Temperature Transmitters

The more popular approach is to use the constant current method.

Hence the reason for the 3 and 4 wire RTDs.

By far the 4-wire is the most accurate and reliable with separate pairs for exciatation and measurement.

The wheatstone bridge is used for RTD's thusly: The RTD element,including 2 lead wires, is placed in one leg of a wheatstone bridge, and the compensating lead wire is placed in the opposite leg.This compensates for lead length. An op amp is placed diagonally across the bridge,and the result of any imbalance is amplified by the op amp and conditioned by further electronics.Additional lead wires are accommodated in a like manner. Simple.