ProMinent DULCOMETER diaLog DACb Assembly And Operating Instruction page 124

[Control]
Setting the
Eff. direction of the [Control], bidirectional or monodirectional
[control] based on various features.
You can vary the
Function: A bidirectional
ured value).
Application: Acidic or alkaline waste water is produced alternately in a neutralisation process in an
industrial waste water system. Before the water can be fed into the sewerage system, the pH value
must be set, for example, to a value between pH 6.8 and 7.5. A bidirectional controller with two
metering pumps for metering acid and alkali is used for this purpose. The pH value can be both
decreased or increased to come within the necessary setpoint range.
Negative
deviation
Positive
Control variable
Fig. 83: Control type PID bidirectional. Control characteristic without dead zone
124
[control] operates in two possible directions (increase AND decrease meas‐
Positive
deviation
Negative
Control variable
Setpoint
Time
Time
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