The traditional valve surge arrester was patented in 1935 and its basic design is a spark gap for overvoltage discharge, and a series resistor to limit freewheeling. This was the best design on the market for many years, but the silicon oxide varistor (SOV) surge arrester appeared now.

  The basic design of a silicon oxide varistor (SOV) surge arrester is a pair of metal electrodes separated by a silicon oxide compound. Under normal circumstances, silicon oxide is a good insulator, so there is no line current flowing between the electrodes to the ground. When an excessively high voltage appears on the electrode, the high-energy electric field ionizes the silicon oxide, changing it from a compound to silicon separated from oxygen. Since silicon ions are a good conductor, high-energy currents can be conducted to the ground. When the voltage drops to a normal level, silicon and oxygen will recombine to form silicon oxide and cut off conduction.

  The reason why the silicon oxide varistor (SOV) design is effective is that there is no series resistance to limit the freewheeling. In the valve surge arrester, the role of the resistor is to limit the freewheeling, but it also hinders the lightning discharge. Since the silicon oxide varistor (SOV) surge arrester does not require resistance, it can conduct more current faster.

  As the MOV unit ages, its clamping voltage decreases, causing a short-circuit failure. Silicon surge arresters will not change with age or use. As the age increases or the conductivity increases sharply, the movement deteriorates. Silicon surge arresters will not degrade with age. Silicon surge arresters rarely fail, but when they fail, they fail to "open circuit", allowing the power system to continue to use.