JPH0218909A - Disc winding for induction electric apparatus - Google Patents

Abstract

PURPOSE:To obtain minimum oil flow rate necessary and sufficient for cooing horizontal cooling passages in cooling zones and to avoid partly excessive temperature rise by gradually reducing the number of the cooling passages composed in the zones from the lower part to the upper part of a disc winding. CONSTITUTION:The number of horizontal cooling passages composed in one cooling zone is reduced gradually from the lower part to the upper part of a disc winding 3, i.e., an interval between inner and outer blocking plugs 10a, 11a is gradually reduced from the upper part to the lower part. Accordingly, an oil flowing speed distribution 13 in each horizontal cooling passage when insulating fluid flows to the winding 3 is such that the oil flowing speed is increased since the number of the passages is less in the cooling zone of the upper part of the winding. Thus, sufficient oil flowing speed necessary to cool the passages is obtained in each zone, a partial excessive temperature rise is avoided, and it is effectively cooled thereby to reduce a winding highest temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Operational Application) The present invention relates to an induction electric disc winding that is cooled by natural convection of oil.

(Prior Art) Conventionally, a disk winding used as a winding of an induction electric device such as a transformer is constructed as shown in FIG. That is, a plurality of disc windings 3 each formed by winding a wire conductor between an inner insulating cylinder 1 and an outer insulating cylinder 2 are stacked in multiple stages at equal intervals in the axial direction, and each disc winding is stacked at equal intervals in the axial direction. are electrically connected in series by crossover wires. A plurality of horizontal corner pieces 4 are arranged radially at equal intervals between each disc winding 3, and a radial horizontal cooling path 5 is formed between each disc winding 3.
Vertical corner pieces 6 and 7 are provided between the outer insulating cylinders 1 and 2 and each of the disc windings 3 at positions corresponding to the horizontal corner pieces, so that the disc windings 3 are connected to the inner and outer sides. An inner vertical cooling passage 8 and an outer vertical cooling passage 9 communicating with the horizontal cooling passage 5 are formed between the insulating cylinders 1 and 2, respectively. The insulating oil is stored together with insulating oil in a tank (not shown), and the insulating oil is circulated in each cooling path by natural convection of the insulating oil to cool the windings.

In order to further enhance the cooling effect of this type of disc winding, the fourth
As shown in the figure, an inner blocker 10 and an outer blocker 11 are installed along the entire circumference of every several stages of the disc winding so that one cooling zone is formed by several stages of the disc winding 3. The vertical cooling passages 8 and 9 are alternately provided and are alternately closed on the inside and outside.

Therefore, the insulating oil flows between each disk winding 3 in a zigzag pattern with the insulating oil inlet and outlet reversed inward and outward in each cooling zone, thereby efficiently cooling the entire winding. I am doing it.

(Problem to be Solved by the Invention) However, even in the disk winding having the above structure, there is a certain block partitioned by an inner blocker 10 and an outer blocker 11.
Looking at the flow of insulating oil that branches into each horizontal cooling passage 5 in the two cooling zones, it is found that it is not necessarily uniform, and generally the oil flow in the upper horizontal cooling passage 5 near the insulating oil outlet. The velocity is very small compared to the oil flow velocity in the lower horizontal cooling path 5 near the insulating oil inlet, and this tendency is more pronounced in the upper part of the disc winding. . That is, when looking at the oil flow velocity distribution in each horizontal cooling path 5 in such a disk winding, it becomes smaller as it approaches the insulating oil outlet, as shown by the dotted arrow 12 in FIG. The difference in flow velocity within roughly one cooling zone is
The upper part of the disc winding is very large. In some cases, stagnation or backflow of insulating oil may occur near the outlet in the cooling zone above the disc winding.

FIG. 5 shows the winding temperature rise and average oil temperature rise in the vertical cooling path in such a case. Near the bottom of the disc winding, the oil flow velocity in the horizontal cooling path is relatively uniform, so the difference between the winding temperature rise and the average oil temperature rise is almost constant, which is due to the This shows that the heat transfer coefficient to the insulating oil is almost constant.

On the other hand, in the upper part of the disk winding where there is a large difference in oil flow velocity in the horizontal cooling path, the winding temperature in one cooling zone, especially near the upper outlet, increases significantly, and the oil flow velocity increases. This indicates that the heat transfer rate deteriorated due to the slowness.

Therefore, compared to the disc winding 3 located near the inlet, the disc winding 3 located near the outlet is not sufficiently cooled, and the inner and outer plugs 10 and 11 are attached to the winding. Even if insulating oil is passed through the entire wire in a zigzag pattern, the expected cooling effect of the disk winding 3 cannot be obtained, especially in the upper cooling zone, so the winding temperature rise is not uniform. This has the disadvantage that excessive temperature rise occurs locally, degrading the winding insulation and shortening the life of the transformer.

As a countermeasure for such problems, it is possible to increase the cross-sectional area of the wire conductor forming the disc winding 3 to lower the current density, and to increase the current density by increasing the current density by increasing the cross-sectional area of the wire conductor forming the disc winding 3. It is also possible to use a winding cooling design, but either method has the drawback of making the transformer larger.

The present invention eliminates the above drawbacks, secures the minimum oil flow velocity necessary and sufficient for cooling each horizontal cooling path in each cooling zone without increasing the size, avoids excessive temperature rise in some parts, and is effective. The purpose of this invention is to obtain a naturally cooled induction electric disc winding that can be cooled in a natural manner.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides blocking plugs alternately inside and outside along the entire circumference of the disc winding in the inside and outside vertical cooling paths. In an induction electric disk winding in which an insulating fluid flows in a zigzag pattern, the number of horizontal cooling paths in one cooling area gradually decreases from the bottom to the top of the disk winding. Also, the interval between the outer obstructing plugs is gradually reduced from the lower part to the upper part.

(Function) As a result, in each cooling zone, sufficient oil flow velocity is ensured for cooling each horizontal cooling path, avoiding excessive temperature rise in some areas, and cooling effectively.

In particular, it reduces the maximum winding temperature.

(Example) An example of the present invention will be described below with reference to FIG. In the figure, the same parts as in FIG. 4 are indicated by the same reference numerals.

In the disc winding of the present invention, a plurality of disc windings 3 made by winding a wire conductor between an inner insulating cylinder 1 and an outer insulating cylinder 2 are stacked in the axial direction, and each disc winding is 3 are electrically connected by crossover wires.

A plurality of horizontal corner pieces are arranged radially at equal intervals between each disc winding 3, forming a radial horizontal cooling path 5 between each disc winding 3, and Vertical corner pieces are provided between the insulating tubes 1 and 2 and the disk winding 3 at positions corresponding to the horizontal corner pieces, so that the disk winding 3 and the inner and outer insulating tubes 1,
An inner vertical cooling passage 8 communicating with the horizontal cooling passage 5 and an outer vertical cooling passage 9 are formed between the two.

The inner vertical cooling passage 8 and the outer vertical cooling passage 9 configured in this way are provided with an inner blocking plug 10a and an outer blocking plug 11a along the entire circumference of the disc winding 3 every several stages of the disc winding 3. Attach each alternately. Here, in the present invention, the number of horizontal cooling paths in each cooling zone formed by the inner blocker 10a and the outer blocker 11a is gradually reduced from the bottom to the top of the disc winding, that is, the inner blocker 10a The interval between the outer obstructing plugs 11a is gradually reduced from the lower part to the upper part.

The oil flow velocity distribution 13 in each horizontal cooling path when the insulating fluid flows through the disk winding configured in this way is as follows: The oil flow velocity increases, and the oil flow velocity necessary and sufficient for cooling is ensured even in the upper horizontal cooling passage near the outlet. In addition, since the oil flow velocity was originally uniform in the cooling zone at the bottom of the disc winding, even if the number of horizontal cooling channels increases slightly, the flow velocity will only decrease slightly and the oil flow necessary and sufficient for cooling will be maintained. Speed is still guaranteed. Therefore, the heat transfer coefficient in the axial direction of the disc winding is made uniform, and the difference between the winding temperature rise and the average oil temperature rise becomes almost constant in the vertical direction, as shown in FIG. For comparison, the winding temperature rise in the conventional case (FIG. 5) is also shown.

In addition, as the oil flow velocity increases at the top of the disc winding, the flow path resistance also increases, but this is canceled out by the decrease in flow path resistance due to the decrease in oil flow speed at the bottom of the disc winding. There is almost no effect on the total flow rate of insulating oil.

Therefore, it is possible to obtain a uniform cooling effect on the entire disk winding, and it is possible to eliminate the disadvantage that the temperature rise in the upper winding becomes excessively high.

This makes it possible to reduce the cross-sectional area of the stranded conductor and increase the current density, thereby improving the cooling effect and reducing the size and weight.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of stages of disc windings are arranged between the inner and outer insulating cylinders, and a plurality of horizontal corner pieces are interposed between each disc winding, thereby forming a plurality of horizontal cooling paths. a plurality of vertical corner pieces are interposed between the inner and outer insulating cylinders and the disc winding, and an inner side communicates with the horizontal cooling path;
An outer vertical cooling path is formed, and plugs are provided alternately inside and outside the inner and outer vertical cooling paths along the entire circumference of the disc winding so that the plurality of horizontal cooling paths constitute one cooling area. In the induction electric disk winding, the number of horizontal cooling channels configured in one cooling section is gradually decreased from the bottom to the top of the disk winding, that is, the distance between the inner and outer plugs is increased from the bottom to the top. The design has been gradually reduced in size over the course of the cooling process, so that the oil flow velocity is sufficient to cool each horizontal cooling path in each cooling zone without increasing the size, and it is possible to avoid excessive temperature rise in some areas, especially in the upper part of the winding. Therefore, it is possible to obtain a naturally cooled induction electric disc winding that can effectively cool down the maximum temperature of the coil.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between height and temperature rise corresponding to Fig. 1, and Fig. 3 is a diagram showing a general induction electric disk winding. FIG. 4 is a cross-sectional view taken along line I-I in FIG. 3 showing a conventional induction electric disc winding, and FIG. 5 shows the relationship between height and temperature rise corresponding to FIG. 4. FIG. 1...Inner insulation tube, 2...Outer insulation tube, 3.
...Disc winding, 4...Horizontal corner piece, 5...
Horizontal cooling path, 6°7... Vertical corner piece 8... Inner vertical cooling path, 9... Outer vertical cooling path, 10.10a... Inner blocking plug, 11, 118... Outer blocking Plug, ...Oil flow velocity distribution.

Claims (1)

[Claims] A plurality of stages of disc windings are arranged between the inner and outer insulating cylinders, and a plurality of horizontal corner pieces are interposed between each disc winding to form a plurality of horizontal cooling passages. and a disc winding, a plurality of vertical corner pieces are interposed between the inner and outer vertical cooling passages that communicate with the horizontal cooling passage, and the plurality of horizontal cooling passages constitute one cooling area. Inside along the entire circumference of the disc winding, into the inside and outside vertical cooling channels so that
In the induction electric disk winding in which blocking plugs are provided alternately on the outside, the number of horizontal cooling paths configured in the cooling area is gradually reduced from the bottom to the top of the disk winding. Cooled induction electric disk winding.