JPS61224304A - Magnetic shielding device for induction electric apparatus - Google Patents

Abstract

PURPOSE:To prevent the local overheating of the tank wall located at the end part of a magnetic shielding plate by method wherein the third bent magnetic shield, with which a vertical direction magnetic shield and a horizontal direction magnetic shield are connected, is properly arranged. CONSTITUTION:The vertical direction magnetic shielding plate 5a, on which magnetic flux passes easily in the height direction of a tank on the part in the vicinity of the center part of phase, is arranged in such a manner that it is brought close to the condition of infiltration of leakage magnetic flux into the wall of the tank, and the magnetic shielding plates 5b1 and 5b2 which easily pass in horizontal direction of the tank on the region located in the vicinity of the interphase part, is arranged. The magnetic shielding plates 5b1 and 5b2 are constituted in such a manner that they are bent at their end part and that they are magnetically coupled through the intermediary of the third magnetic shielding plate 5c having the same laminating direction. According to this constitution, the magnetic flux moving from the end part of the shielding plate 5a to the tank 4 can be smoothly transferred through the intermediary of a shielding plate 5c, the magnetic circuit on the magnetic shield is apparently made longer, and the transfer of concentrical magnetic flux toward the tank wall at the end part of the shield can be prevented, thereby enabling to prevent the local temperature rise on the shield end part.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a novel magnetic shielding device for induction electric appliances, and in particular, by effectively arranging magnetic shielding plates in combination, local losses due to concentration of losses on tank walls can be reduced. Trying to prevent temperature rise.

[Background of the invention]

Generally, in induction electric appliances such as transformers and reactors, leakage magnetic flux generated from one winding can penetrate the tank wall and cause loss, or cause localized overheating due to local concentration of loss. be.

For this reason, conventional methods include installing a highly conductive non-magnetic plate on the inner wall of the tank as a magnetic shield and scattering the leakage magnetic flux by the countermagnetic field of the eddy current flowing through it, and attaching a magnetic plate with high magnetic permeability to the inner wall of the tank. Therefore, a method has been adopted in which most of the leakage magnetic flux passes through this plate to reduce its intrusion into the tank.

Among these methods, the latter method, in which magnetic plates are placed on the tank wall, has recently become widely used, and as shown in Figures 3 and 4, a large number of magnetic shield plates are arranged in parallel. It is something. In other words, the leakage magnetic flux is generated between the windings 2 and 3 wound around the iron core 1, and tries to enter the tank wall 4 as shown by the arrow in the figure. Due to the action of the magnetic shield plate 5 in FIG. As can be seen from the plan view of the device, the leakage magnetic flux generated from the windings 2 and 3 scatters in the radial direction as shown by the arrows in the figure, so the normal U, V,
In the phase-to-phase section of a three-phase transformer consisting of W-phase, the longitudinal direction of the tank (
The magnetic flux component in the X direction (in the figure) inevitably becomes large,
As shown in FIGS. 3 and 4, simply arranging long magnetic shield plates 5 in parallel in the tank height direction (Z direction) has the problem that a sufficient shielding effect cannot be obtained. Therefore, as described in Japanese Utility Model Publication No. 51-32010, a method of deploying a magnetic shield as shown in the plan view of the inner wall of the tank in Fig. 5 is proposed to approximate the form of leakage magnetic flux entering the tank as much as possible. It is shown. In other words,
At the phase center where the leakage magnetic flux has a large component in the tank height direction (Z direction), a magnetic flux path is created in the tank height direction like the magnetic shield plate 5a. In the interphase portion where the component (direction) is large, the magnetic shielding plate 5b forms a path for magnetic flux in the longitudinal direction of the tank, thereby further improving the effectiveness of the magnetic shielding. On the other hand, in transformers with large leakage magnetic flux such as recent ultra-large capacity transformers and high impedance transformers, the loss of the magnetic shield plate itself, which has not been seen as a problem in the past, becomes considerably large, so as shown in Figure 6, The idea was to change the stacking direction of the magnetic shield plate 5 by 90'' from the conventional one and make it parallel to the tank wall 4, thereby subdividing the path of the eddy current flowing through the shield plate itself and drastically reducing the generated loss. 54-24011 and the like.

In other words, as is known from these ideas, the magnetic shield plate 5 laminated parallel to the tank wall 4 shown in FIG. 6 should be arranged so as to be as close as possible to the form of leakage magnetic flux entering the tank as shown in FIG. If this is possible, it will be possible to achieve an extremely large reduction in loss.

However, in ordinary transformers, the shape of the tank to which the magnetic shield plate 5 is attached is often bent, as shown in Figure 7, due to transportation conditions and other factors. With such a magnetic shield plate, the deployment of the magnetic shield must be stopped at the bent portion of the tank. As a result, as shown by the arrow in FIG. 7, the magnetic flux flowing through the magnetic shield plate 5a is concentrated at its end and transferred to the tank 4, causing a problem of local overheating in this area.

[Purpose of the invention]

An object of the present invention is to effectively prevent local overheating on the tank wall at the end of the magnetic shield plate, and is particularly effective in bent tanks where the mounting range of the magnetic shield plate is limited. It is.

(Summary of the Invention) The present invention provides a method for magnetic shielding when a magnetic shield plate made of a large number of magnetic materials laminated in parallel to the tank wall is arranged vertically and horizontally on the tank inner wall in consideration of the penetration form of leakage magnetic flux. The structure is such that a bent third magnetic shield connecting the vertical magnetic shield and the horizontal magnetic shield is appropriately provided to prevent magnetic flux from entering the tank wall from near the tip of the tank.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG.

The stacking direction of all the magnetic shield plates is configured to be parallel to the tank wall 4 so that the loss generated by the magnetic shield plates themselves is as small as possible. In order to approach the form of leakage magnetic flux entering the tank wall as close as possible, a vertical magnetic shield plate 5a is installed near the phase center where the magnetic flux easily passes in the tank height direction, and near the correlation part the magnetic flux is installed in the longitudinal direction of the tank. Easy-to-pass horizontal magnetic shield plate 5b1゜5
5b1 and 5b2 are bent at their ends, and are magnetically coupled through the interposition of a third magnetic shield plate 5c having the same stacking direction.

With this configuration, the magnetic shield 5 becomes a problem when the tank 4 is bent due to transportation conditions and the vertical magnetic shield plate 5a has to be installed only in the straight part excluding the bent part.
Due to the effect of the bent third magnetic shield plate 5c, the magnetic flux flowing from the end of a to the tank 4 can be smoothly transferred to the adjacent horizontal magnetic shield plate 5b1 via the third magnetic shield plate 5c.

This third magnetic shield plate 5c has its lamination direction parallel to the tank wall like the other magnetic shield plates, is held in a predetermined shape by forming annealing, etc., and its end face is vertical. It is in sufficient contact with the directional magnetic shield plate 5a and the lateral magnetic shield plate 5b1.

Therefore, according to this embodiment, the vertical magnetic shield plate 5
Since the range of a is limited to the straight part of the tank, the concentrated magnetic flux transfer phenomenon near the bent part of the tank is no longer observed, and the local temperature increase in the tank in this area, which has been considered a problem in the past, has been reduced. can be almost eliminated.

In FIG. 2, vertical magnetic shielding plates 58i t S a z and horizontal magnetic shielding plates 5b, 5b2 of different lengths are used as appropriate so that the magnetic shielding arrangement is more similar to the form in which leakage magnetic flux enters the tank wall. This is a combination deployment. Moreover, at the ends of the vertical magnetic shield plates 5a and 5at through which a large amount of leakage magnetic flux passes, the magnetic shield plates 5c and 5c2 are bent so that the magnetic path is not cut, and the horizontal magnetic shield plates 5b and 5b2 are bent so that the magnetic path is not cut. combined.

〔Effect of the invention〕

According to the present invention, the magnetic path caused by the magnetic shield is apparently longer, and concentrated magnetic flux transfer to the tank wall at the end of the magnetic shield can be avoided, and local temperature rise in this portion can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a main part showing the inner wall of a tank according to an embodiment of the present invention, FIG. 2 is a diagram of another embodiment showing the same part as FIG. 1, and FIG.
Figure 4 is an explanatory diagram of the leakage magnetic flux of the transformer, Figure 5
6 are diagrams showing an improved structure of the magnetic shield plate presented so far, and FIG. 7 is an explanatory diagram of the current problems. 1... Iron core, 2, 3... Winding wire, 4... Tank, 5
... Magnetic shielding plates, 5a, 5a1, 5a2... Vertical magnetic shielding plates, 5b, 5bL, 5b, ... Lateral magnetic shielding plates, 5c, 5c, 5c, ... Bent third magnetic shield plate.

Claims (1)

[Claims] 1. On the inner wall of the tank of an induction electric appliance in which multiple windings are arranged, magnetic shield plates made of a large number of high permeability magnetic materials laminated parallel to the tank wall are arranged in a linear combination in the vertical and horizontal directions. In the device, both the vertical magnetic shield plate and the horizontal magnetic shield plate are bent at a substantially right angle near their tips, and a third magnetic shield plate laminated in the same direction as the other magnetic shield plates allows magnetic shielding. A magnetic shielding device for induction electric appliances characterized by a combination of the two.