Thermocouple Inputs

[cfordyce]

I am replacing an old TI PLC and T/C input modules with Automation Direct's DL405 and Terminator I/O modules. The existing system utilizes 'ISOTHERMAL BLOCKS' between the T/C junction and the Input to the card. Is this required with my new PLC as well? Or does the Cold Junction compensation feature serve the same purpose?

 

[skills]

CJC should serve the same function. The main point is that both junctions from the TC to terminations be in close proximity and at same temp. then CJC will subtract the voltaic error introduced at the junction.

 

[hacksaw]

there is a big differnece between "should" and "does".

it pays to do a loop check on your calibration in the shop. CJ compensation is not yet an industry standard practice and you can find yourself up to you neck in alligators pretty quick.