Xylem WTW DIQ/S 281 Operating Manual page 110

Outputs
Settings
110
The controller works with the following amplification:
6 mA
= =
K 1
6 mg/l
Within the proportional range an increase of the concentration by 1 mg/l
causes a reduction of the output current by 1 mA. If the measured con-
centration is 5 mg/l, for example, 11 mA is output:
= +
I 12 mA 1
Regler
= +
I 12 mA 1
Regler
mg/l
The highest concentration at which the controller still works in the propor-
tional range is 8 mg/l (corresponding to Imin = 8 mA) and the lowest is
2 mg/l (corresponding to Imax = 14 mA).
Setting
Measured variable
Nominal value
Xp
Imin
Imax
mA
mg/l
mA
(
⋅ −
4 5
mg/l mg/l
mg/l
mA
( )
⋅ − =
1 mg/l 11 mA
Selection/Values
Main variable
Adjoining variable
within the measuring
range (sensor-
dependent)
5 ... 100 %
-5 ... -100 %
% of the measuring
range
0 ... 20 mA
0 ... 20 mA
)
Explanation
Main variable designates the
actual measured parameter of
the sensor (e.g. pH, oxygen,
etc.).
Adjoining variable designates
an additional measured
parameter (e.g. temperature).
Nominal value the measured
value is regulated to
Proportional range of the
controller.
Negative values result in a
positive characteristic curve.
Lower current limitation *
Upper current limitation *
* Note:
Spacing between Imin and
Imax:
at least 5 mA
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DIQ/S 281
08/2020