The action principle of PPTC resettable fuse is a dynamic balance of energy. The current flowing through the PPTC element will generate heat, which is due to PPTC. All or part of the generated heat is dissipated into the environment, and part of the heat that is not dissipated increases the temperature of the PPTC element. It can be widely used in telecommunications and networks, computers and multimedia, industrial and automotive industries, batteries and portable electronic equipment and other industries.