| 摘要 |
PURPOSE:To acquire super-cooled liquid nitrogen only in an inner tank by providing an expansion valve and a heat exchanger in refrigerant of a refrigerant tank which is pressurized to an atmospheric pressure or higher and by discharging a part of refrigerant outside through them. CONSTITUTION:A superconducting transformer which is composed of a core 1, a low pressure winding 2 and a high voltage winding 3 using an oxide super conductor is cooled by liquid nitrogen 7 of a tank 4 which is pressurized to an atmospheric pressure or higher. A part of the liquid nitrogen 7 is depressurized by an atmospheric pressure by an expansion valve 10 and is discharged to atmosphere through a heat exchanger 11. At this time, the tank 4 is cooled to an atmospheric pressure liquid nitrogen temperature of 77.36K. That is, since the liquid nitrogen 7 of the tank 4 is super-cooled, deterioration of insulation strength can be prevented without development of bubbles from the liquid nitrogen 7 even if temperature-up is caused by heat generation of the low pressure winding 2 and the high voltage winding 3. |
