ProMinent DULCOMETER - Page 173

The temperature offset
The setting ‘Temperature offset’ makes it
possible to match the measured tempera‐
ture to a reference value. An offset of
-10.0 ... +10.0 °C is possible.
Additive basic load
The additive basic load should balance
out a continuous requirement for a chem‐
ical in order to maintain the setpoint. The
additive basic load can be set in the range
-100 % … +100 %. The additive basic
load is added to the control variable deter‐
mined by the controller and is effective in
both control directions. E.g., if the control
variable calculated by the controller
n y= -10 % and the additive basic load
equals +3 %, then the resulting con‐
trol variable = Y= -10 % + (+3 %)= -7
%
n y= 10% and the additive basic load
equals +3 %, the resulting control var‐
iable = Y= 10 % + (+3 %)= 13 %
n y= 0 % and the additive basic load
equals +3 %, the resulting control var‐
iable = Y= 0 % + (+3 %)= 3 %
Control time control
The checkout time should prevent over‐
dosing as a result of a malfunction. During
the checkout time the control variable is
compared with an adjustable
[threshold]
(= control variable threshold). Depending
on the control direction, you can set dif‐
ferent values for the checkout times
[Checkout time up] to increase and
[Checkout time down] to decrease the
value. The checkout times depend on the
concentration of the metered chemicals. If
the
[threshold] is exceeded, time
recording starts (checkout time). If during
the checkout time the variable again falls
below the threshold, then the time is again
reset to
[0] s.
However if the disturbance variable
remains above the threshold for longer
than the checkout time, then the reaction
of the controller can be selected
[Checkout time reset] = [Normal] this
selection stops the control immediately.
To enable restarting, an operator must
acknowledge the fault once the cause of
the fault has been cleared.
[Checkout time reset] = [Auto] this selec‐
tion automatically resets the function, if
the threshold is again undershot and the
control restarts automatically.
Dead zone
The dead zone is defined by an upper and
lower setpoint. The dead zone only func‐
tions with a 2-way control and only if an
actuator is available for each direction.
The dead zone should have the effect of
preventing the control path from starting to
oscillate. If the measured value lies within
both the setpoints, then no control of the
actuators takes place even with a PI / PID
controller. Application 2-way neutralisa‐
tion.
Controller type
n P mono-directional
n P bidirectional
n PID mono-directional
n PID bidirectional
n Manual
n Off
Glossary
173