Burkert Type 8620 - Manual (Page 116)

mxCONTROL Type 8620
Page 116
PV
Proportional
Controller
Output CMD
SP
Module - sense of action: normal
Deadband
PV SP
Module - sense of action: inverted
Deadband
Proportional
Controller
Output CMD
Figure 53:
sense of action and
deadband
Example:
If additional dosing of acids is desired, the "normal" sense of action is set,
If additional dosing of bases is desired, the "inverse" sense of action is set.
Output Override
The output of this module is influenced at certain states (see Figure 54).
Figure 54: Output override (PH_ACID_OR_CAUS)
Acid Stop Limit – Pump Stop (ASL PumpStop)
The pH control module can be connected internally by means of configuration with a corrosion display
for an additional failsafe function. Therefore the ASL-Alarm of the assigned Function (configured as
corrosion display) is evaluated in order to prevent overdosing of acids or bases.
If the corrosion rate of the connected corrosion display exceeds the ASL alarm, this alarm becomes
active. As long as the ASL alarm remains active, the controller output is overridden with "0%", i.e.
disabled and the acid or base dosing pump is thereby also shut off for this period.
Maximum Output Timer (MOT)
This function monitors the controller output of the pH controller in automatic mode in order to detect
the faulty output.
If the controller output emits the maximum control output longer than the defined maximum control
output time (MOT), then the controller output will be overridden with "0 %".
In this case an alarm “Out fails” is generated and the common alarm relay is actuated, too.