JPS62181407A - Automatic-cooling-gas insulated transformer - Google Patents

Abstract

PURPOSE:To reduce the increase in temperature of a winding, by dividing the inside of a transformer tank into two upper and lower gas chambers, connecting a color, which is arranged on the side surface of the tank, in the lower gas chamber, and connecting a cooler, which is arranged on the upper surface, in the upper gas chamber. CONSTITUTION:A gas partition plate 20 in a winding, which divides each winding into two upper and lower parts, is arranged at an intermediate part of upper and lower windings 13a and 13b. A gas partition plate 21 is arranged between the gas partition plate 20 in the winding and the inner wall of a transformer tank 1. The inside of the transformer tank 1 is divided into two independent upper and lower gas chambers 1a and 1b. A cooler 14b, which is arranged on the upper surface of the transformer tank 1, is connected to the upper gas chamber 1b through a pipe 15b. A cooler 14a, which is arranged on the side surface of the transformer tank 1, is connected to the lower gas chamber 1a through a pipe 15a. The gas partition plate 20 in the winding and the gas partition plate 21 are formed with an insulating material. In this way, the coolers are effectively arranged, and the increase in temperature of the windings can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a self-cooled gas insulated transformer with an improved cooling structure.

[Technical Background of the Invention and Problems Therewith] In recent years, various electrical equipment constituting a substation is increasingly being installed underground due to reasons such as difficulty in obtaining land.

In particular, if a transformer is installed in the basement of a building or in an underground passageway, it is expected that in the unlikely event that a fire breaks out, there will be many casualties. In order to prevent such fire accidents, instead of the oil-immersed transformers that have been used in the past, we have developed an insulating medium with excellent insulation properties, without changing the basic structure. Gas-insulated transformers that use insulating gas such as SF6 gas to insulate and cool the transformer are attracting attention.

However, the above-mentioned gas insulated transformer has a disadvantage in cooling characteristics compared to an oil-immersed transformer. In other words, the specific heat and heat exchange efficiency of the insulating gas used in gas-insulated transformers are significantly lower than those of the insulating oil used in oil-immersed transformers. The cooling device must be large, and in conventional oil-immersed transformers, a self-cooling system can be easily adopted.
Even with VA, there is always a drawback that a forced gas circulation system using a blower must be used.

Furthermore, from the perspective of reducing the number of maintenance personnel at substations, there is a desire for so-called maintenance-free gas-insulated transformers that do not require maintenance or inspection work.

Figure 2 shows the conventional self-cooling inner iron type gas insulated transformer. That is, an iron core 2 and a winding 3 are housed in a transformer tank 1, and an insulating gas 10 serving as an insulation and cooling medium is sealed at a predetermined pressure. Further, a cooler 4 for cooling the insulating gas 10 is provided outside the transformer tank 1, and is connected to the upper and lower parts of the tank 1 by piping 5. This cooler 4 takes in the heated insulating gas 10 from the upper part by natural convection of the insulating gas 10, and cools the insulating gas 1 from the lower part.
0 is returned to the transformer tank 1 and circulated.

In this case, the insulating gas 10 is cooled by natural heat radiation from the surface of the cooler 4, so the temperature of the upper insulating gas TI
A temperature difference of ΔT° C. occurs between the lower insulating gas temperature T2 and the lower insulating gas temperature T2. In this temperature relationship, the temperature difference of ΔT is determined so that the amount of heat released from the cooler per unit time out of the amount of heat possessed by the insulating medium is equal to the loss occurring within the transformer, and this can be expressed by the formula: Expressed as: L=to-Q-C-r-ΔT ・(1) Here,
K: Constant (KW/KCa l/h) Q: Flow rate of insulating medium flowing through the cooler (H/h) C9: Specific heat of insulating medium KCa 1/Kg ・°C) r: Specific gravity of insulating medium (Kg/A ) becomes. By transforming this equation (1), equation (2) is obtained.

ΔT= (1/ni-Cp-r) X (L/Q) ・(
2> Substituting the specific physical constants when SFs gas is used as the insulating gas into this equation (2), -C,
−r=approximately 6,500 to 7,000. On the other hand, when insulating oil is used as the insulating medium, this value is about 35, which is about 1/200 of the value when SFa gas is used.

From this result, in a gas insulated transformer, in order to keep the temperature difference Δc between the top and bottom almost constant, the flow IQ of the insulating medium flowing into the cooler needs to be approximately 200 times that when using insulating oil. Therefore, a significantly larger number of coolers are required than when using insulating oil. However, in reality, the kinematic viscosity coefficient of insulating gas is about 1/3 that of insulating oil.
By having low circulation friction resistance and easy circulation, and by replacing the insulating material at the bottom of the groove of the winding with 1-1 type etc., which can withstand higher temperatures, and by designing the upper and lower temperature difference ΔT to be higher, It is possible to reduce the required number of coolers to several times the number of oil-immersed transformers.

Gas insulated transformers such as those described above are often directly connected to gas insulated switchgear, and in that case, how to arrange a large number of coolers has been a major problem.

FIG. 3 shows an example of the arrangement of coolers in a conventional gas insulated transformer. That is, the cooler 4a is arranged on the side of the transformer tank 1 where the bushing pocket 6, bushing 7, gas insulated electrical equipment 8, etc. connected to the transformer are not arranged, and the cooler cannot be arranged on the side. 4b is arranged on the upper surface of the transformer tank 1, and connected to each other by pipes 5a and 5b.

In this case, it is known that the circulation force for circulating the insulating medium increases as the difference in thermal center between the center of the transformer, which is a heating element, and the cooler in the height direction increases. That is, in FIG. 3, compared to the thermal center difference D+ between the cooler 4a placed on the side surface of the transformer tank 1 and the contents of the transformer, the difference in thermal center between the cooler 4b placed on the top surface of the transformer tank 1 and the contents of the transformer is The thermal center difference D2 of
The insulating medium flow JAQz flowing into the cooler 4b becomes much larger. In other words, the cooler 4b placed on the top surface of the transformer tank 1 functions efficiently, but the cooler 4a placed on the side of the transformer tank 1 is very inefficient and requires a large number of coolers. However, there was a drawback that an effective cooling operation was not performed.

Furthermore, as described above, the temperature distribution within the winding is determined by the natural convection of gas, and the temperature is higher at the top and lower at the bottom. The temperature rise of the winding is regulated by this R high temperature, but since the specific heat and heat exchange efficiency of the insulating gas are much inferior to that of an oil-immersed transformer, the temperature difference between the top and bottom tends to become much larger. Therefore, an expensive insulating material such as H type having a high allowable temperature had to be used for the winding, which was extremely uneconomical.

[Object of the Invention] The present invention was proposed in order to solve the problems of the conventional self-cooled gas insulated transformer as described above. The present invention aims to provide a self-cooling gas insulated transformer in which a cooler can be effectively arranged and temperature rise in the windings can be reduced.

[Summary of the invention] The self-cooled gas insulated transformer of the present invention has a gas partition plate that allows
The inside of the transformer tank is divided into two gas chambers, upper and lower, and the lower gas chamber is connected to a cooler installed on the side of the transformer tank, while the upper gas chamber is connected to a cooler installed on the top of the transformer tank. By connecting the insulating gas, the insulating gas can be cooled efficiently.

[Embodiment of the Invention] An embodiment of the present invention will be specifically described below with reference to FIG. Note that the same members as those of the conventional self-cooling gas insulated transformer shown in FIGS. 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted.

*Structure* In this embodiment, as shown in FIG. 1, an upper winding 13b and a lower winding 13a are wound around an iron core 2 housed in a transformer tank 1.

In the middle of these upper and lower windings 13a and 13b, there is an in-winding gas partition plate 20 that divides these windings into upper and lower parts.
A gas partition plate 21 is provided between the in-winding gas partition plate 20 and the inner wall of the transformer tank 1, and the inside of the transformer tank 1 is divided into two independent gas chambers 1a, upper and lower. It is divided into 1b.

Note that even if there is a core leg without a winding inserted, such as a side leg, the gas partition plate 21 is disposed between the outer periphery of the core leg and the inner wall of the transformer tank 1, and the gas partition plate 21 The interior of the chamber is divided into two gas chambers.

In addition, the upper gas ff1 of the transformer tank 1 is divided into upper and lower parts by the in-winding gas partition plate 2o and the gas partition plate 21.
1b includes a cooler 1 disposed on the top surface of the transformer tank 1.
4b are connected by piping 15b. On the other hand, a cooler 14a disposed on the side surface of the transformer tank 1 is connected to the lower gas chamber 1a by a pipe 15a.

Note that the in-winding gas partition plate 2o and the gas partition plate 21 are made of an insulator.

*Function* In the self-cooled gas insulated transformer of this embodiment having such a configuration, the winding wound around the iron core 2 is divided into upper and lower parts, and the gas partition plate 20 inside the winding and the gas The interior of the transformer tank 1 is divided by the partition plate 21 into independent gas chambers 1a and 1b containing upper and lower windings, and each gas chamber is roughly connected to a dedicated cooler 14a and 14b. , the gas circulation force is obtained by the unique cooler of each gas chamber and the thermal center difference di, d2 between the windings within the gas chamber. Therefore, it is possible to select the optimum cooler for each gas chamber according to its circulation force, and the cooler can be operated efficiently.

In particular, in this embodiment, by dividing the winding into upper and lower parts, each winding can be cooled separately. It functions efficiently and eliminates the problem that coolers installed on the side do not function efficiently.

Roughly speaking, by dividing the winding into upper and lower halves, the height of the winding is significantly reduced, so the difference between the upper and lower temperatures of each winding becomes smaller.

As a result, for the entire winding, it is sufficient to use the higher temperature rise of the upper gas to 1b or the lower gas to 1a as a reference.
Compared to conventional integrated windings, the highest point temperature is significantly lower, allowing the use of inexpensive insulators with low permissible temperatures for the windings, resulting in significant cost savings. becomes possible.

[Effects of the Invention] As described above, according to the present invention, by configuring the transformer tank to be divided into upper and lower parts and cooled by separate coolers, the coolers can be arranged effectively. death,
Furthermore, it is possible to provide a self-cooling gas insulated transformer that can reduce the temperature rise of the windings.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the self-cooled gas insulated transformer of the present invention, and FIGS. 2 and 3 are side views showing the configuration of a conventional self-cooled gas insulated transformer. 1...Transformer tank, 1a...Lower gas to, 1b.
...Upper gas to, 2...Iron core, 3...Winding, 4...
・Cooler, 5... Piping, 6... Bushing pocket, 7... Bushing, 8... Gas insulated electrical equipment, 1
0... Insulating gas, 13a... Lower winding, 13b...
・Upper winding, 14...Cooler, 15...Piping, 20
... Gas partition plate in the winding, 21... Gas partition plate.

Claims (1)

[Claims] 1) The contents of a transformer consisting of an iron core and a coil are housed in a transformer tank, the transformer body is filled with insulating gas in the tank, and the insulating gas is cooled outside the transformer body. In a self-cooled gas insulated transformer, which is equipped with a cooler for cooling the transformer and uses natural convection of insulating gas to cool the inside of the transformer, the inside of the transformer tank is divided into two upper and lower gas chambers by a gas partition plate. A cooler installed on the side of the transformer tank is connected to the chamber, and a cooler installed on the top of the transformer tank is connected to the upper gas chamber. Gas insulated transformer. 2) the two upper and lower gas chambers are divided into upper and lower parts, and an in-winding gas partition plate is arranged between the windings wound around the iron core;
The self-cooling gas insulated transformer according to claim 1, which is partitioned by a gas partition plate provided between the internal winding gas partition plate and the inner wall of the transformer tank.