The Siemens 5SU1654-7KK25 is a SENTRON RCBO (residual current circuit breaker with overcurrent protection) — a single device that combines a 25 A C-curve MCB with a 300 mA Type A RCD in a 2-module-wide (36 mm) housing. It protects final circuits against overload, short-circuit, and earth leakage in one DIN-rail unit, saving panel space over separate devices. Rated 230/240 V AC at 50 Hz, it carries a 10 kA breaking capacity per EN 60898 and 20 kA per IEC 60947-2 — the higher IEC figure matters for industrial panels where fault currents can exceed domestic levels.
Mounts in any position; feed from top or bottom. Neutral conductor is switched internally (1P+N), so the neutral pole opens with the line — no separate neutral bar needed downstream. Touch-protected terminals reduce arc-flash risk during maintenance.