Pump Used In Presence Of Magnetic Fields - Agilent Technologies Turbo-V 2300 TwisTorr Bedienungshandbuch

17 Technical Information

Pump used in Presence of Magnetic Fields

6 pin connector
Pins A and F are connected to the body temperature sensor, pins B,
D are connected to the purge valve, and pins C, D are connected to
the vent valve; pin E is not connected.
If one temperature sensor is disconnected, the pump will not start.
To prevent damage to the pump when the temperature exceeds
60 °C, the sensor automatically cuts out the power supply.
We recommend that you fit a separate earth (ground) conductor to
the TV 2300 TwisTorr pump. Use a separate insulated green/yellow
conductor, and use a M5 x 10 screw and shake proof washer (fitted to
the earth hole on the pump) to secure the earth conductor to the
pump. The screw must be fixed with a 2 Nm torque. The impedance
between the pump-body and the earth connection point must be
< 0.1 Ω.

Pump used in Presence of Magnetic Fields

Magnetic fields induce eddy currents in the rotor of a turbomolecular
pump that tend to oppose to its rotation.
The result is increased electrical power consumption by the motor,
most of which is dissipated in the rotor.
Since the rotor is not in contact with the stator the above power can
leave the rotor mainly by radia-tion and hence the rotor may be
overheated while static parts of the pump remain cool.
This effect is strongly dependant from the intensity, time function
and distribution of the magnetic field.
In general, therefore, an increase in pump current can be expected.
If this increase is lower than 50 % of the current value drawn by the
motor in high vacuum operation, no particular problem should be
expected.
However if the effect is greater, than the case should be carefully
reviewed by Agilent's special-ist. As a matter of fact, in case of high
magnetic fields, also important forces might be generated and applied
to the rotor.
252/260 Turbo-V 2300 TwisTorr Pumps User Manual / 87-901-017-01 (B)