Advanced Pil Configuration - Emerson Rosemount 3051S Series Reference Manual

Reference Manual
00809-0200-4801, Rev DA
A good "rule of thumb" is to set the detection limit to half of the observed change in standard deviation,
but no less than 20 percent.
6.5.4

Advanced PIL configuration

PIL provides the ability for advanced users to fine-tune some of the algorithm settings.
PLINE_Relearn_Threshold
This adjusts the limit at which the PIL will automatically relearn new baseline values if the process mean
changes. By default, this threshold is:
Two inches of water for DP Range 1 (-25 to 25 inH

Five inches of water for DP Range 2 (-250 to 250 inH

1 percent of Primary Value Range for all other sensors

When PLINE_Relearn_Threshold is at 0 (default) the above values are used for the relearn threshold.
When a positive number is entered here, this value (in % of Primary Value range) overrides the default
relearn threshold values. For example, if the sensor is type DP Range 3 (-1000 to 1000 inH
PLINE_Relearn_Threshold is set to 2%, then PIL will relearn if the mean changes by more than 20 inH
Note
In software revisions 2.0.x and previous, the Relearn Thresholds for DP Range 1 and DP Range 2 are fixed
at the above default values. The PLINE_Relearn_Threshold parameter affects the Relearn Threshold for
only the other sensors. In software revisions 2.1.x and later, the PLINE_Relearn_Threshold affects the
Relearn threshold for all sensor types.
PLINE_Auto_Relearn
This can be used to turn off the automatic relearning. If set to "Disabled", the PIL will not go back into
learning mode, even if there is a large mean change. In most cases, this parameter should be kept at
"Enabled" because without this check, a large change in a flow rate could also cause a change in the
standard deviation, triggering a false detection.
PLINE_Learn_Length
The length of time over which mean and standard deviation are calculated during the learning and
verification phases. Default is five minutes. Allowable range is 1-45 minutes. If the process has a periodic
change in the mean over time (e.g. a slow oscillation), a longer learning cycle may provide a better
baseline.
PLINE_Detect_Length
The length of time over which mean and standard deviation are calculated during the detection phase.
Default is one minute. Allowable range is 1-45 minutes. This value should not be longer than the PLINE
learning cycle. A shorter value will in general allow a plugged impulse line to be detected more quickly.
However, if the process has a dominant cycling or oscillation, this parameter should be set to longer than
the period of oscillation.
Advanced Pressure Diagnostics
Advanced Pressure Diagnostics
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