Question

Why self-heating is a problem in RTDs and not in thermistors.

Answer 1

Thermistors and RTD both are temperature sensors widely used to measure temperature change but the working of both is slightly different.

Thermistors measures the change in resistance directly if there is a temperature change. The resistance will change due to temperature change it can increase or decrease based on thermal coefficient.

On the other hand, in RTD we do not measure the resistance but we measure the voltage difference across the resistance, for that we need external current. Due to this external current there is heat dissipation in resistor and 'self heating' occurs.

Please note that concept behind both the sensors is same that resistance will change with temperature change but the methode of measuring it are different. In thermistor we directly measure the resistance while in RTD we measure the voltage difference. This is the main cause of self heating in RTD.