Emerson 3051S Specifikace stáhnout pdf (Strana 82)

Reference Manual

00809-0200-4801, Rev CA

July 2010

Rosemount 3051S

6-4

SPM Functionality A block diagram of the Statistical Process Monitoring (SPM) diagnostic is

shown in Figure 6-3. Note from Figure 6-1 that the 3051S FF has four

Statistical Process Monitoring blocks (SPM1-SPM4). Figure 6-3 illustrates just

one of the SPM blocks. The process variable (which could be either the

measured pressure or some other variable from the fieldbus segment) is input

to a Statistical Calculations Module where basic high pass filtering is

performed on the pressure signal. The mean (or average) is calculated on the

unfiltered pressure signal, the standard deviation calculated from the filtered

pressure signal. These statistical values are available via handheld

communication devices like the 375 Field Communicator or asset

management software like Emerson Process Management’s AMS

™

Device

Manager, or distributed control systems with Foundation fieldbus, such as

DeltaV.

Figure 6-3. Diagram of 3051S

FF Statistical Process

Monitoring

SPM also contains a learning module that establishes the baseline values for

the process. Baseline values are established under user control at conditions

considered normal for the process and installation. These baseline values are

made available to a decision module that compares the baseline values to the

most current values of the mean and standard deviation. Based on sensitivity

settings and actions selected by the user via the control input, the diagnostic

generates a device alert when a significant change is detected in either mean

or standard deviation.

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Emerson 3051S Specifikace Strana 82