Burkert Type 8620 - Manual (Page 115)

mxCONTROL Type 8620
Page 115
14.5.2 pH Control (PH_ ACID_OR_CAUS)
This module permits a pH-Control with Acids or Bases and with the optional interface to the
"Corrosion Display" module for additional overdosing failsafe function.
Set Point (SP)
Process
value (PV)
4..20mA-Input
Corrosion
Display
Optional link for
Several Events
PH_ACID_OR_CAUS
PI –
Controller
Output Override
Module
Output
CMD
SP Limit
SP Ramp
Acid Stop functionality
(As long as the Acid Stop Alarm in the
Corrosion Display is active, the pump will be
stopped - in Automatic and Manual Mode)
These
modules
are
explained
below.
Figure 52:
(PH_ACID_
OR_CAUS)
Set value limiter (SP Limit)
Please refer to the description on section "Set value limiter (SP Limit)" in chapter 14.5.1
Ramp function for set point setting (SP Ramp)
Please refer to the description on section "Ramp for Set point adjustment" in chapter 14.5.1
PI Controller
The description of the Proportional Integral (PI)-Controller is consistent to the PI-part of the PID
Controller in section “PID Controller” in chapter 14.2. Specifics / differences are described below.
Proportional part / Module sense of action:
The normal module sense of action is defined:
Proportional part: Yp[%] ) ( PV SP Kp
− ∗ − =
It can be illustrated as shown in the following figure: