S/Controller Menu - Hach POLYMETRON 9135 Operator's Manual

Transmitter 9135 – pH/redox measurement

S/CONTROLLER Menu

The built- in proportional controller, abbreviation
controller P. The controller output Y activates the
limit switch r e lays. Y value may correspond to a
control by impulse or a control by frequency. The Y
value is determined by the parameters below :
•
•
•
•
The value of Y in pH corresponds to the equation
below :
Y value is represented as follows :
0.0 pH
-1500 mV
A setpoint (W) : corresponds to the pH value to
control.
A neutral zone (ZN) : may be programmed and
positioned symmetrical ly ± 50% about the
setpoint. Within this neutral band the control
element (valve, dosing pump) is always inactive.
A proportional band (XP) : represents the
regulation slope. A XP value equal to 100% is
defined as a Y controlling value of 100% for a
5 pH (or 1000 mV in redox) drift according to the
neutral zone extremity.
A power factor (Exponent) : which calculates a
controlling value from a lineary (exponent = 1) or
an exponential function.
100
Y =
XP
Y
100%
50%
W
Z N
ZN
[ pH - (W +
2
*
5
(XP=50%)
0%
2.5
0.0 5.0
Exponent
] )
(XP=100%)
(XP=200%)
pH
14.0 pH
+1500 mV
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