Rerange - Emerson Rosemount 3051S Series Reference Manual

Rosemount 3051S Series
Figure 3-8. Square Root Output
Transition Point

Rerange

3-14
Full Scale
Full Scale
Flow (%)
Output
(mA dc)
Transition Point
Slope=1
% Pressure Input
NOTE
For a flow turndown of greater than 10:1 it is not recommended to perform a
square root extraction in the transmitter. Instead, perform the square root
extraction in the system. Alternatively, you can configure Scaled Variable for
square root output. This configuration allows you to select a low flow cutoff
value, which will work best for the application. If low flow cutoff configuration is
desired, use "Scaled Variable Configuration" on page 3-21 to configure
square root and "Re-mapping" on page 3-24 to map Scaled Variable as the
primary variable.
The Range Values command sets the 4 and 20 mA points (lower and upper
range values). In practice, you may reset the transmitter range values as
often as necessary to reflect changing process conditions. Changing the
lower or upper range point results in similar changes to the span. For a
complete listing of Range & Sensor limits, refer to the "Range & Sensor
Limits" table on page A-6.
NOTE
Transmitters are shipped from Rosemount Inc. fully calibrated per request or
by the factory default of full scale (span = upper range limit.)
Select from one of the methods below to rerange the transmitter. Each
method is unique; examine all options closely before deciding which method
works best for your process.
• Rerange with a Field Communicator only.
• Rerange with a pressure input source and a Field Communicator.
• Rerange with a pressure input source and the local zero and span
buttons (option D1).
• Rerange with AMS only.
• Rerange with a pressure input source and AMS.
Sq. Root Curve
Slope=42
Reference Manual
00809-0100-4801, Rev FA
October 2010
Sq. Root
Curve
Transition Point
Linear Section