JPH02234403A - Gas insulation transformer - Google Patents

Abstract

PURPOSE:To sufficiently secure an amount of circulation gas to be generated by natural convection while improving a cooling characteristic by covering the gas piping, through which insulation gas flows from a transformer tank to a cooler, with an insulating material. CONSTITUTION:The subject transformer has the constitution wherein an outer peripheral surface of the gas piping 5a connecting the upper part of a transformer 1 and a cooler 4 set up on a floor of the upper layer story of the transformer tank 1 is covered with an insulating material 9. Accordingly, insulation gas warmed by heat to be generated in the transformer contents reaches the upper part of the cooler 4 from the upper part of the transformer tank 1 through the gas piping 5a. However, since the gas piping 5a is covered with the insulating material 9, the temperature of the insulation gas scarcely drops, and the gas is taken into the cooler 4 even when the transformer tank and the cooler 4 are set up in the separated places. Thereby, a weight difference from the cooled insulation gas returning to the lower part of the transformer tank 1 from the lower part of the cooler 4 through the gas piping 5b increases so as to sufficiently secure a circulating gas amount to be generated by natural convection for improving cooling efficiency.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a gas insulated transformer with an improved cooling structure.

(Prior Art) In recent years, transformers have been increasingly installed in underground substations near cities or in large cities due to restrictions on where they can be installed. Therefore, requirements for flame retardancy are becoming even higher for transformers installed in such locations.

Therefore, recently, gas insulated transformers have been put into practical use in place of the conventional Uraho transformers, which insulate and cool the transformers by using an insulating gas such as SF6 gas, which has excellent insulating properties, as an insulating cooling medium.

However, this insulating gas transformer has the disadvantage of inferior cooling characteristics compared to conventional oil-immersed transformers. That is, the specific heat and heat exchange efficiency of the insulating gas are significantly lower than those of the insulating oil, resulting in poor cooling efficiency.

For this reason, even if the transformer capacity is such that a self-cooling method can be applied to an oil-immersed transformer, a cooling device must be increased in the case of a gas-insulated transformer, and even a transformer with a capacity of about 20 to 30 MVA must be cooled. In order to increase efficiency, it may be necessary to apply a forced circulation method of gas using a blower.

On the other hand, recent transformers are required not only to be flame retardant, but also to require no maintenance or inspection from the perspective of reducing maintenance personnel at substations, etc. In order to meet these requirements, 20-30M
It is desired that gas insulated transformers of approximately VA capacity be fully automated.

Next, the problems of self-cooled gas transformers among such gas insulated transformers will be explained.

FIG. 2 is a conceptual diagram of a conventional core type self-cooling gas transformer. As shown in FIG. 2, the contents of the transformer consisting of an iron core 2 and windings 3 are housed in a transformer tank 1, and SF, which is an insulation and cooling medium. An insulating gas 7 such as gas is sealed at a predetermined pressure.

Further, a gas partition plate 6 is provided between the outer surface of the transformer contents and the inner wall of the transformer tank 1, which is designed to effectively circulate the insulating gas 7 into the iron core 2 and the windings 3. There is.

On the other hand, outside of the transformer tank 1, in order to cool the warmed insulating gas, the upper and lower parts of the transformer tank 1 and gas piping 5 are installed.
A cooler 4 connected by a and 5b is provided.

Therefore, in such a self-cooling gas insulated transformer, the insulating gas 7 heated in the transformer tank 1 passes into the cooler 4 through the gas pipe 5a connecting the upper part of the tank and the upper part of the cooler 4 by natural convection. The insulating gas cooled here is further circulated back into the transformer tank 1 through the gas pipe 5b connecting the lower part of the cooler 4 and the lower part of the transformer tank 1.

By the way, when a gas insulated transformer with such a configuration is installed, for example, in an underground substation in a large city, the cooler 4 may be placed on an upper floor different from the floor on which the transformer tank 1 is installed due to installation space. It may be installed.

FIG. 3 shows an example of the configuration of a gas insulated transformer installed in such a state, and its basic structure is the same as that in FIG. 1. That is, as shown in FIG. 3, the cooler 4 is installed on a pedestal 8 provided on the upper floor of the floor where the transformer tank 1 is installed, and the upper and lower parts of the cooler 4 and the transformer tank are connected to each other. A long gas pipe 5a, 5 is connected between the upper and lower parts of 1.
They are connected to each other by b.

Therefore, in a gas insulated transformer installed in such a state, the insulating gas 7 circulates between the transformer tank 1 and the cooler 4 through the pipes 5a and 5b as shown by the arrow 11 by natural convection. In this case, the force that causes natural convection (hereinafter referred to as circulation force) is generated by the difference in weight per unit body of the heated insulating gas and the cooled insulating gas.

Here, if the position where the insulating gas flows into the tank from the bottom of the transformer tank 1 is A, and the position where the insulating gas flows into the cooler from the top of the cooler 4 is B, then the contents of the transformer are determined from A. A gas route I that goes from the upper part of the transformer tank 1 to B through the gas pipe 5a, and a gas route that goes from B to A through the cooler 4 and from the lower part of the cooler through the gas pipe 5b.
Let's pay attention to this. The gas path I is filled with insulating gas warmed by heat generated from the contents of the transformer, while the gas path I is filled with insulating gas cooled by the cooler 4.

Therefore, these gas paths I. When the weight of each insulating gas filled in II is determined by integrating the gas weight per unit volume, the gas weight of gas route II is heavier than that of gas route I. In other words, the pressure generated by the gas weight at position A is higher in gas path H than in gas path I.

Therefore, in the natural convection of the insulating gas, this difference in pressure becomes a circulation force, so the larger the difference in pressure, the better in order to circulate more insulating gas and improve the cooling characteristics.

(Problem to be Solved by the Invention) However, as described above, when the cooler 4 is installed on the floor above the floor installed in the transformer tank 1, the gas path connecting these, especially the transformer When the gas piping 5a from the top of the tank 1 to the cooler 4 becomes longer, the insulating gas in this piping part is cooled and the insulating gas weight per unit volume increases, so the difference between the insulating gas weight at position A and the insulating gas weight at position A increases. This results in a reduction in the circulation force that causes natural convection.

An object of the present invention is to provide a gas-insulated transformer that can secure a sufficient amount of circulating gas generated by natural convection and improve cooling characteristics even when a transformer tank and a cooler are installed at separate locations. purpose.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has an insulating gas sealed at a predetermined pressure in a transformer tank together with the contents of the transformer consisting of an iron core and windings. In a gas insulated transformer in which a cooler is provided outside the transformer tank and the transformer tank and the cooler are connected by gas piping through which insulating gas circulates, the insulating gas flows from the transformer tank toward the cooler. The gas pipe through which the gas flows is covered with a heat insulating material.

(Function) In an insulating gas transformer with such a configuration, by covering the gas pipe through which insulating gas flows from the transformer tank to the cooler with a heat insulating material, even if the distance between them is long, This reduces the temperature drop of the insulating gas heated inside the transformer, making it possible to increase the weight difference between the cooled insulating gas that returns from the cooler to the transformer tank, and ensuring that the amount of circulating gas generated by natural convection is sufficient. Can be secured.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the structure of an insulated gas transformer according to the present invention, and the same parts as in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted, and only the different points will be described here.

In this embodiment, as shown in FIG. This is a horizontal structure covered with a heat insulating material 9.

With such a configuration, the insulating gas heated by the heat generated inside the transformer reaches the upper part of the cooler 4 from the upper part of the transformer tank 1 through the gas pipe 5a, but in this case, the gas pipe 5a is made of heat insulating material. 9, even if the transformer tank and the cooler 4 are installed at a separate location, the temperature of the insulating gas is introduced into the cooler 4 with almost no drop. Therefore, the gas pipe 5 is connected to the lower part of the cooler 4.
The weight difference with the cooled insulating gas that returns to the lower part of the transformer tank 1 through b becomes large, and a sufficient amount of circulating gas generated by natural convection can be secured, so that the cooling effect can be improved.

In the above embodiment, a case has been described in which the insulating gas is completely self-cooled by natural convection between the transformer tank 1 and the cooler 4 provided outside the transformer tank 1. Even when the insulating gas is forcibly circulated by the provided blower, the circulation force of the insulating gas can be supplementarily increased by applying the present invention.

[Effects of the Invention] As described above, according to the present invention, even when the transformer tank and the cooler are installed at separate locations, a sufficient amount of circulating gas generated by natural convection can be secured, and the cooling characteristics are improved. We can provide gas insulated transformers that can

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of a gas insulated transformer according to the present invention, and FIGS. 2 and 3 are configuration diagrams each showing four conventional gas insulated transformers with different layouts. be. 1...Transformer tank, 2...Iron core, 3...Winding wire,
4...Cooler '5a, 5b...Gas piping, 6...
Gas partition plate, 7... Insulating gas, 8... Frame, 9...
・Insulation material. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] Gas piping in which insulating gas is sealed at a predetermined pressure in the transformer tank together with the transformer contents consisting of the iron core and windings, a cooler is provided outside the transformer tank, and the insulating gas circulates between the transformer tank and the cooler. What is claimed is: 1. A gas insulated transformer configured to be connected by a gas insulated transformer, characterized in that a gas pipe through which insulating gas flows from the transformer tank toward the cooler is covered with a heat insulating material.