Gas arrester

Surge arresters (GDT) consist of a spark gap, which is installed in a
sealed ceramic or glass tube filled with inert gas.
Under normal conditions the operating voltage does not reach the
sparkover voltage and the GDT maintains its very high
Resistance value.
As soon as the voltage applied to the arrester exceeds the ignition voltage, it forms
within nanoseconds, an electric arc forms in the gas-tight discharge space
After the influence has subsided, the arrester and the internal resistor extinguish
resumes its original operating state with several 100 MΩ.