A gain of .3 means that the output moves 0.3 p.u. when a 1 p.u. step difference between setpoint and actual is applied to the input. AKA 3.33 proportional band.
A 1 minute integral means that it takes 1 minute for the output to change linearly with 1 p.u. when same step is applied to input.
These definitions do not take saturation into account. If controller saturates, then work with smaller signals, 0.1 input for instance, and do not forget to scale down expected outputs.
Maypot
A simple search of Eng-tips may get you a better explanation.
In a PID controller
P = Proportional gain. This is the factor by which the error is multiplied in the loop algorithm to produce the error correction term.
Increasing this value increases your transient speed response meaning "how fast do you want the response to a disturbance?" If u take it too far the drive will become unstable.
I = Integral gain This factor sums all of the small errors that can accumulate over time. This insures actually reaching zero during steady state load conditions. With out the integral the controller may reach a point where it is happy but still not quite at SP. Increasing this value results in a faster recovery from a disturbance while exactly reaching SP, but if taken too high, can cause oscillatory conditions.
D = derivative. The derivative term will take into account the rate of change of the error signal. So if there is a large change in error, you will see a large change in output. As the PV gets close to the setpoint, the error will get smaller and the output will start to anticipate reaching SP and start cutting back earlier than it would have using only PI control. This will help reduce any overshoot of your controlled output.
Hope this helped
Life is what happens while we're making other plans.
