OBV1- B series surge protector is suitable for TT, IT, TN-S, TN-C-S etc. power supply system of AC50/60Hz, 380V, installed on the joint of LPZ0A zone or LPZ0B and LPZ1 zone, which peotects the electric network not shocked by the thunder and lightning. It's designed according to GB18802.1, IEC6 1643-1. It adopts 35mm standard rail, there is a failure release mounted on the module of surge protector. When the SPD fails in breakdown for over-heat and over-current, the failure release will help electric device separate from the power system and give the indication signal, green means normal, red means abnormal.