ABB 800xA Operation page 101

Section 8 Control Loop Asset Monitor (CLAM)
Sl.No Name
27. Shut-off Process
Value Index
28. Stiction Index 1
(Cross Correlation
Method)
29. Stiction Index 2
(Histogram
Method)
30. Valve travel per
hour
31. Valve reversals per
hour
3BUA000150-600
Table 9. Indices used in CLAM
Description
Index detecting valve leakage or zero
instrument errors. The index requires the
controller output to be zero for a significant
amount of time, since it is calculated based on
the flow when the output is set to zero. The
result is the average process value when during
CO=0% and should nominally be 0%.
When an oscillation is detected this index can
be used for Stiction detection for self-regulating
loops and non-compressible fluids. The index is
based on an analysis of the cross-correlation
between the control error and controller output.
The result is [-1,0,1] where -1 means that no
safe decision could be made, 0 means no
Stiction and 1 means that Stiction is detected.
Index for detecting Stiction based on a
histogram method that can be used for both
self-regulating and integrating loops. The result
is just like Stiction Index 1 [-1,0,1].
Index that quantifies the valve actuation effort
by measuring the distance travelled. [0...Inf]
A high value means that the valve has to work a
lot and that the controller is aggressively tuned.
Nominal: low value (depending on loop type).
Index counting the number of valve direction
changes during a data batch. The result is
[0...Inf], where a high value means that the
valve is moving around a lot and this might lead
to excessive mechanical wear. Nominal: low
value (depending on loop type).
Performance indices
Index class
Valve
Valve
Valve
Valve
Valve
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