Protective device and method for a turbomolecular pump

摘要

To provide a protective device for a turbo molecular pump and a method of protecting a turbo molecular pump that may cope with abnormal phenomenon according to a kind thereof when the abnormal phenomenon occurs. A kind of abnormal phenomenon is inferred from a change rate in rpm of a rotor when the abnormal phenomenon such as an injection of atmospheric air into an intake port is generated in the turbo molecular pump or the like and a magnitude of the damage imparted to the turbo molecular pump by the abnormal phenomenon is inferred from the rpm of the rotor upon the generation of the abnormal phenomenon. Furthermore, a value weighted to the magnitude of the damage is caused to correspond to and the value is accumulated whenever the abnormal phenomenon occurs in the turbo molecular pump. When the accumulated value reaches a certain value, the protective function is effected so that the turbo molecular pump is stopped to disable its re-operation or to display an alarm to the operator or the like.