JPS607112A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To prevent the generation of winding wrinkles and thus prevent the decrease of the cooling efficiency due to them by giving tensile force to the axial direction, utilizing small holes bored at the end in the axial direction of an insulation sheet in the process of foil winding. CONSTITUTION:A metallic sheet 2 and the insulation sheet 3 are wound outside an iron core by superposition. The end in the axial direction of the sheet 3 is provided with the small holes 16 in order to give the tensile force to the axial direction. The pawl of a ratchet 17 is inserted to a small hole 16, and the sheet is rolled up in the state of tensile force in the axial direction by means of this ratchet. Besides, the tensile force in the diameter direction is also given by means of a tensile roll at the time of roll-up. Roll-up under tensile force in axial and diameter directions as above causes no hindrance of the cooling efficiency without the generation of winding wrinkles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foil-wound transformer having a foil-shaped winding formed by overlapping a metal sheet and an insulating sheet and having a cooling duct built into the winding.

[Technical background of the invention and its problems]

Foil-wound transformers have a good winding space factor, so they have the advantage of being 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.

Recently, in view of its excellent advantages, research has been conducted to expand its application to higher voltage and larger capacity transformers, such as 275 kV and 300 MVA. The biggest technical issue is how to improve cooling capacity and provide high insulation capacity to the windings. Such high-voltage, large-capacity transformers have not yet been put to practical use, but foil-wound transformers, which are already known and are being researched, have cooling ducts built into the windings and have excellent insulation properties. A so-called heat-vib type system is considered, in which a refrigerant is pumped in to directly cool the heat generated from winding loss.

1 shows the known foil-wound transformer of FIG. 1; A metal sheet 2 and an insulating sheet 3 are stacked on the outside of the iron core 1, and a low voltage winding 4 and a high voltage winding 5 of a known foil winding method are wound, and an annular cooling duct 6 is built in between these windings.

There is a thin gap inside this cooling duct 6, and the fluorocarbon R, -
It is filled with a refrigerant 15 such as 113 or Fe12, which is caused to flow by a pump 7, and the heat generated in the foil-wound winding 4.5 is absorbed by the latent heat of vaporization of the refrigerant. A known method is to cool and condense the steam in a condenser 8 and a water cooler 9. The liquefied refrigerant is stored in the refrigerant tank 14, and then pumped into the winding 4 by the pump 7.
．． A refrigerant circulation cooling circuit is used in which the refrigerant is fed into the tank. That is, this refrigerant circulation circuit and the transformer body are separated.

The liquid collection pipe 10 is made of metal such as stainless steel, and an insulated pipe 11 is used to connect it to the cooling duct 6, and the liquid collection pipe 1o has a ground potential of the tank 12 or the like.

The potential of the cooling duct 6 is electrically coupled to the same potential as the winding 4.5 since it is wound up in the winding.

The winding 4.5 is insulated with an insulating medium 13 such as insulating oil, SF, or gas sealed in a tank.

Incidentally, in FIG. 1, the lead wires of the windings and the bushings that lead the wires out to the outside of the tank, which are not directly related to the present invention, are omitted.

As explained above, in the transformer of this system, the circulation circuit through which the refrigerant for cooling flows and the insulating medium 13 for insulation are completely separated.

For this reason, this type of foil-wound transformer is called a separate type foil-wound transformer1.Since this type of transformer uses the latent heat of vaporization of the refrigerant,
It is promising for large-capacity transformers because it can be expected to have excellent cooling characteristics. However, the conventional separate foil-wound transformer as shown in FIG. 1 has the following problems.

As mentioned above, the low-voltage winding 4 and the high-voltage winding 5 are constructed so that the insulating sheets 3 and the metal sheets 2 are alternately wound around the iron core 1, and long foils are wound in the axial direction. Therefore, even if a tensile force is applied in the radial direction using, for example, a tension roll (not shown in the figure, which applies a tensile force in the radial direction), the balance of the tension in the axial direction will partially collapse as the roll is wound in several layers. There is a problem in that wrinkles occur, and the wrinkles create further wrinkles, which weakens the winding force in the radial direction.

Further, in the foil-wound wire that has been completely wound, a cavity is formed between the insulating sheet 3 and the metal sheet 2 due to the generation of wrinkles, which poses a problem in cooling efficiency.

If winding wrinkles occur and the radial winding force weakens, the insulation sheet 3 and the metal sheet 2 may shift vertically and fall if the foil-wound winding is arranged as shown in Figure 1 during the assembly process. There was a drawback that caused problems.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a foil-wound transformer that eliminates winding wrinkles that cause a decrease in cooling efficiency.

[Summary of the invention]

In order to achieve these objects, the present invention provides an insulating sheet and a small hole provided at the axial end of the insulating sheet to prevent wrinkles during the foil wrapping process of the metal sheet.

[Embodiments of the invention]

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

In FIG. 2, 2 is a metal sheet, and 3 is an insulating sheet, which are usually fed and wound horizontally to form a foil-wound wire. Therefore, while applying tension in the radial direction to the insulating sheet 3 and the metal sheet 2 using a predetermined tension roll or the like using a winding machine or the like, at the same time, using a small hole provided at the axial end of the insulating sheet 3,
For example, as shown in FIG. 3, a special ratchet wheel 17 or the like is used to apply a tensile force in the axial direction so that the material is wound in an axially and radially tensioned state during winding.

The receiving roll 18 shown in FIG. 3 is designed so that an elastic body is attached to the part where the pawl of the ratchet wheel 17 comes into contact, so that when it is pressed in the radial direction by a spring 19 or the like, the protruding part is absorbed.

Figure 4 is a modified example of Figure 2 with some changes, but the same effect can be obtained by changing the arrangement of the small holes, for example by attaching a ratchet wheel at the top and bottom, so that the top and bottom engage alternately. [Effects of the Invention] As explained above, according to the present invention, winding wrinkles, etc. can be prevented by applying tensile force in the radial direction of the shaft and winding the foil-wound wire in which an insulating sheet and a metal sheet are wound in layers. It is possible to provide a foil-wound transformer in which the windings do not shift or fall off even when the foil windings are vertically tightened without damaging the cooling efficiency by μ0.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the structure of a conventional foil-wound transformer;
The figure is a front view of main parts showing one embodiment of the present invention, and FIG.
A cross-sectional view of main parts showing an example of forming the sheet shown in the figure, No. 4
The figure is a front view of main parts showing another embodiment. 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 ... Water cooling 10 ... Liquid collection pipe 11 ... Insulating vibrator 12 ... Tank 13 ... Insulating medium 14 ... Refrigerant tank 15 ... Refrigerant 16
... Small hole 17 ... Pawl wheel 18 ... Receiving roll 19 ... Spring agent Patent attorney Nori Kei Chika (1 idiot) Figure 1

Claims (1)

[Claims] In a foil-wound transformer, a metal sheet and an insulating sheet are layered around the outer circumference of an iron core, and a low-voltage winding and a high-voltage winding are wound around the core, and a cooling duct is built in between the windings. A foil-wound transformer is characterized by having a continuous small hole, a ratchet wheel inserted into the small hole, and equipped with a winding that is tightened while applying a tensile force in the axial direction.