Host machine adopts the advanced the new 3rd generation 5:6 asymmetric rotor tooth shaped semi closed screw compressor, the compressor motor and integration without shaft seal leakage concerns two or more compressors there is reincarnation start and stop control program, balancing the head component of load, to extend the use life of two or more compressors using multiple sets of refrigeration circuit unit, which a loop shall repair and maintenance, the rest of the loop is still running, with standby function compressor start to use the unloading buck, to avoid the impact on the power grid