Focusens PTC thermistor is a leader in the field of motor protection with excellent quality. Its core feature is the sudden increase in resistance at critical temperature. It is high quality and low price, and performs well in heavy-duty motors. To avoid the risk of direct interruption of large currents, the PTC sensor intelligently monitors the temperature and provides high-resistance protection when exceeding the threshold, safely cutting off the circuit and preventing the motor from overheating.
This sensor is essentially a reed switch, encased in an ABS plastic shell. Normally the reed is 'open' (no connection between the two wires). The other half is a magnet. They're often used to detect when a door or drawer is open, which is why they have mounting tabs and screws.