1. The structure and working principle of the varistor: The varistor, a polycrystalline semiconductor ceramic component made of a variety of metal oxides, is a classic product of electronic ceramic technology. Their working principle is based on their unique grain boundary properties, which change conductivity through thermionic emission and electron tunneling effects under a certain electric field strength. As the applied voltage increases, the resistance value of the varistor will drop sharply, showing significant nonlinear volt-ampere characteristics. This unique property makes its application in circuits particularly important, especially in lightning protection.
2. Application of varistor in lightning protection: When the circuit encounters overvoltage, such as an instantaneous voltage impact caused by lightning, the varistor can suppress the growth of the voltage peak through its grain boundary electron tunneling effect and absorb the excessive voltage. part of the voltage energy. In this way, they effectively protect lines or equipment from overvoltage damage. However, it should be noted that if the circuit is frequently subjected to various types of over-voltage shocks, the varistor frequently performs over-voltage suppression and energy absorption, which may cause its performance to gradually deteriorate or even fail completely.
3. Modern solutions for overvoltage protection: Currently, internationally popular overvoltage protection solutions combine varistors with current limiting, overcurrent and fixed alarm devices. This combination not only provides effective overvoltage protection, but also prevents circuit short circuit problems caused by the varistor's own degradation. This integrated and multi-protection approach provides more comprehensive and reliable protection for electronic equipment, especially in the face of unpredictable lightning strikes.