A RTD sensor which is manufactured in a three wire configuration, ie (1 red and 2 white wires) can be connected to a bench top multimeter as shown in figure 2. The red wire is connected to 1 input and the two white wires are connected together to the 2nd input.
Note
When connecting a three wire RTD to a 2 input multimeter, significant error can result from the resistance of the wire. To avoid this error, connect 1 white wire to the 1st input and the 2nd white wire to the 2nd input, and measure the resistance value. This is the lead loop resistance. This value is automatically calculated and subtracted by instruments which are designed for 3 wire RTD input.
The measured value in ohms of the two white wires should be subtracted from your readings when connecting the RTD as a two wire sensor. Some bench top multimeters will allow you to measure the lead loop resistance and program the multimeter to automatically subtract it from future readings. Refer to the technical manual for your multimeter.
