JPH0352207A - Gas-insulated transformer - Google Patents

Abstract

PURPOSE:To reduce eddy-current loss occurring in a winding and to prevent local overheating without making the winding and a tank of a transformer large in size, by a method wherein a linear winding causing little occurrence of the eddy-current loss is disposed either inside or outside of a main winding. CONSTITUTION:A low-tension winding 4 and a high-tension winding 5 which are main windings are constructed of sheet-shaped conductors, and a tertiary winding 20 disposed inside of the low-tension winding 4 and a tap winding 21 disposed outside of the high-tension winding 5 are constructed of linear conductors formed by winding a flat-type linear conductor round respectively. These linear windings 20 and 21 are disposed at least either inside or outside of the main windings 4 and 5. By this method, an eddy-current loss occurring in the windings is reduced and local overheating can be prevented without making the windings and a tank of a transformer large in size, and a gas- insulated transformer having high performances and high quality and being compact and inexpensive can be obtained.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to main windings such as low voltage windings and high voltage windings, tertiary windings, stable windings, tap windings, etc. This relates to a gas insulated transformer in which a main winding and a winding having a smaller capacity than the main winding are housed in the same tank.

(Conventional technology) In recent years, due to demands for nonflammability, weight reduction, and simplification of on-site installation and maintenance, transformers have been replaced by gas-insulated transformers using gas insulating media such as SF6 gas. Transformers are increasingly being used.

As the filler gas used in such gas-insulated transformers, SF6 gas, which is also used in gas-sealed switchgears, is generally used because it has excellent insulation properties. However, although SF6 gas has excellent insulating properties, its cooling performance is inferior to that of insulating oil, and conventional gas insulated transformers have been limited to medium- and small-capacity transformers of up to several tens of MVA.

However, in order to realize higher voltage and larger capacity transformers, it is necessary to further improve the cooling efficiency of the windings, and
It is essential to provide the winding with high insulation capacity, and sheet-like winding with high dielectric strength is used because it has an excellent winding space factor, good cooling characteristics, and good potential distribution characteristics. is considered.

Examples of this type of transformer include JP-A-54-168
The one shown in Publication No. 613 is known. That is, as shown in FIG. 4, a metal sheet 2 is placed around the core leg 1.
The winding wire is constructed by overlapping and winding the insulating sheet 3 and the insulating sheet 3. Further, the windings include a low voltage winding 4 and a high voltage winding 5, and an annular cooling panel 6 is built in each of these windings. The cooling panel 6 is constructed by welding or the like to seal two metal plates stacked one on top of the other with a narrow gap for the coolant to flow. Then, in this gap, Freon R-
Cooling is performed by constantly flowing a refrigerant such as 113 or Fluorinert FC-75 with a pump 7 and allowing the refrigerant to remove the heat generated within the windings. In addition, the refrigerant that has absorbed the heat is sent out to the outside of the winding by the outlet nozzle, and is sent to the tank 8.
It is cooled in a cooler 9 provided outside of the cooling panel 6 and fed into the cooling panel 6 again.

Note that before the refrigerant is sent to the cooling panel 6, it is once collected in the liquid collecting pipe 10, but since this liquid collecting pipe 10 maintains the same ground potential as the tank 8, etc., the metal sheet 2 The connection to the cooling panel 6 having the same potential as that is made through an insulating pipe 11. In addition, the cooling panel 6
In order to cool the metal sheet 2 by thermal conduction, it is in contact with the metal sheet 2 or the insulating sheet 3, and is further wound in the winding, so almost the same voltage is applied to the cooling panel 6. The metal sheet 2 and the cooling panel 6 are insulated from the outside by an insulating gas such as SF6 gas sealed in the tank 8.

The gas insulated transformer described above can be significantly smaller, lighter, larger in capacity, and higher in voltage than conventional gas insulated transformers using rectangular wire conductors, and has high insulation reliability. It has the following advantages.

(Problems to be Solved by the Invention) However, in the gas insulated transformer having the configuration as described above, there are problems to be solved as described below. That is, it is known that as the capacity of the transformer increases, the amount of leakage magnetic flux from the windings 4.5 increases, causing large eddy current loss in the windings 4 and 5 themselves, causing local overheating. , the leakage magnetic flux 12 generated from the windings 4 and 5 is
As shown in Figure 5, from the winding to the insulation space 13 and the iron core 1.
, or create a loop via the insulating space 13 and the tank 8. At this time, the leakage magnetic flux 12 crosses the metal sheet 2 and tries to form a loop through the shortest magnetic path (minimum magnetic energy), but since the vertical width of the metal sheet 2 is large, , an eddy current flows in the metal sheet 2 in a direction that cancels the leakage of the leakage magnetic flux 12 in the radial direction. This eddy current is
The flow is particularly concentrated at the bottom end of the metal sheet 2, causing large losses. Furthermore, as shown in FIG. 6, this eddy current loss has the characteristic that it becomes larger the closer it is to the core legs or the tank wall. Furthermore, this phenomenon occurs compared to transformers using conventional rectangular wire conductors.
In a transformer using a sheet-like conductor, this problem is more noticeable because the width of the conductor is wider.

By the way, a transformer generally has a main winding consisting of a low-voltage winding, a high-voltage winding, etc., as well as tap windings, tertiary windings, etc., which have a smaller capacity and lower voltage than the main winding. A low winding is often used in combination with the main winding. That is, as shown in FIG. 7, a tertiary winding 14, a low voltage winding 4 and a high voltage winding 5, which are main windings, and a tap winding 15 are wound around the core leg 1 in order from the inside. It's being passed around. When each of these windings is composed of sheet-shaped windings, when the capacity of the transformer increases, each winding 14.4.
The leakage magnetic flux from 5.15 becomes large, causing large eddy current loss in each winding. Moreover, as shown in FIG. 8, this eddy current loss becomes large in the tertiary winding 14 closest to the core leg 1 and in the tap winding 15 closest to the tank wall. Therefore, the tertiary winding 14 and tap winding 1 with small winding capacity are
Excessive loss will occur in the windings, etc., and there is a risk of local overheating of the windings, as well as the need to cool windings other than the main winding, which will require an increase in the number of cooling panels. This inevitably increases costs and increases the size of the winding. Furthermore, in order to solve these drawbacks, by increasing the distance between the core leg and the winding, or between the winding and the tank wall, and increasing the magnetic path length of the leakage magnetic flux,
Although it is possible to suppress the loss occurring in the sheet-shaped winding, there is a drawback that the winding and tank of the transformer are increased in size, resulting in an increase in cost.

The present invention was proposed to eliminate the above-mentioned drawbacks, and its purpose is to reduce eddy current loss occurring in the windings and reduce local overheating without increasing the size of the transformer windings and tank. Our goal is to provide high-performance, high-quality, compact, and inexpensive gas-insulated transformers that are designed for prevention.

[Structure of the Invention] (Means for Solving the Problem) The present invention provides a main winding such as a low voltage winding and a high voltage winding on an iron core leg,
In gas-insulated transformers, which are wound with windings with a smaller capacity than the main winding, such as tertiary windings, stabilizing windings, and tap windings, and housed in the same tank, the main winding is made of metal sheets and insulating sheets. It is composed of sheet-like windings wound on top of each other, and the windings other than the main winding are composed of wire-like windings in which rectangular wire-like conductors are wound. It is characterized in that it is arranged at least either inside or outside the line.

(Function) According to the gas insulated transformer of the present invention, the wire winding, which generates less eddy current loss than the sheet winding, is arranged at least on either the inside or outside of the main winding. This makes it possible to suppress eddy current loss due to leakage magnetic flux. In addition, the eddy current loss generated in the main winding can be reduced because the distance from the iron core or tank wall is maintained by the wire winding arranged on at least one of the inside and outside of the main winding. can.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 to 3. Note that the same members as those of the conventional type shown in FIGS. 4 to 8 are designated by the same reference numerals, and explanations thereof will be omitted.

In this embodiment, as shown in FIGS. 1 and 2,
The low-voltage winding 4 and the high-voltage winding 5, which are the main windings, are composed of sheet-like conductors.
The tap winding 21 disposed outside the secondary winding 20 and the high voltage winding 5 is constructed from a linear conductor formed by winding a rectangular wire conductor.

In the gas insulated transformer of this embodiment having such a structure, the windings closest to the core legs and the tank wall are constructed of linear windings, as shown in FIG. Eddy current loss generated in the windings can be significantly reduced.

In addition, as a result, local overheating can be prevented, making it possible to reduce the number of cooling panels installed.Also, since there is no need to leave a gap between the winding and the iron core or between the winding and the tank wall, the winding The dimensions of can also be reduced.

On the other hand, in main winding 4.5 using sheet-like winding,
The tertiary winding 20 and the tap winding 21 arranged inside and outside of the tertiary winding 20 and the tap winding 21 ensure a distance from the iron core 1 or the tank 8, so the eddy current can be avoided without increasing the dimensions of the winding. Loss can be reduced.

Note that the present invention is not limited to the above-described embodiments, and if the winding is a linear winding, the winding disposed inside or outside the main winding separated from the sheet winding is a tertiary winding. It may be a winding, a stable winding, a tap winding, etc., and the same effect can be obtained even if the windings arranged inside and outside the main winding are made of the same winding.

[Effects of the Invention] As described above, according to the present invention, the main windings such as the low-voltage winding and the high-voltage winding are constructed from sheet-shaped windings, and the windings other than the main windings are constructed by rectangular windings. The windings of a transformer are constructed by a wire winding wound around a wire conductor, and these wire windings are arranged inside or at least outside the main winding. It is possible to provide a high-performance, high-quality, compact, and inexpensive gas-insulated transformer that reduces eddy current loss generated in the windings and prevents local overheating without increasing the size of the wires and tank. .

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the gas insulated transformer of the present invention, Fig. 2 is an enlarged sectional view of the main part thereof, and Fig. 3 is a diagram showing the operation of the present invention, and shows eddy current loss. Fig. 4 is a radial distribution diagram; Fig. 4 is a sectional view showing the configuration of a conventional gas insulated transformer;
The figure is a cross-sectional view showing the leakage magnetic flux generated in the winding, Figure 6 is a radial distribution diagram of eddy current loss in the conventional gas insulated transformer shown in Figure 4, and Figure 7 is a diagram of the conventional gas insulated transformer. FIG. 8 is a radial distribution diagram of the eddy current loss. DESCRIPTION OF SYMBOLS 1... Iron core leg, 2... Metal sheet, 3... Insulating sheet, 4... Low voltage winding, 5... High voltage winding, 6...
Cooling panel, 7...pump, 8...tank, 9...
・Cooler, 10... Fruit tube, 11... Insulated pipe,
12... Leakage magnetic flux, 14... Tertiary winding, 15...
Tap winding, 20... tertiary winding, 21... tap winding.

Claims (1)

[Claims] Main windings such as low voltage windings and high voltage windings, tertiary windings,
In a gas insulated transformer in which a winding with a smaller capacity than the main winding, such as a stable winding or a tap winding, is wound and housed in the same tank, the main winding is wound with a metal sheet and an insulating sheet overlapped. It is composed of a rolled sheet-like winding, and the windings other than the main winding are composed of a wire-shaped winding in which a rectangular wire-shaped conductor is wound,
A gas insulated transformer characterized in that these linear windings are arranged at least either inside or outside the main winding.