EP3204: Pt100 (RTD)

The advantage of four-wire technique is that the error resulting from the cable and contacts is included in the measurement and cancelled out. In the 3-wire technique, the line resistance to the resistance sensor is measured in one direction only, and is multiplied by two. This requires the outward and return lines to have approximately the same ohmic resistance. An error is present in the two-wire technique; temperature differences and cable cross-sections can make this error vary considerably.