En
gl
is
h (
G
B)
52
15.2.10 Three-position step controller with disturbance variable feedforward
Application
•
Open-loop control of dosed chlorine proportional
to the flow and closed-loop control dependent on
the measured value.
•
Control of dosing pump or gas dosing unit using
servomotor.
Description
A varying flow of water is to be chlorinated by a
uniform amount. The electromagnetic flowmeter
measures the flow quantity and passes it on to the
controller. The result (the chlorine concentration) is
also measured and the dosed quantity controlled
accordingly.
•
When the flow of water increases:
– The servomotor moves in the direction of the
increased dosing capacity.
•
When the flow of water decreases:
– The servomotor moves in the direction of the
decreased dosing capacity.
•
The closed-loop control is dependent on the
measured value:
– When the chlorine concentration decreases,
the servomotor moves additionally in the
direction of the increased dosing capacity.
– When the chlorine concentration increases, the
servomotor moves additionally in the direction
of decreased dosing capacity.
Parameter settings
SP 1
Required chlorine concentration, e.g. 55 %.
Pulse frequency for SP 1
-
*)
SP 2
-
Pulse frequency for SP 2
-
X
p
e.g. 100 % (transmission ratio 1:1):
• > 100 % (transmission ratio 1: > 1)
• < 100 % (transmission ratio 1: < 1)
T
n
> 0
T
v
0
Hysteresis
e.g. 1 %
Interpulse period
e.g. 2 sec
Actuating time
0
Minimum pulse width
≥
0.3 sec
Required code functions
1, 3, 4, 10, 11, 14, 17
Other code functions
As required
*)
"-": without function (no setting required)
