ML1 series module surge protective device (short for SPD), suits for the AC 50Hz/60Hz, rated working voltage is 400V, for the TT, TN-S, TN-C, IT etc. series. It is used to protect the direct or indirect thunder influence or other instantaneous over-voltage surge. This product is mainly used in house, third industry, and industry field for surge protection. This product is comply with GB18802.1-2002; IEC 61643-1:1998; BG50057-2000 I Building Lightning proof Design Rules SPD has the protection way of common mode (MC), and differential mode.