Technical Manual
–
Central Operation Unit Smart
MDT technologies GmbH •
51766 Engelskirchen • Papiermühle 1
Phone: +49-2263-
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4.8.3.4 Direction of controller
The direction of controller describes the response of the control value to a change in the system
deviation as the temperature rises. The control value can exhibit normal control response to a rising
temperature or inverted control response. The direction of action is available for all settings of the
control value (PI control; PWM; 2-point).
In PWM and 2-point control, an inverted control value is used for adaptation to valves that are open
when no current is applied.
For the individual controllers, an inverted correcting variable, here in the example for controller type
heating, means:
•
PI-Controller
The control value decreases with increasing system deviation and increases with decreasing
system deviation.
•
PWM- Controller
The ratio of the duty cycle to the total PWM cycle increases with rising temperature and
decreases with falling temperature.
•
2-Point Controller
The controller switches itself on at the actual switch-off point and off at the actual switch-on
point.
