Rosemount 3051S Electronic Remote Sensors - Emerson Process ...

Reference Manual
00809-0100-4804, Rev AA
January 2011
Rosemount 3051S ERS System
DP Calibration The DP calibration function can be used to adjust the calculated DP
Fast Keys 3, 4, 2, 1
measurement of the ERS system. For example, a DP zero trim can be
performed if the calculated DP of the ERS system has a small offset when the
expected output should be “0 DP.”
NOTE
Because the DP calculation is dependent on the P HI and P LO pressure
measurements, all DP calibration functions should be performed after
completing the calibration functions on the individual P HI and P LO sensors.
While a lower or upper DP trim is not required, a zero DP trim should be
performed after installing and calibrating the individual pressure sensors and
before subjecting the ERS system to the actual process conditions in order to
establish a zero-based DP measurement.
DP Zero Trim
The DP Zero Trim function establishes a true zero-based DP calculation by
taking the current measurement output and forcing that value as the new
zero-reference. A DP Zero Trim should only be performed when the expected
output of the ERS system is “0 DP.” For non-zero based trims, a DP Lower
Trim should be performed instead.
The DP zero trim function requires both pressure sensors to be wired and
connected.
To perform a DP zero trim, follow the procedure below:
1. Ensure that the individual PHI and PLO pressure sensors have been
calibrated as detailed on page 4-3 and are wired together as shown in
Figure 2-9, Figure 2-10, or Figure 2-11.
2. Launch the “DP Zero Trim” function using AMS or a Field Communicator.
3. Apply “0 DP” to the ERS System and wait for the DP measurement to
stabilize.
4. Using AMS or a Field Communicator, perform the zero trim function on
the 3051S ERS System.
Upper and Lower DP Trims
The DP calculation can be trimmed using a two-point calibration where lower
and upper end-point pressures are applied, and all readings are linearized
between the two points.
Unlike the DP Zero Trim function, the Upper and Lower DP Trims can be
performed when the ERS system is pressurized under actual process
conditions.
Always perform a lower DP trim first to establish the correct offset. The upper
DP trim provides a slope correction.
4-5