Designing with temperature sensors, part four: thermocouples

摘要

Thermocouples offer distinct advantages over other temperature sensors, such as thermistors, RTDs (resistance-temperature detectors), and silicon sensors. Thermocouples respond to the widest temperature range. Different environment requirements, such as vibration resistance or corrosion resistance, can help determine the correct thermocouple type for your application. You can construct a thermocouple with two wires of dissimilar metals or alloys, such as iron and constantan (Type J). A weld bead bonds the two dissimilar metals on one end of bodi wires. If there is a temperature difference between the bead and the open end of the thermocouple wires, an EMF (electromotive-force) voltage appears between the open end of the two wires.