JPS58279Y2 - stationary induction appliance - Google Patents

Description

[Detailed description of the invention] This invention relates to a stationary induction electric appliance that has a magnetic shielding device attached to the inner surface of the oil tank.By effectively installing the magnetic shield, loss in the oil tank wall due to leakage magnetic flux can be reduced and local overheating can be prevented. This is the purpose.

In general, as the capacity of induction electric devices such as transformers and reactors increases, the leakage magnetic flux generated from the windings increases, and this leakage flux penetrates into structural materials such as oil tank walls and iron core clamping plates, causing the oil tank and internal structure of the oil tank to increase. This increases stray loss in the material and causes local overheating.

In order to reduce these stray losses and prevent local overheating, conventional methods include shielding the oil tank wall with a good conductor plate and passing an eddy current that cancels out the leakage magnetic flux penetrating the tank wall, and using silicon steel with high magnetic permeability on the oil tank inner wall. There is a method of attaching a shielding member with a band and absorbing the leakage magnetic flux therein to prevent the leakage magnetic flux from entering into the oil type, thereby reducing loss and preventing local overheating.

Among the above methods, the latter method using magnetic shielding is often used in large-capacity induction appliances and has achieved some degree of effectiveness.

Ideally, the magnetic shield should be installed all around the inner wall of the oil tank, but from the perspective of cost and shielding efficiency, it is recommended to clarify the leakage magnetic flux distribution on the inner wall of the oil tank and install it in areas with large leakage magnetic flux. This is the actual situation.

In the case of a three-phase transformer, when a balanced three-phase current is passed through the three-phase windings of U, V, and W, the leakage magnetic flux distribution of the windings divided within the oil tank wall facing the windings is investigated. It becomes larger as it faces towards the front.

Therefore, simply attaching a strip-shaped magnetic shielding plate in the same direction as the magnetic flux only to the oil tank wall facing each winding has a considerable effect, and in reality, it is often attached only to this part.

However, when each winding terminal is pulled out into the bushing pocket through the oil tank wall, it is necessary to divide the magnetic shielding plate in order to pass through a through hole provided in the oil tank wall facing the front of the winding.

As a result, magnetic resistance increases and leakage magnetic flux invades the oil tank wall around the through hole, resulting in increased loss and local overheating, making it impossible to achieve a sufficient shielding effect.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide a stationary induction electric appliance that can provide effective magnetic shielding by considering the leakage magnetic flux distribution on the wall of an induction electric oil tank.

Embodiments of the present invention shown in the drawings will be described below.

As shown in FIGS. 1 to 3, an induction electric appliance main body 3 in which windings 2a, 2b, and 2c of each phase are wound around three main legs of an iron core is housed in an oil tank 4, and each phase winding 2a, 2b, 2
c. A strip-shaped magnetic shielding plate 5 made of laminated silicon steel strips is attached to the inner surface of the wall of the oil tank 4 facing the front.

The terminal beams 7 of the phase windings 2a, 2b, and 2c pass through the through holes 6 formed in the wall of the oil tank 4 and are guided into the bushing pocket 8 provided on the outside of the wall of the oil tank 4.

In this case, the through hole 6 should avoid the mounting part of the magnetic shielding plate 5,
They are provided at laterally offset positions within the winding height.

Therefore, with this configuration, the lead through hole 6
The magnetic shielding plate 5 is no longer divided around the periphery, and the leakage magnetic flux of the winding is prevented from entering into the oil tank wall through the gap in the magnetic shielding plate 5. The magnetic shielding of the leakage magnetic flux of the winding on the magnetic shielding plate is further improved. It can be done effectively.

Furthermore, since the magnetic shielding plate 5 is not divided, the 50 types of magnetic shielding plates are unified, and there is also the advantage that the manufacturing and assembly operations thereof are simplified.

As described above, in this invention, each winding terminal is pulled out from the oil tank wall facing the front of each phase winding at a position laterally shifted from the front of the winding, so there is no need to divide the magnetic shield plate in the longitudinal direction in front of the winding. It becomes possible to enhance the effect of reducing the loss generated in the oil tank wall due to the winding leakage magnetic flux, and it is possible to provide a high-quality stationary induction electric appliance with low loss and no local overheating.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the stationary induction electric appliance of the present invention;
Figure 2 is a front view of Figure 1 taken along the line ■ and viewed in the direction of the arrow, and Figure 3 is a side view of Figure 1 taken along the line ■-■ and viewed in the direction of the arrow. . 1... Iron core, 2a, 2b, 2c...
...Each phase winding, 3...Induction electric appliance body, 4...
... Oil tank, 5 ... Magnetic shielding plate, 6 ...
...Through hole, 7...Lead, 8...Bushing pocket.

Claims (1)

[Scope of utility model registration request] The induction electric device, in which the windings of each phase are wound around the three main legs of the iron core, is housed in an oil tank, and a magnetic shielding plate is attached to the inner surface of the oil tank wall facing each phase winding, and magnetic shielding plates are installed on the inner surface of the oil tank wall facing each phase winding. A stationary induction electric appliance, wherein the lead is drawn out into a bushing pocket through a through hole formed in the oil tank wall, and the through hole is provided at a position avoiding a mounting part of the magnetic shielding plate.