ABB COMMANDER 351 - Page 28

26
…2 OPERATOR LEVEL
2.9.2 Using the Control Efficiency Monitor
Press and hold the and keys for 2 seconds.
Note.
If the front panel keys are not operated for 60 seconds whilst
any Control Efficiency Monitor frame is being displayed, the
instrument reverts to the first operating frame.
Rate of Approach to Set Point
The rate of change of the process variable between 5 and 95%
of the step change (Y
2
), measured in engineering units per
minute.
Rate of approach =
Y1
t
approach
Overshoot
The maximum error, expressed as a percentage of the set
point.
Overshoot =
X 1
Set Point
x100
Decay Ratio
The ratio of the amplitude of the first and second overshoots.
Ratio =
X 2
X 1
Period
The time (in seconds) between the first two peaks (t
period
).
Settling Time
The time taken (in minutes) for the process variable to settle
within ±2% of the set point value (t
settle
).
Error Integral
The integral of the error value until the process variable settles
to within ±2% of the set point value in 'engineering-unit hours'.
Error integral =
|
PV – SP
| dt
0
t
settle
Return to the first operating frame.
+
10.1
rAtE
10
OVEr
0.25
rAtO
35
Prd
0.3
SEtL
2.1
IAE
351.5
350.0
350.0
351.5
70