Chemtrac HydroAct HA4, Руководство пользователя

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4. Controls
4.1 PID Control
4.1.1 General Information
4.1.1.1 Theory of Operation
The PID control calculates an error value as the difference between a desired setpoint and a measured
sensor input, called the process variable. The control then calculates an output using this error value
based on proportional, integral and derivative terms. The output of these terms is combined to give a
final output.
Figure 4.1: PID Calculation
The PID implementation of the HydroAct 4 is very flexible and can be configured as any permutation
of P, I and D. This allows P, I, PI, PD or PID controllers to be implemented using the same interface.
The optimal control response for any application requires the correct selection of control components.
Some examples are given below.
P Controller
A simple linear control algorithm ideally suited to recirculating systems with small
deviations such as those found in pools and spas. Major deviations may result in an overshoot