Process Unit 73 LF - Knick

Process Unit 73 LF
Controller Function
You can only make use of the controller function if
your unit is equipped with option 353 for the digital
controller or options 350 and 483 for the analog
controller (output 2).
Without this option, the Parameter Setting menu
will only read “Limits” instead of “Limits / Controller”
and “Output Current 2” or “Output Current 2
(Optional)” instead of “Output 2 / Controller” for the
analog controller.
Digital Controller
The parameters of the digital controller are set
with the “Limit Values / Controller” menu item.
The bidirectional PI controller enables quasi-continuous
(switched) control.
Two controller types can be selected:
Type A: Pulse length controller (see Pg. 9–37)
Type B: Pulse frequency controller (see
Pg. 9–37)
Analog Controller
The parameters of the analog controller are set
with the “Output 2 / Controller” menu item.
Three controller types can be selected:
Type A: 3-way mixing valve (see Pg. 9–38)
Type B: Straightway valve (< setpoint) (see
Pg. 9–39)
Type C: Straightway valve ( > setpoint) (see
Pg. 9–40)
Controlled Variables
You can define as controlled variables:
conductivity value
resistivity
measured temperature value (C)
Since the relationship between conductivity and
concentration is strongly nonlinear and partially
ambiguous, concentration cannot be selected as
controlled variable.
9–32 Capabilities