JPS6258643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transformer winding structure, and is particularly applicable to a transformer having a case in which a plurality of windings are arranged concentrically on a core leg and which fits within the limits of railway transport. Concerning optimal transformer winding structure.

Transformers designed for rail transportation must have an external shape that does not exceed the rail transportation limits specified by the authorities. An example of a transformer adapted to this railway limit is shown in FIG. 1 and will be described.

The transformer shown in FIG. 1 is an example of an autotransformer, and a sectional view of the main parts around the winding section is shown. As shown in the figure, a tertiary winding 2, a shunt winding 3, and a series winding 4 are arranged concentrically outside an iron core 1, and housed in a tank 5 filled with oil. In the series winding 4, a high voltage line terminal U is drawn out from the center of the winding, and the upper and lower terminals are connected to a medium voltage line terminal U of the shunt winding. Generally, in the case of concentric winding, the high voltage winding is placed on the tank wall side. FIG. 2 shows in detail the arrangement relationship between the series winding 4 and the tank 5. Due to the railway transport limit 6 shown in Figure 1, the tank 5
As shown in FIG. 2, the tank width is smaller in the range _B3 facing the upper and lower terminals u' than in the range _B1 facing the high voltage line terminal U. Because of this configuration, for example, EHV (Extra High
Voltage) class autotransformer, high voltage line is 500KV
The upper and lower terminals connected to the medium voltage line are
It is a 275KV terminal. The potential gradient at the high-voltage line terminal portion is almost the same as that at the upper and lower end portions where the width of the tank is reduced. In other words, as shown in FIG. 2, the series winding is constructed by sequentially arranging twin coils A ₁ . . . consisting of two disc coils a formed by winding the conductor 10. Here twin coils
The insulation distance between A ₁ , A _o and the tank 5 facing each other is
Let l ₁ and l ₂ be the generated voltages of A ₁ and A _o as V ₁ and _Vo , respectively. Then, the insulation distance l ₁ is such that V ₁ /l ₁ ≒V _o /l ₂ .
The relationship between and l ₂ has been determined.

In such a conventional series winding configuration, when the outermost diameter of the series winding 4 becomes large due to the transformer specifications and structure, the tank 5 at the high voltage line terminal area is within the railway transport limit 6, and to some extent In this case, the rise in potential gradient at the center of the series winding 4 can be suppressed by increasing the tank width. However, the tank width of the upper and lower terminals of the series winding is determined by the current railway limit 6, and the tank width is determined by the current railway transport limit 6, and since the tank width cannot be increased, the insulation distance l ₂ becomes smaller. Therefore, the potential gradient at that part increases,
This reduced the reliability of the insulation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transformer winding structure that suppresses an increase in potential gradient at upper and lower terminals of a series winding, and maintains reliability of insulation while keeping the voltage within the railway limit.

In the present invention, the winding facing the tank 5 is composed of a plurality of twin coil sections, and the twin coil sections arranged at the upper and lower ends of the winding where the tank width becomes smaller are composed of coils with a small number of turns. Further, by providing an insulator on the side of the coil facing the tank wall, the insulation dimension between the coil surface and the tank wall is ensured.

FIG. 3 is a cross-sectional view showing the series winding portion of the embodiment of the present invention. In FIG. 3, the same members and parts used in FIG. 2 are given the same reference numerals. Moreover, the description of the overall structure of the transformer will be omitted since it will be redundant. In FIG. 3, the series winding 4 consists of a plurality of twin coils A ₁ , A ₂ . . . A _o . The coils are sequentially arranged from the high-voltage line terminal U side to the upper and lower terminals U' side connected to the medium-voltage line terminal.
Furthermore, shield rings 11 are provided at each of the upper and lower ends of the series winding 4 to improve electric field concentration in the end coils.
is placed. Further, as shown in FIG. 3, the tank 5 has a tank wall B ₁ corresponding to the railway transportation limit 6.
(tank width is large), tank wall B ₂ parts (tank diagonal part), and tank wall B ₃ parts (tank width small) are arranged.

Of these tank walls, at least the tank wall
For the twin coil group facing the _three parts of B (from A _o-1 to u' in the figure), the number of turns of the conductor is reduced, and the space created by this is secured on the tank wall side.
The insulator 12 is attached to this part. Note that the reduced number of turns is distributed to the twin coils facing the tank wall _B1 , so that the overall number of turns of the series winding 4 does not change. When providing the insulator 12, the width should be the same as that of only the twin coils to facilitate the coil insertion and fixing work, and the material of the insulator 12 may be, for example, pressboard.

In this configuration, the distance between the twin coils A ₁ and A _o and the opposing wall of the tank 5 is l ₁
and l ₂ , and the voltages generated by the twin coils A ₁ and A _o are V ₁ and V _o , respectively, then determine the insulation distance l ₂ so that V ₁ /l ₁ =V _o /l ₂ , i.e. By determining the dimensions of the insulator 12 and adjusting the winding of the coil accordingly, insulation reliability of the winding can be ensured.

As is clear from the above, according to the present invention, it is possible to suppress the increase in the potential gradient of the upper and lower terminal portions of the high-voltage winding of the transformer with respect to the tank wall, so that the reliability of the winding can be ensured.

Although the above explanation uses an autotransformer as an example, the present invention is not limited to this, but can be applied to any transformer that has a configuration in which the windings are concentric and the high voltage side winding is placed on the tank wall side. It is.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a conventional autotransformer, Fig. 2 is a sectional view showing the vicinity of the series winding of the conventional transformer, and Fig. 3 is a sectional view of the main part showing an embodiment of the present invention. It is a diagram. 1... Iron core, 2... Tertiary winding, 3... Shunt winding, 4...
Series winding, 5...tank, 6...rail transport limit, 10
...Conductor, 11...Shield ring, 12...Insulator.

Claims (1)

[Claims] 1 At least a low-voltage winding and a high-voltage winding are installed concentrically in a tank whose ends are narrower than the center, and at least the end of the high-voltage winding is located at the end of the tank. In a transformer having a structure close to an inner wall surface, on the end side of the high voltage winding and facing the inner wall surface of the tank,
A transformer winding structure, characterized in that an insulator is installed so that the winding width is the same as the width of the center portion of the high voltage winding.