Emerson Rosemount 3051CF Series Reference Manual page 123

Reference Manual
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SPM also contains a learning module that establishes the baseline values for the process.
The learning module establishes baseline values under user control at conditions
considered normal for the process and installation. The learning module makes these
baseline values available to a decision module, which compares the baseline values to the
most current values of the mean and standard deviation. Based on sensitivity settings and
actions you select via the control input, the diagnostic generates a device alert when it
detects a significant change in either mean or standard deviation.
Figure 7-4: Rosemount 3051 FF SPM
Further detail of the operation of the SPM diagnostic is shown in the
This is a simplified version showing operation using the default values. After configuration,
SPM calculates mean and standard deviation, used in both the learning and the
monitoring modes. Once enabled, SPM enters the learning/verification mode. SPM
calculates the baseline mean and standard deviation over a period of time you control
(SPM Monitoring Cycle; default is 15 minutes). The status will be Learning . SPm
calculates a second set of values and compares them to the original set to verify that the
measured process is stable and repeatable. During this period, the status will change to
Verifying
values and move to Monitoring status. If the process is unstable, the diagnostic will
continue to verify until stability is achieved.
In the Monitoring mode, SPM continuously calculates new mean and standard deviation
values, with new values available every few seconds. SPM compares the mean value to the
baseline mean value and the standard deviation to the baseline standard deviation value. If
either the mean or the standard deviation has changed more than user-defined sensitivity
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. If the process is stable, the diagnostic will use the last set of values as baseline
Advanced pressure diagnostics
July 2020
Figure 7-4 flowchart.
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