15.DISCHARGE CONTROL
15.2.5 Integral Action:
In some systems the control of fans with only proportional action (Setpoint and hysteresis) tends to present an error in steady state (not reaching the
setpoint) or to show oscillatory behavior (excessive pressure variation around the setpoint and high number of fan activations).
In theses cases, the use of integral action together with proportional control has the objective of keeping the control pressure stable, converging to
values close to the setpoint.
The integral action can be used in all control modes, including those that operate only on the ON I OFF outputs. To activate the integral action, simply set
a value other than Off outputs. To activate the integral action, simply set a value other than Off in the parameter Integral time (1.3.x.39).
The higher the configured value, the slower and more stable the system’s behavior.
The lower the configured value, the faster and more oscillatory the behavior is.
Hysteresis
Setpoint
Time
Suction pressure
Hysteresis
Setpoint
Time
Discharge pressure
Proportional + Integral Control
Proportional-only control
Hysteresis
Setpoint
Discharge pressure
Time
Note: Integral effect reduced the oscillation and brought the
system closer to the setpoint.
Note: The definition of this parameter depends on the capacity of the system and the response speed of its pressure fluctuations.
It is suggested to start the tests to define these parameters using the value of 350 seconds.
30
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