JPS63111605A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To prevent an electric field from being concentrated thereby to improve insulating performance and to stabilize a winding support by removing an insulating pipe disposing position of upper or lower end of a winding, and obtaining a suitable interval between a columnar space disposed at the end of the winding and a high voltage shield. CONSTITUTION:A high voltage shield 6 for moderating an electric field is disposed at the end of a high voltage winding 5. The shape of the shield 6 is projected from the end of a metal sheet 2 toward a yoke core, and so composed as to be projected outside the winding. A columnar spacer 31 is disposed at the lower or upper and lower ends of the winding except the disposing position of an insulating pipe 12. In order to support the winding, the diameter L2 of the center is composed to be smaller than the diameter L1 of the end of the winding, and an interval (d) between the shield 6 and the spacer 31 is set at 3-5mm or longer. Accordingly, it can prevent an electric field generated by the difference of the dielectric constant between an insulating medium having a low dielectric constant and the spacer 31 having a high dielectric constant from being concentrated and also prevent an insulator from breaking down.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to a foil-wound transformer using a winding formed by overlapping a metal sheet and an insulating sheet. This article relates to a foil-wound transformer that alleviates the electric field that is applied to the coil.

(Prior Art) A foil-wound transformer has a good winding space factor and can be made smaller and lighter. It has already been put to practical use in small capacity transformers with relatively low voltages of several KV and several hundred KVA. In recent years, in view of its excellent advantages, research has been conducted to expand its application to higher voltage, larger capacity transformers, such as 275KV and 300MVA class transformers, but the biggest technical problem is how to improve cooling capacity and achieve high insulation. The two issues are whether the winding can be given sufficient capacity and whether it can withstand 1q of radial mechanical force in the event of a short-circuit accident. Although such high-voltage, large-capacity transformers have not yet been put into practical use, as shown in Figure 4, a cooling duct is built into the winding, and a refrigerant with excellent insulation properties is fed into this cooling duct. The most popular type of transformer is a so-called heat pipe type foil-wound transformer, which uses the latent heat of vaporization of a refrigerant to cool the heat generated from winding loss.

That is, in this foil-wound transformer, a low-voltage winding 4 and a high-voltage winding 5 each made of a metal sheet 2 and an insulating sheet 3 wound over each other are wound around a leg 1 of an iron core, and the outermost part of the high-voltage winding 5 is A high voltage shield 6 is disposed at the upper and lower ends of. Moreover, a hollow cooling duct 7 extending in the axial direction of the windings is built into the windings of the low-voltage winding 4 and the high-voltage winding 5. Refrigerant such as Freon R-113 or Fluorinert FC75 is sealed in the thin gap in the hollow part of cooling duct] 7, and is circulated by pump 8, removing the heat generated in the windings with the latent heat of evaporation of the refrigerant. The vapor is cooled and condensed in a condenser 9. A cooling system is constructed in which the liquefied refrigerant is stored in a refrigerant tank 10 and roughly sent into the windings by a pump 8. The liquid guide pipe 11 that constitutes the cooling system is made of metal such as stainless steel, and the liquid guide pipe 11 and the cooling duct 6 are made of an insulating pipe 1 made of Teflon resin or the like.
Connected via 2. Moreover, this liquid guide pipe 11 is
It is also connected to the ground potential of the tank 13 and the like. on the other hand,
Since the cooling duct 7 is built into the winding, it is electrically connected to the same potential as the adjacent winding. moreover,
Insulation of each part of the winding is ensured by an insulating gas such as SF6 gas sealed in the tank 13. Further, grounding components 14 are arranged above and below the winding.

By the way, the above-mentioned foil-wound transformer uses a thin metal sheet 2.
Since the low voltage winding 4 and the high voltage winding 5 are formed by overlapping and winding the insulating sheet 3, the winding space factor within the core window increases, but on the other hand, there are the following problems. .

In other words, in a foil-wound transformer of several KV or several KVA,
Because of the relatively low voltage and small capacity, the radius of the winding is small, the stack height is low, and the weight of the winding is small, so the winding can be tightened in the winding direction without the need for special support means. The windings could be stably supported by force alone, but in high-voltage, large-capacity foil-wound transformers, the weight of the windings increases, and the windings themselves cannot be tightened by force alone. , some support means is required to support the windings.

Conventionally, in a gas insulated foil-wound transformer in which SF6 gas or the like is sealed, a support insulator 20 as shown in FIG. Although this method allows the winding to be stably supported, the relative dielectric constant of the support insulator 20 is lower than that of the S sealed inside the tank.
Since the dielectric constant is higher than that of an insulating medium such as F6 gas, an electric field is concentrated at the end of the winding in the portion where the supporting insulator 20 is present, and dielectric breakdown may occur.

Moreover, the installation of the support insulator 20, which is disposed over the entire surface of the end of the winding as described above, is very complicated work and has the disadvantage of being economically expensive. .

In particular, in a heat pipe type foil-wound transformer as shown in Fig. 4, a cooling duct 7 disposed within the winding
Since the insulating pipe 12 connecting the coil and the liquid guiding pipe 11 is disposed at the end of the winding, the supporting insulator 20 cannot be disposed over the entire surface of the end of the winding. Therefore, as shown in FIG. 5, a post spacer 21 made of an insulator capable of supporting a portion of the end of the winding has been used.

However, as shown in Figure 5, boss 1 to space 1
The side portion of the opening 21 and the gap d of the high voltage shield 6 disposed at the end of the high voltage winding are close to each other, and a minute gap is formed.

In particular, when the insulating medium is a gas such as SF6 gas, the relative permittivity is 1.0, whereas the relative permittivity of the post spacer 21 is several times that. The electric field concentrates in the gas part according to the inverse ratio of , causing dielectric breakdown.

Furthermore, in order to effectively alleviate the electric field at the end of the winding, if the high-voltage shield is made to protrude in the direction of the winding stack so that the cover of the high-voltage shield can be increased, the distance between the high-voltage shield 6 and the post spacer 21 can be increased. It became very narrow, causing electric field concentration and significantly reducing the insulation strength of the foil-wound transformer.

(Problems to be Solved by the Invention) As described above, in conventional foil-wound transformers, the distance between the supporting insulator and the high voltage shield provided to support the winding is small, Dielectric breakdown occurred due to the difference in dielectric constant.

In addition, the work of attaching supporting insulators to the ends of the windings was extremely complicated.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks.The purpose of the present invention is to stably support the windings with a support insulator that is easy to install, has high insulation reliability, and has excellent mechanical strength. The object of the present invention is to provide a foil-wound transformer.

[Structure of the Invention] (Means for Solving the Problems) The foil-wound transformer of the present invention has high voltage shields disposed at the ends of the windings that protrude from the upper and lower ends of the metal sheet in the direction of the winding stack. In addition, a columnar spacer made of an insulating material is arranged at least at the bottom of the winding among the upper and lower ends of the winding, and the diameter of the end surface of the columnar spacer on the winding side is larger than the diameter of the central part. The space between the side part of the columnar spacer and the high voltage shield is 3 to 5 mm or more.

(Function) In the foil-wound transformer of the present invention, the insulating pipe is removed from the lower end or the upper and lower ends of the winding, and between the columnar spacer and the high voltage shield, which is disposed at the end of the winding. By ensuring a spacing of ~5 mm or more, concentration of the electric field is prevented, insulation performance is greatly improved, and the winding can be supported stably.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 to 3. Note that the same parts as in the conventional type shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted.

■First Embodiment Configuration of this Embodiment* In this embodiment, as shown in FIG. 1, a high voltage shield 6 for mitigating the electric field is provided at the end of the high voltage winding 5.

The shape of the high voltage shield 6 is configured so that it protrudes from the end of the metal sheet 2 toward the yoke core, and also protrudes to the outside of the winding.

In addition, an insulating pipe 1 is installed at the lower end or upper and lower ends of the winding.
A columnar spacer 31 is disposed apart from the location where the columnar spacer 31 is disposed. As shown in FIG. 1, the shape of the columnar spacer 31 is such that the diameter L1 of the end face on the winding side is larger than the diameter L2 of the central part, and the side part of the high voltage shield 6 and the spacer 31 They are arranged so that the distance d between them is 3 to 5 mm or more.

Note that the columnar spacer 31 is manufactured by casting epoxy resin or the like into a mold.

Effects of this embodiment* In the foil-wound transformer of this embodiment having such a configuration, the spacer provided to support the winding has a diameter 12 at the center that is equal to the diameter of the winding side end surface. L1 is configured to be smaller than L1, and the space d between the high voltage shield 6 and the side portion of the columnar spacer 31 is secured to be 3 to 5 mm or more.
It is possible to prevent the concentration of electric fields caused by the difference in dielectric constant between the insulating medium with a low dielectric constant and the spacer 31 with a high dielectric constant, and also to prevent dielectric breakdown, which greatly improves the insulation reliability of the foil-wound transformer. improves.

In addition, in the columnar spacer 31 of this embodiment, the diameter L2 of the central portion only needs to be smaller than the diameter "1" of the end surface on the winding side.
The manufacturing process by casting epoxy resin or the like is also greatly simplified. In addition, spacers made of epoxy resin have high dielectric strength, especially in gas, and can be used for long periods of time.They also have high mechanical strength, so they can withstand vibrations during transportation. can.

Further, since the spacer 31 is formed into a columnar shape, it is very easy to attach and detach the spacer 31 to the winding end where the insulating pipe 12 is provided, and the workability is greatly improved.

■Second Embodiment Configuration of this Embodiment* In this embodiment, as shown in FIG. 2, a high voltage shield 6 for mitigating the electric field is provided at the end of the high voltage winding 5.

The shape of the high voltage shield 6 is configured so that it projects from the end of the metal sheet 2 toward the yoke core and also projects outside the winding.

In addition, an insulating pipe 1 is installed at the lower end or upper and lower ends of the winding.
A columnar spacer 41 is disposed apart from the second disposed location. As shown in FIG. 2, the shape of the columnar spacer 41 is such that the diameter 1 of the end surface on the winding side is shorter than the diameter of the winding wire by d, and the diameter 1 of the end surface on the winding side is , is configured to be larger than the diameter 2 of the central portion.

Effects of this embodiment* In the foil-wound transformer of this embodiment having such a configuration, the spacer provided to support the winding has a diameter of 1 on the winding side end face that is equal to the diameter of the winding. The diameter 1 on the end face of the winding wire is made larger than the diameter 2 on the center part, and a gap of 3 to 5 mm or more is secured as d. It is possible to prevent the concentration of electric fields caused by the difference in dielectric constant between the insulating medium with a low dielectric constant and the spacer 41 with a high dielectric constant, and also to prevent dielectric breakdown, which greatly improves the insulation reliability of the foil-wound transformer. improves.

Also, in the columnar spacer 41 of this embodiment, the diameter 2 of the central portion only needs to be smaller than the diameter IL1 of the winding side end face, so the manufacturing process by casting epoxy resin or the like is greatly simplified. In addition, spacers made of epoxy resin have high dielectric strength, especially in gas, and can be used for long periods of time.They also have high mechanical strength, so they can withstand vibrations during transportation. can.

Further, since the spacer 41 is formed into a columnar shape, it is very easy to attach and detach the spacer 41 to the end of the winding, and the workability is greatly improved.

■Third Embodiment Configuration of this embodiment* In this embodiment, as shown in FIG. 3, a high voltage shield 6 for mitigating the electric field is provided at the end of the high voltage winding 5.

The shape of the high voltage shield 6 is configured so that it projects from the end of the metal sheet 2 toward the yoke core and also projects outside the winding.

In addition, an insulating pipe 1 is installed at the lower end or upper and lower ends of the winding.
A columnar spacer 51 is disposed apart from the second disposed location. As shown in FIG. 3, the shape of the columnar spacer 51 is such that the diameter L1- of the winding side end surface is larger than the diameter of the winding, and the columnar spacer 51 is provided at the position where the columnar spacer 51 is disposed. An engagement hole 52 into which the end of the columnar spacer 51 fits is formed in the side of the high-voltage shield 6 . and,
At the joint between the columnar spacer 51 and the high voltage shield 6, the upper end of the columnar spacer is arranged perpendicularly to the high voltage shield 6.

Further, the diameter L+' of the winding side end face is configured to be larger than the diameter L2- of the central part, and the distance d between the high voltage shield 6 and the side part of the spacer 51 is 3 to 5 mm or more. has been done.

Note that the columnar spacer 51 is manufactured by casting epoxy resin or the like into a mold.

Effect of this embodiment* In the foil-wound transformer of this embodiment having such a configuration, the columnar spacer provided to support the winding has a diameter of 11''' on the end surface of the winding. The diameter of the wire is larger than that of the wire, and its upper end is fitted into the engagement hole 52 formed on the side of the high voltage shield, so the columnar spacer 51 connects the winding wire and the high voltage shield 6 together. can be supported.

In addition, since the gap d between the high voltage shield 6 and the side part of the columnar spacer 51 is secured to be 3 to 5 mm or more, the difference in dielectric constant between the insulating medium with a low dielectric constant and the spacer 51 with a high dielectric constant can occur. Since it is possible to prevent electric field concentration and also to prevent dielectric breakdown, the insulation reliability of the foil-wound transformer is greatly improved.

In addition, since the diameter L2- of the central portion of the columnar spacer 51 of this embodiment only needs to be smaller than the diameter 1-1- of the end face on the winding side, the manufacturing process by casting epoxy resin or the like is greatly simplified. Ru. In addition, spacers made of epoxy resin have high dielectric strength, especially in gas, and can be used for long periods of time.They also have high mechanical strength, so they can withstand vibrations during transportation. can.

In general, since the spacer 51 is formed into a columnar shape, it is very easy to attach and detach it from the end of the winding, and the workability is greatly improved.

(2) Other Embodiments Note that the present invention is not limited to the embodiments described above, and the diameter of the columnar spacer on the tank side may be the same as or larger than the diameter of the central portion.

[Effects of the Invention] As described above, according to the present invention, the high voltage shield attached to the end of the high voltage winding is configured to protrude in the winding stack direction, and the high voltage shield attached to the end of the high voltage winding is configured to protrude in the winding stack direction. As a supporting insulator disposed in the section, a columnar spacer configured such that the diameter of the end face on the winding side is larger than the diameter of the center part is used, and the distance between the side part of the columnar spacer and the high voltage shield is 3 to 3.
A foil-wound transformer with high insulation reliability and excellent mechanical strength that can stably support the windings with a support insulator that is easy to install by simply installing them with a gap of 5 mm or more. can be provided.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part of a first embodiment of a foil-wound transformer of the present invention, and FIG. 2 is a second embodiment of a foil-wound transformer of the present invention.
FIG. 3 is an enlarged sectional view of main parts showing a third embodiment of the foil-wound transformer of the present invention; FIG. 4 is a cross-sectional view showing the configuration of a conventional foil-wound transformer. , FIG. 5 is an enlarged sectional view of the main part of a conventional foil-wound transformer. DESCRIPTION OF SYMBOLS 1... Leg of iron core, 2... Metal sheet, 3... Insulating sheet, 4... Low voltage winding, 5... High voltage winding, 6...
...High pressure shield, 7...Cooling duct, 8...Pump, 9...Condenser, 10...Refrigerant tank, 11...
・Liquid pipe, 12... Insulated pipe, 13... Tank,
14... Grounding component, 20... Supporting insulator, 21...
...Post spacer, 31°41.51...Column spacer, 52...Engagement hole.

Claims (6)

[Claims] (1) A low-voltage winding and a high-voltage winding made by overlapping and winding a metal sheet and an insulating sheet are wound around the legs of the iron core, a high-voltage shield is placed at the end of the winding, and an insulating medium is enclosed. In the foil-wound transformer in which the winding is housed in a tank, the high-voltage shield is configured to protrude from the upper and lower ends of the metal sheet in the winding stack direction, and at least the upper and lower ends of the winding are A foil-wound transformer characterized in that a columnar spacer made of an insulating material is disposed below the winding, and the diameter of the end face of the columnar spacer on the winding side is larger than the diameter of the central portion. (2) The foil-wound transformer according to claim 1, wherein the diameter of the winding side end face of the columnar spacer is the same as the diameter of the winding. (3) The diameter of the end surface of the winding side of the columnar spacer is configured to be smaller than the diameter of the winding, and the columnar spacer is arranged in a part of the winding in the radial direction so as to have an appropriate distance from the high voltage shield. A foil-wound transformer according to claim 1, which is a foil-wound transformer according to claim 1. (4) The diameter of the winding side end surface of the columnar spacer is configured to be larger than the diameter of the winding, and an engagement hole is formed in the high voltage shield, and the upper end of the columnar spacer is configured to engage with the high voltage shield. The foil-wound transformer according to claim 1, which is fitted into a matching hole. (5) The foil-wound transformer according to claim 1, wherein the diameter of the columnar spacer on the tank side is the same as the diameter of the central portion thereof. (6) The foil-wound transformer according to claim 1, wherein the diameter of the columnar spacer on the tank side is larger than the diameter of the central portion thereof.