JPH01196108A - stationary induction appliance - Google Patents

Abstract

PURPOSE:To inhibit partial overheat due to eddy currents concentrating on the upper and lower ends of windings, and to improve reliability by changing the sectional areas of metallic sheets almost continuously every wound layer. CONSTITUTION:Metallic sheets constituting internal and external windings 2a, 2b are wound in the state in which they are bent at the end sections of coils positioned at upper and lower ends. Bending lengths l, l0 are lengthened toward an inside section near a leg 1 in the internal winding 2a and toward an outside section near a tank 4 in the external winding 2b, and the relationship of l>l0 is held. A metallic sheet 5a for the internal winding 2a is made so that the width of the metallic sheet 5a is increased linearly toward the inside section while a metallic sheet 5b for the external winding 2b is made so that the width of the metallic sheet is increased linearly toward the outside section, and these metallic sheets 5a, 5b are bent along the lines shown by dotted lines so that the widths of the windings are constant. According to the constitution, a foil winding, winding width of which is held constant in the radial direction easily and the sectional areas of the metallic sheets 5a, 5b of which continuously change, can be formed.

Description

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

[Conventional technology]

Foil-wrapped stationary induction appliances that have foil windings made of metal sheets around the core legs have a better space factor than induction appliances that use regular windings, so they have the advantage of being smaller and lighter.
It has already been put to practical use in low-voltage, small-capacity transformers of several tens of kVA or 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, larger capacity transformers, such as 275 kV and 100 MVA class transformers.

[Problem to be solved by the invention]

As mentioned above, research is actively being conducted to expand the application of foil-wound transformers to high-voltage, large-capacity transformers, but the biggest drawback of foil-wound transformers is that eddy currents concentrate near the top and bottom ends of the windings. How to effectively solve the local overheating caused by this remains a major research issue. That is, as shown in FIG. 9, which shows a foil-wound transformer, when a load current flows through the inner winding 2a and the outer winding 2b of the foil winding wound around the core leg 1, Leakage magnetic flux as shown by the dotted line in the figure occurs (see (a) in the figure), and when this radial component enters each sheet, large loop-shaped eddy currents are generated at the upper and lower ends of each winding. As shown in the same figure (b), the load currents are superimposed, resulting in a particularly high current density in the inner part P of the inner winding 2a and the outer part S of the outer winding 2b, resulting in localized overheating that locally becomes high temperature in these areas. may cause problems.

Therefore, as a countermeasure to solve this phenomenon,
1- ], Publication No. 994807 and Japanese Unexamined Patent Publication No. 1822-1982
Publication No. 12 describes changing the material of the sheet so that the conductivity is increased at the end of each sheet and the outer part of the inner winding, but changing the material partially is difficult to work with. There are aspects that make it difficult to put it into practical use. Also, JP-A-59-], 1607
The publication attempts to alleviate the concentration of eddy currents by dividing the foil winding in the axial direction and transposing them to each other, but transposition of wide foil windings is difficult to do using normal methods, and special measures are required. It takes. Furthermore, in Japanese Patent Application Laid-Open No. 58-219720, the bending width of the can end is widened in the direction toward the outside of the winding to gradually reduce the apparent height of the winding. Therefore, it is insufficient as a measure to prevent local overheating.

The present invention has been made in view of the above points, and an object of the present invention is to provide a stationary induction electric appliance that suppresses local overheating due to overcurrent concentrated at the upper and lower ends of the winding and improves reliability. be.

[Means to solve the problem]

The above object is achieved by varying the cross-sectional area of the metal sheet 1- almost continuously for each winding layer.

[Effect]

Since the cross-sectional area of the metal sheet is changed almost continuously for each winding layer, the cross-sectional area of the metal sheet 1- changes in accordance with the distribution form of the eddy current concentrated at the upper and lower ends of each sheet 1-, i.e. The cross-sectional area of parts with large eddy currents can be made large, and the cross-sectional area of parts with small eddy currents can be made small, which prevents eddy currents from concentrating and creating a high current density, which increases the local temperature by 1. Problems such as these can be solved, and the reliability of stationary induction appliances can be improved.

〔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 reference numerals have been used for parts that are the same as those in the prior art, so a description thereof will be omitted. In this example, the cross-sectional area of the metal sheet was changed almost continuously for each winding layer. By doing this, the cross-sectional area of the metal sheet changes in accordance with the distribution form of eddy currents concentrated at the lower ends of each seam, thereby preventing local overheating due to eddy currents concentrated at the upper and lower ends of the winding. It is possible to obtain a stationary induction electric appliance that suppresses the noise and improves reliability.

That is, an inner winding 2a and an outer winding 2b, which are made of foil windings in which a metal sheet and an insulating sheet are wound in layers, are wound concentrically around the iron core leg 1 of the transformer. Clamps 3 are provided to support the transformers, and the contents of these transformers are housed in a tank 4.

Note that the inner winding 2a and the outer winding 2b have a structure in which they are divided into four parts in the axial direction, but this is due to the fact that as the capacity of foil-wound transformers increases, it becomes difficult to manufacture a metal sheet with the same width as the foil-wound transformer.
It was also adopted in order to avoid manufacturing inconveniences such as poor winding workability. Each time, the metal sheath 1- constituting the outer windings 2a, 2b is wound with the ends of the coils located at the upper and lower ends bent.

As shown in FIG. 1, the bending length of this bending portion is shown as Q for the inner winding 2a and [0 for the outer winding 2b. In the case of the outer winding 2b, the outer part near the tank 4 has a bending length Q.

flo is long, and the relationship is Q > Q o.

The bending lengths Q and QO of such bending portions are determined by the eddy current generated by the radial component of the leakage magnetic flux from the inner and outer windings 2a and 2b, as mentioned in the explanation of the prior art above. determined by the size of That is, the bending length Q and Ω0 were increased in areas where eddy currents were large, so that the cross-sectional area of the metal sheet was increased and the electrical resistance was decreased. In particular, in the inner part of the inner winding 2a, which is close to the core leg 1 and where the radial component of the large leakage magnetic flux enters, the bending length Q of the bent part is the longest and the cross-sectional area of the metal sheet is the largest. .

These new foil windings are shown in Figures 2 (a) to (d).
It can be constructed by winding a metal sheet as shown in .

That is, the metal sheet 5a of the inner winding 2a is arranged so that the width of the metal sheet increases linearly at the inner side, while the metal sheet 5b of the outer winding 2b is arranged so that the width of the metal sheet increases linearly at the outer side. These metal sheets 5a and 5b were bent and wound at the dotted line positions in the figure so that the winding width was constant.

By doing this, it is easy to create a foil winding in which the winding width is constant in the radial direction and the cross-sectional area of the metal sheets 5a and 5b continuously changes as shown in FIG. Can be configured. Therefore, according to this embodiment, 4
Among the divided foil winding groups, the cross-sectional area of the metal sheets 5a and 5b is continuously increased approximately in accordance with the degree of concentration of the eddy current of the windings at the upper and lower ends where eddy currents caused by leakage magnetic flux are concentrated, Since we have reduced the generated loss efficiently,
A highly reliable transformer that does not cause local overheating can be obtained.

Another embodiment of the invention is shown in FIG.

In this embodiment, the inner winding 2a has an almost continuous width.
metal sheet 5a for the outer winding 2b and metal sheet 5b for the outer winding 2b
The edges of each metal seam 1" 5 a are not straight lines as shown in FIG. 2 above.

It was made to follow the distribution form of the eddy current flowing through 5b as much as possible. That is, as shown in Figures (B) and (D), the curve was made to have a gentle slope at the inner side of the inner winding 2a and at the outer side of the outer winding 2b. By doing this, the metal sheets 5a, 5 can be
Since the increase in the cross-sectional area of b can be controlled, it is possible to prevent an increase in loss due to concentration of eddy currents and local overheating due to this increase in loss.

FIG. 4 shows yet another embodiment of the invention. In this embodiment, the metal sheet 5a (
(see figure (b))) and a metal seal l-5b (see figure (d)), which has a large outer cross-sectional area (see figure (d)). It was bent twice at the dotted line position (see (C) and (E) in the same figure) so that the increased cross-sectional area was particularly near the ends of the metal seams h5a and 5b. By doing so, the increase in the cross-sectional area of the metal sheets 5εh and 5b can be accurately controlled, and the same effects as in the case described above can be achieved. Although the present embodiment is bent twice, it is also possible to optimize the increase in cross-sectional area by combining multi-stage bending of two or more degrees.

FIG. 5 shows yet another embodiment of the invention. In this embodiment, a metal sheet 5 whose width is almost continuously widened is bent at its ends and wound with an insulating sheet 6 interposed therebetween. Although the metal sheet 5 was bent only once, another metal member 7 was added to the bent portion to ensure electrical conduction so that a sufficient cross-sectional area could be secured at the end of the metal sheet 5. By doing so, the apparent cross-sectional area of the end of the metal sheet is increased, and eddy current concentration at the end of the metal sheet can be alleviated more easily than in the case described above. Note that the added metal material may be the same as the metal sheet 5 to be bent, but the use of a material with higher conductivity than the metal sheet 5 has a greater effect of mitigating eddy currents.

Furthermore, it goes without saying that the same effect can be achieved by adding the metal member 7 to the metal sheet 1 without forming the bent portion at 5.

FIG. 6 shows yet another embodiment of the invention. In this embodiment, among the inner winding 2a and the outer winding 2b which are divided into four parts in the axial direction, the two windings at the upper and lower ends of the inner winding 2a are arranged so that the bending width changes up to the maximum bending length Q. The remaining two windings in the middle are also wound with a maximum bending length Q.
The bending width can be changed up to 2. In the outer winding 2b where the eddy current is relatively small, only the two windings at the upper and lower ends are bent and wound to the maximum bending length Q3.

By doing so, the cross-sectional area of the metal sheet changes over almost the entire inner winding 2a, which is particularly effective for transformers and the like in which leakage magnetic flux from the inner winding 2a increases.

FIG. 7 shows yet another embodiment of the invention. In this embodiment, the width of the wound metal sheet is kept constant and the thickness of the sheet is changed almost continuously as a means for changing the cross-sectional area of the metal sheet almost continuously11). . That is, the metal sheet 5a used for the inner winding 2a (see (a) and (b) in the same figure) is thicker on the inside as shown by the thickness tl, and the metal sheet 5b used for the outer winding 2b (see (c) in the same figure) is thicker on the inside as shown by the thickness tl. .

(d)) is thicker on the outside as shown by the thickness t2, and the cross-sectional area changes almost in accordance with the distribution form of the eddy current flowing through the metal sheets 5a and 5b. In this embodiment, the thickness of the metal sheet 1 is constant in the width direction, but if the metal sheets 5a and 5b are further bent at the ends as shown in FIG. The plate thickness also changes, and a cross-sectional area along the eddy current distribution can be realized more than in the above case, and the loss reduction effect can be improved more than in the above case.

FIG. 8 shows yet another embodiment of the invention. This example shows a case where a normal two-winding transformer is divided into two parts so that the outer winding sandwiches the inner winding (see figure (A)).
reference). This is done to disperse leakage magnetic flux from the windings, resulting in a distribution of leakage magnetic flux as shown by the dotted line in FIG. For this reason, the appearance of the radial component of the leakage magnetic flux penetrating the metal sheets constituting each winding is also different from that of a normal two-winding transformer, in that the innermost winding 2bi and the outermost winding 2b2 have inner and outer components, respectively. Eddy currents concentrate at the ends of the intermediate winding 2a (+), but rather concentrate at the intermediate ends of the intermediate winding 2a (+).Therefore, the shapes of the metal sheets constituting each of the windings 2ao, 2bz, and 2b2 also differ from those shown in FIG. As shown in d), in the innermost winding 2bx, the metal seam h5
As shown in b 1, the inner part near the core leg 1 is the metal seat 1-
In order to increase the width linearly, the outermost winding 2bz is configured so that the width of the metal sheet at the outer part increases linearly as shown in the metal sheet 5b2.In the middle winding 2ao, the width of the metal sheet 5ao is increased linearly. The width of the metal sheet was made to increase linearly in the central part.And these metal sheets h5bi,
5bz and 5ao were bent and wound at the dotted line in the figure. By doing this, each winding 2ao, 2b1, 2
Metal seam h5ao constituting b2.

The cross-sectional areas of the sections 5b and 5b2 change in accordance with the distribution form of the eddy current, and the same effects as in the other embodiments described above can be achieved. In this embodiment, the case of three windings has been described, but even if three or more windings are used in combination, the concentration of eddy current flowing through the metal sheath 1 can be alleviated using the same idea.

As described above, according to each of these embodiments, the cross-sectional area of the metal sheet constituting the foil winding increases and decreases almost continuously for each winding layer, so that leakage magnetic flux from various windings It is now possible to wind the metal sheet 1 so that the cross-sectional area changes approximately in accordance with the shape of the overcurrent distribution that occurs, effectively reducing eddy currents that concentrate at the ends of the foil winding, which was considered a problem in the past. This makes it possible to easily solve problems such as an increase in local temperature caused by loss concentration.

〔Effect of the invention〕

As described above, the present invention suppresses local overheating due to eddy currents concentrated at the lower end of the winding, improving reliability. , (a stationary induction electric appliance with improved reliability can be obtained).

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional side view of one embodiment of the stationary induction electric device of the present invention, and Figs. 2 (a) to (d) also show metal sheets of one embodiment, in which (a) constitutes the inner winding. A front view of the metal sheet, (b) is a side view showing the bent state of (a),
(c) is a front view of the metal sheet constituting the outer winding, (d) is a side view showing the bent state of (c), and Figure 3 (a)
~(E) shows the configuration and metal sheet of a static induction device according to another embodiment of the stationary induction device of the present invention, (A) is a longitudinal cross-sectional side view of the static induction device, and (B) shows the structure of the inner winding. (C) is a side view showing the state in which (B) is folded; (D) is a front view of the metal sheet that constitutes the outer winding; (E) is a side view showing the state in which (D) is folded. Side views showing the state, FIGS. 4(A) to 4(E) show the structure and metal sheet of the static induction appliance of still another embodiment of the static induction appliance of the present invention, and (A) shows the configuration of the static induction appliance of still another embodiment of the static induction appliance of the present invention. Vertical side view, (B) is a front view of the metal sheet that makes up the inner winding, (C) is a side view showing the state in which (B) is folded, (D) is the metal sheet that makes up the inner winding. A front view, (E) and (D) a side view showing the folded state, FIG. 5 is an enlarged vertical sectional side view of the winding end of still another embodiment of the stationary induction electric appliance of the present invention, and FIG. 7 is a longitudinal sectional side view of still another embodiment of the stationary induction appliance of the present invention, and FIGS. (A) is a side view of the metal sheet that makes up the inner winding, (B) is a front view of (A), (C) is a side view of the metal sheet that makes up the outer winding, (
d) is a front view of (c), and FIGS. 8(a) to 8(d) show the structure of a static induction electric device according to still another embodiment of the present invention and a view toward the metal sheath 1. ) is a vertical side view of the stationary induction electric appliance, (b) is a front view of the metal sheet that makes up the innermost winding, (c) is a front view of the metal sheet that makes up the intermediate winding, and (d) is the outermost winding. Figures 9 (a) and 9 (b), a front view of the metal sheet that makes up the wire, show the configuration and current density distribution of a conventional stationary induction electric appliance, and (a) is a vertical side view of the static induction electric appliance, and (b). ) is a current density distribution map. 1... Core leg, 2a... Inner winding, 2ao... Intermediate winding, 2b... Outer winding, 2b1... Innermost winding, 2
b2... Outermost winding, 5, 5a, 5ao, 5b, 5bx
, 5b2-metal sheet, 6... insulation sheet, 7...
metal parts. ←Soya@Introduction

Claims (6)

[Claims] 1. In a stationary induction electric appliance in which an insulating sheet and a metal sheet are stacked and wound around a core leg to form a foil winding, the cross-sectional area of the metal sheet changes almost continuously for each winding layer. A stationary induction electric appliance characterized by: 2. 2. The static induction electric appliance according to claim 1, wherein the metal sheet has a cross-sectional area that is changed substantially along the distribution form of the radial component of leakage magnetic flux from the foil winding. 3. The foil winding divides the metal sheet into at least two in the axial direction to form a parallel winding group, and the cross-sectional area of the metal sheet of the winding located at least at the upper and lower ends of this winding group. The stationary induction electric appliance according to claim 1, wherein the static induction electric appliance is changed. 4. Claim 1: The wound metal sheet has at least one bent portion formed at its end, and the sheet width of each wound layer is substantially the same from the beginning of winding to the end of winding. Stationary induction appliance as described. 5. A stationary induction electric appliance according to claim 1, wherein the metal sheet has a thickness that changes substantially continuously from the beginning of winding to the end of winding. 6. 2. The stationary induction electric appliance according to claim 1, wherein the wound metal sheet has another metal member added to a part thereof so that the two are electrically conductive.