JPH04192508A - Self-cooling type gas-insulated transformer - Google Patents

Abstract

PURPOSE:To improve cooling characteristics of an external cooling device by providing metallic heat radiators to an upper gas piping of a self-cooling type gas-insulated transformer in such a manner that the radiator becomes vertical to the ground. CONSTITUTION:A plurality of metallic heat radiators 9 are provided with adequate intervals to the upper gas piping 6 provided horizontally in such a manner that these radiators become vertical to the gas piping and the ground. In the case the upper piping 6 is inclined, the heat radiators 9 are provided in the desired angle for the piping but vertically to the ground considering the circulation of the external air. Therefore, the heat is radiated externally by the heat radiators 9 from the upper piping 6 having a high cooling efficiency due to the random flow of the insulating gas 4 and moreover the heat radiators 9 accelerate circulation of heated air. Thereby, the cooling efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a self-cooled gas insulated transformer using an insulating gas such as SF or gas as an insulation and cooling medium.

(Prior Art) In recent years, there has been an increasing demand for power receiving and transforming equipment installed in urbanized areas, such as transformers, to be non-combustible to prevent disasters caused by fire in the event of an accident. In response to this demand, so-called gas-insulated transformers have been put into practical use in transformers that use nonflammable sulfur hexafluoride (SF4) gas as a cooling and insulating medium instead of conventional insulating oil. .

Among such gas insulated transformers, the self-cooled gas insulated transformer does not require any auxiliary equipment for circulating gas, so its structure and maintenance are significantly simplified. On the other hand, however, insulating gas generally has a smaller heat capacity and inferior cooling properties than insulating oil, so external coolers for cooling insulating gas are generally larger than external coolers for oil-immersed transformers, especially self-contained transformers. The cold type had the disadvantage of being larger because it had a sufficient cooling effect.

3 and 4 are a side view and a plan view of a conventional self-cooling gas insulated transformer. Transformer tank l as shown in the figure
The contents of the transformer consisting of an iron core 2 and a winding 3 wound around the iron core 2 are housed inside the transformer, and a nonflammable insulating gas 4 such as SF6 scum, which is an insulation and cooling medium, is sealed at a predetermined pressure. There is.

Furthermore, a cooler 5 for cooling the insulating gas 4 warmed in the tank is provided outside the transformer tank l, and the upper gas pipe 6, the lower gas pipe 7, and the insulating gas 4 are connected to each cooler 5. The transformer tank 1 is connected to the common waste piping 8, etc. that separates the flow.
It is connected to the. Inside each piping S in Figures 3 and 4
The arrows shown here each indicate the flow of the insulating gas 4.

(Problems to be Solved by the Invention) However, in the conventional self-cooled gas insulated transformer having the above configuration, there were problems to be solved as described below.

That is, as mentioned above, the insulating gas 4 has a lower heat capacity than the insulating oil of an oil-immersed transformer, so its cooling characteristics are poor, and the cooling efficiency of the winding 3 is inferior (the losses generated in the transformer are reduced). Compared to the same oil-immersed transformer, the size of the cooler 5 is several times larger, and the cooling properties of the insulation scum in the cooler 5 are significantly worse. This is due to the difference in heat transfer coefficient on the inner surface of the cooler.

The present invention was proposed to eliminate the drawbacks of the prior art as described above, and its purpose is to improve cooling efficiency,
An object of the present invention is to provide a self-cooling gas insulated transformer having a compact external cooler.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized in that an insulating gas is sealed in a transformer tank containing an iron core and a winding, and the w7! In a gas insulated transformer equipped with a cooler for cooling edge gas, install multiple metal heat sinks at appropriate intervals on the upper gas pipe connecting the transformer tank and the gas cooler, at least perpendicular to the ground. It is characterized by the fact that it is attached.

(Function) With this configuration, heat is released to the outside by the heat sink from the upper gas pipe with high cooling efficiency, where the flow of insulating gas is turbulent, and the heat sink further releases the heated air. It can promote convection and improve cooling efficiency.

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

1 and 2 are a side view and a plan view showing the configuration of a self-cooled gas-insulated transformer according to the present invention, and the same parts as in FIGS. Omitted.

In the present invention, as shown in the figure, a plurality of metal heat sinks are installed at appropriate intervals on the upper gas pipe 6 installed horizontally so as to extend perpendicularly to the pipe and also perpendicularly to the ground. It is installed.

If the upper piping 6 is sloped, etc., use a metal heat sink 9.
is installed perpendicular to the ground at an arbitrary angle to the piping, taking into account the convection of external air.

In general, interesting things are revealed when temperature tests are performed on self-cooled gas insulated transformers. That is, the temperature of the upper gas pipe 6 of the self-cooling gas insulated transformer shown in FIG. 3 is considerably higher than the temperature of the upper part of the cooler 6. However, it is unlikely that there is such a temperature difference between the insulation scum flowing in the upper gas pipe 6 and the cooler 5.

The reason for this is thought to be that the flow rates of the insulating gases flowing through each are different, and the heat transfer coefficients between the insulating gas and the inner surface of the gas pipe or cooler are significantly different.

Inside the gas pipe, the insulating gas flows in a concentrated manner, so the flow rate is significantly faster than elsewhere. Theoretically, the relationship between the flow velocity V of the insulating gas and the heat transfer coefficient on the metal surface in contact is as follows: (1) If the insulating gas flow is a uniform laminar flow, 11ocy"' (11) 11cc if the insulating gas flow is turbulent with thin flow
It is known that y”.

In an actual temperature test, the amount of gas circulation was determined from the loss generated inside the gas insulated transformer and the temperature difference of the insulating gas between the upper and lower parts of the cooler. From this, the gas flow velocity in the upper waste pipe was estimated to be several meters and 7' seconds. It is thought that In this state! ! The edge gas flow becomes turbulent, and the heat transfer coefficient with the inner surface of the upper gas pipe has increased to the extent that it is comparable to the heat transfer coefficient between the insulating oil and the inner surface of the cooler in a self-cooling oil-immersed transformer.

FIGS. 5 and 6 show the temperature distribution on the insulating gas side and outside air side via the upper wall surface of the cooler and the wall surface of the upper waste pipe. The cross-sectional area of the wall surface 6a of the upper gas pipe 6 shown in FIG. 6 is considerably smaller than the total cross-sectional area of the cooler, so the flow concentrates, the flow speed increases, the heat transfer coefficient increases, and the insulation The difference between the gas temperature θGas and the wall internal temperature θ′1 is small,
The difference between the external air temperature θAir and the wall external temperature θ'2 is large.

As for the upper wall surface 5a of the cooler 5 in FIG. 5, contrary to the case in FIG. 6, the flow rate of the insulating gas is slow, so the heat transfer coefficient is low, and the temperature of the wall surface is higher as it approaches the upper piping surface. do not have.

Now, considering the amount of waste heat Q per constant area of both surfaces, Q=tlA;r −3−(θ2−θ1..)]IAi
r: Air side heat transfer coefficient S D Constant area θ2: Surface temperature of the upper part of the pipe or cooler θ^, r = external air temperature, and the amount of exhaust heat Q, that is, the cooling efficiency, is the difference between the surface temperature and the external air temperature. It can be seen that the cooling efficiency is clearly higher on the upper gas pipe wall surface 6a.

Therefore, by vertically attaching a metal heat radiating plate 9 around the upper gas pipe to improve the convection of external air, the heat radiating area is expanded and the cooling efficiency is further increased.

〔Effect of the invention〕

As explained above, in the present invention, a metal heat sink is attached to the upper gas piping of a self-cooled gas insulated transformer so that it is at least perpendicular to the ground. The cooling characteristics of the transformer can be improved, and a self-cooled gas insulated transformer with a compact external cooler can be provided.

[Brief explanation of the drawing]

1 and 2 are a side view and a plan view of a self-cooled gas insulated transformer according to the present invention, and FIGS. 3 and 4 are side views and plan views showing the arrangement of a conventional self-cooled gas insulated transformer. The plan view, FIGS. 5 and 6 are temperature distribution diagrams on the internal insulating gas side and the external air side via the cooler upper wall surface and the upper gas pipe. 1...Transformer tank, 2...Iron core, 3...Winding wire,
4... Insulating gas, 5... Cooler, 6... Upper gas piping, 7... Lower gas piping, 8... Common gas piping,
9... Heat sink, work 0... Cooler upper wall surface, 11...
・Upper gas piping wall. Applicant's representative Patent attorney Takehiko Suzue Figure 1 112 Figure 3 Figure 5a Figure 5

Claims (1)

[Claims] The transformer contents, which consist of an iron core and the windings wound around the iron core, are stored in a transformer tank along with insulating gas at a predetermined pressure.
In self-cooled gas insulated transformers that have a cooler installed outside the transformer tank and connect the transformer tank and cooler with upper gas piping and lower gas piping, an appropriate space is provided around the front upper gas piping. A self-cooling gas insulated transformer characterized by having a plurality of metal heat sinks attached at least perpendicularly to the ground.