ATI
Q46C2 2Electode Conductivity System
Part 8
– Calibration
46
O&M Manual
Rev-H (6/19)
6. Once completed, the display will indicate
PASS
or
FAIL
. If the unit fails, the temperature
adjustment may be out of range, the sensor may not have achieved complete temperature
equilibrium, or there may be a problem with the temperature element. In the event of calibration
failure, it is recommended to attempt the calibration again immediately.
8.6
TC Factor Calibration
This function is intended to give the user direct control of the temperature calibration offset value
without having to proceed through the temperature calibration procedure. Sensor TC offset is a
number that indicates the sensor RTD output at 0 ºC. Ideally, the sensor temperature output will
be 0 ºC (1000 Ohms) under these conditions. Sensor offset is primarily the result of sensor RTD
tolerance and connecting cable resistance. Large offsets are typically the result of large sensor
cable lengths. A sensor reading of +1 ºC indicates that the sensor will output an uncalibrated
reading of +1 ºC when placed in a theoretically perfect 0 ºC temperature bath. In other words, the
offset shifts the entire sensor response curve up or down. Since the slope of an RTD is fixed and
highly repeatable, the slope is not adjusted in this calibration.
Certain Q25 series sensors are labeled with a specific TC factor. Entering this factor directly allows
the user to quickly calibrate the transmitter for the sensor being used without performing a time
consuming full temperature calibration. However, if the sensor cable length is modified or a new
sensor is used, a new TC factor must be entered or the user must perform a full temperature
calibration. The default value for the TC factor is 7.50. Increasing this value increases the
temperature reading and decreasing the value decreases the temperature reading. A change of
approxi0.1 is equivalent to +0.1 ºC. This function is directly related to the full temperature
calibration function in that a new offset number is produced if a full temperature calibration has
already been performed. If the TC factor is modified, it overrides any previous full temperature
calibration data.
Procedure
Press ENTER to initiate user entry mode and the first digit will flash. Use arrow keys to modify
value; range is 00.00 to 15.00. Press ENTER to save the new value.
