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15.2.5 Two-position pulse frequency controller for pH
Application
•
Downward control direction of pH value using
acid.
•
Control of dosing pump via contact input.
Description
•
The actual required pH value exceeds the
setpoint:
– Dosing pump for acid carries out individually
controlled dosing strokes.
•
The measured value deviates from the setpoint:
– Frequency of dosing strokes increases.
– If the deviation is large, the pump runs
continuously with maximum frequency of
dosing strokes.
Fig. 59
Two-position pulse frequency controller for pH
Parameter settings
TM
03 71
13
16
13
Off
On
Off
On
Off
On
SP 1
pH value
Deviation from
setpoint
Switching status of the pump
(individual dosing strokes).
SP 1
Required pH value, e.g. 50 % (correlates with pH 7.00).
Pulse frequency for SP 1
72 (maximum value (correlates with 7,200 strokes per hour).
The dosing capacity of the pump is then fully utilised.
SP 2
-
*)
Pulse frequency for SP 2
-
X
p
According to local conditions, e.g. 100 %
• Higher setting results in smaller control steps.
• Lower setting results in larger control steps.
T
n
According to local conditions, e.g. 300 sec
• Higher setting results in slower control.
• Lower setting results in faster control.
T
v
0
Hysteresis
e.g. 1 %
Interpulse period
-
Actuating time
0
Minimum pulse width
≥
0.3 sec
Required code functions
None
Other code functions
As required
*)
"-": without function (no setting required)
