LY1-D series surge protective device(in short SPD)is suitably used in the IT, TT, TN-C, TN-S, TN-C-S and etc power supply system of AC 50/60Hz, rated voltage up to 380V, to protect from direct and indirect lightning impulse and other transient over voltage. As per the conditions of IEC6164-1: 1998-02 standard. Class Ⅲ Surge protective device, it is category D surge protective device. SPD has two protection modes: MC and MD, SPD is in compliance with GB18802.1/IEC61643-1 standards.