JP3028853B2 - Stationary induction device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a static induction device, and more particularly to a static induction device suitable for filling a tank with a liquid and cooling and insulating the winding by the liquid.

BACKGROUND ART In general, stationary induction devices such as transformers and reactors are
An insulating liquid such as mineral oil is used for the purpose of maintaining insulation at a high voltage portion and cooling the heat generating portion. In particular, recently, from the viewpoint of disaster prevention, devices are required to be made nonflammable, and stationary induction devices using nonflammable liquids as insulating and cooling media have been put to practical use.

Perchlorethylene, Freon 11
2, which has no flash point and no combustion point by mixing Freon 113, is manufactured and sold by Kansai Tec under the trade name "San-Ohm Non-flammable" as an insulating liquid for transformers.

In addition, there are various types of static induction devices using nonflammable liquids, such as high-voltage transformers, depending on the cooling system and liquid circulation system. In Japanese Patent Application Laid-Open No. H11-260, there is described an apparatus in which only a winding is placed in a liquid container and circulated and cooled. In addition, special fair 3
Japanese Patent Publication No. 13730 (hereinafter referred to as "known example 2") discloses an arrangement in which a cooling duct is provided inside a sheet winding to circulate and cool a fluorocarbon liquid collected in a liquid collecting pipe. Further, Japanese Patent Application Laid-Open No. 3-91904 (hereinafter referred to as "known example 3") discloses that a transformer body consisting of an iron core and a winding is housed in an insulating container, filled with a refrigerant liquid, and the insulating body is placed in a pressure tank filled with gas. It describes that a container is housed therein to circulate and cool a refrigerant liquid. In addition, Japanese Patent Application Laid-Open No. 3-129710 (known example 4) discloses that
It describes that a winding and an iron core are housed in a closed container filled with a nonflammable liquid to circulate and cool the liquid.

The mixed solution of perchlorethylene, freon 112, and freon 113 is a substance containing chlorine, and movements to suppress or completely eliminate production from the viewpoint of preventing ozone layer destruction are spreading worldwide. Therefore, there is a concern that the manufacturer of the stationary induction device cannot receive a stable supply of the liquid, and it will not be possible to manufacture a stationary induction device using this liquid in the future.

Transformers using chlorine-free perfluorocarbon liquid have already been put into practical use and are operating as power transformers.
A perfluorocarbon liquid has advantages such as nonflammability and low viscosity, but 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 at atmospheric pressure.
° C. There are also perfluorocarbon liquids having different molecular structures and different boiling points. If the liquid is brought into a boiling state during the operation of the transformer, the insulating system in the high electric field portion becomes a mixed state of a gas phase and a liquid phase, and the insulation strength is greatly reduced. Therefore, measures have been taken to pressurize the liquid surface and raise the boiling point to widen the temperature range during operation.

The boiling point of a liquid with a specific molecular structure is determined. To increase the boiling point, it is necessary to increase the pressure applied to the liquid surface. A strong structure is required for the transformer tank, which increases the weight and the price. Leads to. In addition, a liquid having a specific molecular structure having a high boiling point has a drawback that the cooling performance is reduced due to a large kinematic viscosity, and the price of the liquid is increased.

The present invention has been made in view of the above points, and uses a liquid having a kinematic viscosity equivalent to that of a low-boiling liquid and having the most reasonable boiling point for operating conditions, and is economical and has a high performance It is intended to provide an induction appliance.

DISCLOSURE OF THE INVENTION The above object has a boiling point at atmospheric pressure of approximately 130 ° C. and 0.3 MPa
aAchieved by applying a non-flammable insulating liquid having a boiling point of approximately 165 ° C under pressure and a kinematic viscosity at room temperature of 20 ° C of approximately 0.9 centistokes to a static induction appliance.

That is, by using a liquid having a boiling point of approximately 130 ° C. under atmospheric pressure as a cooling medium for an insulation type E-insulated stationary induction device having a maximum operating temperature of 120 ° C., there is no need for pressurization, and the tank strength is reduced. It may be small. The maximum operating temperature is 15
In the case of a class F insulated stationary induction device with a temperature of 5 ° C., if the pressure is 0.3 MPa, the boiling point will be 165 ° C., and no boiling will occur. Therefore, the tank structure can be made within the limit of the pressure vessel, so that the tank strength can be reduced and the weight can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the stationary induction electric device of the present invention, FIG. 2 is a longitudinal sectional view showing another embodiment of the static induction electric device of the present invention, and FIG. FIG. 4 is a longitudinal sectional view showing another embodiment of the stationary induction device of the present invention, FIG. 4 is a characteristic diagram showing the relationship between the vapor pressure and the temperature of the liquid filled in the container,
FIG. 5 is a characteristic diagram showing the relationship between the kinematic viscosity of the liquid filled in the container and the temperature.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a static induction device according to the present invention will be described in detail based on the illustrated embodiment.

FIG. 1 shows an example of a transformer, which is one of stationary induction devices.

As shown in the figure, pipes 7 and 8 are provided on the upper and lower sides of the closed tank 1, and are connected to the cooler 6. The iron core 2 and the winding 3 are housed in the tank 1, and a space 5 is provided above the tank 1 so that the boiling point at atmospheric pressure is approximately 130 ° C., 20 ° C.
Is filled with a nonflammable liquid 4 having a kinematic viscosity of 0.9 centistokes, and the nonflammable liquid 4 is circulated to cool the iron core 2 and the winding 3.

In this embodiment, the operating temperature range of the transformer is from -30 ° C to 12 ° C.
The temperature is lowered to 0 ° C., the temperature decreases, the liquid 4 contracts, and the height position of the liquid surface 41 when the liquid amount becomes the minimum becomes H1, the liquid temperature increases, the liquid 4 expands, and the liquid surface 42 expands. Is filled with the liquid 4 so that the height position becomes H2. In other words, the volume of the space 5 is ensured so that the pressure in the space 5 gradually increases as the liquid 4 expands, and the pressure does not exceed 0.3 MPa at 120 ° C.

The volume expansion coefficient of the liquid 4 applied to this embodiment is about 0.13% /
Since the temperature is 20 ° C., if the liquid is to be filled at a temperature of 20 ° C., it is sufficient to fill the tank up to 84.5% of the internal volume and to set the gas pressure in the space 5 to 0.113 MPa. When the liquid temperature is -30 ° C, the liquid volume is 79.4% of the tank internal volume, the pressure in the space 5 is almost 0.1 MPa, and when the liquid temperature is 120 ° C, the liquid volume is 94.
It increases to 8%, and the pressure in the space 5 becomes approximately 0.3 MPa.

Therefore, it is possible to use a transformer with a tank structure that is not restricted by the pressure vessel, and when operating at a high load factor, the pressure in the tank increases with the rise of the liquid temperature, and the reliability of boiling is reduced. Certain transformers can be provided.

 Another embodiment of the present invention will be described with reference to FIG.

The tank 1, the iron core 2, the windings 3, and the cooler 6 operate in the same manner as in the embodiment shown in FIG. 1, and the filling liquid 4 has a boiling point at atmospheric pressure of approximately 130 ° C. and a kinematic viscosity at 20 ° C. 0.9 centistokes non-flammable refrigerant liquid.

In the present embodiment, a diaphragm type conservator 9 having a liquid / gas separation membrane 10 is attached to the upper part of the tank 1, and the space 5 above the separation membrane 10 is open and is always at atmospheric pressure. In addition, the internal volume of the conservator 9 is
20%. That is, the separation membrane 10 responds to a change in the liquid temperature from −30 ° C. to 120 ° C., and absorbs the maximum expansion amount of the liquid 4.

Generally, in oil-immersed transformers, the expansion rate of oil is 0.07%
/ ° C., and even if there is a temperature change of 100 ° C., the expansion is 7%, so that the present embodiment is characterized in that it is larger than the conventional conservator. In the present embodiment, since the liquid surface is prevented from directly contacting the atmosphere by the separation membrane 10, the liquid amount does not decrease due to evaporation.
Also, it does not boil even when pressure is not applied to the liquid surface,
The insulation performance in the high temperature range is not impaired.

In this embodiment, the same effect can be obtained even if a static induction device other than a transformer, for example, a shunt reactor is configured.

Still another embodiment of the present invention will be described with reference to FIGS.

In the embodiment shown in FIG. 3, a winding 13 is wound around an iron core 12 and housed in an insulating container 17 so that the boiling point at the atmospheric pressure is approximately 130.
A nonflammable liquid 4 having a kinematic viscosity of 0.9 centistokes at 20 ° C. and 20 ° C. is filled. Liquid / gas separation membrane on top of insulating container 17
16 is provided in the pressure tank 11 and the SF ₆ gas 15 is sealed therein.

On the other hand, a pipe 19 penetrates the pressure tank 11 from the lower part of the insulating container 17 and a pipe 18 is drawn out from the upper part, and the pump 20 and the heat exchanger
The liquid 4 is circulated by connecting to the liquid 21. A water circulation pipe 22 is installed inside the heat exchanger 21, and pipes 23, 24
And is connected to the hot water tank 25 via a circulation pump (not shown). The hot water tank 25 is provided with a cold water inlet 27 and a hot water outlet 26 so that hot water can be taken out and cold water can be supplied. The filling pressure of the SF ₆ gas 15 is set to be 0.3 MPa or less at the maximum temperature of the liquid 4.

FIG. 4 shows the vapor pressure characteristics of the liquid 4 of the present embodiment.

As shown in the figure, the temperature is approximately 130 ° C. at the atmospheric pressure of 760 torr (0.1 MPa), and the higher the temperature, the higher the vapor pressure. 0.3
It becomes about 165 ° C at MPa (2280torr), and can be used without boiling to a very high temperature.

Therefore, the tank can be structured so as not to be restricted by the pressure vessel, and the weight of the tank can be reduced. In this embodiment, the temperature of the liquid 4 is positively raised so that hot water having the highest possible temperature can be taken out. That is, when the transformer is operated at a low load factor, the amount of circulating liquid of the liquid 4 is reduced to raise the temperature of the liquid 4, and further, by controlling the amount of circulation of the water circulation system, high-temperature hot water can be obtained. In the case of high load factor operation, it is possible to take out hot water at a constant temperature by increasing the circulating liquid amount, increasing the water circulation amount, and controlling the water intake and the water supply.
Furthermore, hot water has the advantage that the higher the temperature, the wider the range of use.

FIG. 5 shows the kinematic viscosity characteristics of the liquid 4 of the present embodiment, and the kinematic viscosity decreases as the temperature increases.
Therefore, the load on the circulating pump is reduced in the higher temperature range, so that the circulation is facilitated and the circulating fluid amount is easily controlled.

Conventionally, a transformer using a perfluorocarbon liquid containing C ₈ F ₁₆ O as a main component as a nonflammable refrigerant liquid is known,
Boiling point is about 100 ℃ (atmospheric pressure).
It was used under a pressure of 0.4 to 0.5 MPa. The tank strength had to be increased, and the weight was heavy.
Further, if the liquid temperature is positively raised to a high temperature and high-temperature water is to be taken out, a high-pressure vessel is required correspondingly, which has not been realized. This embodiment is characterized in that the strength of the tank can be reduced and high-temperature water can be taken out.

Further, in combination with an existing heat-resistant insulating material, for example, a class F insulating material, the liquid of the present embodiment is characterized in that it can be used in a pressurized state of 0.3 MPa or less.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the boiling point at atmospheric pressure is approximately 130 ° C, the boiling point at 0.3 MPa is approximately 165 ° C under normal pressure,
A non-flammable insulating liquid with a kinematic viscosity at 20 ° C of approximately 0.9 centistokes can be applied to a static induction device, so a liquid with a boiling point of approximately 130 ° C at atmospheric pressure and a maximum operating temperature of 120 ° C By using a cooling medium for a class E insulated stationary induction device, there is no need for pressurization, the tank strength can be reduced, and in the case of a class F insulated stationary induction device with a maximum operating temperature of 155 ° C, 0.3% If the pressure is MPa, the boiling point will be 165 ° C and it will not boil.

Therefore, the tank structure can be made within the limit of the pressure vessel, and the tank strength can be reduced and the weight can be reduced.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoto Hiraishi 5-17-3 Jonanmachi, Hitachi City, Ibaraki Prefecture (72) Inventor Hiroyuki Fujita 3156-11 Mayumicho, Hitachiota City, Ibaraki Prefecture (72) Inventor Obata Toshimitsu 1-9-6 Hanawayamacho, Hitachi City, Ibaraki Prefecture (72) Inventor Hideki Masuhara 1-15-1 Matsudocho, Hitachinaka City, Ibaraki Prefecture Sunrise Matsudo 402 (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01F 27/10 H01F 27/14

Claims (6)

(57) [Claims] 1. A static induction device in which at least a winding is in contact with a liquid in a tank and the liquid cools and insulates at least the winding, wherein a boiling point at atmospheric pressure is approximately 130 ° C. and a pressure of 0.3 MPa is applied. A static induction electric appliance characterized by using a non-flammable insulating liquid having a boiling point of approximately 165 ° C and a kinematic viscosity at room temperature of 20 ° C of approximately 0.9 centistokes as a cooling medium. 2. The sealed tank is filled with the insulating liquid, immersed in an iron core and a winding to provide a pressurized space portion, and a gas of 0.1 MPa or more is sealed therein. The static induction device according to the item. 3. The pressure in the pressurized space is 0.1 M at a liquid temperature of -30 ° C.
3. The static induction device according to claim 2, wherein the volume of the liquid in the tank and the volume of the space are set so as to be 0.3 MPa at Pa and 120 ° C. 4. The pressurized space portion is a diaphragm type conservator, and the internal volume of the conservator is 20% or more of the liquid volume of the main body tank containing the iron core and the windings and the cooler. The static induction device according to claim 2, wherein 5. The method according to claim 5, wherein the boiling point in the insulating container is substantially the same as that of the atmospheric pressure.
Boiling point at 130 ℃, 0.3MPa pressurized state is almost 165 ℃, normal temperature is 20 ℃
And a winding wound around an iron core and iron legs filled with a nonflammable insulating liquid having a kinematic viscosity of approximately 0.9 centistokes, and the insulating container is provided with a pressurized space in a pressure tank. And a device for enclosing a gas of 0.3 MPa or less in the pressurized space and circulating the insulating liquid through a heat exchanger. 6. The heat exchanger according to claim 1, wherein the heat exchanger is a water circulation type heat exchanger, and controls a flow rate of the circulating system of the insulating liquid and a flow rate of the water cooling system so as to take out hot water having a constant temperature. The static induction device according to claim 5, wherein