Evoqua WALLACE & TIERNAN MFC, Инструкция по эксплуатации

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94
WT.050.580.000.DE.IM.0714
Functions
MFC
4.
Dosing contact
for OSEC-A
A special controller is required for controlling electrolyte devices,
which prevents excessive activation/deactivation (caused by
electrolyte device response times).
This controller output, therefore, uses a minimum duty cycle as
well as a switching hysteresis to minimise the switching cycles.
If the value falls below the specified Cl
2
setpoint minus hysteresis
(e.g. setpoint 0.50mg/l - hysteresis 0.05 = 0.45mg/l), the controller
output switches on.
The controller output remains active for at least the set minimum
duty cycle. If the setpoint is exceeded and the minimum duty cycle
has expired, the contact switches off.
The minimum duty cycle is ignored in manual mode.
Controller with mA output The MFC has up to four analog mA outputs. These can be
assigned individually as registration or controller outputs.
If module 1 dosing "analog output 2p" or "analog output 3p" is
selected, the mA output 1 is permanently assigned.
If module 2 dosing "analog output 2p" or "analog output 3p" is
selected, the output 2 is permanently assigned.
Analog output controller 2-point With a controller output of 0 %, the output current is 0 or 4 mA; with
a higher controller output, the output current reaches up to 20 mA.
Pumps with current input, thyristor controllers with DC or 3-phase
pumps or analog control valves can be used as dosing equipment.
Analog output controller 3-point Pump 1 decreases the control value.
Pump 2 increases the control value.
Output behaviour similar is similar to "analog output controller (2-
point)", but with 50 % offset. This means that with a control
deviation of 0 % (setpoint = actual value) a current of 10 or 12 mA
is output (pump is idle).
Therefore, 2 suitable pumps can be controlled with one mA current
loop.
1 0 0 %
5 0 %
5 0 %
0 %
1 0 0 %
D o s i n g r a t e
A n a l o g o u t p u t
X
s h
P u m p 1 P u m p 2
N e u t r a l z o n e
Setting Signal Pump Signal Pump
0–20 mA 0–20 mA Pump 1 10–20 mA Pump 2
4–20 mA 4–20 mA Pump 1 12–20 mA Pump 2