User guide

I-E67-84-1B February,2002 8-12
to enter the new value.
7) Set the REFZ (i.e., reference impedance)
by using the Key to increment the
blinking digit and the Key to move to
the next digit and pressing the ENTER Key
to enter the new value.
Temperature Sensor State (Basic/Advanced)
The Temperature Sensor State configures the
temperature input for a Pt100, 3 kohm Balco,
or no (i.e., NONE) RTD.
Set the Temperature Sensor State using the
following procedure.
1) Select the TMP.SNS State using the SELECT
Key.
2) Choose the desired temperature sensor by
using the NEXT Key to toggle between
NONE, 3K.BLCO (i.e., 3 kohm Balco), and
PT100, and enter the temperature sensor
by using the ENTER Key when the correct
sensor is displayed in the secondary
display.
Temperature Compensation State (Basic/Advanced)
Temperature affects the process variable in
two ways. The first effect (i.e., Nernstian
Effect) causes the sensor output to increase
with increasing temperature. In the case of a
pH sensor, the increase is roughly 0.03 pH/pH
Unit From 7pH/10 C. Since ABB pH sensors use
o
Silver/Silver Chloride Measurement and
Reference Half Cells, the isopotential point
(i.e., the pH value that is unaffected by
temperature) of these sensors is 7 pH.
The second temperature effect is on the actual
chemistry of the solution. Since ion
disassociation can be a function of
temperature, ion properties such as pH, ORP,
and pION are affected by changes in process
temperature. These effects can be empirically
determined and included in the temperature
compensation process using the Automatic
Nernstian with Solution Coefficient
Temperature Compensation option.
The Temperature Compensation State sets the
desired compensating method. The three states
of temperature compensation include Manual
Nernstian, Automatic Nernstian, and Automatic
Nernstian with Solution Coefficient. Table 8-