JP3161337B2 - Transformer shield plate device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to prevent the occurrence of eddy currents due to crossing of leakage magnetic fluxes generated from windings on a tank side wall of a transformer, a reactor or the like, thereby causing a local overheating phenomenon. The present invention relates to a shield plate device provided.

[0002]

2. Description of the Related Art Normally, eddy current is generated in a portion relatively close to a winding on a tank side wall of a gas insulated transformer or the like by a magnetic flux leaking from the winding. The phenomenon of overheating occurs. Conventionally, a magnetic shielding plate with good conductivity is inserted between the winding and the tank side wall to prevent such leakage magnetic flux from intermingling with the tank side wall, and the reverse magnetic flux due to the eddy current flowing through the magnetic shielding plate is avoided. This structure repels magnetic flux leakage and prevents leakage magnetic flux from reaching the tank side wall.

However, when attaching such a magnetic shielding plate, taking a transformer tank as an example, as shown in FIG. 3, the tank side wall 1 is composed of an upper tank side wall 10 and a lower tank side wall 11.
Are separately manufactured, the windings 2 are assembled, and the upper tank side wall 10 and the lower tank 11 are combined to form a tank flange 5.
And integrated via the bolt 15. For this reason, the magnetic shielding plates 3 and 4 also include the upper tank side wall 10 and the lower tank side wall 1 respectively.
In order to attach them separately to each other, they are divided by a tank flange 5.

[0004] In recent years, in gas-insulated transformers whose capacity has been increasing more and more, the leakage flux of the windings tends to increase, and the eddy current due to the leakage flux also increases. In such a case, an eddy current flows through the upper magnetic shield plate 3 and the upper magnetic shield plate 4 as shown in FIG. 4 according to the conventional magnetic shield plate. Since the side wall 10 and the lower tank side wall 11 are divided, most of the eddy current moves to the upper flange 6 near the tank flange portion 5 as shown by an arrow 13, passes through the lower flange 7 via the bolt 15, and moves to the lower portion. As a result of flowing through the magnetic shielding plate 4,
There was a problem that local overheating was induced in the tank flange 5.

On the other hand, as a structure for preventing local overheating of the tank flange, the magnetic shielding plates arranged in the upper tank and the lower tank are electrically connected by a magnetic shielding plate connector in Japanese Patent Publication No. Sho 42-10447. Then, a method of flowing an eddy current has been proposed. However, the gas insulation transformer has a high internal pressure, so the upper and lower flanges are open, and between the magnetic shielding plate connector that electrically connects the magnetic shielding plates arranged on the upper tank and the lower tank of the tank side wall. Since a gap is generated and eddy current flows from the upper flange to the lower flange and flows, local overheating in the tank flange is concerned.

[0006]

In the above-mentioned prior art, workability is difficult because local overheating is prevented at the tank flange of the transformer and a magnetic shielding plate is electrically connected inside the transformer. There were issues to be solved.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent eddy current from flowing to the tank flange by disposing an eddy current bypass connection metal fitting outside the upper flange and the lower flange in order to prevent local overheating in the tank flange. Another object of the present invention is to provide a transformer which is inexpensive and easy to operate.

[0008]

According to the present invention, a side wall of a tank containing a winding is divided into an upper tank side wall having an upper flange and a lower tank side wall having a lower flange, and a magnetic shielding plate is provided on the inner surface of the tank side wall. And an eddy current bypass fitting is disposed outside the upper flange and the lower flange.

According to the transformer shield device of the present invention, the eddy current flowing through the upper magnetic shield plate moves to the upper flange near the tank flange, passes through the lower flange via the bolt, and passes through the lower magnetic shield. Even if it tries to flow to the plate, it flows through the eddy current bypass connection metal fittings provided outside the upper flange and the lower flange, so that local overheating at the tank flange can be prevented.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described more specifically with reference to FIG. FIG. 1 is a cross-sectional view of a main part of a tank flange portion, and FIG. 2 shows an eddy current bypass connection fitting 60 according to the present invention. In FIG.
An eddy current bypass connection fitting 60 smaller than the specific resistance of the material used for the upper flange 6 and the lower flange 7 is provided outside the lower flange 7. In addition, the upper flange 6, the lower flange 7, and the eddy current bypass connection bracket 60 provided on the outside are integrated via the bolt 15.

According to this configuration, the eddy current flowing through the upper magnetic shield plate 3 tends to move to the upper flange 6 and the lower flange 7 near the tank flange 5 as shown by an arrow 13, but the upper flange Outside the lower flange 6 and the lower flange 7, the fluid flows to the lower magnetic shield plate 4 via the eddy current bypass coupling 60 that is smaller than the specific resistance of the material used for the upper flange 6 and the lower flange 7. For this reason, it is possible to prevent loss occurring in the tank flange portion 5 and to prevent a local temperature rise, and to significantly improve the performance and durability of the transformer and the like. In addition, since there is no need to electrically connect the upper magnetic shield plate 3 and the lower magnetic shield plate 4 inside the transformer, there is no need for a magnetic shield plate connector, and work can be easily performed since work can be performed from the outside. is there. In addition, a U-shaped structure is provided so that the eddy current bypass connection fitting 60 can be in close contact with the upper flange 6 and the lower flange 7 via the bolt 15. Further, the eddy current 13 can be transferred to the eddy current bypass connection fitting 60 by applying a conductive paint to the contact surface between the eddy current bypass connection fitting and the upper flange 6 and the lower flange 7. As a material of the eddy current bypass connection fitting 60, copper or aluminum having a lower specific resistance than, for example, a steel plate or the like usually used for the tank side plate 1 is effective.
The present invention has been described by taking as an example the case where the cooling medium is an insulating gas in the non-combustible transformer, but the cooling medium is perfluorocarbon (P
FC) is also effective. Further, although the upper flange 6 and the lower flange 7 are shown as an example of an integrated structure via the bolt 15, the same effect can be expected even when the ends of the upper flange 6 and the lower flange 7 are welded.

[0012]

According to the shield plate device of the present invention, the eddy current flowing through the upper magnetic shield plate is provided near the tank flange and outside the upper flange and the lower flange. As a result, local overheating at the tank flange can be prevented, and the performance and durability of the transformer and the like can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a shield plate device of a tank flange portion showing one embodiment of the present invention.

FIG. 2 is a perspective view of a shield plate device of a tank flange portion showing one embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a transformer showing a conventional shield plate device for a tank flange portion.

FIG. 4 is a sectional view of a main part of a conventional shield plate device for a tank flange portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tank side wall, 3, 4 ... Magnetic shielding plate, 5 ... Tank flange part, 6 ... Upper flange, 7 ... Lower flange, 10 ...
Upper tank side wall, 11 ... Lower tank side wall, 13 ... Eddy current,
15: bolt, 60: connecting bracket.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Umene ▲ Iwan ▼ 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant of Hitachi, Ltd. (72) Yoshihiro Nagao Inventor Yoshihiro Kokubuncho, Hitachi City, Ibaraki Prefecture 1-1-1 1-1 Kokubu Plant, Hitachi, Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 27/36

Claims (4)

(57) [Claims] 1. A tank wherein a tank side wall incorporating a winding is divided into an upper tank side wall having an upper flange and a lower tank side wall having a lower flange, and a magnetic shielding plate is provided on an inner surface of the tank side wall. A transformer shield plate device, wherein a coupling metal for eddy current bypass is arranged outside the upper flange and the lower flange. 2. The transformer shield plate device according to claim 1, wherein the eddy current bypass connection metal fittings provided outside the upper flange and the lower flange have a U-shape. 3. The transformer shield plate device according to claim 1, wherein the material of the eddy current bypass connection metal is copper or aluminum having a lower specific resistance than a steel plate used for the tank side plate. 4. The transformer shield plate device according to claim 1, wherein a conductive paint is applied to a contact surface between the eddy current bypass connection fitting and the upper flange and the lower flange.