Operating functions via HART
7.6 Blind setting of zero point and limit point
SITRANS P300 with HART communication
Operating Instructions, 06/2005, A5E00359579-02
7-17
7.6 Blind setting of zero point and limit point
• Zero point and limit point can be set without creating a reference pressure.
• Both values can be selected as any point within the sensor limits.
• The maximum downscaling is 1:100, depending on model and measuring range.
7.7 Zero point calibration (position correction)
Description
A zero point calibration is used to correct a zero point error resulting from the installation
position.
Procedure
• Pressurize the device (Pressure, Level) or evacuate it (Absolute pressure, <0.1 ‰ of the
measuring span).
• Perform the zero point calibration using SIMATIC PDM or the HART Communicator.
• If you do not have a vacuum, perform a trimming of the lower sensor trim point for a
known reference pressure.
Caution
For absolute pressure transmitters, the zero point is at vacuum. A zero point calibration
with a pressurized transmitter will lead to faulty settings!
Note
The effective measuring range is reduced by the amount of the upstream pressure.
Example:
With an upstream pressure of 100 mbar, the effective measuring range of a 1-bar
transmitter is reduced to a point between 0 and 0.9 bar.
See also
Trimming of the sensor trim point (Page 7-23)
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