JPS5816326B2 - Magnetic shielding device for stationary induction appliances - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in magnetic shielding devices for stationary induction appliances.

As the capacity of stationary induction electric appliances such as transformers and accelerators increases, leakage magnetic flux from the coil also increases.

Therefore, the amount of leakage magnetic flux that enters structural materials such as transformers increases, causing problems such as increased loss due to eddy currents or overheating due to eddy currents.

In particular, since one side of the tank structural material is in contact with air, its cooling effect is lower than that of oil, making overheating an even more problematic issue.

Generally, in large-capacity transformers, etc., a magnetic shield made of a silicon steel strip or an electromagnetic shield made of a good conductor such as aluminum is attached to the inner surface of the tank facing the coil to prevent leakage magnetic flux from the coil from entering the tank structural material. It solves the problem mentioned above.

As shown in FIGS. 1 and 2, such a conventional magnetic shield is used, for example, in a transformer, and its contents, which consist of an iron core 1 and a coil 2, are housed inside a tank 4 filled with insulating oil.

On the inner surface of the tank 4 facing the coil 2,
As described above, a magnetic shield 8 is attached to prevent an increase in loss due to the coil leakage magnetic flux 7 or local heating of the structural material of the tank 4 due to this.

In addition, the magnetic shield 8 has a third
As shown in the figure, a plurality of narrow shield units 8A and 8B are arranged in parallel facing the coil.

On the other hand, the inside of the transformer connects the connecting lead 3 to the bushing 6, and is connected from there to an external power generation device or power transmission line.

When the high voltage coil end is in the center of the coil, it is better to connect the high voltage lead 3 to the bushing 6 directly by making a through hole 9 in the side wall of the tank 4 and attaching the bushing pocket 5 there. This is very advantageous in terms of making the device more compact than increasing the size of the device, or in terms of arranging external parts of the device.

FIG. 3 shows a through-hole portion when the side wall surface of the tank 4 in the part facing the coil has a through-hole 9 and a silicon steel strip 8, and 8B of the plurality of silicon steel strips is a through-hole of the tank. 9
It is divided into upper and lower parts.

In such a case, the magnetic flux 70 that passes through the silicon steel strip 8B will either enter the tank structural material at the through hole 9 section, or enter the adjacent silicon steel strip 8A and flow into the silicon steel strip 8B on the opposite side of the through hole. Get out.

Therefore, the tank structural material near the through hole 9 is locally overheated, causing thermal decomposition or deterioration of the insulating oil, which significantly reduces the effectiveness of installing the magnetic shield, which should be improved.

The purpose of the present invention is to eliminate the drawbacks that occur when a magnetic shield is divided in the middle by a through hole such as a connection lead as described above. By placing
The purpose of the present invention is to prevent local heating of tank structural materials and provide high-quality stationary induction appliances.

The present invention will be described below with reference to the embodiments shown in FIGS. 4 and 5.

The same parts as in FIGS. 1 to 3 are given the same reference numerals.

As shown in FIGS. 4 and 5, a portion of the plurality of silicon steel strip shields 8 attached to the coil facing surface is divided in the middle by the through hole 9 of the connection lead 3 and attached as shown in 8B. .

Reference numeral 8C denotes a shield member made of a silicon steel strip attached near the aforementioned divided silicon steel strip 8B and around the through hole 9.

This shield member 8C is attached sufficiently close to the divided shield 8B.

Therefore, by setting the cross-sectional area of the shield member 8C to an appropriate value, most of the magnetic flux 70 passes through the shield member 8C to the silicon steel strip 8B on the opposite side, thereby preventing local heating in the tank structural material.

The shield member 8C to be attached around the through hole 9 is formed to have the required cross-sectional area by stacking non-oriented silicon steel plates or rolling up non-oriented silicon steel plates.

Further, by providing the slit 13 in the shield member 8C, circulating current can be prevented.

Note that when the coil 2 or the connecting wire 3 facing the magnetic shield is at a high voltage, an electric field shield 10 made of an insulator or metal is attached to the end of the silicon steel strip 8C to alleviate the electric field.

Further, the shield member 8C can be easily fixed using the mounting bolts 12 or the like.

Other embodiments of the present invention are shown in FIGS. 6 and 7.

The same parts as in Figures 4 and 5 are given the same numbers.

The shield member 8D is attached sufficiently close to the divided shield 8B and inside the through hole 9.

This shield member 8D is formed by winding up a non-directional silicon steel strip to have an appropriate cross-sectional area, and is provided with a slit 13.

Electric field shields 10 and 11 made of an insulator or metal are attached to the ends of the shield member 8D to alleviate the electric field.

In this way, the magnetic flux 7 passing through the shield 8B passes through the shield member 8D without passing through the tank structural member, and has the same effect as the present invention.

As described above, according to the present invention, there is a through hole for a connection lead etc. on the magnetic shield mounting surface, and even if some of the silicon steel strips are divided into upper and lower parts in the middle, the through hole is By arranging a shielding member made of another silicon steel strip around or inside the divided silicon steel strip, the magnetic flux entering the tank structural material from the divided magnetic shield portion becomes sufficiently small and localized. Problems such as heating can be prevented and high quality static induction appliances can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 are plan and side sectional views showing the arrangement of a magnetic shield installed opposite the coil of a transformer, and Figure 3 is a cross-sectional view of a magnetic shield divided into upper and lower parts by a through hole of a conventional connection lead. Fig. 2 is a view taken along the line ■-■ in Fig. 2 showing the state of the raw steel strip and magnetic flux, Fig. 4 is a diagram showing the installation structure of the shield member in the through-hole portion according to the present invention, and Fig. 5 is a view taken from V-V in Fig. 4. Line sectional view, 6th
The figure is a diagram of the mounting structure of a shield member showing another embodiment of the present invention, and FIG. 7 is a sectional view taken along the line ■--■ in FIG. 6. 2... Coil, 3... Connection lead, 4
...Tank, 7...Leakage magnetic flux, 8,8
At8B...°°tank wall magnetic shield, 8C, 8
B... Shield member for the through hole portion, 9...
・Tank through hole.

Claims (1)

[Claims] 1. A plurality of magnetic shields are attached to the coil-opposing parts inside the tank of a stationary induction electric appliance, and when this magnetic shield is divided by a tank through hole, a magnetic path is installed in the through hole in the vicinity of the divided magnetic shield. A magnetic shielding device for a stationary induction electric appliance, characterized in that a shielding member is provided.