Pil Functionality - Emerson Rosemount 3051S Series Reference Manual

Reference Manual
00809-0200-4801, Rev DA
6.4.4

PIL functionality

The Advanced Diagnostics Suite provides the PIL diagnostic, as an easy way to apply SPM technology
specifically for detecting plugging in pressure measurement impulse lines. Similar to SPM, PIL also
calculates the mean and standard deviation of the pressure measurement and generates an alert when
the standard deviation exceeds an upper or lower limit.
Figure 6-19
the diagram for SPM shown in
The pressure measurement is fixed as the input

Statistical values (mean and standard deviation) are not available as outputs

The PlantWeb alert generated specifically indicates "Plugged Impulse Line Detected"

Figure 6-19. Overview of Plugged Impulse Line Diagnostics
PIL also includes some additional features to make it especially suitable for detecting plugging in
pressure measurement impulse lines. PIL has the ability to:
Automatically relearn new baseline values if the pressure measurement changes significantly

Set the status quality of the pressure measurement to "Uncertain" if a plugged impulse line is detected

Check for a minimum process dynamics during the learning process

Adjust the verification settings

Set separate learning and detection periods

Figure 6-20
steps using the default configuration settings. Information for adjusting these settings is found in
"Configuration of PIL detection" on page
1. Learning phase
PIL begins the learning process when the PIL is Enabled, when the User Command is set to "Relearn", or
when a mean change is detected during the Detection Phase. PIL collects the pressure values for five
minutes and computes the mean and the standard deviation.
Note
The length of the learning period is user-adjustable, with five minutes as the default value. During the
learning phase, the status is "Learning".
Advanced Pressure Diagnostics
illustrates a block diagram of the plugged impulse line diagnostic. Notice it is very similar to
Figure
shows a flow chart of the PIL algorithm. Note that this diagram shows the sequence of PIL
6-3. However, there are a couple of notable differences with PIL:
91. The specific steps that PIL goes through are as follows:
Advanced Pressure Diagnostics
October 2016
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