ComAp InteliDrive DCU Industrial - Page 324

InteliDrive DCU Industrial 3.4.0 Global Guide
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Example 1 shows the correct temperature measurement. The 3rd metal (the cable between IS-AIN8 and
thermocouple) is connected in cold bath which temperature is 0°C. This is very difficult to provide in real
application.
Example 2 shows the correct temperature measurement. The 3rd metal (the cable between IS-AIN8 and
thermocouple) is connected in ambient environment which temperature is not 0°C, but T1°C. Resultant
temperature is correct, because is compensated by internal IS-AIN8 temperature sensor. The temperature
of IS-AIN8 and junction is the same T-T1+T1 (reduced and compensated by T1).
Example 3 shows the incorrect temperature measurement. The 3rd metal (the cable between IS-AIN8 and
thermocouple) is connected in ambient environment which temperature is not 0°C, but T1°C. Resultant
temperature is T-T1 (reduced by T1). Internal IS-AIN8 compensation should not by used because measures
T2 temperature, not T1!
Example 4 shows the correct temperature measurement. The 3rd metal (the cable between IS-AIN8 and
thermocouple) is connected in ambient environment which temperature is not 0°C, but T1°C. Resultant
temperature is correct, because is compensated by external temperature sensor, T+T1 (reduced and
compensated by T1).
Cold Junction Compensation (CJC) settings
Example 1 is not a practical in regard of ice bath. In this case should any of not compensated (nc) sensors
for analog input be selected base on used thermocouple.