JPS6057604A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To obtain the foil-wound transformer of high cooling efficiency by a method wherein a cooling duct is composed of two metallic plates one of which has projections and another of which is flat and these plates are combined so as to form a space where a cooling medium flows in the inside of said two plates. CONSTITUTION:Metallic plates 29 and 30 are formed e.g. of stainless and the plate 30 is flat and the plate 29 is shaped so as to have projections on one side in a certain intervals by pressing and etc. Then, the metallic plates 30 and 29 are combined and spot welding is performed at contact parts B of the plates 30 and 29 to form a cooling duct. Next, a metallic sheet 31 and an insulating sheet 32 are wound on a foot part of an iron core in a manner these overlap on the metallic plate 29 having projections and the plate 30 respectively to form a winding of a transformer. At this time, a cooling duct 6 is formed by the metallic plates 29 and 30 and it contains a cooling medium 7. Thus, the foil-wound transformer provided with the cooling duct of high cooling efficiency, which is easily fabricated, can be obtained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a foil winding method having a foil winding formed by overlapping a metal sheet and an insulating sheet and having a cooling duct built into the winding. Regarding transformers.

[Technical background of the invention and its problems]

A foil-wound transformer having a foil winding has a good space factor of the winding, so it has the feature of being able to be made smaller and lighter. Already several KV
, has been put into practical use in small capacity transformers with relatively low voltages of about several 100 KVA.

Recently, research has been conducted to expand its application to high-voltage, large-capacity transformers, such as 275 KV and 300 MVA. The point is how to improve the cooling capacity and provide the winding with high insulation capacity. As described above, there are various problems in the practical application of high-voltage, high-capacity transformers using foil-wound wires. There is a heat pipe type that has a built-in duct, into which a refrigerant with excellent evaporation properties is pumped, and the heat generated from the winding is cooled down.

Figure 1 shows the structure of this heat pipe type foil-wound transformer.

A metal sheet 2 is overlapped with an insulating sheet 3 and wound many times around the outer periphery of a leg portion 1 of the iron core to form a low-voltage winding 4 and a high-voltage winding 5. A hollow metal cooling duct 6 is built in between these low and high JEE windings 4.5. This cooling duct 6 has a cylindrical shape or a divided cylindrical shape along the winding direction of the winding wire, and a refrigerant 7 such as Freon R-113 or Fluoriner) Fe12 is contained in the thin gap that is the hollow part. is included. This refrigerant 7 is pumped into the liquid guide pipe 10 by a pump 8 of a cooling device provided outside the transformer.
and is circulated to the cooling duct 6 via the insulated pipe 9,
The heat generated within the winding is removed by the latent heat of vaporization of the refrigerant 7, and then the refrigerant is led to the cooling device 11 via the insulating pipe 9 and the liquid guide pipe 10 again. In the condenser 11 of the cooling device, the water cooling pipe 1
2, it is cooled and condensed again. The condensed and liquefied refrigerant 7 is stored in a refrigerant tank 13,
Furthermore, the pump 8 sends the liquid again into the cooling duct 6 inside the winding.

The main body of the foil-wound transformer, which is provided with a circulation circuit for the refrigerant 7 in this manner, is housed in a tank 15 together with an insulating medium 14 such as insulating oil or 8F6 gas.

In this case, the liquid conduit 10 made of metal such as stainless steel is connected to the ground potential of the tank 15, etc., and the cooling duct 6 is
Because it is installed between the windings 4 and 5, it has the same potential as the adjacent windings (they are electrically connected).

In the transformer having the structure as explained above, the refrigerant for cooling and the insulating medium 14 for insulation are completely separated (separated). It is called a depressor.

This type of foil-wound transformer uses the latent heat of vaporization of the refrigerant, so it can be expected to have excellent cooling characteristics, making it promising for large-capacity transformers.

However, the conventional separate type T5-winding transformer as shown in Figure 1C-2 has the following problem.
By flowing refrigerant inside the coil, the latent heat of vaporization must be used to remove heat from the windings. Therefore, the cooling duct 6 must have good adhesion to the insulating sheet 3 and the metal sheet 2. On the other hand, if the refrigerant 7 does not flow uniformly northward in the cooling duct 6, the heat generated from the entire winding will be uniform (2 degrees Celsius). The second factor shows a cross section of such a cooling duct. In the second factor, 21 is a duct installed in the metal plates 22 and 23. And 24 is a cooling duct that is installed in the metal plates 22 and 23. A vertical cross-sectional view of the cooling duct 6 configured as described above is shown in FIG. 3. In FIG. Since the metal plates 22 and 23 must be in close contact with each other, they are attached by spot welding. Although it has good adhesion to the insulating sheet 3 and metal sheet 2 attached to the outside of the rib 23, it has the disadvantage that it is difficult to work.In other words, the rib 21 is attached to the metal plate 22.
Spot welding must be performed at certain intervals in between, which requires a large number of man-hours, and the ribs 21 must be prepared anew.

In order to solve this problem, a mini structure as shown in Fig. 4 has been considered. Tsume0α1.4to4 (2, 24.
Reference numerals 25 are metal plates, and each of the metal plates 24 and 25 is pressed so that one side protrudes, and the protruding portions are spot welded to each other to form a cavity 26. This structure requires shaping the metal plates 24 and 25 by pressing, so although some molding costs are required, it is easier to work than the structure shown in FIG. 3 described above.

However, unlike the structure shown in FIG. 3, the following new drawbacks arise. In other words, the purpose of the cooling duct 6 is to cool the windings by flowing the refrigerant 7 inside and using the heat of evaporation.
The more the metal sheet 28 is fixed to the cooling duct 6, the higher the cooling efficiency becomes. However, in the structure shown in FIG. 4, since the metal plates 24 and 25 have recesses, a space A is created between the insulating sheet 27 and the metal sheet 28 at that part, and an insulating medium such as SF or gas enters there, so that heat is generated. The drawback is that the transmission is poor and the cooling efficiency is poor.

[Purpose of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a foil-wound transformer equipped with a cooling duct that has high cooling efficiency, is easy to manufacture, and is inexpensive.

[Summary of the invention]

In order to achieve the above object, the present invention (= attaching protrusions at certain intervals only on one side of a metal plate forming a cooling duct,
The other metal plates are flat plates, and the flat plate side (two insulating sheets) is attached to the projection side (two metal sheets are attached).

[Embodiments of the invention]

The present invention will be explained below with reference to FIG. In FIG. 5, 29.30 is a metal plate, and is made of stainless steel, for example. And 30 of the 29.30 metal plates are flat plates,
29 is shaped with a press or the like so that it has two protrusions on one side at a certain interval.Then, the metal plate 30 and the metal plate 29 are overlapped, spot welding is performed at the contact part B of the metal plates 29 and 30, and the metal plate 29 is cooled. Then, the metal sheet 31 is placed on the metal plate 29 side to which the protrusion is attached, and the insulating sheet 32 is placed on the other metal plate 30 side so that they overlap (the cooling duct 6 is arranged when two windings are wound). .

In the present invention configured in this manner, the following operations are performed. That is, since only one of the metal plates 29, 30 forming the cooling duct 6 can be formed by pressing and the other can be a flat plate, it is not only possible to manufacture it at a lower cost than the conventional structure, but also to form the two metal plates 29, 30 after shaping. 30 are overlapped and the contact portions are spot welded, making manufacturing easy.

In addition, an absolute sheet 32 is placed on the flat metal plate 30 side,
Since the metal sheet 31 is placed on the side of the metal plate 29 to which the protrusion is attached, a space C is created between the metal sheet 31 and the metal plate 29, but the tightening force when winding the wire (the metal sheet 3
1 and the metal plate 29 are integrated, and the cooling efficiency does not decrease due to the presence of the space C, resulting in an extremely efficient cooling structure.

Furthermore, since the metal plate 30 is a flat plate and the protrusions are only attached to the metal plate 29 by pressing, the intervals at which the protrusions are attached can be set freely, so that a cooling duct with a customizable structure can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the cooling duct is constructed by combining a flat metal plate and a metal plate with protrusions formed at certain intervals, so it is not only easy and inexpensive to manufacture, but also improves cooling efficiency. It is possible to obtain foil-wound transformers with high cooling ducts.

[Brief Description of the Drawings] Figure 1 is a cross-sectional view showing the structure of a conventional separate foil-wound transformer, Figure 2 is a schematic cross-sectional view showing a conventional cooling duct, and Figures 3 and 4 are conventional Schematic sectional view showing a cooling duct. FIG. 5 is a schematic sectional view of a cooling duct of a foil-wound transformer according to an embodiment of the present invention. 1 #heart leg, 2 metal sheet, 3 insulating sheet, 4
...Low voltage winding, 5..High voltage winding, 6..Cooling duct, 7.Refrigerant, 8. Pump, 9..Insulated pipe, 10..
Liquid guide pipe, 11... Condenser, 12... Water cooling pipe, 13
- Refrigerant tank, 14... Insulating medium, 15... Transformer tank, 16 Yoke core, 22. 23 - Metal plate, 21...
・Rib, 29.30・Friday plate, 31...Metal sheet,
Double...Insulating sheet, Agent: Patent attorney Noriyuki Chika (1 person) Figure 1

Claims (2)

[Claims] (1) In a foil-wound transformer in which a winding made by overlapping metal foil and insulating sheets is wound around the legs of an iron core, and a cooling duct is built into this winding, the cooling duct is formed by two sheets. A foil roll consisting of metal plates, with protrusions attached to one metal plate and the other metal plate being a flat plate, and these two metal plates are combined so as to create a space for the refrigerant to flow inside. transformer. (2) The foil-wound transformer according to claim 1, wherein a metal foil is arranged on the protrusion side of the cooling duct and an insulating sheet is arranged on the other side.