Evoqua WALLACE & TIERNAN MFC, Instruction Manual

Page: 93 / 268

MFC
Functions
4.
93
Positioner (with and
without feedback)
With the selection of the integrated controller for "positioner", for
example, it is possible to use chlorineoverfeed control in
connection with a positioner as dosing equipment in a chlorinator.
2-point pulse
duration controller
for dosing pumps
The dosing pump is switched on for the calculated time within an
adjustable cycle period TP (relay contact). The cycle period is
mainly determined by the reaction time of the connected system
and entered as the cycle period TP.
Example: Cycle period TP = 100 s
Output value Yout = 30 %
Duty cycle
30 s
Off duty cycle 70 s
2-point pulse
frequency controller
for pulse pumps
Pulse pumps are controlled with 0 to 100 or 0 to 120 pulses per
minute, depending on the specification of the connected pump.
The duty cycle during each dosing is 0.3 s. The break time is
calculated between 0.2 and 60 s depending on the dosing rate.
Example for a solenoid pump with 120 pulses/min.:
3-point pulse duration
controller for dosing pumps and
3-point pulse frequency
controller for solenoid pump
Pump 1 decreases the control value.
Pump 2 increases the control value.
The control range is between -100 % (pump 1) and +100 % (pump
2); this range can also be set in manual mode.
If the setpoint = actual value, no pump is activated (neutral zone
Xsh).
Output signals as for 2-point pulse-duration controller and
2-point pulse-frequency controller.
Yout in % 100... 84... 72... 56 50... 33... 25... 10... 5... 10
Pulses/min 120... 96... 85... 75 60... 40... 30... 12... 6... 10
1 0 0 %
0 %
- 1 0 0 %
1 0 0 %
O u t p u t s i g n a l
D o s i n g r a t e
X
s h
P u m p 2
P u m p 1
- 1 0 0 %