Emerson Rosemount 3051S Series Reference Manual page 85

Reference Manual
00809-0200-4801, Rev DA
appropriate. The allowable range is 1 to 1440 minutes (for software revisions 2.0.x or earlier, the
minimum SPM Monitoring Cycle is 5 minutes).
Figure 6-5
with a shorter sampling window there is more variation (e.g. the plot looks noisier) in the trend. With the
longer sampling window the trend looks smoother because the SPM uses process data averaged over a
longer period of time.
Figure 6-5. SPM Monitoring Cycle Effect on Statistical Values
SPM#_User_Command
Select Learn after all parameters have been configured to begin the Learning Phase. The monitoring
phase will start automatically after the learning process is complete. Select Quit to stop the SPM.
"Detect" may be selected to return to the monitoring phase.
SPM_Active
The SPM_Active parameter starts the Statistical Process Monitoring when "Enabled". "Disabled"
(default) turns the diagnostic monitoring off. Must be set to "Disabled" for configuration. Only set to
"Enabled" after fully configuring the SPM. When Enabling SPM, you may select one of two options:
Enabled with 1st-order HP filter
Applies a high-pass filter to the pressure measurement prior to calculating standard deviation. This
removes the effect of slow or gradual process changes from the standard deviation calculation while
preserving the higher-frequency process fluctuations. Using the high-pass filter reduces the likelihood of
generating a false detection if there is a normal process or setpoint change. For most diagnostics
applications, you will want to use the filter.
Enabled w/o filter
This enables SPM without applying the high-pass filter. Without the filter, changes in the mean of the
process variable will cause an increase in the standard deviation. Use this option only if there are very
slow process changes (e.g. an oscillation with a long period), which you wish to monitor using the
standard deviation.
Advanced Pressure Diagnostics
illustrates the effect of the SPM Monitoring Cycle on the Statistical Calculations. Notice how
Advanced Pressure Diagnostics
October 2016
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