Square D by Schneider Electric SDSA3650 Secondary Surge Arrester

Square D by Schneider Electric SDSA3650 is a Type T1 secondary surge protective device (SPD) designed for service entrances on three‑phase, grounded systems from 208Y/120 V up to 600 V. This 3‑pole, 4‑wire unit supports indoor or outdoor installations and uses an MOV‑based design with response times under 50 nanoseconds and a clamping voltage around 510 VAC, typically lower than traditional gas‑tube arresters. Key ratings include a 40 kA peak surge rating, a 200 kA short‑circuit current rating (SCCR), and a nominal discharge current of 10 kA; enclosure is NEMA 4X, black plastic, with dimensions about 3 in W x 3.39 in D x 3.6 in H and an LED status indicator. It is commonly used in service‑entrance panels to protect downstream equipment such as motors, drives, and control panels from surge events.