JPS5867011A - Transformer - Google Patents

Abstract

PURPOSE:To increase mechanical strength of a separated type of foil wrapped transformer and to make it possible to satisfactorily apply to large capacity of transformers by dividing metal sheets axially in the winding direction, and forming a clearance between the each divided metal sheet. CONSTITUTION:A clearance 17 is formed between each metal sheets 7-1, 7-2 which are divided from a metal sheet 7 of a low pressure and a high pressure windings 4, 5. Thereby, when to be extended by thermal expansion, the metal sheets 7-1, 7-2 can linearly expand widthwise without any restriction. Therefore, they would not be deformed undulatingly under forced stress caused by obstruction of its expansion, thus the sheets 7-1, 7-2 can cope with a mechanical force caused by short current of a transformer with their mechanical strength, and the windings 4, 5 can be protected from an incident of damage.

Description

[Detailed description of the invention] (Turtle) Technical field The present invention relates to a foil I in which a metal sheet and an insulating sheet are overlapped and wound.
#Related to a transformer that includes a winding and has a cooling duct built into the winding through which a cooling medium is passed.

(b) Background of the Invention Foil-wound transformers equipped with foil-wound windings have a good space factor, are compact and
Because it has the feature of realizing weight reduction, @kV number 100
Small capacity transformers with relatively low voltages of the order of kV have already been put into practical use and are widely available on the market.

Recently, in view of its excellent advantages, research has been conducted to expand its application to higher voltage and larger capacity transformers, such as 275kV and 300mV input transformers, but the biggest key is to improve the cooling capacity for the windings. It all depends on whether the winding can have high insulation capacity. Although such high-voltage, large-capacity transformers have not yet been put to practical use, the cooling method for the windings in foil-wound transformers is to incorporate a cooling duct inside the windings, which has excellent insulation properties. A so-called heat/temperature type is being considered, which directly cools the heat generated from winding loss by feeding a refrigerant into the coil.

Figure @1 shows a transformer of this type. 1 in the diagram
1 is a tank filled with an insulating gas such as insulating oil or SF4 gas as an insulating medium, and an iron core 2 is provided inside this tank 1.

A low-voltage winding 4 is wound around the outside of the main leg 2a of the iron core 2 via an insulating tube 3, and a high-voltage winding 5 is wound around the outside of the low-voltage winding 4 through an insulating barrier 6. ing. These low-voltage windings 4 and high-voltage windings 5tI'i are composed of foil-wound windings formed by overlapping and winding a metal sheet 7 made of aluminum foil or the like and an insulating sheet 8 such as a resin film. Winding valve valves 9 are provided on both end sides of these low voltage and high voltage windings 4.5.
is provided, and both ends of each winding 4, 5 are fixed by this winding valve 9. That is, the metal sheet 7 in each of the windings 4 and 5 is held by the winding presser 9 via the insulator 10 that is wrapped around both ends of the sheet, and the insulating sheet 8 has both ends attached to the winding valve 9. is held in contact with. Note that each of the windings 4 and 5 is sealed within the tank 1.

Further, for example, one cooling duct 11 is built inside the low voltage winding 1/M4, and a plurality of cooling ducts 11 are built inside the high voltage winding 5, respectively. The cooling duct 11Fi is a thin flat duct made of a stainless steel plate or the like, curved into a substantially cylindrical shape, and is wound together into the winding [4, j]. A refrigerant such as Freon-113 or Fe12 is passed through the cooling duct 11, and as the refrigerant passes through the cooling duct 1), the winding 4.
The windings 4 and 5 are cooled by removing the heat generated in the coil 5 with the latent heat of evaporation of the refrigerant. This refrigerant is then cooled and condensed by water cooling in the condenser 12, and the liquefied refrigerant is transferred to the refrigerant tank 1.
It saved up to 3! 14 into the cooling duct 11 provided within the windings 4 and 5. That is, the refrigerant circulation circuit and the transformer are separated. In addition, the liquid guide pipe 15 is made of metal such as stainless steel, and an insulated pipe F16 is used to connect it to the cooling duct 11, and the liquid guide pipe 15 is connected to the ground potential of the tank 1, etc. It is insulated from the The potential of the cooling duct 1 is electrically coupled to the same potential as the windings 4, 5 since it is wound up in the winding 4.5.

In this cooling type transformer, the circulation circuit through which the refrigerant for cooling flows and the insulating medium for insulation are completely separated (cell 4 rate). For this reason, this type of foil-wound transformer is particularly called a separate foil-wound transformer.

Transformers using this cooling method utilize the latent heat of vaporization of the refrigerant, so they can be expected to have excellent cooling characteristics, making them promising for large-capacity transformers.

Let us consider the relationship between cooling and temperature distribution in the windings in such a Sefrit-type transformer. Since the windings 4 and 5 are cooled by the refrigerant passing through the cooling duct 11 built into them, the portion located near the cooling duct 11 has a diameter of 30 mm.
The temperature rise can be suppressed to ~40°C, but the temperature rise can be suppressed to a temperature rise of ~40°C.
The part located between 1 and the cooling duct 11) is separated from the cooling duct 11 and is no longer affected by the cooling effect] when the temperature is T
o) The temperature does not drop and becomes high temperature.

FIG. 2 shows, as an example, the temperature distribution between the second and third cooling ducts 1 from the inside of the high-voltage winding 5. As shown in this figure, points a and b near the cooling duct 11 in the winding 5 have a temperature of 30° C., but six points in the center between the cooling ducts 11 have a temperature of 100′CK. This temperature distribution poses no problem since it is the permissible operating temperature of the insulating sheet 8 in terms of cooling design. However, the distance between points a and b between the cooling ducts 11 is as small as 20 to 40 cm, and a temperature difference of 70 DEG C. occurs between half of this distance. Such a large temperature difference occurs because the metal sheet 7 and the insulating sheet 8 of the winding have constant thermal conductivity, which allows a large amount of heat to be conducted.

And the heat flux due to the temperature difference in such a winding is lW/cII? It also reaches large values of . However, Se/
The greatest feature of the 4-rate transformer is that it can be designed with such a large fIIk flow. In other words, by incorporating a cooling duct into the winding to cool the winding mt-m, the heat flux can be set high.The ability to set the heat flux high is due to the cooling characteristics of the winding in the transformer. This means that it can be applied to large-capacity transformers.

(C) Prior Art However, the following problems arise when this central plate type foil-wound transformer is applied to a large-capacity transformer.

That is, taking the high-voltage winding 5 shown in Figure 3 as an example, the temperature rise in the central part located between the cooling ducts 110 is greater than that in the vicinity of the cooling duct 11 in the winding @5. The metal sheet 7 located in the central portion undergoes particularly large thermal expansion and stretches in the width direction, while the metal sheet 7 in the vicinity of the cooling duct 11 does not expand as much.

In this case, if the metal sheet 7 of the entire wire 5 expands and stretches in the width direction, the force associated with the expansion pushes the winding presser 9 outward through the insulator 10, causing a part of the central part of the wire to expand. Since only the metal sheet 7 is under tension, the force accompanying the expansion does not reach the winding presser 9 until it is pressed. For this reason, the expanded metal sheet 7Fi winding presser 9 presses the metal sheet from both ends and prevents it from expanding, so an unreasonable stress is applied in the width direction and it deforms in a wave pattern. It will be absorbed. Note that the insulating sheet 8 of the winding has a small s&expansion, so there is no problem. However, when the metal sheet 7 is deformed in a wave-like manner, it becomes extremely weak against the mechanical force caused by the short-circuit current of the transformer, which may result in a fatal accident in which the winding 5 ruptures. . In particular, when a separate type transformer is applied to a large capacity transformer, the temperature rise of the foil winding is high and the thermal expansion of the metal sheet 7 is large.
There is a high possibility that damage to the windings will occur due to expansion and deformation of the metal sheet F.

Furthermore, when a 1/4 rate type transformer is applied to a large capacity transformer, the width of the metal sheet 7 constituting the winding becomes 15001J or more, and in some cases 2000J or more.
It can even reach -. Such a wide metal sheet 7
When winding a wire using a sheet winding machine, when the multi-metal sheet 2 and the insulating sheet 8 are layered and coaxially wound using a sheet winding machine, the tension applied to the sheet is reduced, especially when the metal sheet 7 is thin. Even if efforts are made to achieve flatness, wrinkles often occur in the metal sheet 7. Note that the loquat sheet 8 does not wrinkle and poses no problem. For this reason,
The metal sheet 7 is wrinkled, resulting in a decrease in mechanical strength and a decrease in insulation with respect to the gold nugget sheet 7.

(d) Purpose of the Invention The present invention has been made in view of the above circumstances, and it is possible to prevent the deformation of the metal sheet of the foil-wound wire due to thermal expansion and the occurrence of wrinkles when the wire is wound, and to prevent the occurrence of wrinkles during the winding of the metal sheet of the gold bullion sheet. Reduce mechanical strength,
This provides a transformer that can be well applied to large capacity transformers.

(・) Summary of the Invention The transformer of the present invention divides a metal sheet of a foil-wound winding in the axial direction of the winding, and provides Kl! between each divided metal sheet. By forming gaps li, this gap absorbs deformation caused by thermal expansion in the metal sheet and wrinkles during winding.

(f) Examples of the invention Embodiments of the present invention illustrated in the drawings will be described below.

4 and 5 show an embodiment of the transformer of the present invention. FIG. 4 shows the entire transformer, and FIG. 5 shows the portion between each cooling duct 7 of the high voltage winding 5. ing. In FIGS. 4 and 5, the same parts as in FIG. 1 are designated by the same reference numerals.

The main S2m of the iron core 2 installed in the tank 1 has an i* cylinder 3.
A low-voltage winding 4 is wound around the low-voltage winding 4, and a high-voltage winding 5 is wound around the outside of the low-voltage winding 4 with an insulating barrier 6 interposed therebetween. It is composed of a foil-wound wire formed by overlapping and winding insulating sheets 8. In this example, low pressure &+4 and high pressure li8! St/C
The metal sheets 7 provided respectively are 92 metal sheets 1-1 extending in the axial direction of the winding, that is, in the width direction of the metal sheet 7.
and a metal sheet 7-2. These divided metal sheets) 7-J.

The wires 7-2 each have a width dimension of -, and a gap 17 is formed between the opposing inner ends of the winding 4.5 at the center in the axial direction. This gap 17 is number 1 from the Joten
The size is 0■.

The outer ends of each of the divided metal sheets 1-1 and 7-2 are held at both ends 111 of the windings 4.5 by the winding presser 9 provided via the insulator 10.

Note that the insulation sheet 8 in the low voltage and high voltage windings 4 and 5
IIi It has the same configuration as the conventional one and is not divided into nine parts.

Also, each winding 4. '5 has a cooling duct 1 as before.
1 is built-in, and a refrigerant circulation circuit including this cooling duct 11, an insulating/main ignition 16, a liquid guide pipe 15, a condenser 12, a tank 13, and a sonde 14 is constructed in the same manner as before. .

The metal sheet 7 of the high voltage winding 4.5 and the metal sheet 7-1.
fl-IK divided, each divided metal sheet r-z,
A gap 17 is formed between r and x. Therefore, when the metal sheets r-z, y-2 are expanded (due to thermal expansion), the inner end of each metal sheet 1-1-1.1-1 forming one gap will be in the space of the gap 11. Stretch towards. That is,
The thermal expansion of each metal sheet r-1, 7-2 is the gap 1flK
If you run away, you will get K. As a result, the metal sheets ri, r
-z expands in the width direction kf line without difficulty due to thermal expansion. Therefore, in the winding 4.5, the metal sheet 7-7.1 located at a point with a high temperature rise away from the cooling duct 1
-2, for example cooling in high voltage winding 5? The metal sheets r-1 and 7-2 located in the central part between the ducts 11 are particularly sensitive (even if they expand, the metal sheets ?-1).

1-2 extends into the gap 11 without any force, so the extension is prevented and unreasonable stress is applied and the material does not deform in a wave-like manner as in the conventional case. Therefore, metal sheet 7/-1,
fl-1 can cope with the mechanical force caused by the short-circuit current of the transformer with great mechanical strength, and can prevent the occurrence of an accident that would damage the windings 4 and 5. Therefore, even when this transformer is applied to a large capacity transformer, the metal seam) '141゜7
-2 can be thermally expanded without difficulty, and the mechanical strength of the windings 4 and 5 can be increased.

Moreover, the divided metal sheet v-i-a-r-x has a width dimension that is half of the width dimension of the entire metal sheet 7. For this reason, when winding the metal sheet 7 during winding production, it is necessary to use a wire having a width half the width of the entire metal sheet 7.
7-J, line up v-x and roll i,
The metal sheet 7-1, 7-2 can be rolled evenly and without strain to prevent wrinkles from forming. That is, even if the width of the entire metal sheet 7 is 2,000 cm in a large capacity transformer, the metal sheet 7-1.7- has a width of 1,000 cm.
Wrapping the J's side by side creates a perfect storm and prevents wrinkles in the metal sheet without requiring sophisticated tension control. Therefore, it is possible to prevent a decrease in mechanical strength due to the occurrence of wrinkles in the metal sheet.

Figure 6 is another 1N! This is a partial diagram of a winding wire showing an example, in which a divided metal sheet 1-1゜y-ztD is shown.
Between f1 171fC metal'/-) 7-111-2) Insert thin metal foil 18 and create gap 11 through this metal foil 18
The inner ends of the metal sheets 7-1°r-x forming the metal sheet 7-1°r-x are electrically connected to each other. Note that the metal foils 18 are provided along the entire length of the turns of the winding or at predetermined intervals. Therefore, no potential difference occurs between the metal seams r-J and fl-2,
Due to the generation of potential difference, each metal sheet) 7-7. , 7-J
It is also possible to prevent eddy currents from occurring, and also to prevent accidents caused by lightning impulse penetration.

FIG. 7 shows a further different embodiment. In this embodiment, in addition to the metal sheets y-x, v-z and the insulation sheet), there is also a gap 1 at the inner end of each metal sheet 7-har r-x.
If the insulating sheets 19 are stacked as an insulator i times so as to overlap Kt in a stepped manner through the coils 7, a multi-winding wire is constructed. Therefore, each of the gold nugget sheets r-1 and 7-2 are insulated from each other by the insulation sheet Z#.

In addition, in the above-mentioned embodiment, the metal sheet is divided into two parts, but the present invention is not limited to this, and the Japanese metal sheet is divided into three parts in the axial direction of the winding wire.
It may be divided more than once.

Also, metal sheets are used throughout the low-pressure and high-pressure winding machines)
It is not limited to dividing, but may be summed by partially dividing as necessary.

(g) Effects of the Invention As explained above, the transformer of the present invention improves the mechanical reliability of the metal sheet of the foil-wound wire in a separate foil-wound transformer, and is well suited for large-capacity transformers. can.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram showing a separate type transformer.
Fig. 2 is an explanatory diagram showing the temperature distribution in the winding, Fig. 3 is an explanatory diagram showing the expansion deformation in the metal sheet of the winding, and Fig. 4 is an explanatory diagram showing the temperature distribution in the winding.
The figure is a vertical sectional view showing an embodiment of the transformer of the present invention, #! 5
The figures are an enlarged view, FIG. 6, and a second enlarged view showing the windings in the same embodiment. 1.-tank! -...Iron core, 4...Low voltage winding, 5...
...High voltage winding, 7.--Metal sheet, 7-1. r-2・
... Metal sheet, 8... Insulating sheet, 9... Winding holder, 10... Insulator, 1... Cooling duct, 11...
...Gap, 18...Metal foil, 19...Insulating sheet. Applicant's agent Patent attorney Takehiko Suzue Figure 1, Figure 3W! J Fig. 41 12 151) 1) 5th vA

Claims (1)

[Scope of Claims] 1. In a transformer equipped with a foil-wound winding formed by overlappingly wound a metal sheet and an insulating sheet, and a cooling duct for flowing a cooling medium built into the foil-wound winding, A transformer characterized in that a metal sheet of a foil-wound winding is divided into a number of sheets in the axial direction of the foil-wound winding, and a gap is formed between each of the divided metal sheets. 2. Claim 1 in which each divided metal sheet is connected to each other by an IC using a thin metal foil than the metal sheet.
Transformer mentioned in section. 3. The transformer according to claim 1, wherein an insulator is interposed between each of the divided metal sheets.