Re: PT100 color lead
In the most cases you will be using only white and red ..
Blue/Black wires are used only for compensation purposes, when you connect PT100 on longer wires: one pair white/red is used for "pumping" current, the other pair, blue/black, is used for reading voltage drop across the sensor ..
See attachment ..
If your sensor has only 3 wires, use red and white for current and voltage, then white-black for voltage drop across white, and apply the same "error" to red ..
Regards,
IanP