Operation Manual

Continuous valve actuator CHEOPS control
theben
As of: Jul-11 (Subject to change without notice) Page 62 of 71
P-control as temperature control
The P-control behaves during heating control as shown in the previous example.
The set point temperature (21
o
C) can never quite be reached.
The permanent control deviation increases as the heat loss increases and as the ambient
temperature decreases.
5.9.3 Response of the PI-control
Unlike the pure P-control, the PI-control works dynamically.
With this type of control, the actuating value will not remain unchanged, even at constant
deviation.
In the first instant, the PI-control sends the same actuating value as the P-control, although the
longer the set point value is not reached, the more this value increases.
This increases is time-controlled over the integration time.
With this calculation method, the actuating value does not change if the set point value and
the actual value are the same.
Our example, therefore, shows equivalent in and outflow.
Notes on temperature control:
Effective control depends on agreement of bandwidth and integration time with the room to
be heated.
The bandwidth influences the increment of the actuating value change:
Large bandwidth = finer increment on actuating value change.
The integration time influences the response time to temperature changes:
Long integration time = slow response.
Poor agreement can result in either the set point value being exceeded (overshoot) or the
control taking too long to reach the set point value.
Usually, the best results are achieved with the standard settings or the settings via system
type.
Standard settings:
Control by system type