When the traditional fuse being used for overcurrent protection, it only can protect one time; once burned out it must be replaced. But the resettable fuse has a double functions: overcurrent protection and automatic reset.

Overcurrent protection JKPPTC element is in series with the circuit, under nomal circumstances it presents low resistance to ensure the normal work of circuit: once the short circuit or other unusually high current happened, the self-heating of JKPPTC cause its impedance increase to prevent the current increase, So playing the role of protecting current.

Automatic reset- once the fault resulting in overcurrent being removed, JKPPTC element will automatically return to its low resistance state, with no need for replacement and keep away from the continuously circulating on-off state which can cause circuit damage. The JKPPTC resettable fuse's special structure determines their double functions. It is manufactured by mixing high polymer and conducting materials. Under normal circumstances, conducting materials forms a three-dimensional electric passage by the polymeric materials which keep the JKPPTC's resistance low. In case of passing unusually high current, JKPPTC element's temperature will rapidly rise, cause the polymer materials expand, then the conducting passage break, the impedance rapidly rise and the passing current turn low, the circuit like break off to protect itself. When the high current disappearing, the self-heating of JKPPTC will be not enough to keep it in high resistance state, so its impedance will turn to low resistance state. Compared to the traditional fuse, JKPPTC has the advantages of resettable, smaller and stronger.