Evoqua WALLACE & TIERNAN SFC, Original Instruction Manual

Page: 85 / 288

SFC
Functions
4.
85
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.
2-point pulse
frequency controller
for pulse pumps
Pulse pumps are controlled with 0 to max. pulse rate per minute,
depending on the specification of the connected pump. The SFC
supports pumps with 100, 120, 140, 160 and 180 pulses per
minute.
The duty cycle during each dosing is 0.3 s. The break time is
calculated to be between 0.2 and 60 s, depending on the dosing
rate.
Example for a pulse pump with 120 pulses/min:
3-point pulse-duration
controller for dosing pump and
3-point
pulse-frequency
controller for pulse 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.
Example: Cycle period TP = 100 s
Output value Yout = 30 %
Duty cycle 30 s
Off duty cycle 70 s
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 %