Additive And Multiplicative Feed Forward Control - ProMinent DULCOMETER diaLog DACb Assembly And Operating Instructions Manual

13.10.1

Additive and multiplicative feed forward control

Alongside information relating to the actual measured variable, e.g.
the chlorine concentration, the interference variable is a further
source of information for the controller that makes it easier for the
controller to provide stable control during flow processes. During
flow processes, both the above parameters change frequently
within wide ranges. If one parameter variable is not known, then it
is impossible to achieve stable control of the other parameter vari‐
able. If processing of an interference variable is enabled, then the
processing of the interference variable is signalled on the control‐
ler's continuous display under
[NAME OF INTERFERENCE VARIABLE] and [UNIT] with the letter
[ Q] . Depending on the configuration, an interference variable can
be effective for one or both measuring channels
The signal source of the interference variable can be supplied to
the controller via an analogue signal or a pulse frequency from a
flow meter.
The following options are available in the basic version of the con‐
troller with measured variables VA and AA:
Pulse frequency interference variable,
n
mA interference variable,
n
pH compensation for chlorine.
n
If both channels of the VA or AA module are used for measured
variables, then you will need equipment package 4 to process the
interference variable as an analogue signal.
A pulse frequency signal can be connected to digital input 2 and an
analogue signal, depending on the identity code, to mA input 2 or
3.
With equipment package 4, the multiplicative interference variable
can act on channel 1 and channel 2.
An additive interference variable can only act on channel 1 or 2.
e.g. Identity code: ...VA0
mV input, channel 1: pH measurement
n
mA input, channel 2: chlorine measurement
n
Correction functions included:
n
– pH compensation for chlorine
– Temperature for pH
e.g. Identity code: ...VA0
mV input, channel 1: pH measurement
n
mA input, channel 2: mA interference variable
n
Correction functions included:
n
– Flow interference variable for channel 1
– Temperature for pH
e.g. Identity code: ...AA0
mA input, channel 1: chlorine measurement
n
mA input, channel 2: mA interference variable
n
Correction functions included:
n
– Flow interference variable for channel 1
e.g. Identity code: ...VA4
mV input, channel 1: pH measurement
n
mA input, channel 2: chlorine measurement
n
[Control]
Setting the
125