wtw TresCon UNO A111, Operating Manual

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Operation TresCon UNO
5 - 32 ba43134e08 05/2017
Frequency controller Switching frequency control is used, e.g. for controlling dosing pumps.
In contrast to the pulse-width controller, the frequency controller is not
modulated by the pulse width, but by the switching frequency of the out-
put signal. Depending on the position of the measured value in the pro-
portional range, the relay is switched more often or less often.
Fig. 5-8 Relay output of the frequency controller
While the selected switching duration (t
on
= 0.3 s) always remains con-
stant, the switching frequency at which the relay switches changes de-
pending on the measured value.

If the measured value is at the end of the proportional range ( End
value ), the switching frequency is higher.

If the measured value is at the beginning of the proportional range
(
Start value ), the switching frequency is low.
Time [s]
t = 0.3 s
On
Relay
Off
On
T