Surge Protective Devices,surge protector,arrester,SPD Surge Protective Devices,surge protector,arrester,SPD Usage and application scope Usage and application scope of BY10 type surge protective device (short name "SPD") is suitable for AC 50/60 Hz, 380V and the following electric power systems, such as TT, IT, TN-S, TN-C, TN-C-S. It protects the electric network shocked by the thunder or over ...