PPTC（Polymer Positive Temperature Coefficient）is an over - current protection component with automatic recovery function. When abnormal overcurrent passes through PPTC, the heat generated expands the polymer matrix material, and the conductive particles wrapped outside the polymer matrix material will separate, thus cutting off the conductive channel of PPTC and increasing the resistance of PPTC and reducing the abnormal overcurrent. When the abnormal over-current fault disappears, the PPTC polymer matrix material contracts to the original shape and connects the conductive particles again, the conductive channel will be restored, and the PPTC resistance will return to the original low-resistance state. This process can be repeated many times. 

The greatest advantage of PPTC is that in its rated range of use, it does not need to be replaced after each fault clearance, and can be repeatedly applied in the circuit to maximize the effective saving of maintenance time and cost. PPTC is sensitive to current and temperature, and is widely used in computer, electronic rectifier, automobile, communication, household electrical canal, battery and other industrial field.