak into the windings 4, It will be warm due to the heat of 5. Then, as the insulating medium warms up, the cooling efficiency due to deflection and latent heat of vaporization decreases, and the foil-wound transformer lfi 'I! Not only will this result in failure, but it may also cause sub-bar heat and thermal damage.

In particular, the cooling of the insulating medium between the windings and the tank is carried out exclusively by the refrigerant flowing in the liquid conduit exposed at that part, but there is a disc between the windings and the yoke 15 of the iron core. Since the shaped shield 14 is arranged, this prevents the circulation of the insulating medium, and the insulating medium that has been cooled by contacting the liquid conduit does not reach the entire tank including the winding surface, which reduces the cooling efficiency. A phenomenon occurs in which the value decreases.

In order to solve this problem, between the windings 4 and 5 and the tank 13,
A foil-wound transformer has also been proposed in which a cooling duct or cooling pipe similar to that built into the winding is provided, and the insulating medium is cooled by direct contact with the refrigerant flowing inside these cooling ducts. However, in this type of foil-wound transformer, there are cooling ducts and cooling pipes that are at ground potential between the windings and the transformer tank, so in order to ensure sufficient insulation distance, it is necessary to It had the disadvantage of becoming larger. Furthermore, since the number of extra parts such as cooling ducts increases, the overall structure becomes complicated and the number of man-hours required to manufacture the transformer also increases.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to eliminate the need for extra members such as a cooling duct [-] between the windings and the tank, and to eliminate the need for an insulating medium. An object of the present invention is to provide a foil-wound transformer that can efficiently perform cooling.

[Summary of the Invention] The foil-wound transformer of the present invention has an opening through which an insulating medium passes through a shield provided between a winding and an iron core, and effectively allows the insulating medium cooled by a liquid conduit to pass through. It is designed so that it flows to the winding side.

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

In FIG. 2, the same parts as those of the conventional foil-wound transformer are designated by the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, the peripheral edge 17 of the shield 16 installed between the windings 4 and 5 and the tank 13 is curved like a conventional shield, and the shield 16 has an iron core leg in the center. A hole 18 is provided for insertion. The surface of this shield 16 has at least two
A plurality of circular openings 19 are formed. In some of the openings 19 provided in the shield 16, insulated pipes through which a refrigerant passes are inserted.

In the foil-wound transformer of this embodiment having the shield 16 formed with the grooves as described above, the following effects are produced.

- Since the shield 16 has a large number of openings 19, the insulating medium that has been cooled by the liquid guide pipe 11 can pass through the opening 19 of the shield, improving the flow of the insulating medium. The cooling efficiency of the insulating medium is increased, and a foil-wound transformer with a large capacity can be obtained.

■ Create an opening in the shield 16.
Since the refrigerant cooled in step 1 flows freely and produces the effect (2), the conventionally required cooling ducts and cooling pipes are no longer necessary, and the insulation distance can be easily ensured, resulting in a compact transformer. Furthermore, since cooling ducts and cooling pipes are no longer required, the number of parts is reduced accordingly, the structure can be simplified, the number of manufacturing steps is reduced, and reliability is improved.

■ Attach the shield 16 to the top of the winding (if you pull it, the insulating medium warmed by the winding will pass through the opening of the shield 16,
The liquid conductive material is cooled by the liquid conduit pipe 11 and acts as a cooling device for the insulating medium (there is no need to use any means specifically for cooling the insulating medium).

■ Since the shield 16 has a large number of circular openings 19, the insulating pipe 12 can be freely passed through any opening when assembling the transformer, which makes it possible to standardize the design and improve the assembly becomes easy.

The platform with the shield 16 installed only at the bottom of the winding has an opening so that even if impurities that have fallen from the high and low voltage winding 5.4 fall onto the shield 16, there is no opening. Since the impurities fall onto the bottom of the tank 13 without being deposited on the shield, there is no risk of a drop in withstand voltage due to impurities, and an extremely reliable transformer can be obtained.

J3, the present invention is not limited to the above-mentioned embodiment, and even if the opening provided in the shield 16 is a slit 30 as shown in FIG. It is demonstrated. In addition, the shape of the opening does not need to be particularly limited, such as a combination of Surin 1- and a circular hole. As long as the shield has an opening to pass through, there will be no problem.

[Effects of the Invention] As described above, according to the present invention, by simply providing an opening in a conventional shield, the flow of the TC insulating medium that is cooled in the liquid conduit pipe portion is improved. Since overheating due to heating of the insulating medium can be prevented without using the previously required cooling duct, it is possible to provide a small, highly reliable foil-wound transformer with fewer parts.

[Brief explanation of the drawing]

Fig. 1 is a sectional view schematically showing a conventional foil-wound transformer, Fig. 2 is a sectional view showing a foil-wound transformer of the present invention, and Fig. 3 is a shield included in the foil-wound transformer of the present invention. FIG. 4 is a perspective view showing another embodiment of the shield. DESCRIPTION OF SYMBOLS 1... Iron core, 2... Metal sheet, 3... Insulating sheet, 4... Low voltage winding, 5... High voltage winding, 6... Cooling duct, 7... Pump, 8 ...Condenser, 9...
Cooling water pipe, 10... Refrigerant tank, 11... Liquid guide pipe,
12... Insulated pipe, 13... Tank, 14.16
...Shield, 17...Shield end, 18...
Core leg hole, 19...frontage, 30...slit. 7317 Representative Patent Attorney Kensuke Norichika (and 1 other person) Figure 1 14 11 Figure 2

Claims (1)

[Scope of Claims] (1) A metal sheet and an insulating sheath 1 to 1 are overlapped and wound around the leg of an iron core to form a foil winding, and this foil wire is placed in a transformer tank together with an insulating medium. A cooling duct is built into the foil winding, and a refrigerant is circulated through the cooling duct from a cooling device installed outside the transformer tank. A foil-wound transformer equipped with a shield, characterized in that the shield has a plurality of openings through which an insulating medium in the tank can pass. (2) The opening of the shield is , the foil-wound transformer according to claim 1, which is a circular hole. (3) The opening of the shield is inserted with an insulating pipe connecting the cooling duct 1 to the liquid guide pipe on the cooling device side. (4) The foil-wound transformer according to claim 1, wherein the opening of the shield is a slit. (5) The frontage of the shield. The foil-wound transformer according to claim 1, wherein the part is a combination of a circular hole and a slit. (6) A shield having an opening is attached only to the lower part of the winding. A foil-wound transformer according to claim 1.