Varistors need to absorb the energy deposited by temporary overvoltage, switching surges, or lightning impulses. Experiments show that differences in grain sizes and grain boundary characteristics cause nonuniform microstructure.

Why would a varistor burn out?

When the varistor leakage current is too large, and the temperature rises to a certain extent, the low melting point metal is melted, thereby varistor from The cutting in the circuit can effectively prevent the varistor from burning.

Can a varistor go bad?

If the varistor is visibly burnt through or broken, it is bad; replace it. If it appears intact, proceed to Step 3. A varistor is an electronic component that acts as a shock absorber, protecting expensive devices from harmful power surges. The varistor will likely be wired to a fuse holder.