JPH11345720A - Gas insulating transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an economical gas insulating transformer capable of reducing the using quantity of SF6 gas by using mixed gas of SF6 gas and other gas, reducing influence upon the rise of temperature on the earth and having high cooling performance and insulating performance. SOLUTION: Mixed gas of SF6 gas and other gas is sealed in a tank, heat generated from an iron core, a high voltage winding 2a and a low voltage winding 2b is cooled by the circulation of insulating gas and insulation in the winding 2a held at a high electric field is simultaneously held by the insulating gas. For holding the strength of insulation, it is effective to fill the tank with 10 to 30% SF6 gas and nitrogen gas of the remaining percentage. In order to maintain cooling performance, mixed gas in the tank is constituted of 30 to 50% SF6 gas and nitrogen gas of the remaining percentage. When the gas in the tank is constituted of mixed gas of SF6 gas and nitrogen gas, a mixing ratio satisfying the cooling and insulating performance is 30 to 50% SF6 gas and nitrogen gas of the remaining percentage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas insulated transformer used in the field of power receiving and transforming of a power system, and in particular, stores a core and windings wound around iron legs in a tank, and fills the tank with an insulating gas. This is related to a transformer that has been used.

[0002]

FIG. 13 is a sectional view showing the internal structure of a typical gas-insulated transformer. In the figure, 1 is a tank container, 2 is a winding, 2a is a high-voltage winding, 2b is a low-voltage winding, 3 is an iron core, 4 is an insulating gas, and 5 is a cooler. In such a tank container 1, the insulating gas 4 is filled with 0.2 MPa to 0.3 MPa SF ₆ gas having a purity of 97% or more. The SF ₆ gas maintains insulation between the high-voltage winding 2 a and the low-voltage winding 2 b, insulation within the winding 2, insulation between the winding 2 and the iron core 3, and insulation between the winding 2 and the tank container 1. . The insulating gas 4 is circulated by using a pump inside the transformer tank or by utilizing buoyancy due to a temperature difference of the gas in order to cool the heat generated in the iron core 3 and the winding 2. . Therefore, the gas-insulated transformer contributes to the high performance of the equipment due to the excellent insulation performance and cooling performance of SF ₆ gas. However, several hundred kg to several thousand kg of SF ₆ gas is required for the entire gas insulated transformer depending on the rating, but the economics of expensive SF ₆ gas and the possibility of SF ₆ gas leaking outside It has problems such as impact on global warming.

FIG. 14 is a cross-sectional view showing another conventional gas-insulated transformer disclosed in, for example, Japanese Patent Application Laid-Open No. 2-110910, in which a winding serving as a heat generating source, or a winding and an iron core are connected to a refrigerant liquid ( In a semi-pool gas insulating transformer immersed in perfluorocarbon), an insulating gas (a mixture of SF ₆ gas and nitrogen gas) is used as an insulating medium in a sealed space. In the figure, 2 is a winding, 3 is an iron core, 6 is a perfluorocarbon liquid, 7 is a heat exchanger, 8 is a circulation pump,
9 is an outlet pipe, 10 is an inlet pipe, 11 is a sealing tank, 12 is an insulating container, and 13 is a mixed gas. In the transformer having such a configuration, the mixed gas 13 is used as an insulating gas between the insulating container 12 containing the refrigerant liquid containing the windings 2 and the iron core 3 and the sealing tank 11 to cool the iron core 3 and the windings 2. A perfluorocarbon liquid 6 is used as an agent. Further, in the above-mentioned semi-pool type transformer, SF ₆ gas is easily dissolved in the perfluorocarbon liquid 6, and when the temperature of the perfluorocarbon liquid 6 rises, bubbles are generated from the liquid, and these bubbles cause a decrease in insulation performance. was there. To solve this problem, in Japanese Laid-2-110910 discloses a low nitrogen gas solubility in perfluorocarbon liquid is mixed with SF _6, SF _6, gas in order not to lower the dielectric strength 20
% And nitrogen gas are mixed at a ratio of 80%, and the gas filling pressure in the sealing tank is increased in order to reduce bubbles on the liquid surface.

[0004]

On the other hand, the core and the winding wound around the iron core leg are stored in a tank, and the tank is filled with only an insulating gas.
In a gas-conducting water-cooled type or gas-conducting gas-cooled transformer, SF ₆ gas as an insulating medium is circulated in a tank and used as a cooling medium for cooling heat generated by a winding or an iron core as a heat generating source. Therefore, in designing such a gas-insulated transformer, it is necessary to consider not only the insulation performance but also the cooling performance. In addition, conventional gas-insulated transformers vary depending on the rating, but as a whole several hundred kg to several thousand k.
g SF ₆ gas is required, and the cost is low due to the expensive SF ₆ gas, and if SF ₆ gas leaks to the outside, there is a problem such as an influence on global warming.

[0005] The present invention has been made to solve the above problems, by reducing the SF ₆ gas consumption by mixing SF ₆ gas and other gases in specific proportions, global warming The purpose of the present invention is to provide an economical gas-input self-cooling type, gas-conduction air-cooling type, gas-conduction water-cooling type, and gas-conduction self-cooling type transformer with less influence on gasification and excellent cooling performance and insulation performance. .

[0006]

SUMMARY OF THE INVENTION The first gas insulated transformer according to the configuration of the present invention, 30% to 50% of the SF ₆ gas in a tank container which stores the winding wound around the core and the core leg The remaining gas is filled with a mixed gas composed of nitrogen gas or dry air to constitute an economical gas insulation transformer having excellent cooling performance and insulation performance.

[0007] A gas-insulated transformer according to a second configuration of the present invention comprises a tank vessel containing an iron core and a winding wound around an iron core leg in which 10% to 30% of SF ₆ gas and the remainder are saturated fluorine compounds ( CnF2n + 2: n = 1 to 10) is filled with a mixed gas to constitute an economical gas insulation transformer having excellent cooling performance and insulation performance.

In a gas insulated transformer according to a third configuration of the present invention, 50% to 70% of SF ₆ gas and the rest are carbon dioxide gas in a tank container storing an iron core and a winding wound around an iron core leg. An economical gas-insulated transformer having excellent cooling performance and insulation performance is provided by enclosing the mixed gas having the above-described structure.

A gas-insulated transformer according to a fourth aspect of the present invention is a gas-insulated transformer, in which a SF ₆ gas and a mixed gas composed of nitrogen gas or dry air are placed in a tank container containing an iron core and a winding wound around an iron core leg. Enclose and set the gas pressure to SF ₆ gas 1
The winding wound around the iron core and the iron core legs with the pressure increased from the rated pressure of 00% is housed in this, thereby constituting an economical gas insulating transformer having excellent cooling performance and insulation performance.

[0010] A gas-insulated transformer according to a fifth configuration of the present invention comprises a tank container containing an iron core and a winding wound around an iron core leg, wherein SF ₆ gas and a saturated fluorine compound (CnF2n +
2: a gas mixture having a configuration of n = 1 to 10) is filled, and the pressure of the filled gas is increased from the rated pressure of 100% of SF ₆ gas to provide an economical gas insulating transformer having excellent cooling performance and insulation performance. It constitutes.

A gas-insulated transformer according to a sixth aspect of the present invention is characterized in that a mixed gas composed of SF ₆ gas and carbon dioxide gas is sealed in a tank container storing an iron core and a winding wound around an iron core leg, The sealed gas pressure is increased from the rated pressure of 100% SF ₆ gas to constitute an economical gas insulation transformer having excellent cooling performance and insulation performance.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a gas insulated transformer according to an embodiment of the present invention, a mixed gas of SF ₆ gas and another gas is used, so that the amount of SF ₆ gas used is small and global warming is reduced. It is possible to provide an economical device having a small cooling effect and an excellent cooling performance and insulation performance.

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. Embodiment 1 FIG. FIG. 1 is a sectional view of a gas-insulated transformer according to Embodiment 1 of the present invention. In the figure, 1 is a tank container, 2 is a winding, 2a is a high voltage winding, 2b is a low voltage winding, 3
Is an iron core, 44 is a specific insulating mixed gas, and 5 is a cooler.
This gas-insulated transformer cools the heat generated from the iron core 3 and the high-voltage windings 2a and the low-voltage windings 2b during operation by circulating the specific insulating mixed gas 44, and at the same time insulates the windings 2 in the high electric field. Is also to be held by this specific insulating mixed gas 44. Therefore, when the gas in the tank is a mixed gas of SF ₆ gas and nitrogen gas, it is necessary to maintain both cooling performance and insulating performance.

FIG. 2 is a block diagram of the first embodiment of the present invention.
FIG. 4 is a graph showing the insulation characteristics of an F ₆ / nitrogen mixed gas, in which the electrode system simulating between the high-voltage winding and the low-voltage winding of the gas-insulated transformer keeps the gas pressure constant to insulate against the mixing ratio of SF ₆ gas and nitrogen gas. It is an experimental example in which the strength was measured. SF ₆ gas 2
If it is reduced to about 0%, the insulation strength will rapidly decrease.
Therefore, if the SF ₆ gas is further reduced, the insulation strength of the winding portion cannot be maintained. Therefore, from the standpoint of insulation strength, it is effective to maintain 10% to 30% SF ₆ gas and the remaining nitrogen gas in the tank in order to maintain insulation strength.

FIG. 3 is a block diagram of the first embodiment of the present invention.
Is a diagram showing the cooling characteristic in the winding unit of F ₆ / nitrogen mixed gas, and the temperature rise in the winding portion of the gas insulated transformer indicates a change with respect to mixing ratio of SF ₆ gas of the gas pressure as a constant . That is, this is a result showing the cooling characteristics when the gas is mixed. When the mixing ratio of SF ₆ is reduced and the mixing ratio of nitrogen gas is increased, the temperature rise in the winding part is increased. SF
_As for the temperature rise, the mixing ratio of SF ₆ gas is about 30% to 50% and the temperature rise is about 10% higher than 100% of ₆ gas. In addition, the temperature rise limit of a gas-insulated transformer employing a class E insulating material is 70%.
(Deg) so that the mixing ratio of SF ₆ gas is 3
It needs to be 0% to 50%. Therefore, in order to maintain the cooling performance, the mixing ratio of SF ₆ gas in the tank must be 3%.
This is a case where the balance is made up of nitrogen gas at 0% to 50%. Therefore, when the gas in the tank is composed of a mixed gas of SF ₆ gas and nitrogen gas, the mixing ratio satisfying the cooling performance and the insulating performance is such that the mixing ratio of SF ₆ gas is 30% to 50% and the rest is composed of nitrogen gas. This is the case.

[0016] Also the structure of the mixed gas to be filled in the tank as a SF ₆ gas and dry air in the first embodiment, SF ₆
Approximately the same performance can be obtained even when the mixing ratio of the gas is 30% to 50% and the remainder is dry air.

Embodiment 2 FIG. The second embodiment shows a case where the mixed gas is composed of SF ₆ gas and CF ₄ gas.
The gas-insulated transformer shown in FIG. 1 cools the heat generated from the iron core and the high-voltage winding 2a and the low-voltage winding 2b during operation by circulating the specific insulating mixed gas 44, and at the same time, insulates the winding in the high electric field. Are also to be held by this insulating gas. Therefore, the gas in the tank is SF ₆ gas and C
When using a mixed gas of F ₄ gas, it is necessary to maintain both cooling performance and insulating performance.

FIG. 4 is a block diagram of a second embodiment of the present invention.
FIG. ₄ is a diagram showing the insulation characteristics of a mixed gas of F ₆ / CF ₄ , wherein the mixing ratio of SF ₆ gas and CF ₄ gas is constant with an electrode system simulating between the high-voltage winding and the low-voltage winding of the gas-insulated transformer; 5 is an experimental example in which insulation strength was measured with respect to FIG. SF ₆ gas 2
If it is reduced to about 0%, the insulation strength will rapidly decrease.
Therefore, if the SF ₆ gas is further reduced, the insulation strength of the winding portion cannot be maintained. Therefore, from the standpoint of insulation strength, it is effective to maintain 5% to 20% of SF ₆ gas and the remainder of CF ₄ gas in the tank in order to maintain insulation strength.

FIG. 5 shows S in Embodiment 2 of the present invention.
Is a diagram showing the cooling characteristic in the winding unit of F ₆ / CF ₄ mixed gas, the temperature increase from ambient temperature at the winding portion of the gas-insulated transformer as constant gas pressure SF ₆ gas and CF ₄ gas The change with respect to the mixing ratio is shown. That is, this is a result showing the cooling characteristics when the gas is mixed. When the mixing ratio of the SF ₆ gas is reduced and the mixing ratio of the CF ₄ gas is increased, the temperature rise in the winding part increases. With respect to 100% of SF ₆ gas, the temperature rise increases by about 10% when the mixing ratio of SF ₆ gas is 10% to 30%. Further, the mixing ratio of SF ₆ gas needs to be 10% to 30% so as not to exceed the temperature rise limit 70 (deg) of the gas insulating transformer employing the class E insulating material. Therefore, in order to maintain the cooling performance, the case where the mixing ratio of SF ₆ gas in the tank is 10% to 30% and the rest is composed of CF ₄ gas. Therefore, when the gas in the tank is composed of a mixed gas of SF ₆ gas and CF ₄ gas, the mixing ratio satisfying the cooling performance and insulating performance is such that the mixing ratio of SF ₆ gas is 10% to 30% and the remaining CF ₄ gas is This is the case when the configuration is made.

In the second embodiment, the composition of the mixed gas filled in the tank is SF ₆ gas and the remainder is a saturated fluorine compound (CnF2n + 2: n = 2 to 10), and the mixing ratio of SF ₆ gas is 10% to 30%. The same performance can be obtained when the remaining is a saturated fluorine compound (CnF2n + 2: n = 2 to 10).

Embodiment 3 Embodiment 3 shows a case where the mixed gas in the tank is composed of SF ₆ gas and CO ₂ gas. The gas-insulated transformer shown in FIG. 1 cools the heat generated from the iron core and the high-voltage winding 2a and the low-voltage winding 2b during operation by circulating the specific insulating mixed gas 44, and at the same time, insulates the winding in the high electric field. Are also to be held by this insulating gas. Therefore, the gas in the tank is
_When a mixed gas of ₆ gases and CO ₂ gas is used, it is necessary to maintain both cooling performance and insulating performance.

FIG. 6 is a block diagram of a third embodiment of the present invention.
FIG. 3 is a diagram showing the insulation characteristics of a mixed gas of F ₆ / CO ₂ , wherein SF ₆ gas and carbon dioxide (CO ₂ ) gas are kept constant by an electrode system simulating between a high voltage winding and a low voltage winding of a gas insulating transformer. 5 is an experimental example in which insulation strength was actually measured with respect to the mixing ratio. When the SF ₆ gas is reduced to about 40%, the insulation strength sharply decreases. Therefore, if the SF ₆ gas is further reduced, the insulation strength of the winding portion cannot be maintained. Therefore, from the standpoint of insulation strength, it is effective to keep the tank with 30% to 50% SF ₆ gas and carbon dioxide gas as the remainder to maintain insulation strength.

FIG. 7 is a block diagram of the third embodiment of the present invention.
FIG. 5 is a diagram showing the cooling characteristics of the F ₆ / CO ₂ mixed gas in the winding portion of the gas mixture, where the temperature rise from room temperature in the winding portion of the gas-insulated transformer is changed with respect to the mixing ratio of SF ₆ gas while keeping the gas pressure constant. Is shown. That is, this is a result showing the cooling characteristics when gas is mixed. When the mixing ratio of SF ₆ is reduced and the mixing ratio of carbon dioxide gas is increased, the temperature rise in the winding part increases. Temperature rise against SF ₆ 100% gas mixing ratio of SF ₆ is increased about 10% at 50% to 70%. Also, E
Temperature rise limit of gas-insulated transformers using various insulating materials 7
In order not to exceed 0 (deg), the mixing ratio of SF ₆ gas needs to be 50% to 70%. Therefore, when the gas in the tank is composed of a mixed gas of SF ₆ gas and carbon dioxide gas, the mixing ratio satisfying the cooling performance and the insulation performance is 50 to 70% of the mixing ratio of SF ₆ , and the remainder is carbon dioxide gas (CO ₂ gas). ).

Embodiment 4 FIG. 1 is a sectional view of a gas-insulated transformer. In the figure, 1 is a tank container, 2 is a winding,
2a is a high voltage winding, 2b is a low voltage winding, 3 is an iron core, 44 is a specific insulating mixed gas, and 5 is a cooler. During operation, the gas-insulated transformer includes an iron core, a high-voltage winding 2a, and a low-voltage winding 2b.
Is cooled by the circulation of the specific insulating mixed gas 44, and at the same time, the insulating gas in the winding, which has a high electric field, is to be maintained by the insulating gas. Therefore, when the gas in the tank is a mixed gas, the cooling performance and the insulation performance must be maintained.

FIG. 8 is a block diagram of a fourth embodiment of the present invention.
FIG. 4 is a diagram showing the insulation characteristics of a mixed gas of F ₆ / nitrogen, in which an electrode system simulating a high-voltage winding and a low-voltage winding of a gas-insulated transformer has a constant mixing gas filling pressure at a certain mixing ratio with a constant distance between the electrodes. It is an experimental example in which the insulation strength with respect to the pressure when it changes is measured. It can be seen that the higher the pressure, the higher the dielectric strength.

FIG. 9 is a block diagram of a fourth embodiment of the present invention.
Is a diagram showing the cooling characteristic in the winding unit of F ₆ / nitrogen mixed gas, the pressure increase in the temperature of the mixture ratio of SF ₆ gas and nitrogen gas as a parameter from the normal temperature in the winding portion of the gas insulated transformer The results of the cooling characteristics when changed are shown. SF
_In order to reduce the usage of the _six gases, for example, consider a case where the mixing ratio of SF ₆ gas and nitrogen gas is 50: 50%. In this case, the pressure needs to be 0.3 MPa in order to increase the temperature as in the case of the rated pressure of 0.24 MPa. Also, the mixing ratio of SF ₆ gas and nitrogen gas is 30:70
%, When the pressure is 0.36 MPa, the temperature rise is the same as the temperature rise at the rated pressure.

In the case where the inside of the winding portion and the cooler is cooled by the gas, when the sealing pressure is increased, the Reynolds number indicating the state of the gas flow in each portion increases, and the winding and the cooler and the gas are cooled. The heat transfer coefficient between them increases. Since the temperature rise is the reciprocal of the heat transfer coefficient, as the heat transfer coefficient increases, the temperature rise decreases. FIG. 10 is a diagram showing a cooling characteristic with respect to a Reynolds number of a gas according to Embodiment 4 of the present invention, and shows a heat transfer coefficient between a gas and a solid wall using the Reynolds number as a parameter. When the Reynolds number exceeds 2000 and becomes a turbulent flow region, the heat transfer coefficient increases. That is, the cooling characteristics in the winding portion and the cooler are improved. When the pressure is increased, considering the state of SF ₆ gas 100%, the gas density becomes larger from the gas state equation. Now, the Reynolds number is represented by (equivalent diameter of flow path * flow velocity) / kinematic viscosity. Since the kinematic viscosity can be expressed by the viscosity / density of the gas, increasing the pressure increases the density of the gas. As a result, the kinematic viscosity decreases, and if the flow velocity and the equivalent diameter are constant, the Reynolds number increases. Therefore, when the sealing pressure is increased, the temperature rise is reduced, and the cooling performance is improved. Even with a mixed gas of SF ₆ and nitrogen, increasing the pressure of the filling gas improves the cooling performance. Therefore, if the gas in the tank is a mixture of SF ₆ gas and nitrogen gas, and if the remaining gas is composed of 30% of SF ₆ gas to satisfy the insulation performance and the remainder is composed of nitrogen gas, the pressure is increased to satisfy the cooling performance and the rated pressure is increased. 0.36 for 0.24MPa pressure
This is the case where the pressure is increased to more than MPa.

Embodiment 5 The gas-insulated transformer cools the heat generated from the iron core, high-voltage windings, and low-voltage windings during operation by circulating the insulating gas, and at the same time, uses the insulating gas to maintain the insulation in the windings, which are in a high electric field. Is what you do. Therefore, when the gas in the tank is a mixed gas, the cooling performance and the insulation performance must be maintained.

FIG. 11 is a diagram showing the cooling characteristics of the SF ₆ / CF ₄ mixed gas at the winding portion in the fifth embodiment of the present invention, and shows the temperature rise from room temperature in the winding portion of the gas insulated transformer. 5 shows the results of the cooling characteristics when the pressure is changed using the mixture ratio of SF ₆ gas and CF ₄ gas as a parameter. S
In order to reduce the usage of F ₆ gas, for example, SF ₆ gas and C
Consider the case where the mixing ratio of F ₄ gas is 50: 50%. In this case, the pressure needs to be 0.27 MPa in order to increase the temperature as in the case of the rated pressure of 0.24 MPa. Further, the mixing ratio of SF ₆ gas and CF ₄ gas is 20:
When the pressure is set to 80% or more and the pressure is set to 0.30 MPa or more, the temperature rise becomes the same as the rated pressure. Therefore, when the gas in the tank is a mixture of SF ₆ gas and CF ₄ gas, the pressure is increased to satisfy the cooling performance when the SF ₆ gas is composed of 20% and the rest is composed of CF ₄ gas to satisfy the insulation performance. In this case, the rated pressure was increased to 0.30 MPa or more with respect to the rated pressure of 0.24 MPa.

In the fifth embodiment, the composition of the mixed gas filled in the tank is SF ₆ gas and saturated fluorine compound (C
nF2n + 2: n = 2 to 10), the mixing ratio of SF ₆ gas is 10% to 30% and the remainder is a saturated fluorine compound (C
Even if the pressure is increased to 0.30 MPa or more as nF2n + 2: n = 2 to 10), almost the same performance can be obtained.

Embodiment 6 FIG. The gas-insulated transformer cools the heat generated from the iron core, high-voltage windings, and low-voltage windings during operation by circulating the insulating gas, and at the same time, uses the insulating gas to maintain the insulation in the windings, which are in a high electric field. Is what you do. Therefore, when the gas in the tank is a mixed gas, the cooling performance and the insulation performance must be maintained.

FIG. 12 is a diagram showing the cooling characteristics of the SF ₆ / CO ₂ mixed gas at the winding portion in the sixth embodiment of the present invention, and shows the temperature rise from room temperature in the winding portion of the gas insulated transformer. 5 shows the results of the cooling characteristics when the pressure is changed using the mixture ratio of SF ₆ gas and CO ₂ gas as a parameter. S
In order to reduce the usage of F ₆ gas, for example, SF ₆ gas and C
Consider a case where the mixing ratio of O ₂ gas is 50: 50%. In this case, in order to increase the temperature to the same level as in the case of the rated pressure of 0.24 MPa, the pressure needs to be 0.33 MPa or more. Therefore, the gas in the tank is SF ₆ gas and C
When O ₂ gas is mixed, SF ₆ gas is 50% in order to satisfy the insulation performance, and when the remainder is composed of CO ₂ gas, the pressure is increased to satisfy the cooling performance and the rated pressure is 0.24MP.
This is the case where it is increased to 0.33 MPa or more with respect to a.

[0033]

According to the gas insulated transformer according to the present invention, since a specific insulating mixed gas composed of SF ₆ gas and another gas is used, the amount of SF ₆ gas used is reduced, and global warming is reduced. Is greatly reduced. Further, an economical device having excellent cooling performance and insulation performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a gas-insulated transformer according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing insulating properties of a mixed gas of SF _{6 and} nitrogen according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a cooling characteristic of a winding of an SF ₆ / nitrogen mixed gas in the first embodiment of the present invention.

FIG. 4 shows SF ₆ / C according to Embodiment 2 of the present invention.
FIG. ₄ is a diagram illustrating insulating properties of an F ₄ mixed gas.

FIG. 5 shows SF ₆ / C according to Embodiment 2 of the present invention.
FIG. 4 is a diagram illustrating cooling characteristics of a F ₄ mixed gas at a winding portion.

FIG. 6 shows SF ₆ / C according to Embodiment 3 of the present invention.
FIG. 3 is a diagram illustrating the insulating characteristics of an O ₂ mixed gas.

FIG. 7 shows SF ₆ / C according to Embodiment 3 of the present invention.
FIG. 4 is a diagram illustrating cooling characteristics of an O ₂ mixed gas in a winding part.

FIG. 8 is a diagram showing insulation characteristics of SF ₆ / nitrogen mixed gas according to Embodiment 4 of the present invention.

FIG. 9 is a diagram showing a cooling characteristic of an SF ₆ / nitrogen mixed gas in a winding part according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a cooling characteristic with respect to a Reynolds number of a gas according to a fourth embodiment of the present invention.

FIG. 11 shows SF ₆ / F in Embodiment 5 of the present invention.
FIG. 3 is a diagram showing cooling characteristics of a CF ₄ mixed gas at a winding portion.

FIG. 12 shows SF ₆ / F in Embodiment 6 of the present invention.
It is a diagram showing the cooling characteristic at the winding portion of the CO ₂ gas mixture.

FIG. 13 is a sectional view of a conventional gas-insulated transformer.

FIG. 14 is a sectional view of another conventional gas-insulated transformer.

[Explanation of symbols]

1 tank vessel, 2 windings, 2a high pressure winding, 2b low pressure winding, 3 iron core, 4 insulating gas, 5 cooler, 6 perfluorocarbon liquid, 7 heat exchanger, 8 circulation pump,
9 Outlet pipe, 10 Inlet pipe, 11 Sealing tank, 12
Insulated container, 13 mixed gas, 44 specific insulating mixed gas.

Claims (6)

[Claims] 1. 30% to 50% SF in a tank container
A gas insulated transformer characterized by containing a mixed gas composed of ₆ gases and the remaining nitrogen gas or dry air, and containing an iron core and windings wound around iron legs. 2. 10% to 30% SF in a tank container
_Six gases and the rest are saturated fluorine compounds (CnF2n + 2: n
= 1 to 10). A gas-insulated transformer, wherein a mixed gas having a configuration of 1 to 10) is enclosed therein, and a coil wound around an iron core and iron core legs is accommodated therein. 3. 50% to 70% SF in a tank container
A gas-insulated transformer comprising a mixture of ₆ gases and a gas mixture of carbon dioxide (CO ₂ ) as a balance, and a coil wound around an iron core and iron core legs accommodated therein. 4. A mixed gas composed of SF ₆ gas and nitrogen gas or dry air is sealed in a tank container, and the mixed gas sealing pressure is increased from the rated pressure of SF ₆ gas 100% to increase the iron core and the iron leg. A gas-insulated transformer, wherein the wound winding is housed therein. 5. A mixed gas having a composition of SF ₆ gas and a saturated fluorine compound (CnF2n + 2: n = 1 to 10) is sealed in a tank container, and the mixed gas sealing pressure is set to 10 SF ₆ gas.
A gas-insulated transformer characterized in that a winding wound around an iron core and an iron core leg, which is increased from a rated pressure of 0%, is housed therein. 6. A mixed gas having a composition of SF ₆ gas and carbon dioxide gas is sealed in a tank container, and the mixed gas sealing pressure is set to SF.
₍₆₎ A gas-insulated transformer, wherein a winding wound around an iron core and iron legs is increased in a rated pressure of 100% of gas and housed therein.