The basic structure of zinc oxide arrester is valve plate. The zinc oxide valve is insulated under the working voltage, and the passing current is very small, generally 10~15 μ A. The nonlinear characteristic of ZnO valve is mainly formed by the grain boundary layer. Its volt ampere characteristic curve is close to ideal arrester.
In addition to excellent nonlinear characteristics, zinc oxide arrester also has the following main advantages:
1. There is no gap. Under the action of working voltage, the zinc oxide valve plate is actually equivalent to an insulator, which will not burn out. Therefore, the operating voltage can be isolated without series gap. Because there is no gap, it can quickly respond to the shock wave of steep head, discharge without delay, and the effect of limiting overvoltage is very good. It not only improves the reliability of power equipment protection, but also reduces the over-voltage acting on power equipment, thus reducing the rated insulation level of power equipment.
2. No continuous flow. It can be seen from the above characteristics that only when the voltage applied to the zinc oxide valve reaches the initial working voltage, will it be "on". After "conduction", the residual voltage on the zinc oxide valve is basically the same as the current flowing through it. Unrelated but constant. When the applied voltage drops below the working voltage, the "on" state of the zinc oxide valve terminates, which is equivalent to an insulator. Therefore, there is no power frequency freewheeling.
