Lauda Viscotemp 15 G, Operation Manual

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ECO Gold 09/2021
18.2 External control variable
The setting options illustrated in this section are only possible with a connected external temperature sensor or with an
existing module (as activated as control variable in Section 16.1) for reading in the actual temperature.
The control system for external actual values is realized as a two-stage cascade controller to improve the response to
setpoint changes. From the temperature setpoint and the external temperature, which is generally measured by the ex-
ternal Pt100, a "master controller" determines the "internal setpoint" which is passed to the slave controller. Its set value
controls the heating and cooling.
Correcting quantity limit
If a step change in set-point temperature is specified, the optimum control might set an outflow temperature which is
substantially higher than the temperature desired on the external vessel. With the correction limitation the maximum
permissible deviation between the temperature in the external consumer and the temperature of the outflow liquid can be
limited. The limit can be set via a menu point (

F.2.1).
These parameters can be set on the master controller (PIDT or external controller):
Description Short form Unit
Gain Kpe -
Proportional range Prop_E K
Reset time Tne s
Derivative time Tve s
Damping time Tde s
These parameters can be set on the slave controller (P-controller):
Description Short form Unit
Proportional range Xpf K
If "Tv manual/auto" is set to "automatic", Tve, Tde and Prop_E cannot be changed. Tve and Tde are in this case derived
from Tne with fixed factors.