External Control Variable - Lauda E 4 G Operating Instructions Manual

F.2

External control variable

The setting options illustrated in this section are only possible with a connected external temperature sen-
sor or with an existing module (as activated as control variable in Section D.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 gen-
erally measured by the external 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 tempera-
ture 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 (
These parameters can be set on the master controller (PIDT or external controller):
These parameters can be set on the slave controller (P-controller):
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.
100
Description
Gain
Proportional range
Reset time
Derivative time
Damping time
Description
Proportional range
Appendix with settings
Short form Unit
Kpe
-
Prop_E K
Tne
s
Tve
s
Tde s
Short form Unit
Xpf K
ECO GOLD
F.2.1).
25/08/2011/ YACE0088