A significant problem with integral action is that when the error signal is large for a significant period of time. This can occur every time when there is large change in set point. If there is a sudden large change in set point, the error will be large and the integrator output in a P-I-D control will build up with time. As a result, the controller output may exceed the saturation limit of the actuator. This windup, unless prevented may cause continuous oscillation of the process that is not desirable.
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