Siemens SITRANS P320, Руководство по эксплуатации, Страница: 148 / 260

See also
Application [05] (Page 106)
9.3.6 Sensor calibration
You use the sensor trim to set the characteristic curve of the device at two trim points. The
results are then correct measured values at the sensor trim points.
The sensor trim points can be selected as any points within the nominal range.
Devices that are not turned down prior to delivery are trimmed at 0 bar and the high limit of
the nominal range.
Devices that are turned down prior to delivery are trimmed at the low and high limits of the set
measuring range.
Examples
● For a particular device that is not turned down (e.g. 63 bar), the typical measured value is
50 bar. To attain the highest possible accuracy for this value, set the upper sensor trim at
50 bar.
● A 63-bar pressure transmitter is turned down to 4 to 7 bar. You can attain the highest
possible accuracy by selecting 4 bar for the low trim point and 7 bar for the high trim point.
● A 250-mbar absolute pressure transmitter shows 25 mbar at 20 mbar. A reference pressure
of 20 mbar is available. To correct the zero point, perform a sensor trim at the lower trim
point with 20 mbar.
Note
Use a test device whose accuracy is at least three times as high as the accuracy of the
pressure transmitter.
Sensor trim at the lower trim point
1. Apply the pressure for the lower sensor trim at the device.
2. Use the "Apply values" menu to enter the pressure value that you have created and assign
the pressure value to the device.
The device calibrates to your value.
The device carries out an offset correction of the characteristic curve.
Parameter assignment
9.3 Parameter assignment over remote operation
SITRANS P320/P420 (mA/HART)
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Operating Instructions, 06/2018, A5E44852162-AA