JPS63224311A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To make the iron core lightweight and accomplish a low loss by constructing the iron core with two legs, separately winding a high-voltage winding and a middle-voltage winding around the respective iron core legs, and winding a low-voltage winding around one iron core leg, thereby reducing the transport size and facilitaing the taking-out of the liquid conducting pipe. CONSTITUTION:A first middle-voltage winding 41 and a line-side winding unit 51 of a high- voltage winding, from the inner side, are wound around a first iron core leg 21 of a two-leg iron core 2, and a low-voltage winding 3, second middle-voltage winding 42 and neutral point-side winding unit 52 of the high-voltage winding, from the inner side, are wound around a second iron core leg 22. The first and second middle-voltage windings 41, 42 are connected in parallel, and the line-side and neutral point-side windings 51, 52 of the high-voltage winding are connected in series. Accordingly, since the windings are separately wound around the iron core legs 21, 22, the diameters and heights of the windings become small, and the transport size depending on the short-side cross section will reduce. Also, since the windings are wound around two-leg iron core with no side leg, the extent of the windings under a yoke 2b becomes small. With this, a liquid conducting pipe 14 can be taken out from a position which is not under the yoke 2b, and the insulation distance of the windings and the yoke can be reduced, thereby reducing the weight of the iron core and the load loss.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a foil-wound transformer in which a cooling duct is built into a winding formed by overlappingly wound a metal sheet and an insulating sheet.

(Conventional Technique 11f) Foil-wound transformers with sheet-shaped windings have a good winding space factor and can be made compact and lightweight. It has already been put to practical use and widely used in capacity transformers.

Recently, in view of the excellent advantages of foil-wound transformers, research has been conducted to expand their application to higher voltage, larger capacity transformers, such as 275KV and 300MVA class transformers, but what are the biggest technical problems? The question is whether to improve the cooling capacity for the windings, give the windings high insulation capacity and short-circuit strength, and overcome strict transportation restrictions. The method for cooling the windings in such foil-wound transformers is to incorporate a cooling duct inside the windings, and send in a refrigerant with excellent insulation properties to directly cool the heat generated from winding losses. I'm thinking of a pipe type.

Figure 4 shows an example of the conventionally known structure of such a foil-wound transformer. In the figure, a tank 1 is filled with an insulating gas such as SF or gas as an insulating medium at high pressure. An iron core 2 is provided inside the tank 1. A low voltage winding 3 is wound on the outside of the main leg 2a of the iron core 2 through an insulation gap 6, and a medium voltage winding 4 is wound around the outside of the low voltage winding 3 through an insulation gap 6. A high voltage winding 5 is wound around the outside of the medium voltage winding 4 with an insulation gap 6 interposed therebetween. These low voltage windings3. The medium-voltage winding 4 and the high-voltage winding 5 are constituted by sheet-like windings formed by overlapping and winding a metal sheet 7 made of aluminum foil or the like and an insulating sheet 8 made of polyester film or the like. Note that each of the windings 3, 4, and 5 is insulated by an insulating medium sealed in the tank 1.

Furthermore, a cooling duct 9 extending in the axial direction is wound around and built into the low-voltage, intermediate-voltage, and high-voltage windings 3, 4.5. The inside of the cooling duct 9 is hollow so that a refrigerant such as Freon 113 or Prolinat FC75 passes therethrough, and this refrigerant cools the windings 4 and 5 as it passes through the inside of the cooling duct 9. This refrigerant is transferred to the liquid guide pipe 14 and the insulating pipe 13.
It is cooled by a cooler 11 provided outside the tank 1 through the tank 1 and circulated by a pump 10.

The conventional foil-wound transformer described above is generally called a separate foil-wound transformer because the cooling system in which the refrigerant circulates and the insulating medium 12 for insulation are completely separated.
Compared to conventional transformers using rectangular wire conductors and insulating oil, this transformer can be significantly smaller and lighter, making it promising as a large-capacity transformer. For this type of transformer, USP-403999
0 is known.

(Problems to be Solved by the Invention) Such a conventional foil-wound transformer has a low voltage winding 3, a medium voltage winding 4. Due to the structure in which the high voltage winding 5 is wound around the main leg 2a of the core, as the capacity of the transformer increases, the diameter of the winding increases, and in addition to the need to maintain insulation distance, the diameter of the tank 1 also increases, which may make it impossible to clear transportation restrictions. arise.

In addition, as shown in the plan view of the main body of the foil-wound transformer in FIG. 5, since the range of the winding that forms the lower part of the yoke 2b is wide, the liquid guiding pipe 14 drawn out from the cooling duct is connected as shown in 14a. There may be cases where it is necessary to place it under the iron. Liquid guide pipe 14
Like the cooling duct, it is made of metal such as stainless steel and has the same potential as the winding, so an insulating distance must be maintained between it and the yoke. This increases the weight of the iron core and increases the loss.

Furthermore, as the capacity of the transformer increases, the mechanical stress generated in the windings in the event of a short circuit also increases. It is known that the buckling stress in the inner circumferential direction of No. 3 becomes excessive.

The present invention was made in consideration of the above-mentioned problems, and reduces the transportation size, makes it easier to pull out the liquid guide pipe, and makes the iron core lighter and lighter.
The purpose of the present invention is to provide a high-performance and highly reliable foil-wound transformer with low loss and reduced short-circuit mechanical force.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the iron core 2 is configured with two legs as shown in FIGS. Each core leg is divided into 21° and 22, and the low voltage winding 3 is wound around the core leg on one side.

(Function) By dividing the winding into two legs, the diameter and height of the winding are reduced, and the transport dimension determined by the cross section of the short side is reduced. Since the winding is wound around the two-leg iron core, the area of the winding that becomes the lower part of the yoke becomes smaller, and there is no need to pull out the liquid guiding pipe 14 from the lower part of the yoke, and the distance between the winding and the yoke is reduced. can be reduced. Furthermore, since the low voltage winding 3 is wound around only one core leg, the low voltage impedance increases and short circuit mechanical force is reduced.

(Embodiment) FIG. 1 is a block diagram of the contents of an embodiment of a foil-wound transformer according to the present invention. FIG. 2 is a plan view including the tank.

The first medium-voltage winding 41 and the line-side winding unit 51 of the high-voltage winding are wound around the first core leg 21 of the two-leg iron core 2 from the inside, and the second
A low voltage winding 3 and a second medium voltage winding 4 are connected to the iron core leg 22 from the inside.
2. The neutral point side winding unit 52 of the high voltage winding is wound. 1st
and second medium voltage windings 41 and 42 are connected in parallel, and winding units 51 and 52 on the line side and neutral point side of the high voltage winding are connected in series.

With the above configuration, since the winding is divided into the core legs 21 and 22 and wound, the diameter and height of the winding are smaller than when wound around one leg, and the transportation dimension determined by the cross section of the short side is to shrink.

In addition, since the winding was wound around a two-leg iron core without side legs, the yoke 2
The range of the winding below b becomes smaller. As a result, the liquid guiding pipe 14 can be pulled out from a position that is not under the yoke 2b, and the insulation distance between the winding and the yoke can be reduced by the amount that the liquid guiding winding is removed. Therefore, the weight of the iron core and load loss are reduced,
Furthermore, eddy current loss generated in the windings is also reduced.

Furthermore, since the low voltage winding 3 is wound only around the second core leg 22, the impedance of the low voltage winding 3 increases, and the short circuit current when the low voltage winding is shorted is suppressed, so that the short circuit mechanical force is also reduced.

The present invention is not limited to the above-mentioned embodiments, and when there is a tap winding 1!53, as shown in FIG. , the line side winding unit 51 of the high voltage winding is wound, and the second medium voltage winding 42 . is wound around the second core leg 22 from the inside. High voltage winding neutral point side winding unit 5
2. The tap winding 53 may be wound.

〔Effect of the invention〕

As described above, according to the present invention, the high voltage winding and the medium voltage winding are
By separately winding each leg of the leg iron core and winding the low-voltage winding around one leg, the transport dimensions are reduced, the liquid guide pipe is easier to pull out, the iron core is lighter, and loss is lower, reducing the mechanical force of short circuits. be done.

[Brief explanation of drawings]

FIG. 1 is a front view showing the configuration of a foil-wound transformer according to the present invention;
2 is a plan view of FIG. 1, FIG. 3 is a front view showing the configuration of another embodiment of the present invention, FIG. 4 is a sectional view illustrating the overall configuration of a conventional foil-wound transformer, and FIG. The figure is a plan view showing the configuration of a conventional foil-wound transformer. 1...tank 2...iron core 21...first
Core leg 22...Second core leg 2a...Main leg
2b...Yoke 3...Low voltage winding 4
... Medium voltage winding 41 ... First medium voltage winding 42 ...
Second medium voltage winding 5...High voltage winding 51...Line side winding unit of high voltage winding 52...Neutral point side winding unit of high voltage winding 53...Tap winding 6. ...Insulation gap 7...Metal sheet 8...Insulation sheet 9...
...Cooling duct 10...Pump 11...Cooling pipe 12...Insulating medium 13...Insulating pipe 14...Liquid pipe agent Patent attorney Noriyoshi Chika Yudo Hirofumi Mitsumata b Figure 1 Figure 3 Figure 5 Figure 2 Figure 4

Claims (2)

[Claims] (1) In a foil-wound transformer in which a metal sheet and an insulating sheet are stacked and wound around the core, the first medium-voltage winding and high-voltage winding are wound on the line side from the inside on the first core leg of the two-legged core. The wire unit is connected to the second core leg from the inside by a low voltage winding, a second medium voltage winding,
The winding unit on the neutral point side of the high voltage winding is wound, the first and second medium voltage windings are connected in parallel, and the winding units on the line side and neutral point side of the high voltage winding are connected in series. Features a foil-wound transformer. (2) The line side winding unit of the low voltage winding, first medium voltage winding, and high voltage winding is attached to the first core leg of the two-leg core from the inside, and the second medium voltage winding is attached to the second core leg from the inside. winding unit on the neutral point side of the high voltage winding, winding the tap winding, connecting the first and second medium voltage windings in parallel, and winding units on the line side and neutral point side of the high voltage winding. 2. A foil-wound transformer according to claim 1, characterized in that a tap winding and a tap winding are connected in series.