Cold frozen type dry machine except refrigeration compressor itself protection device outside, also distribution has air switch, and hot overload protection, and delay control function, and automatically reset run function and the energy bypass regulation function (medium above); wind cold type cold dry mechanism cold system two-way protection control, prevent for environment temperature changes and effect refrigeration effect; water type cold dry machine distribution has water automatically regulation function, prevent for cooling water temperature changes and effect refrigeration effect. Ensure the freeze dryer running safe and reliable.