IEC 60388-1: Thermistors — PTC and NTC Applications in Temperature Sensing and Overcurrent Protection

PTC and NTC — Opposite R-T Curves Covering Everything From Temperature Sensing to Circuit Protection

IEC 60388-1:1972 specifies thermistor requirements. NTC (Negative Temperature Coefficient) — resistance decreases as temperature rises, used for precision temperature measurement (Steinhart-Hart equation). PTC (Positive Temperature Coefficient) — resistance sharply increases near the Curie temperature, used for overcurrent protection and motor starting.

TNLab — The thermistor is the classic component that “combines sensing and protection in a single element.”