The Pfeiffer Vacuum parameter set
27
9.4.3
Gas type dependent operations
Friction causes the rotor to heat up severely under gas load and high rotation speed. To
avoid overheating, the electronic drive unit has implemented power-rotation speed-char-
acteristics, whereby the pump can be operated at every rotation speed with the maxi-
mum allowable gas load without danger of damage. The maximum power consumption
depends on the gas type. Three characteristics are available in order to completely ex-
haust the pump's capacity for each gas type.
●
Gas mode "0" for gases with the molecular mass >39, e.g. argon.
●
Gas mode "1" for gases with the molecular mass
39.
●
Gas mode "2" for helium.
●
Power characteristics according to the technical data of the turbopump.
Check and set-up the gas mode via
[P:027]
.
Fig. 9:
Principle of power characteristics lines for gas type dependent operations,
e.g. gas mode = 0
The turbopump runs up with maximum power consumption. When the nominal and/or set
rotation speed is reached, the pump automatically switches over to the chosen power
characteristic of the selected gas mode. Increasing gas load is initially compensated by
a rise in power consumption in order to keep the rotation speed constant. Increasing gas
friction, however, causes the turbopump to heat up more severely. When the gastype-
dependent maximum power is exceeded, the rotation speed of the turbopump is reduced
until an equilibrium between permissible power and gas friction is attained.
To avoid rotation speed fluctuations, Pfeiffer Vacuum recommends setting a some-
what lower frequency in rotation speed setting mode.
9.4.4
Set value power consumption
Adjust the parameter
[P:708]
to the desired value in %.
If adjusting the set value power consumption below 100 % the run-up time prolongs. To
avoid error messages, the parameter
[P:700] RUTimeSVal
should be adjusted accord-
ingly.
NOTICE
Danger of the pump being destroyed
Pumping of gases with a higher molecular mass in the wrong gas mode can lead to de-
struction of the pump.
Ensure the gas mode is correctly set.
Contact Pfeiffer Vacuum before using gases with a greater molecular mass (> 80).
[P:708]
D
F
B
A
C
E
Pmax
fN
Run-up
Rotation speed
P
ower
C-D = gas mode "0"
A-B = gas mode "1"
E-F = gas mode "2"
