ABB COMMANDER 351 - Control Efficiency Monitor

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…2 OPERATOR LEVEL
2.9 Control Efficiency Monitor
The Control Efficiency Monitor can be used either to compare the relative performance with different
tuning parameters, or when fine tuning the PID settings, to give optimum control.
When the set point is changed, auto mode is selected or following a power failure, input failure or a
large load disturbance, the control monitor performs a series of measurements to indicate the
effectiveness of the current control parameters.
General guidelines are shown in Table 2.2.
Action
• Decrease proportional band
• Decrease integral time
• Increase derivative time
• Increase proportional band
• Increase derivative time
• Increase proportional band
• Increase integral time
• Increase proportional band
• Decrease integral time
If large overshoot and
oscillatory then:
• Increase proportional band
• Increase integral time
• Increase derivative time
If slow approach and
overdamped then:
• Decrease proportional band
• Decrease integral time
Ideal
Setting
Fast
Small
Small
Short
Small
Parameter
Rate of
Approach
Overshoot
Decay Ratio
Settling Time
Error Integral
Actual
Setting
Too slow
Too large
Too large
(Oscill-
atory)
Too long
Too large
Effect on Response
Table 2.2 Control Efficiency Monitor Settings