JPH11144981A - Magnetic shielding device for stationary induction electrical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce losses of magnetic shields themselves and to prevent local overheating, by forming a slit along the straight portion of each magnetic shield and dividing an eddy current flowing over the surface of the magnetic shield into two parts with the slit. SOLUTION: Magnetic shields 8, each formed by laminating thin silicon steel plates, are arranged at such positions as to confront an inner winding 4 and an outer winding 5. The shields 8 are arranged at a predetermined interval horizontally with their longitudinal direction extending perpendicularly. At the center of each shield 8 is formed a slit 10 cut through in the direction of the thickness. Magnetic fluxes 40 from the windings 4 and 5 enter vertically into each shield 8 and flow over the surface of the shield 8 as an eddy current. The slit 10 divides the eddy current into two parts. As a result, the losses of the shields 8 can be reduced and local overheating can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shielding device for stationary induction devices such as transformers and reactors.

[0002]

2. Description of the Related Art Generally, an eddy current flows into a tank such as a transformer or a reactor due to invasion of leakage magnetic flux from a winding and a lead wire, thereby causing a loss. Since this loss increases as the capacity increases, a magnetic shielding device is usually provided in the tank to reduce the loss. As this magnetic shielding device, a nonmagnetic material such as copper or aluminum or a silicon steel plate is laminated. Magnetic shields are used.

However, in a conventional magnetic shielding device using a magnetic shield, eddy current flows through the surface of the magnetic shield when leakage magnetic flux from the winding vertically penetrates into the surface of the magnetic shield, and is generated by the eddy current. However, there is a disadvantage that the magnetic material shield itself causes local overheating.

On the other hand, Japanese Patent Laid-Open No. 52-29 discloses a structure that can reduce the loss in the magnetic shield and prevent local overheating.
No. 928 and Japanese Utility Model Application Laid-Open No. 63-12820 have been proposed. Japanese Unexamined Patent Publication No. 52-29928 discloses a method in which a slit is provided at an end where a large amount of magnetic flux penetrates from a winding. However, since the eddy current flowing on the surface of the magnetic shield cannot be divided, the loss of the magnetic shield itself can be reduced and the local noise can be reduced. Not enough to prevent overheating. In addition, since the slit is provided at the end of the magnetic shield, there is a concern that the mechanical strength is reduced when the magnetic shield is attached to the tank.

On the other hand, in Japanese Utility Model Laid-Open Publication No. 63-12820, a slit is provided in a part of a bent portion of a magnetic shield, and the slit is used to support the magnetic shield and fix the tank to a tank. Since the eddy current flowing on the surface of the magnetic shield cannot be divided when the magnetic flux leaking from the magnetic material vertically penetrates into the surface of the magnetic shield, there is a problem that the loss of the magnetic shield itself cannot be reduced and local overheating cannot be prevented.

[0006]

In the above-mentioned prior art magnetic shielding apparatus for a static induction device, eddy current flows on the magnetic shield surface when leakage magnetic flux from the winding vertically penetrates into the magnetic shield surface. Since no consideration has been given to reducing the loss of the magnetic shield itself caused by the eddy current or taking measures against local overheating, there is a problem to be solved with respect to a structure for reducing the loss of the magnetic shield itself and preventing local overheating.

SUMMARY OF THE INVENTION The present invention effectively solves the problems of the prior art described above, and has as its object to reduce the loss of the magnetic shield itself, prevent local overheating, and reduce the cost of the magnetic shield of an inexpensive static induction device. It is to provide a device.

[0008]

According to the present invention, there is provided a shielding device for a stationary induction electric machine in which a magnetic shield formed by laminating a magnetic material is mounted inside a tank accommodating an induction electric body having an iron core and a winding. A magnetic shielding device for a stationary induction machine, wherein a slit is provided in a linear portion of a magnetic shield.

That is, according to the magnetic shielding device of the stationary induction device of the present invention, the eddy current flowing through the magnetic shield surface is divided by the slit when the magnetic flux leaking from the winding vertically penetrates into the magnetic shield surface. As a result, it is possible to reduce the loss of the magnetic shield itself and to prevent local overheating.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a configuration of a magnetic shield in a single-phase center core transformer, and FIG. 2 is a sectional view taken along line II-II of FIG. 1 and 2, an inner winding 4 and an outer winding are provided inside a tank 7 that houses a transformer body including a main leg 1 and side legs 2, an upper yoke 3, an inner winding 4, and an outer winding 5. A magnetic metal shield 8 formed by laminating a thin silicon steel sheet having a width W at a position opposed to the wire 5 is provided with a longitudinal direction perpendicular to the longitudinal direction of the magnetic shield 8, and a holding member (not shown) is provided so that a predetermined gap is provided in the lateral direction. In order to reduce the loss in the magnetic shield 8, one slit 10 is provided at the center of the magnetic shield 8 in the entire thickness direction.

According to this configuration, the slit 10 is provided even if the leakage magnetic flux 40 from the inner winding 4 and the outer winding 5 penetrates vertically into the magnetic shield 8 as shown by the arrow. Since the eddy current flowing on the surface of the magnetic shield 8 is cut off, the loss can be reduced and local overheating can be prevented. Generally, the loss due to the eddy current of the magnetic shield 8 increases as the square of the width W. However, since one slit 10 is provided at the center of the magnetic shield 8, the width W is reduced by 1 /.
2 and the loss can be greatly reduced to 1/4. The length of the slit 10 needs to be longer than at least the height of the inner winding 4 and the outer winding 5 in order to effectively separate the eddy current flowing on the surface of the magnetic shield 8.

On the other hand, the slit 10 extends to a depth at which no eddy current flows on the surface of the magnetic shield 8 when the leakage flux 40 from the inner winding 4 and the outer winding 5 vertically enters the surface of the magnetic shield 8. It is necessary to insert, slit 1
The depth of 0 can be determined in advance by magnetic field calculation or the like. A slit 10 is formed on the surface of the magnetic shield 8.
Can be simplified by using a dedicated machine, for example, a shear line or the like, so that an inexpensive magnetic shield 8 can be manufactured.

FIGS. 3 and 4 show another embodiment. FIG. 3 is a plan view showing the configuration of a magnetic shield in the single-phase center core transformer, and FIG. 4 is a cross-sectional view of a main part taken along the line I-Ι of FIG. As can be seen from FIGS. 3 and 4, a slit 1 is provided in the magnetic shield 9 wider than the normal magnetic shield 8 at a position facing the inner winding 4 and the outer winding 5.
In this configuration, five 0s are arranged.

According to this configuration, the width of the magnetic shield is made wider than that of the ordinary magnetic shield 8 so that the gap is reduced, and the inner winding 4 that moves from the magnetic shield 9 to the tank 7 is formed. And the leakage flux 40 from the outer winding 5
Can be reduced, and the shielding effect can be improved because the mounting range is expanded by the magnetic shield plate 9. Moreover, even if the leakage magnetic flux 40 from the inner winding 4 and the outer winding 5 penetrates perpendicularly into the magnetic shield 9 as shown by arrows, the five slits 10 are provided, so that the surface of the magnetic shield 9 is formed. Since the eddy current flowing through the circuit is divided, loss can be reduced and local overheating can be prevented. In addition, since the width is wider than that of the normal magnetic shield 8, the number of the magnetic shields 8 is reduced, and the number of presser fittings (not shown) is also reduced. Efficiency can also be improved. Further, it is necessary to provide a large number of slits 10 so as to reduce the loss generated in the magnetic shield and prevent local overheating.

FIGS. 5 and 6 show another embodiment. FIG. 5 is a plan view showing the configuration of a magnetic shield in a single-phase four-legged transformer, and FIG. 6 is a front view taken along the line II in FIG. As can be seen from FIGS. 5 and 6, the width of the magnetic shield 9 is set to be wider than that of the normal magnetic shield 8 at the position facing the inner winding 4 and the outer winding 5 and five slits 10 are inserted. A magnetic shield 11 having no slit 10 is provided between the windings (interphase).

According to this configuration, the leakage flux 40 from the inner winding 4 and the outer winding 5 at the position facing the inner winding 4 and the outer winding 5 is indicated by the arrow, as shown by the arrow.
Even if it enters vertically, the eddy current flowing on the surface of the magnetic shield 9 is divided because the five slits 10 are provided, so that loss can be reduced and local overheating can be prevented.

Further, since the magnetic flux leaking from the inner winding 4 and the outer winding 5 flows between the windings in parallel with the width direction of the magnetic shield 8, it is not necessary to provide the slit 10, and the magnetic shield 8 is manufactured. There is an advantage that man-hours can be reduced. Although the present invention has been described using a single-phase center core and a single-phase four-leg transformer as an example, it goes without saying that the same effect can be expected for a three-phase three-leg, three-phase five-leg transformer.

FIGS. 7 and 8 show another embodiment. FIG. 7 is a longitudinal sectional view in which a magnetic bending shield plate 12 is arranged along the bent portion of the transformer tank 7, and FIG. 8 is a transformer tank. 7 shows a configuration in which one slit 10 is inserted in the linear portion of the magnetic bending shield 12 provided inside the bent portion of FIG.

According to this construction method, since the slit 10 is provided in the linear portion of the magnetic bending shield 12 facing the inner winding 4 and the outer winding 5, the inner winding 4 and the outer winding 5 As shown by the arrow, even if the leakage magnetic flux 40 enters the straight portion of the magnetic bending shield 12 perpendicularly, the eddy current flowing on the surface of the straight portion of the magnetic bending shield 12 is divided, so that the loss can be reduced and the local portion can be reduced. Overheating can be prevented.

In addition, since the magnetic bending shield 12 is provided along the inside of the bent portion of the tank 7, the leakage flux 40 from the inner winding 4 and the outer winding 5 is shown by an arrow as shown by an arrow. Since all the leakage magnetic fluxes 40 flow through the magnetic bending shield 12, the loss of the tank 7 can be greatly reduced. Further, the magnetic material bending shield 12 can be easily manufactured by using a dedicated jig to form the magnetic material bending shield 12 along the bent portion of the tank 7.

[0022]

According to the magnetic shielding apparatus for a stationary induction device of the present invention, when the magnetic flux leaking from the winding perpendicularly enters the magnetic shield surface, the eddy current flowing through the magnetic shield surface passes through the slit. The division makes it possible to reduce the loss in the magnetic shield and to prevent local overheating.

[Brief description of the drawings]

FIG. 1 is a plan view of a magnetic shielding device of a stationary induction device showing one embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of a magnetic shielding device for a stationary induction device according to an embodiment of the present invention.

FIG. 3 is a plan view of a magnetic shielding device of the stationary induction device showing one embodiment of the present invention.

FIG. 4 is a perspective view showing a main part of a magnetic shielding device for a stationary induction device according to an embodiment of the present invention.

FIG. 5 is a plan view of the magnetic shielding device of the stationary induction device showing one embodiment of the present invention.

FIG. 6 is a front view of the magnetic shielding device of the stationary induction device showing one embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a magnetic shielding device for a stationary induction device showing one embodiment of the present invention.

FIG. 8 is a perspective view showing a main part of a magnetic shielding device of a stationary induction device showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main leg, 2 ... Side leg, 3 ... Upper yoke part, 4 ... Inner winding,
5 ... outer winding, 6,7 ... tank, 8,9,11 ... magnetic shield, 10 ... slit, 12 ... magnetic bending shield, 40 ... leakage magnetic flux.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Sakae Kudo 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant of Hitachi, Ltd.

Claims (4)

[Claims] 1. A static induction device shielding apparatus in which a magnetic material shield formed by laminating a magnetic material is mounted inside a tank accommodating an induction device main body having an iron core and a winding, wherein a linear portion of the magnetic material shield is provided. A magnetic shielding device for a stationary induction device, comprising a slit. 2. The magnetic shielding device for a stationary induction electric device according to claim 1, wherein the length of the slit provided in the linear portion of the magnetic shield is longer than the height of the winding. 3. The magnetic shield according to claim 1, wherein a width of the magnetic shield provided at a position facing the inner winding and the outer winding is wider than a normal magnetic shield width, and a plurality of slits are provided. Magnetic shielding device for stationary induction equipment. 4. A shielding device for a stationary induction electric machine to which a magnetic material bending shield formed by laminating magnetic materials along the inside of a bent portion of a tank accommodating an induction electric device main body having an iron core and a winding is provided. A magnetic shielding device for a stationary induction device, wherein a slit is provided in a straight portion of a body bending shield.