Emerson Rosemount 3051S Series Reference Manual page 115

Reference Manual
00809-0100-4801, Rev HA
Figure 7-3. CV is the Ratio of Standard Deviation to Mean
CV is stable if Mean is proportional to Standard Deviation.
This statistical information can be provided to the user in two ways. First, the statistical parameters can
be made available to the host system directly via HART communication protocol or HART to other
protocol converters. Once available, the system can make use of these statistical parameters to indicate
or detect a change in process conditions. In the simplest example, the statistical values may be stored in
a data historian. If a process upset or equipment problem occurs, these values can be examined to
determine if changes in the values foreshadowed or indicated the process upset. The statistical values
can then be made available to the operator directly, or made available to alarm or alert software.
The second way is with software embedded in the Rosemount 3051S with Advanced HART Diagnostic
Suite. The Rosemount 3051S with Advanced HART Diagnostic Suite uses Process Intelligence or Plugged
Impulse Line diagnostics to baseline the process noise or signature via a learning process. Once the
learning process is completed, the user can set thresholds for any of the statistical parameters. The
device itself can then detect significant changes in the noise or variation, and communicate an alarm via
the 4–20 mA output and/or alert via HART Protocol.
Typical applications for the Process Intelligence diagnostic include detecting abnormal process
conditions, such as:
Furnace flame instability

Pump cavitation

Distillation column flooding

Fluid composition change

Entrained air

Agitation loss

Advanced HART Diagnostic Suite
Advanced HART Diagnostic Suite
Mean
Standard
Deviation
Coefficient of
Variation
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