Calibrate for T-thermocouples mounted on the MC USB-TC

[Alex L]

One USB-TC can be mounted 8 thermocouples. I had mounted 8 T-thermocouple on the MC USB-TC. We know that when we start to use the T-thermocouples and USB-TC to measure the temperature, we have to calibrate the system(thermocouples + USB-TC) firstly. During the calibration, we use calibration bath to calibrate thermocouple, which filled with water.

Question 1: Can I calibrate the 8 thermocouples in one time? And the thermocouples could be put in water directly or thermocouples shall be put in a bag which avoid run current between the thermocouples in water(that can have impact on the measurement).

Question 2: I put the 8 thermocouples and one standard PT100 in water. The calibration bath was set at 31℃ and the PT100 showed the temperature was 31.1℃. However the 8 channels of USB-TC showed different values. Showed as attached photos, compare the value measured by PT100 and thermocouples, the max different was about 0.52℃. It was quite big.  Why some thermocouples looks quite different with correct value?

[Fausto]

Dear @Alex L.

Field calibration for the MCC USB-TC is performed via InstaCal and calibration baths are not used.  The process is an internal voltage calibration on all eight channels, so it does not matter which thermocouple type is connected or if any are even connected.  

 

 

After calibration, if you determine that the measurements are still out of specification, then you can choose to send the module in to be factory calibrated for a fee. 

Calibration section on page 7 of the USB-TC User Guide.

https://www.mccdaq.com/pdfs/manuals/USB-TC.pdf

 

Regards,

Fausto