JPH01293507A - Stationary induction apparatus - Google Patents

Abstract

PURPOSE:To obtain a foil winding type stationary induction apparatus in which local overheating caused by eddy currents concentrated to the upper and lower end of its winding can be suppressed and whose reliability can be improved by a method wherein the foil winding is divided into a plurality of windings and the divided windings are classified into the upper winding group and the lower winding group with the center of the axial direction as a boundary and the upper group windings and the lower group windings are connected in parallel with each other and the divided windings in the upper group and the divided windings in the lower group are connected in series respectively. CONSTITUTION:A stationary induction apparatus has foil windings which are formed by putting metal sheets upon insulating sheets and winding around a metal leg 1. The foil winding is divided into a plurality of windings and the divided windings are classified into the upper winding group and the lower winding group with the center of the axial direction as a boundary and the upper group windings and the lower group windings are connected in parallel with each other and the divided windings in the upper group and the divided windings in the lower group are connected in series respectively. For instance, an outer winding 2b is divided into four windings A, B, C and D and the widths of the metal sheets forming the respective divided windings A, B, C and D are approximately equal. The divided windings B and C are connected to a high voltage lead side (u) and the divided windings A and D are connected to a neutral lead side (n). With the center of the axial direction as a boundary, the upper windings A and B and the lower windings C and D are connected in parallel with each other and, further, the winding A is connected to the winding B in series and the winding C is connected to the winding C in series. An inner winding 2a has a structure same as the structure of the cuter winding 2b.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to stationary induction appliances.

[Conventional technology]

Stationary induction appliances equipped with foil windings made of metal sheets around the core legs have a better space factor than induction appliances using regular windings, so they have the advantage of being smaller and lighter; It has been put to practical use in low-voltage, small-capacity transformers of several tens of kVA and several hundred kVA. Recently, in view of the excellent advantages of such foil-wound transformers, research has been actively conducted to expand their application to higher voltage and larger capacity transformers, such as 275 kV and 100 MVAR (7).

[Problem to be solved by the invention]

A major research issue remains as to how effectively the above-mentioned conventional technology can solve the biggest drawback of foil-wound transformers, which is localized overheating caused by eddy currents concentrated near the upper and lower ends of the windings. This will be explained with reference to FIG. When the iron core #1 is composed of an inner winding 2a and an outer winding 2b of foil winding, for example, in the outer winding 2b, the metal sheet 3 is connected from the neutral lead side n to the high voltage lead side U. Since the windings are continuously wound with a constant width up to Eddy currents will occur. This shows the relationship between the winding position on the vertical axis and the radial magnetic flux density on the horizontal axis.As shown in Figure 8(a), the upper and lower ends of one winding This is a phenomenon that occurs because the radial component of the leakage magnetic flux, which is maximum in the vicinity, interlinks the foil winding.The vertical axis shows the position of the winding, and the horizontal axis shows the current value, and the relationship between these two is plotted. As shown in the same figure (b) where is shown.

The state of the current distribution is such that the upper and lower ends of the winding are several times higher than the center, which may cause the problem of local overheating where the temperature locally becomes high in these areas.

Therefore, as a countermeasure to solve this phenomenon, Japanese Patent Laid-Open Nos. 61-194804 and 58-182212 have been proposed.
In the publication, there is an idea to change the material of the sheet so that the conductivity becomes higher near the edge of each sheet, but changing the material locally has poor workability and is difficult to put into practical use. Also,
JP-A No. 59-11607 attempts to alleviate the concentration of eddy current by dividing the foil winding in the axial direction and transposing them to each other, but a special device is required for dislocation of the wide foil winding. is required and is generally quite difficult.

The present invention has been made in view of the above points, and an object of the present invention is to provide a foil-wrapped stationary induction electric appliance that suppresses local overheating due to eddy currents concentrated at the upper and lower ends of the winding, and improves reliability. It is something to do.

[Means to solve the problem]

The above purpose is achieved by dividing the foil winding into a plurality of pieces in the axial direction, connecting the upper and lower winding groups in parallel with the axial center as the boundary, and connecting the winding groups in series at each upper and lower part. achieved.

[Effect]

In addition to dividing the foil winding into multiple pieces in the axial direction, the winding groups above and below the axial center are connected in parallel, and the winding groups at the top and bottom of each are connected in series, so that the leakage magnetic flux is reduced in the radial direction. Eddy currents are no longer induced by the components, and problems such as localized temperature rises caused by this can be resolved.

〔Example〕

The present invention will be explained below based on the illustrated embodiments. An embodiment of the invention is shown in FIGS. 1 and 2. FIG. Note that the same parts as in the past have been given the same reference numerals, so their explanations will be omitted. In this embodiment, the foil winding is divided into a plurality of parts in the axial direction, and the upper and lower winding groups are connected in parallel with the axial center as the boundary. In addition, the winding groups were connected in series at each top and bottom. By doing this, eddy currents due to the radial component of leakage magnetic flux are no longer induced, suppressing local overheating due to eddy currents concentrated at the upper and lower ends of the winding, and improving reliability. A stationary induction appliance can be obtained.

That is, an inner winding 2a and an outer winding 2b, each made of a foil winding in which a metal sheet and an insulating sheet are wound in layers, are concentrically wound around the core leg 1 of the transformer. 2a
, 2b have almost the same structure, therefore, detailed description of the inner winding 2a is omitted not only in this embodiment but also in the detailed explanation of the present invention. The outer winding 2b is composed of winding groups A, B, C, and D divided into four in the axial direction, and the widths of the metal sheets constituting the winding groups A, B, C, and D are approximately equal. Windings B and C are on the high voltage lead side U.
And winding A on the neutral point lead side n.

D is connected to each other. As shown in Fig. 2, each divided foil winding A, B, C, and D is
Upper and lower windings A, B and windings C, D are connected in parallel with the axial center as a boundary, and windings A, B2, and D are connected in series, respectively.

By doing this, windings A, B and winding C,
A closed circuit that serves as a path for eddy current is not formed between D.
Further, in the closed circuit connecting the windings A and B and the windings C and D, interlinking radial leakage magnetic fluxes are canceled out in positive and negative directions, so that almost no induced voltage that causes eddy current is generated. As a result, the concentration of eddy currents normally seen in the windings at the upper and lower ends is greatly alleviated, and a highly reliable transformer without local overheating can be obtained.

As described above, in this embodiment, the foil winding group is divided into four parts in the axial direction, but it goes without saying that it is also possible to divide the foil winding group into an even number of more parts and connect them in the same way. In this case, by manufacturing each winding group individually and connecting the windings based on this example, the phenomenon of concentration of eddy current, which is a drawback of the conventional method, can be significantly alleviated, and manufacturing is also extremely easy. Moreover, there is the advantage that a highly reliable transformer can be obtained.

In this way, according to this embodiment, the foil winding is divided into a plurality of pieces in the axial direction, and the windings are connected in such a way that circulating eddy currents do not flow. Eddy currents concentrated at the ends can be effectively reduced without taking measures such as dislocation, and problems such as local temperature rise caused by loss concentration can be easily solved.

Another embodiment of the invention is shown in FIG.

As shown in Figure (a), the outer winding 2
b is divided into three odd numbers, the central winding F connected to the high voltage lead side U is common, and windings 11E and 11G are connected to this as shown in the same figure (b). As if
Connected in series or in parallel.

In this case as well, the same effects as in the case of the winding group divided into even numbers described above can be achieved.

FIG. 4 shows yet another embodiment of the invention. The width Q1 of the metal sheet of windings 0 and T at the upper and lower ends where eddy currents tend to concentrate especially among the windings divided into an even number of windings, and the width aX of the metal sheet of windings p and s near the center. Winding Q, R
The width Q3 of the metal sheet is made smaller than the width Q3 of the metal sheet, and the eddy current that circulates only within the width of the metal sheet is also reduced as much as possible. In other words, it takes advantage of the property that the loss caused by eddy current changes approximately in proportion to the square of the width of the metal sheet, and in combination with the above-mentioned effect of reducing the eddy current circulating between each winding group, it is more effective than the case described above. It becomes possible to prevent concentration of eddy currents and local overheating caused by this.

FIG. 5 shows still another embodiment of the present invention. This embodiment is an example in which the current is relatively large, and the metal sheets constituting each winding group wound around the core are Two metal sheets 3a and 3b were connected in parallel. Generally, if such a parallel configuration is used, there is a concern about the circulation of eddy currents caused by the axial component of leakage magnetic flux, but since the metal sheet is extremely thin, ranging from several tens of micrometers to several hundred micrometers, such foil-wound transformers The magnetic flux that interlinks between the parallel sheets is small, and eddy currents, which are often considered a problem, do not occur. Therefore, with the winding connection configuration as shown in FIG. 1 described above, it is possible to use two or more metal sheets in parallel as in this embodiment to cope with cases where the current flowing is large.

FIG. 6 shows yet another embodiment of the invention. This embodiment shows a winding configuration of a transformer with a relatively high voltage. The connection form of the winding groups divided in the axial direction is the same as in the case of FIG.

2, the windings w, x, y,
A part of the end face of z has an inclined shape. In order to realize such a winding shape, many methods are used, such as winding a metal sheet 3 whose width is changed in advance, or changing the width while bending the ends of a metal sheet of the same width. can. By doing so, even a transformer with a relatively high voltage can achieve the same effects as in the above case.

In the embodiments shown in FIGS. 5 and 6, the number of windings divided in the axial direction is four.

Needless to say, the present invention can also be applied to cases where the number of windings is varied or the width of the metal sheet is varied.

Although the above embodiments have been described with respect to transformers, the present invention can also be applied to other static induction devices such as induction voltage regulators, reactors, etc., and the same effects can be achieved.

〔Effect of the invention〕

As described above, the present invention suppresses local overheating due to eddy currents concentrated at the upper and lower ends of the winding, improving reliability. It is possible to obtain a foil-wrapped stationary induction appliance that can be improved.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view of an embodiment of the stationary induction electric appliance of the present invention, Fig. 2 is an explanatory diagram showing the connection of the winding group in Fig. 1, and Fig. 3 (a) and (b) are the inventive invention. Fig. 4 shows another embodiment of the static induction electric appliance of the present invention, (a) is a longitudinal sectional side view, (b) is an explanatory diagram showing the connection of the winding group of (a), and Fig. 4 shows the static induction electric power of the present invention. FIG. 5 is a partial vertical side view of still another embodiment of the stationary induction appliance of the present invention, and FIG. 6 is a partial longitudinal side view of still another embodiment of the stationary induction appliance of the present invention. Figure 7 is a vertical side view of a conventional stationary induction appliance, Figure 8 is a vertical side view of a conventional stationary induction electric appliance.
(a) and (b) explain the problems of conventional static induction electric appliances. (a) is a characteristic diagram showing the relationship between the axial height of the winding and the radial magnetic flux density, and (b) is the same as that of the winding. FIG. 3 is a characteristic diagram showing the relationship between the height of the current and the current value. DESCRIPTION OF SYMBOLS 1... Iron core leg, 2a... Inner winding, 2b... Outer winding, 3.3a, 3b... Metal sheet. High school 1st grade (b) High school 5th grade Ka6th 3--Ichireiho sheet

Claims (4)

[Claims] 1. In a stationary induction electric appliance equipped with a foil winding formed by overlapping a metal sheet and an insulating sheet and winding them around a core leg, the foil winding is divided into a plurality of pieces in the axial direction, and the foil winding is divided into a plurality of pieces along the axial center. A stationary induction electric appliance characterized in that upper and lower winding groups are connected in parallel, and each upper and lower winding group is connected in series. 2. The stationary induction electric appliance according to claim 1, wherein the foil winding is formed such that the sheet width is narrower as the winding is closer to the upper and lower ends. 3. The stationary induction electric appliance according to claim 1, wherein the metal sheet is a group of metal sheets connected in parallel in the radial direction. 4. 2. The stationary induction electric appliance according to claim 1, wherein a gap size between opposing winding wire groups divided in the axial direction changes in accordance with electric field strength.