JPS61105816A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To prevent dielectric breakdown at the ends of cooling ducts by providing a construction in which the cooling ducts are placed between an auxiliary foil conductor and a metal sheet adjacent to the cooling ducts. CONSTITUTION:Into a winding comprising a metal sheet 7 and an insulating sheet 8 which are layed one upon another and wound, cooling ducts 9a, 9b having coolant sealed therein are inserted. An auxiliary foil conductor 17 is wound between the cooling ducts 9a, 9b and the insulating sheet 8 that is adjacent to the outer sides of the cooling ducts 9a, 9b, and both ends of this auxiliary foil conductor 17 are connected to the metal sheet 7 that is adjacent to the inner sides of the cooling ducts 9a, 9b, thereby wrapping the cooling ducts 9 with the metal sheet 7 and the auxiliary foil conductor 17. In a foil winding transformer constructed as this, since both cooling ducts 9a, 9b have one side covered with the metal sheet 7 and the other side covered with the auxiliary foil conductor 17, and moreover the metal sheet 7 and the auxiliary foil conductor 17 have a same electric potential, dielectric breakdown which has been occurring between the ends of the cooling ducts 9a, 9b can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foil-wound transformer in which a cooling duct is built into a winding formed by overlappingly wound a metal sheet and an insulating sheet.

[Technical Background of the Invention] Foil-wound transformers have a good winding space factor and can be made compact and lightweight, and are small-capacity transformers with relatively low voltages of several KV or several hundred KVA. It has been put into practical use. 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 275 KV and 300 MVA.

In order to put such high-voltage, large-capacity transformers into practical use, it is important to consider how to increase the insulation ability of the windings, suppress potential fluctuations in the windings due to the intrusion of lightning surges, and further improve the potential distribution of the windings. An important technical issue is whether to do so. Although such high-voltage, large-capacity transformers have not yet been put into practical use, as shown in Figure 3, a cooling duct is built into the windings, and a refrigerant with excellent insulation properties is fed into the cooling ducts, and the windings are A so-called Hepaibe type heat exchanger, which cools the heat generated from the loss by using the latent heat of vaporization of the refrigerant, is promising.

That is, an iron core 2 is installed inside a tank 1 in which insulating oil or an insulating gas such as SF6 gas is used as an insulating medium. A low-voltage winding 4 is wound on the outside of the El-leg 2a of this iron core 2 via an insulating cylinder 3, and this low-voltage winding 4
A high-voltage winding 5 is wound on the outside of the coil with an insulating pole X-p 6 interposed therebetween. These low voltage windings 4 and high 11-windings 5 are
It is constituted by a foil-like winding formed by overlapping and winding a metal sheet 7 made of aluminum foil or the like and an insulating sheet F3 made of resin film or the like.

A cold duct 1-9 extending in the axial direction is wound around and built into the low-voltage winding 4 and the high-voltage winding 5. Inside this cooling tact 9, Freon 113 and Ichino [-1
Liner 1-F Hollow <7 so that refrigerant such as C75 can pass through.
(1 tari, this refrigerant passes through the inside of the refrigerating chamber 1 C, the heat generated by the windings 4 and 5 is used as the latent heat of evaporation of the refrigerant, and the winding 4.;) is cooled by 7 Jl. Then, this refrigerant is cooled and condensed by water cooling W in a condenser 10 installed outside the tank 1. It is sent out into the cooling duct 9 via the insulated pipe 14.

Note that the metal liquid guide pipes 13 are arranged at both ends of the winding 4.5, and connection ports are formed at both ends of the cooling duct 9.
The connection port between the liquid guide pipe 13 and the cooling ducts 1 to 9 is the insulated pipe 1.
Connected via 4.

[Problems with backing technology] By the way, the arrangement of the cooling ducts 1 to 9 built into the windings of the foil-wound transformer as described above is as shown in the sectional view of FIG. 4. That is, the shape of the cooling duct 9 is set so that the length of the circular arc is smaller than 180° in circumferential angle from the viewpoint of ease of attachment to the windings and structural integrity. , 9b are arranged on the same winding, and cooling ducts 9 arranged in this manner are inserted at predetermined intervals in the radial direction of the winding. Here, the thickness of the metal sheet 7 is generally several hundreds of tons! m or less, insulation sheet 1 to 8
The thickness of the ducts 1 to 9 is often about 2 to 5 mm, so the thickness of the ducts 1 to 9 is approximately 2 to 5 mm, so the thickness of the ducts 1 to 9 is approximately 2 to 5 mm. There is a metal sheet 7 wrapped around the inside of the edge of the
Since the insulating sheet 8 moves to the outside of the cooling duct 1-0 and a loose transition portion 15 is formed, the end circumference of the cooling duct 9) is shown in Fig. 4. A similar gap 16 is created. This gap 16 has a curved triangular shape formed by the ends of the cold section ducts I to 9, the metal sheet 7, and the insulating sheet 8.

However, in a foil-wound transformer, such a gap of 1G
When C decreases, the dielectric constant of that part becomes extremely low, and the electric current W decreases.
There were vacancies where there was a concentration of 1 person in the tank, and the insulating effect of the insulating gas was insufficient. Furthermore, the cold 7.11 duct arranged in the same winding 1]・9a
Depending on the potential difference between and 9b, A.1 cooling ducts 1 to 9
There is also the drawback that dielectric breakdown may occur between the ends of the windings a and 9b, and the insulation +11 ability of the windings is weakened between the cooling ducts.

In particular, as mentioned above, the cooling duct 9 is considerably thicker than the metal sheet 7, so J-jitsu is likely to form at the end of the cooling duct 9, and the electric field concentrates, causing dielectric breakdown. Sometimes it happened.

[Object of the Invention] The present invention was proposed in order to eliminate the drawbacks of the prior art as described above, and its purpose is to improve the insulation of the winding at the end of the cooling dow 1 inserted into the winding. improved performance,
The objective is to provide a highly reliable foil-wound transformer.

[Summary of the Invention] The foil-wound transformer of the present invention has an auxiliary foil conductor tightly wound between a cooling duct and an insulating sheet adjacent to the cooling duct. By configuring the cooling duct to be sandwiched between adjacent metal sheets, dielectric breakdown at the ends of the cooling duct is prevented.

Example 1 of the E invention An embodiment of the present invention will be described below with reference to FIG.

Note that the same members as those of the conventional foil-wound transformer shown in FIGS. 3 to 5 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, cooling ducts 1-9a, 9b, . . ., each having a refrigerant sealed therein, are inserted into a winding formed by overlapping metal sheets I to 7 and an insulating sheet 8.
, an auxiliary foil conductor 17 is wound between the cooling 711 ducts 9a, 9b, . ]
9a, 9b, .

In the foil-wound transformer of this embodiment configured in this way,
The cold 1 (II ducts 1 to 9a, 9b are both covered with the metal sheet 7 on one side and the auxiliary foil conductor 171 on the other side, and are covered with the metal sheet 7 and the auxiliary foil conductor 1.
7 are at the same potential, it is possible to prevent dielectric breakdown between the ends of the cooling ducts 1 to 9a, 9tl). Furthermore, even if a gap 16 is formed at the end of the cooling duct or at the transition portion 15 around the end to the cooling duct 1, this gap 16 is surrounded by the metal sheet 7 and the auxiliary foil conductor 17 having the same potential, so there is no gap. No electrical stress is applied to 16, and the dielectric strength between the cooling ducts increases dramatically. Furthermore, since the cooling duct 98.9b is surrounded by the metal sheet 7 and the auxiliary foil conductor 17, the potential distribution between the foil windings sandwiching the cooling ducts 9a and 9b causes potential discontinuity in the cooling duct portion. It will be distributed evenly without any incident.

It should be noted that the present invention is not limited to the embodiments shown in "-", but may also be constructed as shown in FIG. One end of the auxiliary foil conductor 27 disposed in close contact with one side of the cooling ducts 9a, 9b is electrically connected to the metal sheet 7 wound adjacent to the cooling duct 9a, and has the same potential. However, the thin end of the auxiliary foil winding 27 is disposed halfway in the cooling duct 9b and is insulated. Further, at the end 9b- of the cooling duct 9b, an auxiliary insulating sheet 28 is placed between them to insulate the cooling duct 9b, and an auxiliary foil conductor 27 is placed, Cold section, 0 tak[・9
It may be connected to a metal sheet wound adjacently. In this way, the auxiliary 05-shaped conductor does not need to have one side or both ends directly connected to the metal sheet. It may be configured as follows.

[Effects of the Invention] As described below, according to the present invention, the cooling duct is located adjacent to the cooling duct.
-('?+fin)+A configuration in which a foil-like conductor is tightly wound, and this is connected to a metal sheet that is wound adjacent to the cooling pipe 1 to wrap around the cold N1 duct 1~. By moving the cold part, 11 duct ◇i: part [J:? )
This has the effect of improving the insulation performance of the windings and providing a highly reliable foil-wound transformer.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an embodiment of the three-turn transformer of the present invention, Fig. 2 is an enlarged cross-sectional view of the main part of the third embodiment of the invention, and Fig. 3 is The structure of a conventional foil-wound transformer is shown in section H, FIG. 4 is a cross-sectional view thereof, and FIG. 5 is an enlarged view of the main part of FIG. 4. 1...Tank, 2...Ore core, 2a...Main landing gear, 3...
...Insulating tube, 4...Low voltage winding, 5...Tall winding, 6
...Insulating barrier, 7...Metal sheet. 8... To insulation sheath 1, 9... Cooling duct, 10... Condenser, 1
DESCRIPTION OF SYMBOLS 1... Refrigerant tank, 12... Pump, 13... Liquid guide pipe, 14... Insulating barb, 15... Transition part,
16...Gap, 17.27...Auxiliary foil conductor, 28
... Auxiliary insulation sheet 1-. 7317 Sokujin Patent Attorney Rule 311 Kei (1)
1 person) Figure 1 II 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A foil winding made by overlapping and winding a metal sheet and an insulating sheet is wound around the legs of the iron core, and a cooling duct curved into an arc is arranged within this winding. In a foil-wound transformer that cools a foil winding by circulating a refrigerant in the cooling duct, an auxiliary foil conductor is closely wound between the cooling duct and an insulating sheet adjacent to the cooling duct. A foil-wound transformer, characterized in that a cooling duct is sandwiched between a metal sheet adjacent to the cooling duct and the auxiliary foil conductor. (2) The foil-wound transformer according to claim 1, wherein both ends of the auxiliary foil conductor are electrically connected to a metal sheet adjacent to the cooling duct. (3) The foil-wound transformer according to claim 1, wherein at least one end of the auxiliary foil conductor is electrically insulated from a metal sheet adjacent to the cooling duct.