JPS60105206A - Evaporative cooling type gas-insulated electrical apparatus - Google Patents

Abstract

PURPOSE:To obtain the equivalent cooling capability with a lower temperature and a lower interior pressure than the conventional temperature and pressure by providing a bellows which is capable of changing a volume within a constant range in accordance with a difference between internal pressure of case and atmospheric pressure in connection with the case. CONSTITUTION:Under the lowest pressure condition, volume and pressure of gas are the same as the conventional case and a bellows 21 is compressed with an internal volume V1 of zero and in this case, a volume of compressive coolant 15 in the case 2 is considered as Vl1 and a volume of gas 13 as Vg1. Meanwhile, under the rated operating condition where a compressor 3 in filled with a coolant vapor 14 up to the height h and continuing the compressing operation, when a volume of coolant vapor 14 at the lower part of case 2 is considered as Vv, a volume of gas 13 in the case 2 as Vg3, and a volume of gas in the bellows 21 as V3, a change of volume DELTAV under the conditions between the lowest pressure condition and the rated operating condition is expressed as DELTAV=Vg1-(V3+Vg3). Therefore, a volume of gas 13 is compressed with a rate of (V3+Vg3)/Vg1 and necessary pressure and temperature of case become lower than the conventional pressure and temperature.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention cools evaporatively cooled gas-insulated electrical equipment, particularly electrical equipment that generates heat during operation by changing the gas-liquid phase of a condensable refrigerant, and improves insulation maintenance. This invention relates to an evaporative cooling type gas insulated electrical device which is filled with a non-condensable gas and is designed to lower the pressure inside a container housing electrical equipment.

[Prior art]

Conventionally, an example of this type of device is shown in FIG.

That is, in the figure, the symbol / is an electric device that generates heat, q is a container for storing the electric device, 3 is a condenser that condenses and reduces the vapor of the condensable refrigerant vaporized from the heat generation 9 of the electric device 1, and q
The symbol on the left is a duct that communicates the container and the condenser 3 at their lower parts, and the symbol on the left is a duct that circulates the liquid phase condensable refrigerant (hereinafter simply referred to as condensable refrigerant) through the piping in order to distribute it to electrical equipment. Circulation pump, B is piping in which condensable refrigerant circulates,
7 is a dispersion device for dispersing condensable refrigerant to electric equipment/, l/ indicates the flow of the condensable refrigerant, and 7.2 is the condensable refrigerant vapor (
13 is a non-condensable gas (hereinafter simply referred to as gas), /4' is a refrigerant vapor, and /A is a condensable refrigerant. The gas may be, for example, nitrogen gas (N), and the condensable refrigerant may be, for example, fluorocarbon FC-7 manufactured by 3M. t is commonly used. In addition, in order to prevent dielectric strength and leakage of electricity from the atmosphere side into the container, the inside of the container for storing electrical equipment should be kept at a minimum operating pressure of at least atmospheric pressure, even at -20°C, and the operating temperature should be kept at above atmospheric pressure. The temperature is set at about 130°C.

The conventional device is configured as described above, and its operation will be explained next.

First, when the electric equipment/ is activated and generates heat, the condensable refrigerant/S is sprayed there from the spraying device 7.
On the left, it evaporates and becomes refrigerant vapor/l/. If the relationship between the specific weight of refrigerant vapor/j and the specific weight of gas/3 satisfies the relationship where the specific weight of refrigerant vapor is greater than the specific gravity of gas -l, then gas/3 and refrigerant vapor/'% separate vertically and form a clear boundary layer. The refrigerant vapor /4' separated in the lower part of the container in this way flows into the condenser 3 through the duct, where it is condensed and liquefied to form the condensable refrigerant /4'.
Return to j and return to the spraying device 7 again. Since the refrigerant vapor is condensed and liquefied in this way, the volume of the refrigerant vapor is reduced, and a suction force is generated from the condenser 3 to the container. 3, and condensation and liquefaction of the refrigerant vapor/soot in the condenser 3 continues. The condensable refrigerant /j that has been condensed and liquefied in the condenser 3 is guided to the upper part of the electrical equipment l by a circulation pump S through a pipe 6 at the top of the condenser 3, and is again sprayed onto the electrical equipment.

On the other hand, the gas 13 is separated and remains in the upper part of the container.

In order for such a cooling system to be established, the refrigerant vapor level must rise to a certain height inside the condenser 3.

In this case, the pressure inside container a is as shown in Fig.
Ru. In the figure, P' is the refrigerant vapor pressure at part A where gas/3 is accumulated.

p/, is the refrigerant vapor/4ZIJ' - the gas pressure in some part B; As mentioned above, when condensable refrigerant and gas are selected, P′akio (kg/c4 abs
), P'b* o (kg/cIIIabs
).

where Pa is the gas pressure in part A, and Pb is the refrigerant vapor pressure in part B. Therefore, gas 13
If separation of P and refrigerant vapor is performed, P
, -7-o, from PbkiO, P, middle PkiP1.
holds true. Note that such a state occurs in a temperature range equal to or higher than the temperature at which the refrigerant vapor pressure Pb becomes equal to the gas pressure pa.

Now, seven examples of the relationship between the internal pressure of the container 2 and the gas temperature are as shown in FIG. is a temperature range of 12 or more where Pb is approximately equal to the refrigerant vapor pressure Pb.

In FIG. 1, which shows a conventional device that operates in this way, the height to which the refrigerant vapor /4' rises in the condenser 3 is determined by how much the volume of gas /3' is compressed by the pressure increase in the container. Determined by Taka.

In the case of the conventional device, gas 1 at 730°C
3 without any change in volume θ℃, / kg / cd
The pressure of the gas 13 when the temperature rises from abs is i S ? from Boile-Charles' law. kg/cIIa
It becomes bs. This gas pressure is compressed from below by refrigerant vapor/// 1.2. ．． 7 kg/
d abs, so the volume is compressed to about 70%.

In this way, in the conventional device, as mentioned in 7 above,
Since the minimum pressure at -20°C is set to atmospheric pressure, in order to operate the condenser 3, it is necessary to compress the gas /3, and for this purpose the pressure inside the container λ is reduced to 2. ,?
kg/1ffl abs. For this purpose, it was necessary to raise the liquid temperature of the condensable refrigerant IS to the point where it had a vapor pressure equal to the pressure inside the container 2.

The conventional device is constructed as described above, and therefore, in order to operate the above-mentioned condenser 3, high pressure and liquid temperature are necessary.
As a result, there is a drawback that the strength of the container unit and the insulating material constituting the electrical device are required to have high heat resistance.

[Summary of the invention]

The present invention is as described above, whereas in the conventional device, high temperature,
This was done with the aim of eliminating the disadvantage that the condensing system does not operate unless the pressure is high, and providing an evaporative cooling type gas insulated electrical device in which the condensing system operates at lower temperatures and lower pressures. For this purpose, a bellows whose volume can be varied within a certain range depending on the difference between the internal pressure of the container and the atmospheric pressure is communicated with the container and the gas can be taken in at a low temperature. The present invention provides an evaporatively cooled gas insulated electrical device in which the condensing system operates at low pressures.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on figures showing one embodiment thereof.

In Fig. 7, a bellows with the symbol ``Yuko'' which can expand and contract by a distance 1 due to the difference between the pressure inside the container ``K'' and the atmospheric pressure is shown. Bellows on the left, 2 on the left
/, a can housing a top plate, 22 and a stopper, 23, and a ventilation hole, 2+! Therefore, the pressure inside the can is always atmospheric pressure. The configuration of other parts is the same as that of the conventional device shown in FIG. Further, the internal volume of the Perot 'I', 2/ is set to be approximately zero in the lowest pressure state.

The device of the present invention is configured as described above, and its operation will be explained next.

Figure 5A shows the lowest pressure condition, in which the volume and pressure of the gas are the same as in the conventional device shown in Figure 6A, and the bellows, 2/ is contracted. , and its internal volume v7 is zero. In this state, the volume of condensable refrigerant/S in the container is 11, the volume of gas/3 is V, and 9/.

On the other hand, No.
In the state shown in Figure B, the volume occupied by the refrigerant vapor/4' below the container λ is vv, the volume occupied in the container λ of gas/3 in that case is V&J, and the volume occupied by the bellows 2/ Assuming that the volume is ■J, the change in volume of the gas 130 between the lowest pressure state, the rated operation time, and 9 times can be expressed as △v = vgz - (v, +vg, y). Therefore, the volume of gas 130 is V3 + VH
It is reduced by a ratio of 2 Vy/.

On the other hand, in the case of the conventional device, the volume change △V' of the gas space between the lowest pressure state and the rated operation is shown in Figure 6B.
As shown, △V'''=VH7-VH2.

It won't happen.

Here, in the case of gas, the pressure and volume are inversely proportional, so the pressure when the refrigerant vapor surface height inside the condenser 3 becomes h is required to be higher in the case of the conventional device. becomes. The above comparison is shown in FIG. As can be seen from this, the pressure and temperature inside the container necessary to obtain cooling performance equivalent to that of the conventional apparatus can be lower in the present invention than in the conventional apparatus.

In addition, in FIG. 7, the symbol 3/ is the rated operating point of the electrical equipment of the conventional device, and 3 is the rated operating point of the electrical equipment of the present invention, 33
3D is a container pressure-temperature characteristic curve of the conventional device, 3D is a container pressure-temperature characteristic curve of the present invention, and 3S is a refrigerant vapor pressure-temperature characteristic curve. In addition, Fig. g shows the state of the bellows 21 that changes due to the pressure inside the container, A shows the state at the lowest pressure state, the internal volume of the bellows 2/ is zero, and B shows the state at the seventh In the state shown in the figure, the bellows 2/ is in the middle of expansion, and the pressure inside the container is Pt and the atmospheric pressure P. In addition, C shows the state in region (3) of FIG. 7, where the top plate of the bellows 21 is in contact with the stopper 23, and the relationship between Po and Pt is P. < This indicates a state in the relationship of Pt.

〔Effect of the invention〕

As described above, according to the present invention, the volume can be varied within a certain range depending on the difference between the internal pressure of the container and the atmospheric pressure.
By communicating with the container, it is possible to obtain the same cooling capacity at a lower temperature and lower pressure inside the container than with conventional equipment, making the container lighter and cheaper, and reducing temperature rise, making it more reliable. This has the effect of providing evaporative cooling type gas insulated electrical equipment with improved performance.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing an example of a conventional evaporative cooling type gas insulated electrical device, Figure 2A is a schematic cross-sectional view showing the distribution of gas and refrigerant vapor in Figure 1, and Figure 2 is a schematic cross-sectional view showing the distribution of the gas and refrigerant vapor in Figure 1. FIG. 3 is a pressure-temperature diagram inside the container of the device shown in FIG. Fig. 6 is a schematic cross-sectional view showing the operating state of the lowest pressure state (A) and the rated operating state (B) of the conventional device.
), FIG. 7 is a pressure-temperature diagram in the container shown in FIG. q, FIG. 3 shows the state of the bellows in FIG. It is an explanatory diagram shown in area I (B) and area U (C). L...Electrical equipment, λ...Container, 3...Condenser, G...Duct, 5...Circulation pump, 6...Piping, 7...Spreading device, //...Liquid phase condensable refrigerant Flow, 12... Flow of condensable refrigerant vapor, 13... Non-condensable gas, /F... Condensable refrigerant vapor, /S... Condensable refrigerant in liquid phase, Nido Bellows 1.2.2... Top plate, 3... Stopper, 211...
Vent hole 1.2 left...Can body. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 3 - Temperature (0C) Figure 4 Figure 5 A Ding Vagina, Supplementary 11:, Kimi): "Spontaneous" Showa Year Month Pa 59.5. 10 1 effect'1 Director-General 1, “19 indications!l1tx year!lll-Permission No. ko/2!r!7 No. 2
Name of the Invention: Iris Cooling Type Gas Insulated Electrical Apparatus 3 Name of Person Who Made the Sleeve 11- (601) Mitsubishi Electric Corporation Representative Hitoshi Katayama ＼＼Miro, amends the detailed description of the amendment as follows.

Claims (1)

[Scope of Claims] (1) An electrical device that generates heat when operated, a container that houses it, a non-condensable gas with insulating properties filled in the container, and a gas-liquid phase change that cools the electrical device that generates heat. It is equipped with a condensable refrigerant placed in a container that cools and liquefies the condensable refrigerant vapor generated by the phase change of the condensable refrigerant, and the non-condensable gas and the condensable refrigerant are converted into non-condensable gas. An evaporative cooling type in which the specific weight of the condensable refrigerant vapor is selected to be thicker than the specific weight of An evaporative cooling type gas insulated electrical device characterized in that a bellows whose volume can be varied within a certain range depending on the difference between the internal pressure of the container and atmospheric pressure is attached in communication with the container. (g) The evaporative cooling type gas insulation according to claim 1, wherein only non-condensable gas separated above the container flows into the bellows communicating with the container when condensable refrigerant vapor is generated. electrical equipment. (3) The evaporative cooling type gas insulated electrical device according to claim 1 or 2, wherein the bellows communicating with the container is mounted on the cover of the container.