Emerson Rosemount 3051S Series, Справочное руководство, Страница: 115 / 240

Reference Manual
00809-0100-4801, Rev FA
October 2010
7-11
Rosemount 3051S Series
Figure 7-9. Baseline
Configuration screen
Learn/Monitor Period:
This is the learning and monitoring time period that SPM diagnostic uses to
sample the pressure signal. The mean and standard deviation or coefficient of
variation values determined during the learning period will become the
Baseline values. Decreasing this period can speed up the set up time and is
recommended for stable process operations. Increasing this value will give a
better baseline value for noisier processes. If false trips for “High Variation
Detected” are occurring due to rapid changes in the process and statistical
value, increasing the learning period is recommended. The
Learning/Monitoring Period is always set in minutes. The default value is 3
minutes and the valid range is 1 to 60 minutes.
Figure 7-10 illustrates the effect of Learn/Monitor Period on the statistical
calculations. Notice how a shorter sampling window of 3 minutes captures
more variation (e.g. plot looks noisier) in the trend. With the longer sampling
window of 10 minutes, the trend looks smoother because SPM uses process
data sampled over a longer period of time.
Figure 7-10. Effect of
Learn/Monitor Period on
Statistical Values
3 min.
5 min.
10 min.