| 摘要 |
PURPOSE:To increase the width of a capacity control range through operation at the outside of a surging region, by varying condensing pressure to control pressure, which corresponds to a surging limit, by the indication of a control motor for driving vanes. CONSTITUTION:When water is fed to a condenser 3 and a turbo-compressor 1 is put in operation, a refrigerant circulates through the condenser 3, an expansion valve 11, an evaporator 12, and the turbo-compressor 1 as a refrigerating cycle, and thus the water is fed to the evaporator 12 to obtain cooling water. When the quantity of the suction of the compressor 1 is varied by varying a load, the opening extent of a vane 7 is varied by detecting the temperature of the cooling water, and the limit switch of a control motor 6 for driving the vane, when the opening extent of the vane reaches a set value, operates to send an indication of variation in condenser control pressure to a controller 4 for cascade control. Consequently, the control pressure of the condenser 3 is varied in three steps corresponding to the opening degree of the vane, and the control range of refrigerating capacity is increased without entering a surging region. |
