WAGO-I/O-SYSTEM 750
Calibrating Measured Values 149
750-489 4AI RTD/TC/Strain Gauge Ex i
Manual
Version 1.1.0, valid from FW Version 02
9
Calibrating Measured Values
The precision that can be achieved in temperature measurement depends on the
following properties:
•
The accuracy of the transducer in the RTD/TC module
•
The accuracy of the linearization in the RTD/TC module
•
The quality of the electrical contact points
•
The quality of the thermal contact points
•
The accuracy class of the thermal sensor and compensating lines
•
The thermal stability in the environment of the RTD/TC module
The first two issues are quality characteristics of the WAGO product; all other
properties are up to the user.
For the RTD/TC module, WAGO offers the option of using the WAGO-IO-
CHECK
calibration dialog to compensate tolerances throughout the entire measurement
chain. This requires reference values to be available for temperatures of the
object to be measured.
Example 1
Requirements:
•
The WAGO node must be installed in the control cabinet; the temperature
in the control cabinet must have settled and be constant.
•
A thermocouple line must be laid up to the measuring point, but not yet
welded on there.
1.
Connect a calibrator to the open ends of the thermocouples.
2.
Use WAGO-IO-
CHECK
to calibrate the equipment via this calibrator.
3.
Remove the calibrator.
4.
Weld the thermocouple and secure it to the measuring point.
Example 2
Requirements:
•
The WAGO node must be installed in the control cabinet; the temperature
in the control cabinet must have settled and be constant.
•
A thermocouple line must be laid up to the measuring point.
•
The temperature of the object to be measured must be known precisely at
at least two points
(e.g., eutectic phase changes => solid and liquid lines)
1.
Calibrate to these points.
The resulting calibration values are stored permanently in the I/O module.
Each supported sensor type has its own storage space available.
