| 摘要 |
To provide a magnetic bearing protective device and a turbomolecular pump in which stable control can be held against the excessive oscillation of a rotator and an externally given shake. A magnetic bearing is stopped for the purpose of protecting the same when the current flowing through radial position controlling electromagnets (3A, 3B) and an axial position controlling electromagnet (5) reaches to a preset value for a given time. At this point, no limitation is put on the current flowing through the radial position controlling electromagnet (3A), etc., so that the oscillation of rotor blades (1) ends early. Therefore, less damage is given to touch down bearings (13, 15).
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