JP2015018912A - Gas insulation transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas insulation transformer that is able to improve insulation intensity by decreasing an electric field in the insulation coated layer of a lead wire, and is able to contribute to a reduction in size and an improvement in reliability.SOLUTION: Pasty metal 3 is applied to the surface of strands 1 of metal, and an insulation coated layer 2 is provided from above it. Accordingly, recessed portions on the surface, formed as a result of twisting the strands 1 of metal, are coated with the pasty metal 3 and thereby filled with it. Thus, the surface of the strands 1 of metal can be made flat and smooth. Additionally, since the pasty metal 3 spreads between the strands 1 of metal and the internal face of the insulation coated layer 2, minute gas gap is prevented. This makes it possible to decrease an electric field in the insulation coated layer 2, and non-uniform electric field in the insulation coated layer 2 is hindered to increase the insulation intensity of a lead wire.

Description

  Embodiments of the present invention relate to a gas insulated transformer with a lead wire drawn from an insulated winding.

  Generally, it is required to install a small and highly safe transformer in an urban underground substation or the like. In order to meet this demand, gas-insulated transformers in which an insulating gas is sealed as an insulating medium are widely used. As the insulating gas sealed in the gas-insulated transformer, SF6 gas that is nonflammable and has no risk of explosion is used.

  Since SF6 gas exhibits insulation characteristics having strong electric field dependence, it is known that dielectric breakdown occurs when the electric field on the surface of the high voltage electrode reaches a certain breakdown voltage. For this reason, in a normal insulation design, the curvature of the high voltage electrode is increased to lower the electric field.

  In recent years, however, gas insulation transformers have been increased in voltage and capacity, and the curvature of the high voltage electrode cannot be sufficiently increased. Therefore, conventionally, a technique for applying an insulating coating layer to a high voltage electrode has been proposed to compensate for the lack of curvature of the electrode. For example, a lead wire is drawn out from an insulated winding in a gas-insulated transformer, and a technique for applying an insulating coating layer is adopted for the insulation design of the lead wire.

  That is, the lead wire shown in FIG. 6 is provided with the insulating coating layer 2 around the metal stranded wire 1 serving as a core wire. In the lead wire having the insulating coating layer 2, the surface of the insulating coating layer 2 has the maximum electric field. Therefore, by winding a large number of insulating films or the like to increase the thickness of the insulating coating layer 2, The electric field in the insulating gas can be weakened and the insulation strength of the entire lead wire can be increased.

  As a conventional technique of the lead wire provided with the insulating coating layer, there are Patent Document 1 and Patent Document 2. In the lead wire disclosed in Patent Document 1, an insulating film is wound around a metal stranded wire while providing a gap of 1 mm or less for insulation coating.

  In addition, the insulation strength of the minute gas gap in the insulating coating layer is determined from the relationship between the gas gap length and the breakdown electric field, but it is important to maintain this insulation strength at a constant value. Therefore, in Patent Document 2, an insulating coating layer is formed by winding an embossed or crepe-like film in multiple layers, so that the electric field in the insulating coating layer is maintained at a constant value.

Japanese Patent Laid-Open No. 2-16705 Japanese Patent Laid-Open No. 9-35946

  With the recent increase in power demand, higher voltage and larger capacity of gas insulation transformers are progressing. When the insulation coating layer is applied to the lead wire of the gas insulation transformer, the electric field of the insulation coating layer is high. Tend to be. Therefore, not only lowering the electric field on the surface of the insulating coating layer but also lowering the electric field inside the insulating coating layer is strongly demanded.

  Embodiments of the present invention have been made to solve the above problems, and can reduce the electric field in the insulating coating layer of the lead wire to increase the insulation strength, thereby contributing to downsizing and improvement in reliability. The purpose is to obtain a gas-insulated transformer.

  In order to achieve the above object, an embodiment of the present invention provides a gas insulated transformer having a lead wire, wherein the lead wire has a metal stranded wire as a core wire, and a paste-like or powdery metal is applied to the metal stranded wire. In addition, an insulating coating layer is provided on the coated layer.

Sectional drawing which shows 1st Embodiment. Sectional drawing which shows 2nd Embodiment. Sectional drawing which shows 3rd Embodiment. Sectional drawing which shows 4th Embodiment. Sectional drawing which shows 5th Embodiment. Sectional drawing of the lead wire of the conventional gas insulation transformer.

[First Embodiment]
(Constitution)
FIG. 1 is a block diagram showing a first embodiment according to the present invention. As shown in FIG. 1, the lead wire according to the first embodiment includes a metal stranded wire 1 as a core wire. The metal stranded wire 1 is formed by twisting seven thin metal wires and exhibits high flexibility.

  A paste-like metal 3 is applied to the surface of the metal stranded wire 1, and an insulating coating layer 2 is provided thereon. The paste-like metal 3 is a substance in which metal particles are dispersed in a liquid, and is, for example, a conductive paste and has fluidity and viscosity. The kind of metal particles in the paste-like metal 3 can be changed as appropriate, such as aluminum and copper, and the fluidity and viscosity can be selected as appropriate.

  The timing at which the paste-like metal 3 is applied to the metal stranded wire 1 can also be appropriately selected. That is, the paste-like metal 3 may be applied to the surface of each metal wire constituting the metal strand 1 and then twisted, or the paste-like metal 3 may be applied to the surface of the metal strand 1 after being twisted. May be. Further, the paste-like metal 3 may be applied to the inner surface of the insulating coating layer 2. The paste-like metal 3 may be dried by heating after application, or may be naturally dried.

(Function and effect)
Since the metal stranded wire 1 is formed by twisting a plurality of metal wires, only a part of the curved surface of each metal wire is exposed, and a plurality of concave portions are formed on the surface of the metal stranded wire 1 along the longitudinal direction of the metal stranded wire 1. It is formed. In this embodiment, the concave part of the surface of the metal strand wire 1 can be filled by apply | coating the paste-form metal 3 to the surface of the metal strand wire 1, and the surface of the metal strand wire 1 can be made flat and smooth. it can. In addition, after the paste-like metal 3 is applied to the surface of the metal stranded wire 1, the paste-like metal 3 exists between the metal stranded wire 1 and the inner surface of the insulation coating layer 2 in order to provide the insulating coating layer 2 from above. However, there is no worry of a minute gas gap.

  As described above, the surface of the metal stranded wire 1 is smoothed by applying the paste-like metal 3 and the minute gas gap inside the insulating coating layer 2 is eliminated, so that the electric field inside the insulating coating layer 2 is lowered. Can do. Accordingly, it is possible to suppress inequality in the electric field inside the insulating coating layer 2 and increase the insulation strength of the lead wire. As a result, it is possible to contribute to the improvement of reliability while promoting the miniaturization of the gas-insulated transformer.

[Modification of First Embodiment]
As a modification of the first embodiment, powder metal may be attached to the surface of the metal strand 1 instead of the paste metal 3. The kind of powder metal can be selected as appropriate, such as aluminum and copper, as with the paste metal 3. Moreover, instead of the paste-like metal 3 or the powder metal, a metal tape 4 such as a copper foil adhesive tape may be wound around the surface of the metal stranded wire 1 as shown in FIG. The material of the metal tape 4 may be aluminum other than copper. According to these embodiments, in addition to the same effects as those of the first embodiment, the following unique effects can be obtained.

  In the embodiment in which the powder metal is adhered, unlike the paste metal 3, the metal does not hang down from the metal strand 1, and workability can be improved. In the embodiment in which the metal tape 4 is wound, the workability is further improved because there is no fear that the powder metal is scattered. If the metal tape 4 is elastic, the working efficiency is further increased. About the kind of powdery metal and the metal tape 4, and conditions when attaching them to the metal stranded wire 1, selection change is possible suitably. Moreover, it replaces with the metal tape 4, and metal foils, such as aluminum foil and copper foil, may be used, and a semiconductive tape, a semiconductive adhesive tape, etc. may be used.

[Second Embodiment]
(Constitution)
FIG. 3 is a block diagram showing a second embodiment according to the present invention. In the lead wire according to the second embodiment, a cylindrical plastic pipe 5 is provided, and a metal vapor deposition layer 6 is formed by vapor-depositing metal inside the plastic pipe 5. In the second embodiment, the metal strand 1 is passed through the hollow portion of the plastic pipe 5. For this reason, the plastic pipe 5 itself serves as the insulating coating layer 2. The metal strand 1 and the metal vapor deposition layer 6 inside the plastic pipe 5 are at the same potential. The metal type of the metal vapor deposition layer 6 can be selected as appropriate. Moreover, the shape, dimension, etc. of the plastic pipe 5 can be changed as appropriate.

(Function and effect)
In the second embodiment, by providing the vapor-deposited metal layer 6 inside the plastic pipe 5, the uneven portion of the high voltage portion is completely eliminated, and the inequality in the electric field inside the plastic pipe 5 can be eliminated. it can. In addition, since the maximum electric field portion in the plastic pipe 5 is the outer portion of the deposited metal layer 6, the electric field in the plastic pipe 5 can be reduced ideally.

  Furthermore, in the second embodiment, the energizing current can be sufficiently increased by passing the metal stranded wire 1 through the inner space of the plastic pipe 5. Therefore, a lead wire with high insulation strength can be realized, and the gas insulation transformer can be downsized and highly reliable.

[Third Embodiment]
(Constitution)
FIG. 4 is a block diagram showing a third embodiment of the present invention. The lead wire according to the third embodiment is characterized in that a metal pipe 7 is provided instead of using the metal stranded wire 1 and the insulating coating layer 2 is provided on the outer peripheral portion of the metal pipe 7. The metal type of the metal pipe 7, the shape and dimensions of the pipe, and the like can be changed as appropriate.

(Function and effect)
In the third embodiment, since the metal pipe 7 does not have a concave portion on the surface like the metal stranded wire 1, the electric field inside the insulating coating layer 2 does not become unequal. Further, the outer surface portion of the metal pipe 7 which is the maximum electric field portion in the insulating coating layer 2 is circular. For this reason, the electric field inside the insulating coating layer 2 can be reduced ideally. Therefore, a lead wire with high insulation strength can be realized, and the gas insulation transformer can be downsized and highly reliable.

(Modification of the third embodiment)
FIG. 5 is a configuration diagram showing a modification of the third embodiment. In the embodiment shown in FIG. 5, a metal stranded wire 1 for energization is passed inside the metal pipe 7 having the configuration shown in FIG. 4. According to this embodiment, the metal stranded wire 1 for energization is arranged in the metal pipe 7, thereby reducing the electric field inside the insulating coating layer 2 and reducing the thickness of the metal pipe 7. Is possible. Therefore, in the embodiment shown in FIG. 5, it is possible to reduce the weight of the lead wire.

[Other Embodiments]
In addition, said embodiment is shown as an example in this specification, Comprising: It does not intend limiting the range of invention. In other words, the present invention can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and gist of the invention. For example, the number of metal wires constituting the metal stranded wire 1, the thickness of the insulating coating layer, and the like can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 ... Metal twisted wire 2 ... Insulation coating layer 3 ... Paste metal 4 ... Semiconductive tape 5 ... Plastic pipe 6 ... Metal vapor deposition layer 7 ... Metal pipe

Claims (5)

In gas-insulated transformers with lead wires,
The lead wire is a gas insulated transformer characterized in that a metal stranded wire is used as a core wire, a paste-like or powdery metal is applied to the metal stranded wire, and an insulating coating layer is provided after the application. In gas-insulated transformers with lead wires,
A gas insulated transformer, wherein the lead wire has a metal stranded wire as a core wire, a metal tape member or a semiconductor tape member is wound around the metal stranded wire, and an insulating coating layer is provided thereon. In gas-insulated transformers with lead wires,
The lead wire is provided with a plastic pipe, a metal is vapor-deposited on the inner surface of the plastic pipe, a vapor-deposited metal layer is provided, and a metal stranded wire having the same potential as the vapor-deposited metal layer is provided inside the plastic pipe. A gas-insulated transformer that has been passed through. In gas-insulated transformers with lead wires,
The lead wire is provided with a metal pipe, and an insulating coating layer is provided on an outer peripheral portion of the metal pipe.   The gas insulated transformer according to claim 4, wherein a metal stranded wire is passed through the metal pipe.

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