Emerson Rosemount 3051 Manual page 109

DIAGNOSTICS (ADB)
TRANSDUCER BLOCK
Plugged Impulse Line
Detection Overview
Statistical Process
Monitoring Overview
The diagnostics block (ADB) is a transducer block that contains two
different algorithms, Plugged Impulse Line Detection and Statistical
Process Monitoring. Learning, detection and configuration are the
three different phases to the Plugged Impulse Line and Statistical
Process Monitoring.
Plugged Impulse Line Detection is designed to be used in a continuous
liquid flow application that is controlled by a set point.
Learning Phase
In the learning phase, the algorithm establishes a baseline of the
process mean and process dynamics. The base line data is used to
compare current process data when determining a plugged impulse
line.
Detection Phase
The detection phase begins after a "Training Complete" message is
posed by the learning phase. To determine if the impulse lines are
plugged., the algorithm compares the baseline process variable mean to
the standard deviation.
Configuration Phase
The configuration phase is an inactive state and the user can determine
the affect on the PV status. Once the configuration is valid, the
message "Valid Configuration is posted and the configuration phase
stops. The configuration phase is also used to set up the parameters
controlling the sensitivity, thresholds, length of leading and detecting
phases.
Statistical Process Monitoring algorithm is intended to provide basic
information regarding the behavior of process measurement, PID
control block and actual valve position. This algorithm can perform
higher levels of diagnostics by distribution of computational power to
field devices. The two statistical parameters monitored by the
Statistical Process Monitoring is mean and standard deviation. By
using the mean and standard deviation, the process or control levels
and dynamics can be monitored for change over time. The algorithm
also provides:
• Configure limits/alarms for changes in mean and standard
deviation with respect to the learned levels
• High variation, low dynamics, and mean changes
• Necessary statistical information for Regulatory Control Loop
Diagnostics, Root Cause Diagnostics, and Operations Diagnostics
Learning Phase
In the learning phase of Statistical Process Monitoring, the algorithm
establishes a baseline of the mean and dynamics of a Statistical Process
Monitoring variable. The baseline data is compared to current data for
calculating any changes in mean or dynamics of the Statistical Process
Monitoring variables.
Block Information
C-15