Yokogawa EXAxt SC450 4-Wire Analyzer for Conductivity/Resistivity - Manual (Page 30)

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IM 12D08N05-01E
5-4. Calibration settings
Air adjust limit
To avoid cable influences on the measurement,
a “zero” calibration with a dry sensor may be
done. If a connection box (BA10) and extension
cable (WF10) are being used, “zero” calibra-
tion should be done including this connection
equipment.
When using a 4-electrode sensor additional
connections are required. Temporarily Intercon-
nect terminals 13 & 14 with each other and 15
& 16 with each other before making the adjust-
ment. This is necessary to eliminate the capaci-
tive influence of the cables. The links should be
removed after this step is completed.
As the calibration is performed in air the
resistivity is infinite (open connection). Higher
conductivity values than the air adjust limit
indicate the cell is not in air or is still wet. To
prevent wrong air calibrations a limit must be
given here.
c.c. high limit
High limit of the cell constant expressed in %
of nominal value. During calibration this value
is used to check if the calibrated cell constant
remains within reasonable limits.
c.c. low limit
Low limit of the cell constant expressed in %
of nominal value. During calibration this value
is used to check if the calibrated cell constant
remains within reasonable limits.
Stabilization time
During calibration the stability of the measure-
ment is constantly monitored. When the value
is within a bandwidth of 1% over a period of the
stabilization time, the calibration is considered
stable and the calibration may be completed.
Calibration Interval
A user defined interval in which a new calibra-
tion should take place. If the interval is ex-
ceeded the instrument will give a warning or a
fail (user definable in error configuration 2/3)
5-5. Concentration
Concentration has a direct relation with the
conductivity value at reference temperature.
This relation is built in every matrix which are
used for temperature compensation. These can
be found in:
Commissioning >> Measurement setup >>
Temp. compensation >> Method
By selecting one of the matrices for tem-
perature compensation directly gives the
concentration value on the main display. If
another temperature compensation method is
chosen (NaCl or T.C.), the relation between the
conductivity at reference temperature and the
concentration is obtained from the “Concentra-
tion table”.
Additional table
This 21x2 user defined concentration table is
used to come to more accurate concentration
values compared to the temperature compen-
sation matrix. Enabling this additional table
overrules the concentration values obtained
from the matrix (if used).
Unit for table
The way the concentration values are pre-
sented to the user. Changing the unit will not
result in a re-calculation of the table.