Prevac MG14 Operating Manual page 31

MG14 operating manual Rev 1.4
It is generally agreed that I
mA ) for all work and above 10
The following sensor parameters are monitored constantly during operation:
- Anode voltage
- Cathode voltage
- Emission current
- Filament voltage
- Filament current
Two tolerance ranges are defined for each parameter . No error is reported within the first tolerance
range. If the value is outside of the first but still inside of the second tolerance range, one can select
from the three possible types of error.
If the value is outside of the second tolerance range, a «Emission error» is issued on principle.
!
Excessive emission current.
A high emission current at relatively high pressure levels can damage the sensor.
Only set the emission current to a fixed value if you can be sure that the sensor will
operate at sufficiently low pressure levels.
4.2.4.4 Sensitivity factor menu – SENSITI. ( CALIB. for extractor IE514/515 )
Function describing relation between gas type, the geometry of the gauge and the absolute
temperature is generally defined as gauge sensitivity factor S
Expression for the gauge sensitivity factor :
– sensitivity factor for gas correction. It can be set in the range 0,1 .... 100.
S
g
Sensitivity factor is also called CALIBration factor in extractor gauge manufacture specification.
NOTE:
For accurate measurement please always set the correct Sensitifity/Calibration factor. This
parameter is given by gauge manufacturer – in some types one for the same type and in
some cases it is exact related to the serial number of the gauge
must be kept in the lowest practical value ( certainly no more than 0.1
e
-3
mbar.
WARNING
Sensitivity = ( Ion Current ) / [(Electron current) x (Pressure)]
g
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