The Siemens 5SM3348-0 is a SENTRON residual current circuit breaker (RCCB), 4-pole, type AC, rated 100 A with 30 mA sensitivity at 400 V AC, 50 Hz. The instantaneous design means it trips without intentional delay — no time-grading built in, so it's the last device in the selectivity chain, not a selective S-type. That 30 mA threshold covers personnel protection (hand-to-hand or hand-to-ground fault paths) per IEC 60364. For a line-down spare, the 4-pole frame handles three-phase plus neutral; the neutral is switched and monitored inside the device.
Mounts on standard DIN rail (EN 60715). The 4-pole width is 4 modules (72 mm). Terminals accept up to 35 mm² conductor for the 100 A rating — verify lug size against your panel's busbar or feeder cable. No auxiliary contact slot on this instantaneous type; if you need remote trip indication, look at the SENTRON RCCB with auxiliary switch option (different order code).