JPS593906A - Gas insulation transformer - Google Patents

Abstract

PURPOSE:To provide a transformer with simple structure, good cooling effect and excellent insulation property, by a method wherein a cooling medium heated by heat from a coil is injected or sprayed into space in a cooler or a tank. CONSTITUTION:A cooling medium 4 heated from a liquid pool 7 is fed to upper portion of a cooler using a second cooling medium pump 9 and sprayed through a number of spray nozzles 10 into the cooler 5. Vapor pressure of the cooling medium in the cooler is considerably lower than the saturation vapor pressure corresponding to temperature of the cooling medium in the liquid pool. Consequently, the cooling medium sprayed in mist is evaporated immediately and increases the partial vapor pressure within the cooler and the vapor temperature thereby the condensation efficiency is improved. If the cooling medium 4 in the tank 3 is sprayed directly from the spray nozzle 10, temperature difference between the cooling medium vapor and mist in the cooler 5 becomes large thereby further effect may be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a gas insulated transformer that insulates a coil, an iron core, etc. with an insulating gas sealed in a tank.

[Prior art and its problems]

For disaster prevention reasons, high-voltage, large-capacity transformers are replaced by oil-filled transformers that fill the tank with insulating oil to insulate and cool the coils, cores, etc. The tank is filled with electrically insulating gas to insulate the coil and iron core, and Freon R113 is used to cool the coil and iron core.
Gas insulated transformers have been developed that are configured to be cooled using cooling media such as Fluorinert FC75 and Fluorinert FC75.

- A conventional example is shown in FIG. This is called a semi-pool cooling type gas insulated transformer, and a coil (2) wound around an iron core (1) is housed in a tank (3). (4) is fulfilled. The cooling medium vapor evaporated from the tank due to the heat generated by the coil loses its latent heat of vaporization on the inner wall of the cooler (5), becomes a liquid phase, and returns to the liquid reservoir (7) at the bottom of the tank (6). The cooling medium in the reservoir is injected into the tank by a pump (8) and returns to the reservoir with a slight overflow.

However, in the tank and cooler, in addition to the cooling medium vapor that has taken heat from the coil and evaporated, there is also SF sealed in the tank.
The presence of insulating gases such as , etc. makes it difficult to condense the cooling medium vapor, leading to an increase in the temperature of the cooling medium in the tank and, in turn, the temperature of the coil.

The reason why condensation is difficult is that if even a small amount of a non-condensable gas such as SF6 is mixed into the vapor of the cooling medium, the condensation heat transfer coefficient will be greatly reduced.

Furthermore, when Freon R113 is used as a cooling medium and 8F6 is used as an insulating gas, due to their density difference, they do not mix uniformly inside the cooler or tank and are separated (SF and gas above, R113 vapor below). A phenomenon occurs.

Such a phenomenon becomes even more remarkable as the voltage of the transformer becomes higher, since the insulating gas with a higher sealing pressure is required.

Since the steam of the cooling medium is in a saturated state, the steam temperature inside the cooler decreases with the steam partial pressure as shown in Figure 2, and as the steam partial pressure decreases, the content of non-condensable gas increases. Furthermore, as the steam temperature decreases, the temperature difference with the condensing surface becomes smaller. ), the condensing performance will be extremely deteriorated.

[Object of the Invention] In consideration of the above-mentioned drawbacks of the conventional transformer, an object of the present invention is to provide a gas-insulated transformer that has a relatively simple structure, improves condensing performance, and has good cooling efficiency.

[Summary of the invention]

The present invention is a gas insulated transformer configured to remove heat from a coil and pour or spray a heated cooling medium into a space within a cooler or tank.

〔Effect of the invention〕

According to the present invention, a transformer with a simple configuration, good cooling efficiency, and excellent insulation performance can be obtained.

[Invention δ Example]

An embodiment of the present invention will be described based on FIG.

Since FIG. 3 shows an embodiment of a cooling gas insulated transformer of the Spool type, the same components as in FIG. 1 are designated by the same numbers and their explanations will be omitted.

Using the second cooling medium pump (9), the heated cooling medium (4) is sent from the liquid reservoir (7) to the upper part of the cooler (5) and sprayed into the cooler (5) from a large number of spray nozzles.

As explained in FIG. 2, the vapor pressure of the cooling medium in the cooler is significantly lower than the saturated vapor pressure at the temperature of the cooling medium in the reservoir.

Therefore, the cooling medium sprayed in the form of a mist evaporates immediately, increasing the steam partial pressure and steam temperature within the cooler, thereby improving the condensing performance.

[Other embodiments of the invention]

Another embodiment of the invention is shown in FIG. In this embodiment, the cooling medium (4) in the tank (3) is directly sprayed from the spray nozzle Ql in the embodiment shown in FIG.
It is possible to increase the temperature difference between the cooling medium vapor and the mist inside, and further effects can be expected.

Another embodiment of the invention is shown in FIG. In the embodiment shown in FIG. 3 of this embodiment, the heated cooling medium (4) is evaporated while flowing down from the upper part of the cooler (5) through a number of baffles a0 instead of being atomized from the spray nozzle.
°Condenses on the cooler wall.

This embodiment also provides the same effects as the embodiment shown in FIG. 3, and is particularly effective even when the space inside the cooler is relatively narrow.

Note 1. Although the above embodiment shows the application of the present invention to a semi-pool cooling type gas insulated transformer, the present invention also applies to a spray cooling type gas insulated transformer in which a liquid cooling medium is poured into the core and coils in a shower to cool them. A similar effect can be obtained when applied to a pool-cooled gas insulated transformer in which the core and coil are completely immersed in the cooling medium.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of a conventional gas insulated transformer, Fig. 2 is a curve diagram showing the pressure distribution and temperature distribution inside the cooler in the conventional example of Fig. 1, and Figs. 3 to 5 are 1 is a sectional view showing an embodiment of the present invention. 2...Coil 4...Cooling medium 5...
Cooler 9... Pump 10... Spray nozzle Agent Patent attorney Kensuke Norichika (and 1 other person) Figure 3 Figure 4

Claims (1)

[Claims] A gas insulated transformer having a configuration in which a coil housed in an envelope filled with an insulating gas is gas-insulated with the insulating gas, and a cooling medium is brought into contact with the coil to cool the coil. A gas insulated transformer characterized in that the cooling medium, which increases in temperature by removing heat from the gas insulated transformer, is poured or sprayed into a space within the cooler or the envelope.