27.5kV系列金属氧化物避雷器（以下简称MOA）是用于保护27.5kV电气化铁道系统设备免受大气过电压和操作过电压损坏的保护电器。
复合外套MOA采用优质硅橡胶为原料，从而使产品体积小、重量轻、防爆性能大大提高，硅橡胶固有的憎水性使其具有良好的耐污性能。
瓷外套MOA带有压力释放装置，MOA故障时内部压力增大，防爆装置动作，释放内部压力。电弧从内部转移到外部，在瓷套外部形成短接，保证瓷套不炸裂,
表.铁道型MOA的技术参数见下表：
Composite jacket MOA high quality silicone rubber as a raw material, so that the products are small, light weight, explosion-proof performance greatly improved, the inherent hydrophobicity of silicone rubber it has a good stain resistance.
Porcelain jacket MOA with a pressure relief device, the internal pressure increases when the MOA failure, explosion-proof device movement, release the internal pressure. Arc transferred from internal to external, external form in porcelain sets short, no guarantee porcelain burst,
Table technical parameters railroad type MOA in the table below:
