JPH0945553A - Transformer with tap winding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax a leakage magnetic field component in the direction of radius near a tap winding of an outer winding by locating a magnetic shield along the inner diameter of the tap winding. SOLUTION: An inner winding 3 and outer windings 4, 5 divided into upper and lower parts are wound about an iron core 2 accommodated in a tank. A tap winding 6 is provided between the outer windings 4, 5. A magnetic shield 10 is provided along the inner diameter of the tap winding 6. Thus, a leakage flux 9 in a region 6A is collected toward the magnetic shield 10, and magnetic field components in the radial direction on the side of region 6A of the outer windings 4, 5 are relaxed. It is not necessary to divide the conductors of the outer windings 4, 5 in the axial direction or to enlarge a cooler, and the electromagnetic and mechanical forces on the outer windings 4, 5 is also relaxed. Therefore, the force for tightening the outer windings 4, 5 in the axial direction may be smaller, and reduction in the cost of the device can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer having a main winding and a tap winding embedded therein.

[0002]

2. Description of the Related Art There are two types of transformers, one in which the tap winding is embedded in the main winding, and the other in which the tap winding is arranged independently of the main winding via an insulating gap in the radial direction. , Here, we will deal with the former type of transformer. A plurality of tap leads are drawn from the tap winding and connected to the tap changer. By selecting this tap, the transformation ratio of the transformer is changed and the transmission voltage of the power line is always kept constant.

FIG. 5 (A) is a one-sided sectional view showing the structure of a conventional transformer with a tap winding, and FIG. 5 (B) is shown in FIG. 5 (A).
It is an A section expanded sectional view of. In FIG. 5 (A), an inner winding 3 and outer windings 4 and 5 which are vertically divided into two are wound around an iron core 2 housed in a tank 1. Also, FIG.
A tap winding 6 is interposed between the outer windings 4 and 5 as shown in FIG. However, the illustration of the tap lead is omitted.

FIG. 6 (A) is a one-sided sectional view showing the structure of a conventional transformer with a different tap winding, and FIG. 6 (B) is shown in FIG.
It is an B section expanded sectional view of (A). An inner winding 3 and an outer winding 7 are wound around an iron core 2 housed in a tank 1. Further, as shown in FIG. 6B, tap windings 8 are arranged at the upper and lower ends of the outer winding 7.

[0005]

However, the conventional device as described above has a problem that the leakage magnetic field component in the radial direction near the tap winding of the outer winding is large. That is, the tap winding has a portion in which current flows depending on the selected position of the tap, so that the leakage flux in this portion spreads in the radial direction. Therefore, a leakage magnetic field component in the radial direction is formed near the tap winding of the outer winding.

FIG. 7A is a magnetic field distribution diagram in the configuration of FIG. 5, and FIG. 7B is an enlarged magnetic field distribution diagram of the A1 portion (dotted line range) of FIG. 7A. In FIG. 7, 9 is a leakage magnetic flux. In the area 6A where the tap windings are arranged, since no current flows, the magnetic field was calculated as a mere space.
As can be seen from FIG. 7B, the leakage magnetic flux 9 spreads in the radial direction in the region 6A, so that a leakage magnetic field component in the radial direction is formed on the tap winding side of the outer windings 4 and 5.

FIG. 8 (A) is a magnetic field distribution diagram in the configuration of FIG. 6, and FIG. 8 (B) is an enlarged magnetic field distribution diagram of the B1 portion (dotted line range) of FIG. 8 (A). In FIG. 8, 9 is a leakage magnetic flux. Area 8A where tap windings are arranged
Was calculated as a mere space because no current was flowing. As can be seen from FIG. 8 (B), since the magnetic flux spreads in the radial direction in the region 8A, a leakage magnetic field component in the radial direction is formed at the end of the outer winding 7.

Generally, the eddy current increases in proportion to the square of the conductor width in the direction perpendicular to the magnetic field. Therefore, to suppress this eddy current, the radial conductor width of the outer winding is reduced with respect to the axial leakage magnetic field, and the axial conductor width of the outer winding is reduced with respect to the radial leakage magnetic field. The width should be reduced. Therefore, in the conventional outer winding, the conductor is divided not only in the radial direction but also in the axial direction. Since dividing the conductor in the axial direction increases the number of manufacturing steps, instead of dividing the conductor, there is also a method of enlarging the cooler to suppress local heating near the tap winding due to eddy current.
However, if the cooler is enlarged, the size of the device becomes large, which eventually leads to an increase in cost.

An object of the present invention is to reduce the leakage magnetic field component in the radial direction near the tap winding of the outer winding.

[0010]

In order to achieve the above object, according to the present invention, an inner winding and an outer winding wound around an iron core are provided, and the outer winding is a tap winding. In the transformer divided in two in the axial direction via the magnetic shield, the magnetic shield is arranged along the inner diameter side of the tap winding.

Alternatively, in a transformer having an inner winding and an outer winding that are wound around an iron core, and a tap winding is arranged at an axial end portion of the outer winding, the magnetic shield is tap-wound. It may be arranged on the side opposite to the outer side of the wire. Further, in each of the above-mentioned configurations, if the magnetic shield is formed of magnetic powder via a binder,
It is still preferable.

[0012]

According to the structure of the present invention, the magnetic shield is arranged along the inner diameter side of the tap winding interposed between the outer windings. As a result, the leakage flux gathers on the magnetic shield side, so that the spread of the leakage flux can be suppressed. Therefore, the leakage magnetic field component in the radial direction near the tap winding of the outer winding is relaxed.

Further, a magnetic shield is arranged on the side opposite to the outer winding of the tap winding provided at the end of the outer winding. This also causes the leakage magnetic flux to gather on the magnetic shield side, so that the spread of the leakage magnetic flux can be suppressed. Therefore, the leakage magnetic field component in the radial direction near the tap winding of the outer winding is relaxed. If the magnetic shield is formed by molding magnetic powder through a binder, it is possible to form a magnetic shield having an arbitrary relative magnetic permeability μ by adjusting the filling rate of the magnetic powder. Therefore, for various types of transformers with tap windings, it is possible to easily create magnetic shields having optimum relative magnetic permeability μ for mitigating radial leakage magnetic field components in the vicinity of the tap windings of the outer windings. You can

[0014]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is an enlarged sectional view of an essential part showing the configuration of a transformer with a tap winding according to an embodiment of the present invention. Tap winding 6
The magnetic shield 10 is arranged along the inner diameter side of the. The other configuration is the same as the conventional configuration described in FIG. The same portions will be denoted by the same reference symbols and repeated detailed description will be omitted.

As the magnetic shield 10 in FIG. 1, for example, a magnetic powder (magnetic powder) molded through a binder, which is also called a magnetic iron core, can be adopted. When the above-mentioned magnetic iron core is adopted as the magnetic shield 10, the relative magnetic permeability μ of the magnetic shield 10 can be arbitrarily adjusted by adjusting the filling rate of the magnetic powder. Although the optimum relative permeability μ of the magnetic shield 10 for relaxing the radial leakage magnetic field formed in the outer windings 4 and 5 differs depending on the structure of the iron core / winding, the tap winding is the main winding. In the case of an embedded transformer with tap winding, radial leakage formed in the outer windings 4 and 5 by setting μ to about 10 to 100, even in consideration of differences between transformer models. The magnetic field can be relaxed.

FIG. 3 (A) is a magnetic field distribution diagram in the configuration of FIG. 1, and FIG. 3 (B) is an enlarged magnetic field distribution diagram of the portion A2 (dotted line range) of FIG. 3 (A). In FIG. 3, 9 is the leakage magnetic flux, and the region 6A in which the tap windings are arranged has no current flowing, so the magnetic field was calculated as a mere space.
The relative permeability μ of the magnetic shield 10 was calculated as 10. The leakage magnetic flux 9 in the area 6A of FIG. 3B is gathered closer to the magnetic shield 10 side, and the radial magnetic field component on the area 6A side of the outer windings 4 and 5 is relaxed as compared with the conventional case in FIG. 7B. You can see that

FIG. 2 is an enlarged sectional view of the essential parts showing the structure of the transformer with tap winding according to another embodiment of the present invention. A magnetic shield 11 is arranged on the upper end of the tap winding 8. Other configurations are the same as the conventional configuration of FIG. The material of the magnetic shield 11 is the magnetic shield 1 of FIG.
It is the same as that of 0. The magnetic shield 11 is also provided on the lower surface side of the tap winding arranged at the lower end of the outer winding 7.

FIG. 4 (A) is a magnetic field distribution diagram in the configuration of FIG. 2, and FIG. 4 (B) is an enlarged magnetic field distribution diagram of B2 portion (dotted line range) of FIG. 4 (A). In FIG. 4, 9 is the leakage magnetic flux, and the region 8A in which the tap windings are arranged has no current flowing therein, so the magnetic field was calculated as a mere space. The relative permeability μ of the magnetic shield 11 was calculated as 10. Leakage magnetic flux 9 in region 8A of FIG. 4 (B)
Are gathered closer to the magnetic shield 11 side, and it can be seen that the radial magnetic field component at the end portion of the outer winding 7 is relaxed as compared with the conventional case in FIG.

[0019]

As described above, the present invention is provided along the inner diameter side of the tap winding interposed between the outer windings, or
The magnetic shield is arranged on the side opposite to the outer winding of the tap winding provided at the end of the outer winding. As a result, the leakage magnetic field component in the radial direction near the tap winding of the outer winding is relaxed. Therefore, it is not necessary to divide the conductor of the outer winding in the axial direction or increase the size of the cooler, and the cost of the device is reduced. Further, when the leakage magnetic field component in the radial direction is relaxed, the electromagnetic mechanical force acting in the axial direction of the outer winding is also relaxed. Therefore, less force is required to tighten the outer winding in the axial direction, and the cost of the device can be reduced from this point as well.

Further, the magnetic shield is formed by molding magnetic powder through a binder. This facilitates the magnetic shield having the optimum relative permeability μ for mitigating the radial leakage magnetic field component near the tap winding of the outer winding, corresponding to various tap winding transformers. It becomes possible to make.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing the configuration of a transformer with tap winding according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing the configuration of a transformer with tap winding according to another embodiment of the present invention.

3A is a magnetic field distribution diagram of FIG. 1, and FIG. 3B is an enlarged magnetic field distribution diagram of an A2 portion of FIG. 3A.

4A is a magnetic field distribution diagram of FIG. 2, and FIG. 4B is an enlarged magnetic field distribution diagram of B2 part of FIG. 4A.

5A is a one-sided cross-sectional view showing the configuration of a conventional transformer with tap winding, and FIG. 5B is an enlarged cross-sectional view of part A of FIG. 5A.

6A is a one-sided cross-sectional view showing the structure of a conventional transformer with a different tap winding, and FIG. 6B is an enlarged cross-sectional view of a B part in FIG. 6A.

7A is a magnetic field distribution diagram of FIG. 5, and FIG. 7B is an enlarged magnetic field distribution diagram of an A1 portion of FIG. 7A.

8A is a magnetic field distribution diagram of FIG. 6, and FIG. 8B is an enlarged magnetic field distribution diagram of a B1 portion of FIG. 8A.

[Explanation of symbols] 2: Iron core, 3: Inner winding, 4, 5, 7: Outer winding, 6,
8: Tap winding, 9: Leakage magnetic flux, 10, 11: Magnetic shield

Claims (3)

[Claims] Claim: What is claimed is: 1. A transformer comprising an inner winding and an outer winding wound around an iron core, the outer winding being axially divided into two parts by tapping the magnetic shield. A transformer with a tap winding, which is arranged along the inner diameter side of the winding. 2. A transformer, comprising an inner winding and an outer winding wound around an iron core, wherein the outer winding has a tap winding arranged at an axial end portion thereof. A transformer with a tap winding, characterized in that it is arranged on the side opposite to the winding side of the wire. 3. The transformer with tap winding according to claim 1 or 2, wherein the magnetic shield is formed by press-molding magnetic powder through a binder. .