JPS61188909A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To reduce a pressure loss of a fluid in an insulation pipe as compared to the loss in the case of only a corrugated tube being employed by providing a double layer structure wherein a corrugated tube is used as an outer insulation pipe and a smooth tube with an outer diameter a little smaller than the inner diameter of the corrugated tube is used as an inner insulation pipe. CONSTITUTION:An insulation pipe of a transformer has a structure wherein a smooth tube 15 is inserted into a corrugated tube 14. A cooling duct is connected in such a manner that the end flange 17 of the insulation pipe is tightened into the nozzle 16 at the end of the cooling duct with a nut 18. Small holes 19 are drilled on the inner tube 15 in order to avoid pressure difference between the inside and the outside of the tube 15. With this constitution, the thickness of the smooth tube 15 can be reduced so that flexibility is maintained. Moreover, as the inner diameter of the smooth tube 15 is not so smaller than that of the corrugated tube 14, a fluid friction coefficient is reduced to approximately 1/10 of that in the case of only the corrugated tube 14 being employed and hence a pressure loss is also reduced to approximately 1/10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foil-wound transformer having a built-in cooling panel and a foil-like winding formed by overlapping and winding a metal sheet and an insulating sheet.

[Technical background of the invention and its problems] Perimeter C of the core leg - A foil-wound transformer in which a foil winding is constructed by overlapping and winding a metal sheet and an insulating sheet has a good space factor for the winding conductor. Therefore, it is smaller and lighter than a transformer using a normal rectangular wire conductor.

However, in order to realize transformers with higher voltage and larger capacity, I
:It is essential to further improve the cooling capacity of the winding (pair) and maintain a high insulation capacity. It has been considered to construct the transformer so that the heat generated from the windings is directly cooled.This type of transformer is known from US Pat. No. 1,039,990.

This conventionally proposed foil-wound transformer, for example,
As shown in Fig. 1, a winding is constructed by overlapping two metal sheets 2 and an insulating sheet 3 around a core leg 1.This winding consists of an inner winding 4 and an outer winding 5. Each of these windings has a built-in annular cooling panel 6.

The cooling panel 6 is made up of two metal plates stacked one on top of the other with a narrow gap for the coolant to flow, and the periphery of the two metal plates is sealed by welding or the like. A refrigerant such as Freon R-113 or Fluoriner) FC-75 is constantly poured into the gap C of the cooling panel 6 using the pump 7.
Refrigerant: Cooling is performed by removing the heat generated within the foil-wound winding.The refrigerant that has absorbed the heat is sent out to the outside of the winding through a lead-out nozzle, and is sent to a cooler 9 provided outside the tank 8.
Note that the refrigerant is cooled in the cooling panel 6 (before being sent into the cooling panel 6), and is once collected in the fruit pipe 10 (-), but this liquid collection pipe 10 fl is collected in the tank 8.
Since the ground potential is the same as that of the manuscript sheet 2 and the cooling panel 6 having the same potential, the connection between the manuscript sheet 2 and the cooling panel 6 having the same potential is made through an insulating pipe 1]. Sharpen the cooling panel to cool the metal sheet 2 by heat conduction C2.
Alternatively, since the insulation sheet 3 (-) is in contact with the metal sheet 2 (-), the cooling panel 6 (2) is wrapped around the winding (2), so almost the same voltage is applied to the cooling panel 6 (2), and this metal sheet 2 and cooling The panel 6 is insulated from the outside by an insulating gas 1, such as sulfur hexafluoride (SP6), which is initially sealed in the tank 8.

The foil-wound transformer described above is called a separate foil-wound transformer because the circulation circuit through which the refrigerant for cooling flows and the insulating gas are completely separated. Compared to transformers using conductors, the transformer can be significantly smaller and lighter, and has the advantages of high insulation reliability.

However, the conventional foil-wound transformer described above has the following problems.
1 is connected to the cooling panel 6 at the upper and lower ends of the winding 4.5, and the other is connected to the liquid collecting pipe 1O (: connected However, since there are also the upper and lower end surfaces 126 of the winding 4.5 and the supporting insulators of the winding 4.5, the connecting part between the cooling panel and the insulating pipe 11 is designed while considering the insulation from these. In order to determine the arrangement and pull out the insulated pipe 11, the insulated pipe 11 needs to be flexible, so for example, as shown in Japanese Utility Model Application Publication No. 56-162800 (although an insulating corrugated pipe is used). Corrugated pipes have higher internal fluid resistance than smooth pipes (-), so the pressure drop in the refrigerant circulation system increases (
For example, let's compare the fluid resistance between a smooth Teflon tube with an inner diameter of φ15 and a full-gate Teflon tube with four diameters as shown in Figure 4C. The calculation method is based on "Fluid resistance of pipes and ducts", Japan Society of Mechanical Engineers, P, 30-P, 33.

For example, the coefficient of fluid friction in a corrugated pipe is: On the other hand, if the surface roughness of a smooth Teflon pipe is about 0.0015, and the flow velocity inside is 2.3 m/S, then λ=O11205, which is as small as 0 for the corrugated pipe.

Therefore, the flow velocity is both Cyuv = 2.3 m/S, and the flow rate of the insulated pipe is 1 = 2 x 90 e- (one cooling panel (total length of insulated pipes on the inlet side and outlet side))
When the refrigerant is FC-75 (density r = 1.6855℃), the pressure loss in the insulated pipe is the same as in the case of a corrugated pipe.
11.3 m water column On the other hand, in a smooth pipe the pressure loss is 0.0205 ΔP = 11.3 X - = 1.12 m water column 0.
207, it is possible to remove the heat of corrugated pipe.

Like this I: It is possible to reduce pressure loss by using a smooth tube, but since a smooth tube is not flexible, various shapes C
1. Cannot be used by bending. If you use a thin and smooth pipe, it will have some flexibility, but this insulated pipe (
U is outside C; it is impossible to use thin-walled tubes because the pressure of the existing insulating gas is added as external pressure.0 In addition, increasing the diameter of the full-gate tube (reducing pressure loss from U Although this is possible, in this case the radius of curvature of the barb increases, and the volume that occupies space also increases, making it difficult to arrange the ends of the winding.

[Object of the Invention] In view of the above-mentioned drawbacks of the prior art, the purpose of the present invention is to reduce the pressure loss of the cooling duct (-connected insulation) and to reduce the head of the pump. To obtain a foil-wound transformer with reduced loss in auxiliary equipment.

[Summary of the Invention] The foil-wound transformer of the present invention has a double structure using an outer Nicol gate pipe as an insulating pipe and a smooth pipe having an outer diameter slightly smaller than the inner diameter of the inner corrugated pipe. From C-, the pressure loss of the fluid inside the insulated pipe is reduced compared to when only the corrugated pipe is used (2).

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. 1. As shown in FIG. be. To connect to the cooling duct, tighten the end flange 17 of the insulated pipe using a nozzle 161n at the end of the cooling duct (Ninatsu) 18 as shown in the figure. A small hole 19 is made in the smooth tube 151- to prevent a pressure difference between the inside and outside of the smooth inner tube 15. In this way, the wall thickness of the smooth tube I5 can be made thinner, making it more flexible. Since the inner diameter of the pipe is not so small compared to the corrugated pipe 14, the fluid friction coefficient is approximately 0 compared to the case of the corrugated pipe 14 alone (compared to Y), and the pressure loss can also be reduced to approximately 0. O As mentioned above, C: has the flexibility to do so, but if the bending curvature becomes small, there is a risk that the smooth tube will collapse and block the flow path. In such a case, C- is shown in Figure 2 (:
As shown, there is also a method in which an internal smooth tube is not attached to the C-portion At2 where the curvature is small.

[Effects of the Invention] As explained above (according to the BA+- of this invention, pressure loss in the insulated pipe can be eliminated by simply inserting a corrugated insulated pipe and a smooth pipe. We can provide equipment.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing an insulated pipe in C unit of the present invention;
FIG. 2 is a perspective view showing a modification of the present invention, FIG. 3 is a sectional view showing a separate transformer, and FIG. 4 is a sectional view of a conventional insulated pipe. l... Iron core leg 2... Metal sheet 3...
Insulating sheet 4...Inner winding 5...Outer winding
6...Cooling panel 7...Pump 8
...Tank 9...Cooler lO...Liquid collection pipe 11...Insulation pipe 12...Outlet lead 13...Support insulator 14...Full gate pipe 1
5...Smooth tube 16...Nozzle 17...
Insulated pipe 7 lunges 18... Nara total 19... Hole agent Patent attorney Nori Chika Kensuke (and 1 other person) 17
/s Figure 1 Figure 2 tQ Figure 3

Claims (1)

[Claims] A foil winding made by overlapping a metal sheet and an insulating sheet is wound around the legs of the iron core, a cooling panel is disposed within the foil winding, and a refrigerant is circulated within the cooling panel. In a foil-wound transformer that cools a foil winding, an insulating pipe connected to the end of the cooling panel for taking refrigerant into and out of the cooling panel has a corrugated pipe on the outside and a smooth circular pipe on the inside. A foil-wound transformer characterized by being constructed from double pipes.