Metal Oxide Type Lightning Arrester (MOA) is an important protective device used to protect the insulation of power transmission and transformation equipment from overvoltage hazards. It has the advantages of fast response, flat volt-ampere characteristics, stable performance, high current carrying capacity, low residual voltage, long service life, and simple structure. It is widely used in power generation, transmission, transformation, and distribution systems.
The metal oxide type lightning arrester is a new type of lightning arrester that only consists of varistor discs. The varistor discs are made from sintered polycrystalline semiconductor ceramic elements, such as zinc oxide and other metal oxides, and have ideal valve characteristics. At the same time, it has advantages such as a small nonlinear coefficient, good protection characteristics, strong energy absorption capacity, large current carrying capacity, simple structure, and good stability.
The nonlinear coefficient α value is very small. Under rated voltage, the current passing through is very small, so it can be made into a gapless lightning arrester. The protection performance is good. It does not require gap operation; once the voltage increases, it can quickly absorb the overvoltage energy and suppress the development of the overvoltage; it has good steepness response characteristics; the performance of the gapless oxide lightning arrester is almost unaffected by environmental conditions such as temperature, humidity, atmospheric pressure, and pollution, thus ensuring stable performance.
The metal oxide type lightning arrester basically has no follow current, light operating load, and strong ability to withstand repeated operations. The volt-ampere characteristics are symmetrical, and there is no polarity issue, so it can be made into a DC lightning arrester.
It has a large current carrying capacity. The lightning arrester can easily absorb energy without the constraints of a series gap, only related to the strength of the varistor discs themselves. Compared to silicon carbide varistor discs, the unit area current carrying capacity of the oxide varistor discs is 4 to 4.5 times larger.
The metal oxide type lightning arrester has a simple structure, small size, is easy to mass produce, and has a low cost.
It is suitable for various special needs. The metal oxide type lightning arrester has good pollution resistance, and its performance will not be affected by pollution or when cleaning is done while energized, which might change the potential distribution of the outer surface of the arrester. At the same time, since the varistor discs are not affected by atmospheric conditions, it can adapt to various insulating media, making it suitable for high-altitude areas and SF6 fully sealed switchgear, among other special needs.
The metal oxide type lightning arrester has a series of advantages, a great development potential, and is the main direction for the development of lightning arresters worldwide. It will gradually replace traditional gap-type lightning arresters and will be a key overvoltage protection device for future ultra-high voltage systems.
English 
