Temperature measurement with three-lead resistance thermometers by dual constant current method

摘要

Measurement with a three-lead resistance thermometer is made using two current sources to set up a current I in the thermometer element and each of its potential leads. A current of 2I is established in the current lead with all currents being in a direction such that the currents in the potential leads are in the same direction with respect to the thermometer element. A voltage measurement is then made across the potential leads to determine the element resistance and hence its temperature without the need for leadwire compensation.