How much influence has the magnetic induction in Thermocouples?

Question

How can we calculate it?. Is there some way to nullify it to have reliable our measurements?.

Answer 1

Magnetic induction can introduce quite a bit of error on a thermocouple wire run. The best way to determine its effect is to measure the thermocouple voltage with the magnetic source on and again with it off.



To mitigate the effects, first route the thermocouple wire as far away as practical from the magnetic source, though keeping the run as short as practical. Second, shield the cable. Third, use a balanced cable such as a twisted pair. The effects of the induction will largely cancel itself out since it will induce opposing currents in each of the wires with a twisted pair.



If the magnetic source is high frequency, you can try using toroids at the ends of the cable run to absorb the induced current as well.

Answer 2

Factors influencing: (1) the strength of the magnetic field (2) the length of the conductor (usually the number of turns) (3) rate of cutting through the magnetic field by the conductor Alternatively if the conductor is held stationary and the magnetic field varied then the rate of change of the magnetic flux.

Answer 3

There will be no effect. However if you include the wiring then of course yes. the effect will be proportional to the change in magnetic flux thru the closed loop. to reduce the effect shielded cable or twisted pair cable sshould be used