Transmitter 9135 – pH/redox measurement
Page 47
S/CONTROLLER Menu
The built-in proportional controller, abbreviation
controller P. The controller output Y activates the
limit switch relays. Y value may correspond to a
control by impulse or a control by frequency. The Y
value is determined by the parameters below :
• A setpoint (W) : corresponds to the pH value to
control.
• A neutral zone (ZN) : may be programmed and
positioned symmetrically ± 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.
The value of Y in pH corresponds to the equation
below :
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