Davey Speedman Dual Pump Variable Speed Pump Control System - Manual (Page 52)

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SYSTEM TUNING
Response Rate
The Speedman has an on board PID controller that calculates the required VSD speed to maintain pressure
at Set Point. This calculation is based on the actual system pressure being read and the speed of any one
pump. Adjustment of the response of the system to varied flows can be made by using the “Response Rate”
(Proportional gain) menu item located in the TUNING menus.
FASTER 100% The scale for Response Rate is 0.1 – 100%.
SLOWER 0.1
Additional to this control there is the ability to dampen the response of the system by limiting the “Acceleration”
(located in the TUNING menu). This will limit the acceleration rate of the system. It is a BRAKING method
only.
Error Correction (Integral Time) and Overshoot Elimination (Derivative Gain) are both found in the TUNING
menu and can be used to further fine tune your system.
Error Correction
The Error Correction is the time it will take to convert a constant error of 1% to a 1% change on the output.
The error correction component is proportional to the tracking error and increases linearly with time. This is
useful when trying to close the gap on small errors near the set-point that cannot be eliminated through the
use of the response rate alone.
FASTER 0.1 sec The scale for Error Correction is OFF, 0.1 – 100 seconds.
SLOWER 100
Overshoot Elimination
The Overshoot Elimination is used to provide a damping effect to eliminate system oscillation and to minimize
overshoot.
MORE 50% The scale for Overshoot Elimination is OFF, 0.1 – 50%.
LESS 0.1
On start-up the Speedman will accelerate the pump at 100% to minimum frequency. From this point on the PID
will control the actual speed of reaction of the controller to the system.
In an attempt to give pump control users a better understanding of the PID control Davey has labelled
the relevant items accordingly.
Proportional Gain = Response Rate
Integral Time = Error Correction
Derivative Gain = Overshoot Elimination
PID CONTROL