Square D Secondary Surge Arrester SDSA3650 NIB SDSA3650 NIB. The Square D SDSA3650 is a heavy-duty, Type 1 Surge Protective Device (SPD). Secondary Surge Arrester. Surge Current Capacity: 40 kA to 50 kA per phase. Common Applications. Unit is pristine, Box is worn. byJuly 3, 2026