Overcurrent protection PTC thermistor

The PTC thermistor for overcurrent protection is a protection element that automatically protects and automatically recovers abnormal temperature and abnormal current. It is commonly called "self-resetting fuse" and "10,000 times fuse". It replaces the traditional fuse and can be widely used for overcurrent protection of motors, transformers, switching power supplies, electronic circuits, etc. PTC thermistors for overcurrent protection reduce the residual current value by limiting the consumption in the entire line by sudden changes in resistance. . The traditional fuse cannot recover itself after the line is blown, and the PTC thermistor for overcurrent protection can be restored to the pre-protected state after the fault is removed. When the fault occurs again, the overcurrent protection function can be realized.

Use PTC thermistor for overcurrent protection as overcurrent protection element, first confirm the normal working current of the line (the non-operating current of the PTC thermistor for overcurrent protection) and the installation position of the PTC thermistor for overcurrent protection (normal During operation, the high ambient temperature, followed by the protection current (the operating current of the PTC thermistor for overcurrent protection), the large operating voltage, and the rated zero-power resistance, should also take into account factors such as the external dimensions of the components.

Its application principle is as follows:

When the circuit is in a normal state, the current through the overcurrent protection PTC thermistor is less than the rated current, and the overcurrent protection PTC thermistor is in a normal state, the resistance value is small, and does not affect the normal operation of the protected circuit. When the circuit fails and the current greatly exceeds the rated current, the PTC thermistor for overcurrent protection suddenly heats up and is in a high-impedance state, so that the circuit is in a relatively "off" state, thereby protecting the circuit from damage. When the fault is removed, the PTC thermistor for overcurrent protection also automatically returns to the low resistance state, and the circuit resumes normal operation.