JPH076922A - Stationary induction electric apparatus - Google Patents

Abstract

PURPOSE:To obtain an economical stationary induction electric apparatus exibiting high performance by adopting a blended liquid made from plural liquids in different boiling points as insulating/cooling medium. CONSTITUTION:An insulating container 2 is filled with a blended liquid 6 made from high boiling point perfluorocarbon liquid and low boiling point perluorocabon liquid so as to immerse a trans-former main body 50. An elastic liquid gas separating film 7 is arranged on the upper of the insulating vessel 2 to bring the sealed pressure of an insulating gas 5 to the level of the blended liquid 6 through the intermediary of the separating film 7. Besides, the blended liquid 6 in the insulating vessel 2 is led outside a tank 1 by a piping 8 to be circulated by a circulating system consisting of a heat exchanger 9 and a pump 10. Thus, the blended liquid 6 having the most reasonable boiling point to meet the operational requirements can be obtained. Through these procedures, an economical stationary induction electric apparatus exibiting high performance can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static induction device, and more particularly to a liquid-filled static induction device.

[0002]

2. Description of the Related Art Generally, in a static induction electric machine such as a transformer, an insulating liquid such as mineral oil is used to maintain insulation at a high voltage portion and to cool a heat generating portion. Particularly in recent years, from the viewpoint of disaster prevention, nonflammable devices have been required, and static induction electric appliances using nonflammable liquids as insulating / cooling media have been put to practical use.

As a non-combustible liquid, perchlorethylene, CFC 112 and CFC 113 are mixed to eliminate the flash point and the combustion point. As an insulating liquid for a transformer, Kansai Tech Co., Ltd. manufactures it under the trade name of "San Ohm non-combustible". Are on sale.

Further, Japanese Patent Application Laid-Open No. 62-256306 also discloses an invention in which a mixed insulating oil obtained by mixing a perchlorethylene insulating oil with a specific volume ratio of a mineral oil insulating oil is used as an insulating medium of an oil-filled induction machine. ing.

[0005]

[Problems to be Solved by the Invention] Perchlorethylene,
Both of the mixed liquids of CFC 112 and CFC 113 are substances containing chlorine, and from the viewpoint of prevention of ozone layer depletion, the movement to suppress the production or to abolish the production thereof is spreading all over the world. Therefore, there is a concern that manufacturers of stationary induction devices cannot receive a stable supply of liquid. Also, the mixed insulating oil described in JP-A-62-256306 has the same problem as long as perchlorethylene is mixed.

A transformer using a chlorine-free perfluorocarbon liquid has already been put to practical use and is operating as a power transformer. While perfluorocarbon liquid has advantages such as noncombustibility and low viscosity, it has a drawback that its boiling point is lower than that of mineral oil. For example, a liquid having a molecular structure of C ₈ F ₁₆ O has a boiling point of about 100 ° C. at atmospheric pressure. Further, there are perfluorocarbon liquids having different molecular structures, and their boiling points are different. If the liquid is in a boiling state during transformer operation, the insulation system in the high electric field region will be in a mixed state of a gas phase and a liquid phase, and the insulation strength will be greatly reduced. Therefore, measures have been taken to pressurize the liquid surface and raise the boiling point to widen the temperature range during operation.

Since the boiling point of a liquid having a specific molecular structure is determined, it is necessary to increase the pressure applied to the liquid surface in order to raise the boiling point, and the transformer tank is required to have a strong structure.
This leads to an increase in weight and price. Further, a liquid having a specific molecular structure having a high boiling point has drawbacks such that cooling performance is lowered and cost is increased because the kinematic viscosity is large.

Further, since the maximum permissible temperature during operation of the transformer is set in accordance with operating conditions such as the load condition, applying a liquid having an optimum boiling point leads to rational design and manufacture. Therefore, when manufacturing a transformer by applying a liquid with a specific molecular structure, the boiling point of the liquid cannot be freely selected.
There is a drawback that rational liquid level pressure setting and economical tank design are not possible.

An object of the present invention is to apply a liquid having a boiling point most rational to operating conditions, and to provide an economical and high-performance static induction generator.

[0010]

The above object is achieved by mixing a liquid having a high boiling point and a liquid having a low boiling point at an appropriate ratio to obtain a mixed liquid having an intermediate boiling point and applying the liquid to a static induction electric machine. To be done.

[0011]

The specific gravity of the perfluorocarbon liquids having different boiling points is different, and the higher the boiling point is, the larger the specific gravity is. When liquids having extremely different boiling points are mixed, the low boiling point liquid layer and the high boiling point liquid layer are separated. However, when the difference in boiling point is small, that is, when the difference in specific gravity is small, what is once mixed and stirred does not easily separate. The boiling point of the mixed liquid is as shown in FIG. 4, and the boiling point can be changed depending on the mixing ratio. That is, when the proportion of the high boiling point liquid is small, the boiling point approaches T _1, and when it is large, it approaches T ₂ . Therefore,
A liquid having an arbitrary boiling point can be obtained by adjusting the mixing ratio.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view showing the structure of the present invention. An insulating container 2 is housed in a tank 1, and a transformer main body 11 composed of an iron core 3, a winding wire 4 and the like is contained in the insulating container 2. An insulating gas 5 is filled in the space between the insulating container 2 and the tank 1,
The insulating container 2 is filled with a mixed liquid 6 (hereinafter referred to as a mixed liquid) of a high boiling point perfluorocarbon liquid and a low boiling point perfluorocarbon liquid, and the transformer body 50 is immersed therein. A stretchable liquid / gas separation membrane 7 is arranged on the upper part of the insulating container 2, and the sealing pressure of the insulating gas is transmitted to the liquid surface of the mixed liquid 6 through the separation membrane 7. The mixed liquid 6 in the insulating container 2 is drawn to the outside of the tank 1 by the pipe 8 and circulated by the circulation system of the heat exchanger 9 and the pump 10.

The vapor pressure characteristic curve A of the high boiling point perfluorocarbon liquid and the vapor pressure characteristic curve B of the low boiling point perfluorocarbon liquid are as shown in FIG. 2, and the vapor pressure characteristic of the mixed liquid 6 is like C between the two. It becomes a characteristic. At the temperature T at which the liquid does not boil during the operation of the transformer, the pressure P _B is required due to the vapor pressure characteristic B when only the low-boiling point perfluorocarbon liquid is used, but the pressure P _B is lower when the liquid is mixed with the high-boiling point perfluorocarbon liquid. Boiling can be eliminated by pressurizing _C. That is, the filling pressure of the insulating gas 5 shown in FIG. 1 may be low. If the pressure of the enclosed gas is low, the strength of the tank can be reduced accordingly, so that the weight can be reduced.

If the mixing ratio of the high-boiling point perfluorocarbon liquid is increased, the vapor pressure characteristic C of FIG. 2 approaches the A characteristic, and if the ratio of the low-boiling point perfluorocarbon liquid increases, it approaches the B characteristic, and the mixing ratio is changed. Thus, the pressure of the enclosed gas at the temperature T can be changed, and the pressure can be freely set according to the operating conditions of the transformer.

In general, the high boiling point liquid is more expensive than the low boiling point liquid. Therefore, it is more economical to use it as an optimum mixed liquid that satisfies the operating conditions of the transformer.

Further, the kinematic viscosity of the high-boiling liquid is higher than that of the low-boiling liquid, and changes depending on the mixing ratio such that it approaches the kinematic viscosity of the high-boiling liquid or approaches the low-boiling liquid side. Therefore, if a single high-boiling-point liquid is selected only by the superiority of the boiling point, the cooling efficiency is lowered, so that it is possible to mix the low-boiling-point liquid to form a mixed liquid and prevent the cooling efficiency from being largely lowered.

FIG. 3 is an explanatory view of another embodiment of the present invention.

A transformer main body 60 in which a winding 13 is wound around an iron core 12 is housed in a tank 11, and the tank is filled with a mixed liquid 14 of perfluorocarbon liquid. A conservator 15 for absorbing expansion and contraction of the liquid is provided on the upper part of the tank, and a separator 16 for separating the expandable liquid and the gas is attached to the liquid surface. This liquid surface is operated at almost atmospheric pressure and not pressurized. Further, a cooler 17 is provided outside the tank 11 so that the liquid is cooled by natural circulation. Mixed liquid in this type of transformer 14
Is characterized by mixing liquids whose specific gravity ratios are not significantly different. That is, the mixed liquid is prepared so that the stirring and mixing are sufficiently performed by natural circulation. For example, if the ratio of specific gravities ((specific gravity of liquid A) / (specific gravity of liquid B)) is 1.05 or less, it is possible to prepare a mixed liquid having different boiling points as described above, which is optimal for operating conditions. It can be a liquid transformer having a different boiling point.

When a liquid having a specific gravity ratio of 1.05 or more is mixed at a weight ratio of 50:50, the boiling point varies greatly, and it becomes difficult to obtain an optimum mixed liquid. But,
In the operating transformer, the higher the load current and the higher the temperature, the larger the temperature difference between the inlet and the outlet of the cooler, and the smaller the kinematic viscosity, and the more vigorous the mixing and stirring. As a result, a uniform mixed liquid is obtained, and it is difficult for the liquid to be separated. Further, if the mixing ratio is determined with the lowest value of the boiling point of the mixed solution as a guide, the transformer can be optimized as a solution having an intermediate boiling point.

[0021]

According to the present invention, liquids having different boiling points are mixed to form a liquid having an intermediate boiling point, which is used as an insulating / cooling medium for a transformer, thereby reducing the gas filling pressure to reduce the transformer pressure. The strength of the tank can be reduced. Further, by adjusting the mixing ratio of the liquid, the liquid having a boiling point suitable for the operating condition of the transformer can be obtained, so that an economical transformer with good cooling efficiency can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a static induction generator of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between vapor pressure and temperature of a refrigerant liquid of a static induction electric device.

FIG. 3 is an explanatory view of an embodiment of another static induction generator of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a mixing ratio and a boiling point of a mixed refrigerant liquid of a static induction electric device.

[Explanation of symbols]

1 ... Tank, 2 ... Insulation container, 3 ... Iron core, 4 ... Winding, 5 ...
Insulating gas, 6 ... Mixed liquid, 7 ... Liquid / gas separation membrane, 8 ... Piping, 9 ... Cooler, 10 ... Pump, 50 ... Transformer body.

Claims (4)

[Claims] 1. A tank in which an iron core and windings wound around an iron core leg are housed and hermetically sealed, and a liquid is filled for insulation and cooling. The liquids are a plurality of mixed liquids having different boiling points. A static induction electric device characterized in that 2. The static induction electric device according to claim 1, wherein the boiling point of the liquid can be adjusted by the mixing ratio of the liquid having a high boiling point and the liquid having a low boiling point. 3. The static induction electric device according to claim 1, wherein the viscosity of the liquid can be adjusted by the mixing ratio of the high viscosity liquid and the low viscosity liquid. 4. The static induction electric device according to claim 1, wherein the mixed liquid is at least one perfluorocarbon liquid.