JPS6072207A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To prevent an eddy current loss due to a leakage flux and to obtain the transformer having a high electrical insulation strength by composing the inlet and outlet parts for a cooling medium of a cooling duct out of a ceramic insulator when a metallic sheet and an insulating sheet are laminated and wound around an iron core and a cooling duct is arranged among them for cooling the windings by flowing the cooling medium through it. CONSTITUTION:A metallic sheet 2 and an insulating sheet 3 are laminated and wound around an iron core 1 to compose a low-voltage winding 4 and a high- voltage winding 5. At this time, a cooling duct 6 is arranged amoung the respective layers of the windings 4 and 5 in parallel to the iron core 1 and with being located between a winding end position 16. After that, a cooling medium 15 from a cooling medium tank 14 circulates in that and an insulation pipe 11 to be attached to an end connection part 17 for introducing and exhausting the cooling medium 15 in and out of duct 6 is made of a ceramic insulator. Namely, the pipe 11 is made of Al2O3, SiO2, BeO, SiC, AlN, Si3N4 and etc. to form the high-reliability transformer.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a foil-wound transformer that is equipped with a foil-shaped winding formed by overlapping Kinwa sheets and insulating sheets and has a cooling duct built into the winding. Regarding.

[Technical background of the invention and its problems]

A foil-wound transformer, in which a foil winding is wound around an iron core, has a good 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 1100 kVAi degrees.

Recently, in view of its excellent advantages, there has been a desire to expand its application to higher voltage, larger capacity transformers, such as 275 kV and 300 MVA. However, the biggest technical problem in realizing this is how to improve the cooling capacity and provide high insulation capacity to the windings. In addition, although such high normal voltage, large response capacity transformers have not been put into practical use, foil-wound transformers, which are already known and are being researched, have cooling ducts built into the windings and have excellent insulation properties. Cooling I# Full feed, directly cools the heat generated from winding loss,
A so-called heat pipe type is being considered.

FIG. 1 shows the structure of a conventionally known foil-wound transformer.

Overlapping the area sheet 2 and the insulation sheet 3 on the outside of the iron core 1,
A low voltage winding 4 and a high 17 winding 5 are wound using a known foil winding method, and an annular cooling duct 6 is built in between each of the low voltage and high voltage windings 4 and 5, respectively. This cooling duct 6 includes
There is a thin gap, and Freon ■-113 or 70 Linato 75
The refrigerant 15 is circulated by the pump 7 to the external cooling system, and the heat generated within the foil winding is absorbed by the latent heat of evaporation of the refrigerant. There is a known method in which the steam is cooled and condensed in a condenser 8 by a water cooler 9. Furthermore, this mono-liquefied refrigerant is stored in the refrigerant tank 14, and the pump 7
A refrigerant circulation cooling circuit is used in which the refrigerant is fed into the windings. That is, the refrigeration circuit and the transformer are separated.

The liquid collection pipe 10 is made of metal such as stainless steel, and an insulated pipe 11 is used to connect it to the cooling duct 6, and the liquid collection pipe 10 is at a ground potential such as a wire 12. The potential of the cooling duct 6 is electrically coupled to the same potential as the winding because it is wound within the winding.

The windings are insulated with an insulating medium 13 such as insulating oil or SF6 gas sealed in a tank 12.

In FIG. 1, winding lead wires that are not directly related to the present invention, bushings that lead the wires to the outside of the tank, and the like are omitted.

In the foil-wound transformer of the type described above, the circulation circuit through which the refrigerant for cooling flows and the insulating medium 13 for insulation are completely separated. Here, the transformer will be specifically referred to as a separate foil-wound transformer.

Separate foil-wound transformers 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. However, the conventional separate foil-wound transformer as shown in FIG. 1 has the following problems.

Front 113. A number of cooling ducts through which a refrigerant such as Solorinat 75 is passed are installed. This cooling duct 6 as shown in FIG. 1 is formed hollow, and the coolant flow path is divided by partitions 9, so that the fluid path and flow rate are designed to change uniformly.

This cooling duct is made of a metal material with high thermal conductivity.
It is inserted between the layers of the metal sheet and the insulation sheet of the foil winding.

These cooling ducts form the refrigerant circulation path described in the technical background of the invention by connection with the insulating vibrator.

Therefore, the connection part between the cooling duct and the insulated vibe (hereinafter referred to as the end connection part of the cooling duct) is located outside the end of the foil winding due to the design, so there is a problem of insulation for the conductor between the windings, and ■ insulation to ground. It has been desired to insulate the end connections of this cooling duct in order to solve the problem of eddy current product due to leakage magnetic flux.

Conventionally, the base of the end connection portion of this cooling duct is made of metal, and its surface is coated with an insulating material, taped, etc., to perform insulation treatment.

According to this method, among the above-mentioned problems, the problems of gauze edges for the conductor between the windings and insulation between the ground and the ground can be solved, but due to the leakage magnetic flux distribution caused by the current flowing in the winding conductor, the end of the cooling duct An overcurrent loss occurs at the connection portion that is proportional to the square of the thickness of the metal conductor at the connection portion, and at the connection portion of the cooling duct, resistance loss due to load current and eddy current are added, causing a temperature rise. This is a particularly serious problem in foil-wound transformers with large currents and large capacities. %, the above-mentioned problems were important issues that had to be solved in separate foil-wound transformers.

[Purpose of the invention]

An object of the present invention is to eliminate the problems of the prior art listed above, and to provide a highly reliable foil-wound transformer that prevents the occurrence of eddy current loss due to leakage magnetic flux and improves electrical insulation strength. The purpose is to

[Summary of the invention]

In the present invention, prior to incorporating the cooling duct of a separate transformer into the foil winding, the end connecting portion of the cooling duct is made of a ceramic inorganic composition that has good electrical insulation, mechanical strength characteristics, and workability. It is characterized by

[Embodiments of the invention]

An embodiment of this invention will be described below.

FIG. 2 is a perspective view of the cooling duct. The dotted line is a diagram showing the position of the winding end. Cooling in the shaded area Oe.

The cut end connection portion (I7) has a winding configuration that is wound at a position outside the winding. The end connection of this cooling duct is connected to an insulated pipe and leads to a liquid collecting pipe. In the present invention, a ceramic composition such as alumina At203 silica (Si
02), BeO, SiC, known as high-strength ceramics. Alumina nitride AzN, silicon nitride, Si
3N4 was used. In particular, alumina nitride AtN is preferred from the viewpoint of high insulation properties, thermal conductivity, mechanical strength characteristics, corrosion resistance, workability, and the like.

As described above, according to the present invention, by insulating the end connection portion of the cooling duct, various problems related to electrical insulation can be overcome, and in particular, compared to the conventional technology, eddy current loss due to leakage magnetic flux can be eliminated. is possible. Therefore, cooling efficiency can be significantly increased, and a high quality and highly reliable separate foil winding can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a foil-wound transformer, and FIG. 2 is a perspective view of a cooling duct used in a foil-wound transformer according to an embodiment of the present invention.

Claims (1)

[Claims] In foil-wound transformers, the windings are cooled by placing a cooling duct inside the foil winding, which is made by overlapping metal sheets and edge sheets wound around the iron core, and passing a refrigerant through the cooling duct. A foil-wound transformer, characterized in that a refrigerant inlet portion and an outlet portion of the cooling duct are made of a ceramic insulator.