26
Manual Supplement
00809-0200-4853, Rev AB
Rosemount 3051S Series Pressure Transmitter
November 2017
Rosemount 3051S Series Pressure Transmitter
Figure 20. Plugged Impulse Line Diagnostics Flow
Figure 20 on page 26 shows a flow chart of the PIL algorithm. Note this diagram shows the sequence of
PIL steps using the default configuration settings. The specific steps that PIL goes through are as follows:
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”.
2. Sufficient variation
During the Learning and the Verify modes, the PIL checks that the noise level (e.g. the standard deviation)
is high enough for reliable detection of plugged impulse lines. If the noise level is too low, the status goes
to “Insufficient Dynamics”, and the PIL stops. PIL will not resume learning again until a “Relearn”
command is given.
3. Verification phase
PIL collects the pressure values for an additional five minutes (or same length as learning period) and
computes a second mean and standard deviation. During this phase, the PIL status is “Verifying”.
Status = Learning
Compute Mean and
Std Dev over X
minutes
Sufficient
Variation?
Status = Verifying
Compute Mean and
Std Dev over next X
minutes
Start (Relearn)
No
Yes
Learning/Verification
Phases
ĞƚĞĐƚŝŽŶPhase
Sufficient
Variation?
No
Yes
Steady
Process?
No
Yes
Establish Baseline
Status = OK
Compute Mean and
Std Dev over Y
minutes
Relearn
Required?
No
Yes
Compare Std Dev to
High and Low Limits
Std Dev Change
Exceeds Limit?
No
Yes
Stop
Status =
Plugged
Impulse Line
Status =
Insufficient
Dynamics
X = Learning Cycle
Y = Detecting Cycle
To Next Page
Loading...
