The Siemens SENTRON 5SP3725-3 is a 1-pole miniature circuit breaker with an E tripping characteristic, rated 25 A at 30 °C and breaking 25 kA per EN 60898. That E-curve means it's designed for motor and transformer protection — it handles inrush without nuisance tripping, unlike a B or C curve that would pop on the first start.
That's high for a single-pole device — you'd typically see 10 kA or 15 kA on residential-grade breakers. The 25 kA rating means it's suitable for industrial panelboards with high available fault current, like a main distribution board fed by a large transformer. The E-curve trips magnetically at 10–20× In (250–500 A), which is why it's specified for motor circuits: it ignores the starting surge and only opens on a hard short. Temperature derating is built into the spec: at 40 °C ambient it carries 23.75 A, at 50 °C it's 22.5 A, and at 55 °C it drops to 21.875 A. The 25 A rating is only valid at 30 °C; above that, the thermal element heats up faster and the breaker will trip earlier than the label suggests. Panel builders should treat the 50 °C figure (22.5 A) as the practical continuous rating for a warm enclosure. The 1.5 modular width units (about 27 mm on a DIN rail) is wider than a standard 1-pole MCB (1 MW = 18 mm). That extra space houses the higher breaking capacity internals and the larger terminals — solid/stranded up to 50 mm², minimum 2.5 mm². The saddle terminals and box-terminal infeed make it easier to land larger conductors without wrestling with screw clamps. Shock-rated to 30 g, 11 ms duration, so it holds up in railway or marine auxiliary panels where vibration is a factor.
The 76.3 mm depth includes the housing — check enclosure depth if using a shallow gland plate. IP40 with conductors connected, so it's fine inside a panel but not for wet locations. The integrated locking slide accepts a padlock, wire seal, or cable tie for lockout/tagout — no separate accessory needed.