ABB ControlMaster CM10 User Manual page 35

ControlMaster CM10, CM30 and CM50
Universal process controllers,
...Basic / ...Loop 1 Mot Valve
Calculation for Control Pulses (Boundless Control)
The following calculations are for guidance when setting Deadband, proportional and integral values.
The Deadband on the ControlMaster is set in engineering units, but in order to be applied to the calculations it must be set
as a %, this can be calculated in the following way:
Minimum 'ON' time of integral action pulses (for a fixed control deviation)
Minimum (approximate) time between integral action pulses (for a fixed control deviation)
Duration of the proportional step
% Control Deviation
Ratio*
Bias*
*Applicable only for motorized valve with feedback only – see page
IM/CM/S–EN Rev. R
1 1 1
/ , / and / DIN
8 4 2
% Deadband = Deadband (eng units) x 100
Eng Hi - Eng Lo
= Travel Time x Deadband% (in seconds)
% Proportional Band
= Integral Action Time x Deadband% (in seconds)
2 x Control Deviation
= 2 x (% Control Deviation) x Travel Time in seconds
(% Proportional Band)
= Setpoint - Process Variable x 100%
Eng Hi - Eng Lo
The required valve position = (Ratio x PID O/P) + Bias.
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6 Basic Level
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