Accident
Effect
Result
The pump-to-controller cable is
disconnected or broken.
The electrical supply to the
electromagnetic bearing is lost.
The rotor assembly drops
immediately onto the safety
bearings with considerable noise
as the EXT250M decelerates. The
‘Emergency’ LED on the
EXC300M will go on.
The EXT250M is suddenly
exposed to atmospheric pressure
due to a massive leak or rupture
of the vacuum system.
The force on the rotor will
overcome the force of the
electromagnetic bearing and the
rotor will rebound against the
safety bearings.
The ‘Emergency’ LED on the
EXC300M will go on. There may
be considerable noise if the pump
rotor remains in contact with the
safety bearings.
The EXT250M is exposed to
excessive mechanical shock.
The rotor remains in contact with
the safety bearings when the
centrifugal force of the rotor
exceeds the restoring force of the
magnetic bearings.
The ‘Emergency’ LED on the
EXC300M will go on. There may
be considerable noise if the rotor
remains in contact with the safety
bearings.
Table 1 - Accidents which affect the life of the safety bearings
EXT250M Turbomolecular Pump
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