What role do thermistors play in overcurrent protection?

Thermistors are semiconductor devices that change their resistance with temperature variations. In overcurrent protection systems, thermistors play a critical role by providing temperature sensing capabilities that help to interrupt current flow when excessive current is detected. This response is due to the thermistor's resistance dropping significantly with an increase in temperature, which typically occurs when the current exceeds safe levels. As the temperature rises from overcurrent conditions, the thermistor can effectively limit the current by increasing its resistance or switching into a higher resistance state when a pre-determined threshold is reached.

This mechanism ensures that circuits are protected from damage caused by overcurrents, thus preventing overheating and potential failure of electrical components. The ability of thermistors to respond quickly to rising temperatures allows them to be effectively used in applications where rapid response to overcurrent conditions is critical.