daleyd
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RTD are more picky, but depending what type you have they can self compensate (2 wire rtd don’t have any compensation, 3 and 4 wire do) for length of wires. As you add more length the resistance of the whole system changes, a 3 or 4 wire measures the resistance of the 3rd/4th wire and subtracts it from the actual “measured”resistance.lol Something I never knew until I covered Thermocouples as part of an HNC course last year, was that thermocouples are a precise loop, so if you change any wiring, you may need to re-calibrate them.
I'll admit it's something that I've never personally used, but always thought the wiring between the actual thermocouple and the interface wasn't that critical, but apparently it is![]()
Thermocouples usually aren’t as susceptible using the correct compensating cable, but depending on the application you might be asked to calibrate the whole thing again - aerospace have particularly stringent requirements (as you’d expect I guess). For aerospace heat treatment the thermocouples also have a lifespan, depending on the number of uses and the temperature they are used at (hotter temps = less uses and vice versa), irrespective of if they are in cal or not.