JP3750045B2 - Electric equipment cooling gas - Google Patents

Description

OBJECT OF THE INVENTION
[0001]
[Problem to be Solved by the Invention]
This invention intends to provide a gas having a low windage loss and an electric withstand voltage for cooling gas in the machine for the purpose of reducing the loss of a rotating machine such as a vertical shaft type generator or a motor generator with a flywheel. Is.
[0002]
[Industrial application fields]
For generator cooling, when the generator type is a horizontal shaft type (turbine type), hydrogen is mainly used as the internal cooling gas, but when it is a vertical shaft type (water turbine type), air at atmospheric pressure is used as it is. is doing.
[0003]
Conventionally, the vertical shaft machine has been operated in the atmospheric pressure air as it is without causing a problem of windage loss due to the rotation because the rotational speed per minute is low unlike the case of the horizontal turbine type. .
[0004]
In recent years, vertical shaft machines have also been rotating at high speed, and generators having flywheels have been put into practical use, and wind loss has become large among rotor rotation failures, and it has become impossible to ignore in terms of operating efficiency.
[0005]
[Target of the present invention]
In order to reduce windage loss of electrical equipment such as a rotary machine that has been operated in the air, such as a vertical shaft generator, it is possible to use a gas mainly composed of helium and to allow a reduction in electrical withstand voltage. The gas thus mixed is intended to be provided as a cooling gas for electrical equipment.
[0006]
[Prior art]
Conventionally, air at atmospheric pressure has been used for cooling the vertical shaft generator, but since it was a low-speed rotating machine, windage loss was not a problem.
[0007]
As the vertical shaft machine is also increased in speed and with a flywheel, wind damage increases. For example, the world's largest generator with a flywheel built in 1985 at the Japan Atomic Energy Research Institute The loss was 2650 kW.
[0008]
We examined the use of hydrogen cooling, which has already been put to practical use in horizontal axis machines, but in the case of flywheels in particular, it has not been adopted due to performance degradation due to hydrogen in high stress repeated fatigue parts and operational maintenance problems. .
[0009]
Means to be Solved by the Invention
Therefore, using helium gas that is safe against fire and has no problem even in high-stressed areas can greatly reduce windage loss, making it possible to increase the withstand voltage by compensating for the lack of withstand voltage of pure helium. Invented a new mixed gas.
[0010]
Nearly pure helium has an electrical withstand voltage as low as about 30% of air under the same conditions, and if adopted, requires a substantial redesign of the electrical insulation design inside the generator.
[0011]
If a small amount of negative gas such as SF6 (sulfur hexafluoride), which has a high dielectric strength, is mixed in helium, and if the withstand voltage can be improved to the same level, this cooling gas is replaced with the conventional insulation design. be able to.
[0012]
[Action]
Although helium has a low electrical withstand voltage, it is known to improve if it is mixed with a small amount of SF6 gas. However, SF6 is a heavy gas and no significant effect can be obtained. The gas may be limited and the price is also expensive.
[0013]
The windage loss increases at about the third power of the rotation speed, but varies greatly in proportion to the gas density.
[0014]
If sufficient generator cooling gas can be obtained by mixing air with helium to reduce windage loss compared to air and withstand voltage, the insulation design can be tolerated. By replacing the gas of the present invention with atmospheric pressure and compensating for leakage, windage loss can be reduced.
[0015]
A flywheel generator with a flywheel directly connected to a vertical shaft generator has been created to stabilize the power supply and power system for fusion experimental equipment. The generator of the fusion device JT-60 toroidal magnetic field coil power source has a wind loss of 2650 kW.
[0016]
If the electric equipment cooling gas of the present invention is used for this, the windage loss is halved and the operating power can be reduced by 1300 kW.
【Example】
[0017]
The actual measurement of windage loss was carried out in a gas with various mixing ratios using a rotating disk.
[0018]
The method is to place a rotating disk in the gas, rotate at high speed, and then decelerate naturally and record the number of rotations that change over time (see Fig. 1), and the rotational moment of the rotating body is calculated separately. Therefore, the rotational loss at each rotational speed is obtained from the change in the rotational speed as shown in FIG.
[0019]
Actual measurement of the withstand voltage of the mixed gas was performed with an AC voltage for the sphere gap and the epoxy resin edge gap, and the results as shown in FIG. 3 were obtained.
[0020]
As a result, it is understood that when about 50% of air is mixed with helium, the windage loss is greatly reduced with respect to the air, and the generator rotor cooling gas that can withstand the withstand voltage in the case of air can be obtained.
[0021]
【The invention's effect】
By using the present invention, the wind loss can be reduced to 56% by replacing the cooling gas of the conventional vertical shaft generator with the atmospheric pressure.
[0022]
The previous generator with flywheel for JT-60 had an idling loss of 2650 kW, but 1100 kW can be reduced by using the present invention.
[0023]
Furthermore, for cooling, helium produces very good performance, so it is possible to reduce the flow rate of the in-flight blower.
[0024]
Insulation of the generator rotor slip ring and armature coil connection is important for the withstand voltage of the generator, but when using the gas of the present invention as it is with a conventional machine, increase the air mixing ratio according to the degree. However, the effect of reducing windage loss is also reduced accordingly.
[0025]
In the case of a new design, an insulation design that considers operation in a gas with a low withstand voltage is preferable, and increasing the ratio of helium increases the effect of reducing windage loss.
[0026]
As described above, by using the generator cooling gas in which air is mixed with helium according to the present invention, the windage loss can be reduced compared to air, and the cooling effect is also improved.
[0027]
By reducing the windage loss of the rotating body, it is possible to reduce the rotation loss of the generator and the flywheel, and at the same time, the increase in the cooling effect becomes the rationalization of the cooling device, and the energy efficiency of the electrical equipment can be increased overall.
[Brief description of the drawings]
FIG. 1 shows the result of measuring a change in the number of revolutions with time when a mixed gas of helium and air is filled in a container and the rotating machine is in a natural deceleration state.
FIG. 2 is a diagram in which a change in idling loss is calculated for each rotation speed from the result of measuring the change in the rotation speed.
FIG. 3 shows the results of measurement of the discharge breakdown voltage of the mixed gas using AC voltage for the sphere gap and the epoxy resin edge gap, as shown in FIG.

Claims (1)

In electric apparatus having a rotating body which is operated by the generator, to increase the electrical breakdown voltage in the helium gas for the purpose of reducing the windage loss of the rotating body, the atmospheric pressure of a mixed gas of air against the helium gas The electric equipment cooling gas applied to the generator with the flywheel that can reduce the rotation loss due to the wind loss and is directly connected to the generator.

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