JPH0336282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates primarily to foil-wound windings used in transformers.

(b) Background of the Invention Foil-wound wires made by overlapping metal sheets and insulating sheets have a good space factor, easy automation of wire winding work, low axial mechanical force, and potential distribution within the windings. It has many advantages such as good This foil-wound winding has already been widely used in relatively low-voltage, small-capacity transformers, and recently, in view of its excellent advantages, it has been used in high-performance coils for both oil-immersed and gas-insulated transformers. Application to voltage and large capacity transformers is also being considered.

(c) Prior art The foil-wound wire may be one in which a metal sheet and an insulating sheet are alternately laminated, or one in which one metal sheet and a plurality of insulating sheets are alternately laminated. However, all conventional foil-wound wires have a structure in which the metal sheet is in direct contact with the surface of the insulating sheet.

However, in such foil-wound windings in which the metal sheet and the insulating sheet are in direct contact, if there is a solid foreign object between the metal sheet and the insulating sheet, the insulating sheet may be damaged by this foreign object. (The thickness of the insulating sheet is approximately several tens of microns, so it is easily damaged.) Therefore, there was a risk that the insulation between the layers could not be maintained. Therefore, in order to improve the reliability of interlayer insulation, it is necessary to minimize the ingress of foreign matter into the windings, but insulating sheets generally have a surface resistance of about 10 ¹³ to ^{10 14} Ω. Because it has excellent insulating properties, it is easily charged and therefore tends to attract foreign matter in the atmosphere, which often causes foreign matter to get into it during the winding process.

For this reason, in the past, in addition to thorough dust-proof management in the winding work room, a static eliminator was installed in front of the winding machine to neutralize the static charge on the insulating sheet that enters the winding machine. Countermeasures have been taken, such as blowing air onto the sheet surface to blow away foreign objects, but even these measures are not very effective considering the capital investment, so conventional foil-wound windings are The reality is that it has not been possible to ensure the reliability of interlayer insulation.

In addition, during the winding process, not only can foreign matter get into the gap between the metal sheet and the insulating sheet, but also small gaps can sometimes form between the sheets. When this occurs, the area of close contact between the metal sheet and the insulating sheet decreases by the gap, resulting in poor heat transfer between the metal sheet and the insulating sheet, and as a result, heat generated within the winding is transferred to the outside. It also had the disadvantage of reduced heat dissipation efficiency.

(d) Purpose of the Invention The purpose of the present invention is to reduce the absolute amount of foreign matter that gets into the wire during the winding process, and also to reduce the amount of foreign matter that gets into the space between the metal sheet and the insulating sheet. To provide a foil winding which increases the reliability of interlayer insulation by preventing damage to the metal sheet and which can efficiently dissipate heat even when a gap is formed between a metal sheet and an insulating sheet. It is in.

(e) Summary of the invention In other words, the foil-wound wire of the present invention has a structure in which a conductive film or a semi-conductive film is coated on the part of the insulating sheet surface that is in contact with the metal sheet. For example, since the insulating sheet has a conductive film or a semi-conductive film on its surface, it is hardly charged, and therefore no foreign matter is attracted to the insulating sheet, so there is no possibility of foreign matter getting into the foil wrapping process. The amount can be reduced. Also,
In the foil-wound wire of the present invention, since a conductive film or a semi-conductive film is adhered to the surface of the insulating sheet, even if foreign matter enters during the winding process, this foreign matter will be blocked by the conductive film or semi-conductive film. Since the interlayer insulation sheet does not come into direct contact with the insulating sheet, damage to the insulating sheet can be prevented, and the reliability of the interlayer insulation can be increased. Furthermore, in the foil-wound wire of the present invention, even if a gap is partially formed between the metal sheet and the insulating sheet, the conductive film or semiconductive film on the surface of the insulating sheet has good thermal conductivity, As long as the metal sheet and the insulating sheet are in contact with each other over a certain area, heat transfer between the metal sheet and the insulating sheet will be good, and the heat dissipation efficiency will be sufficient.

(f) Embodiment of the invention FIGS. 1 and 2 show an embodiment of the invention.

In Fig. 1, 1 is a metal sheet, 2 is an insulating sheet wider than the metal sheet 1, and 3 is an insulating sheet with sufficient mechanical strength to fit into the main leg part (not shown) of the core. It is a cylinder. The foil-wound winding of this embodiment is of a type in which one metal sheet 1 and a plurality of, for example, two insulating sheets 2 are wound so as to be alternately laminated. As shown in FIG. 1, the surface in contact with the metal sheet 1 is coated with a metal conductive film 4 over the entire area in contact with the metal sheet 1.

Therefore, the insulating sheet 2 has a conductive film 4 on its surface.
By having a wire, it is no longer charged, and as a result, foreign matter is no longer attracted by static electricity, so the absolute amount of foreign matter that gets into the wire winding process can be reduced without having to take any special measures when winding the wire. . In addition, in this foil-wound winding, even if foreign matter enters, the foreign matter will enter between the conductive film 4 and the metal sheet 1 because the conductive film 4 is coated on the two surfaces of the insulating sheet. Therefore, since this foreign matter is blocked by the conductive film 4 and does not come into direct contact with the insulating sheet 2, damage to the insulating sheet 2 due to foreign matter can be prevented and the reliability of the interlayer insulation can be increased. , and further foreign matter is metal sheet 1
Since it is sandwiched between the conductor and the conductive film 4, it is also possible to eliminate disturbances in the electric field caused by foreign matter. Moreover, in this foil-wound winding, even if a gap is partially formed between the metal sheet 1 and the insulating sheet 2, the conductive film 4 on the surface of the insulating sheet 2 has good thermal conductivity, so it The heat transfer between the conductive film 4 and the metal sheet 1 is good, so as long as the conductive film 4 and the metal sheet 1 are in contact with each other over a certain area, there will be no temperature difference between them, and the insulating sheet surface Since the conductive film 4 is in complete contact with the insulating sheet 2 over its entire surface, heat transfer between the metal sheet 1 and the insulating sheet 2 is extremely good. Therefore, the heat generated within the windings is efficiently radiated to the outside.

Next, a case where the two surfaces of the insulating sheet are coated with a semiconductive film instead of the conductive film 4 will be described. As the semiconductive film, for example, a carbon film, a metal oxide, etc. can be considered.

Even when an insulating sheet coated with a semiconducting film is used, if the surface resistance of the insulating material is less than about 10 ¹⁰ Ω, the ease with which it will be charged will be extremely reduced, so the insulating sheet should have a surface resistance of about 10 ³ to ^{10 10} Ω. By coating the wire with a semiconductive film having a surface resistance of , it is possible to eliminate the attraction of foreign matter due to static electricity during the winding process. Furthermore, since a semiconducting film generally has higher hardness than a metal conductive film, a semiconducting film is more effective than a conductive film in preventing damage to an insulating sheet due to foreign matter. Furthermore, in terms of preventing electric field disturbances caused by foreign objects and heat transfer between metal sheets and insulating sheets, semiconducting films have the same potential as metals due to their semiconductivity, and their thermal conductivity is similar to that of insulating films. Since this is much better than the above, we can expect an effect similar to that obtained by coating with a metal conductive film.

Figure 3 shows an example of a foil-wound wire wound in such a way that one metal sheet and one insulating sheet are alternately laminated. It is sufficient to coat the conductive film 4 or the semiconductive film, and thereby the same effect as in the previous embodiment can be obtained.

(g) Effects of the Invention As described above, according to the present invention, it is possible to reduce the absolute amount of foreign matter that enters during the winding process, and to reduce the amount of foreign matter that enters between the metal sheet and the insulating sheet. It is possible to prevent damage to the insulating sheet, thereby increasing the reliability of interlayer insulation, and furthermore, even if a gap is formed between the metal sheet and the insulating sheet, efficient heat dissipation can be performed.

[Brief explanation of the drawing]

1 and 2 are a sectional view of the entire winding and an enlarged sectional view of a portion of the winding according to an embodiment of the present invention, and FIG. 3 is an enlarged sectional view of a portion of the winding showing another embodiment of the invention. 1... Metal sheet, 2... Insulating sheet, 4... Conductive film.

Claims (1)

[Claims] 1. A foil-wound wire formed by overlapping a metal sheet and an insulating sheet, the foil-wound wire being characterized in that a conductive film or a semi-conductive film is coated on the portion of the insulating sheet surface that contacts the metal sheet.