Edwards STP-iS2207 Series Instruction Manual page 19

1. Oil free
Rotor blade (1) is supported by the magnetic bearing without mechanical contact. Therefore, the STP
pump requires no lubrication oil unlike conventional turbomolecular pumps using ball bearings.
2. Low vibration
The magnetic bearing consists of 5 pairs of active magnetic bearings. The rotor is supported in the
radial direction by 4 pairs of radial direction active magnetic bearings that consist of radial sensor (3)
and radial electromagnet (4). A pair of axial direction active magnetic bearings consists of axial
sensor (5) and axial electromagnet (6) to support the rotor in the axial direction. Because the rotor is
supported without mechanical contact, it can rotate at low vibration.
3. High reliability
There is no periodic replacement of magnetic bearings unlike conventional turbomolecular pumps
using ball bearings because there is no friction. Taking into consideration a breakage of magnetic
bearings, touch down bearings (7) have been installed. They do not contact with the rotor during the
rated operation. The status of the rotor and magnetic bearing is continuously monitored via circuits
detecting rotor displacement, rotational speed and pump temperature. If an abnormality/error occurs,
the rotor will stop.
4. Compact size (Integrated control unit)
To save space for installation, the STP pump mounts the control unit (8) that includes the power
supply which converts the alternating input to direct current output. In addition, the following circuits
are integrated; the magnetic bearing control circuit, the motor drive circuit which drives rotor blade,
the supervisor circuit which monitors pump operation status and operates the pump in remote
operation mode.
STP-iS2207 Series Turbomolecular Pump
1
MT-89E-001-C
Page 9