Generally, there are three types of thermocouples, platinum resistors and thermistors.

Thermistor: low precision level, as temperature control or temperature protection device, not suitable for stability difference above 100 °C.

PTC positive temperature coefficient / NTC negative temperature coefficient / CTR critical temperature coefficient, negative temperature type thermistor with switching characteristics.

Thermocouple (T/C): generally used between hundreds of degrees and more than one thousand degrees, suitable for medium and high temperature measurement, low price, using two homogeneous metal conductors to form a closed loop, when the temperature difference of the joint makes An electromotive force is generated in the loop. The temperature sensing device formed by the Sibeck effect with two metals and the joints at both ends is called a thermocouple.

Platinum resistance (RTD): Positive temperature coefficient, high precision and stability, PT100 is often used between -250 ° C ~ + 640 ° C, using metal to change the resistance value due to temperature changes to detect temperature values, The materials used are platinum, copper, nickel, etc., which can be divided into Pt100/jPt100/Pt200/Pt500, among which Pt100 is the most widely used.