27
Manual Supplement
00809-0200-4853, Rev AB
Rosemount 3051S Series Pressure Transmitter
November 2017
Rosemount 3051S Series Pressure Transmitter
4. Steady process verification
At the end of the verification phase, the PIL compares the last mean and standard deviation against the
previous mean and standard deviation to determine if the process is at a steady state. If the process is at
a steady-state, then the PIL moves into detection phase. If not, then PIL repeats the verification phase.
5. Establish baseline
At the end of the verification phase, if the process has been determined to be at a steady state, the last
mean and standard deviation are taken to be the “Baseline” values, representative of the normal process
operating condition.
6. Detection phase
During the detection phase, the PIL collects pressure data for one minute and computes the mean and
the standard deviation.
Note
The length of this detection period is user-adjustable, with one minute as the default value.
7. Relearn required
Automatic relearning only applies if “Auto Relearn” is enabled with a relearn threshold configured. At the
end of the detection phase, PIL first compares the current mean with the baseline mean. If the two differ
significantly, then the PIL goes back into the learning phase, because the process conditions have
changed too much for a reliable detection of a plugged impulse line.
8. Compare standard deviations
If no relearn is required, the PIL compares the current standard deviation against the baseline standard
deviation to determine if a plugged impulse line is detected. For all sensor types, the PIL checks if the
standard deviation has decreased below a lower limit. For DP sensors, the PIL also checks if the standard
deviation has increased above an upper limit. If either of these limits is exceeded, the status changes to
“Plugged Impulse Line” and the PIL stops, and will not resume again until a “Relearn” command is given.
If a plugged impulse line is not detected, the status is “OK” and the detection phase is repeated.
6.19 Configuration of PIL detection
This section describes the configuration of the Plugged Impulse Line diagnostic.
6.20 Basic configuration
For some plugged impulse line applications there will be a very significant (> 80%) decrease in standard
deviation. Examples of this would include a plug in the impulse line of a GP/AP measurement in a noisy
process, or a plug in both impulse lines of a DP measurement. In these applications, configuring plugged
impulse line detection requires nothing more than turning it on. To do this, set:
PLINE_ON = Enabled
Once the PIL is enabled, it will automatically start the learning process, and move to the detection phase
if there is sufficient variation and the process is stable.
Optionally, if, when a plugged impulse line is detected, you want to automatically have the status quality
of the pressure measurement go to “Uncertain”, set the parameter:
PLINE_AFFECT_PV_STATUS = Yes
To Next Page
Loading...
