Siemens SENTRON 5SU1324-7FM20 RCBO — 20 A, Type A, 10 kA
The Siemens SENTRON 5SU1324-7FM20 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) rated at 20 A with a Type A fault current sensitivity and a 10 kA breaking capacity per EN 60898. It combines overcurrent and residual current protection in a single 3-module-wide unit (54 mm), saving DIN-rail space compared to separate MCB + RCCD pairs. Rated current is 20 A at 30 °C, derating to 18.8 A at 40 °C, 18.2 A at 45 °C, 17.4 A at 50 °C, 16.2 A at 55 °C, and 14.6 A at 70 °C. The thermal curve means a panel running at 50 °C ambient loses about 13 % of the headline rating — factor that into your load schedule if the enclosure runs warm. Type A fault current detection means it trips on pulsating DC residual currents (typical from single-phase rectifiers, switching power supplies, and variable-speed drives) in addition to sinusoidal AC. That makes it the right choice for modern loads with power electronics — a standard Type AC would not catch the pulsating component. The C tripping characteristic (5–10× In magnetic release) suits mixed resistive-inductive loads like small motor circuits, lighting banks, and general distribution where moderate inrush is expected. Instantaneous design (no intentional delay) for fast fault clearing.
Three width units (54 mm) — check your rail fill before swapping from a narrower breaker. Not for wet or washdown zones without an enclosure — keep it inside a cabinet.
Operating ambient -25 to +55 °C; storage -40 to +75 °C. Halogen-free and silicon-free construction — useful for cleanroom or high-reliability installations where outgassing matters. Overvoltage category III (distribution-level), energy limiting class 3. Lifecycle status is current production.