I need some support on product selection for thermocouple (TC) modules. I need to measure temperature using TC’s on a test section that is energised with DC voltage. The TC’s will need to operate simultaneously on a test section with a voltage range of +/- 10 V. I have had trouble with the TC’s being saturated with common mode voltage when using a Picologger TC-08.
I am looking at getting a new NI module (9212 or 9213) or maybe a Redlion E2-16ISOTC-D. Im not sure the metric to qualify these units for this particular issue. The NI modules give two common mode voltage ranges CH-COM and COM-Earth. Can you offer any advice on which metric should be used to assess this?
I would have thought the CH-COM range would be the appropriate value but I have used a NI 9211 units on this same setup and it reads OK. It has a CH-COM range of +/- 1.2 V but the unit is seeing +/- 18 V so Im a little confused on that score. Any insights here? Else any other product suggestions for high common mode voltage range?