Reference Manual
00809-0100-4801, Rev FA
October 2010
Rosemount 3051S Series
3-24
DP Flow Example
A differential transmitter is used in conjunction with an orifice plate in a
flow application where the differential pressure at full scale flow is 125
inH2O. In this particular application, the flow rate at full scale flow is
20,000 gallons of water per hour. It is highly recommended to use the low
flow cutoff function in order to have a stable output and avoid problems
due to process noise at a low flow or no flow condition. A low flow cutoff
value that is practical for the flow element in the application should be
entered. In this particular example, the low flow cutoff value is 1000
gallons of water per hour. Based on this information, the Scaled Variable
configuration would be as follows:
NOTE
Pressure value position 1 and Scaled Variable position 1 are always set to
zero for a flow application. No configuration of these values is required.
Re-mapping The re-mapping function allows the transmitter primary, secondary, and
tertiary variables to be configured as desired. Default configuration for
transmitter variables is as shown below:
Primary variable (PV) = Pressure
Secondary variable (SV) = Temperature
Tertiary variable (TV) = Scaled Variable
NOTE
Variable assigned as the primary variable drives the 4-20 mA analog output.
The scaled variable can be remapped as the primary variable if desired.
Field Communicator v3.3
From the HOME screen, enter the fast key sequence “Re-mapping.”
1. Select OK after the control loop is set to manual (see “Setting the Loop
to Manual” on page 3-2).
2. Choose desired primary variable and select Enter.
3. Choose desired secondary variable and select Enter.
4. Select OK to acknowledge the tertiary variable setting.
5. Select OK to acknowledge that the loop can be returned to automatic
control.
Scaled Variable units: gal/h
Scaled data options: square root
Pressure value position 2: 125 inH2O (311 mbar)
Scaled Variable position 2: 20,000 gal/h (75,708 lt/hr)
Low Flow Cutoff: 1000 gal/h (ON)
Traditional Fast Keys
1, 4, 3, 6
Device Dashboard
Fast Keys
2, 2, 4, 1
(182 Seiten)
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