The M100-RTD monitors the resistance of either 100 Ohm platinum or 120 Ohm Nickel. The RTDs resistance increase as the temperature rises, this resistance change is detected by the M100-RTD, which provides an output corresponding to the temperature being measured. The temperature versus resistance values are provided by the supplier of the RTD used. RTD measurement of temperature is used in large transformers and large motors to ensure winding temperatures do not rise to a level that would change the winding.
