What it is and what it does
The Siemens 5SU1354-7LB13 is a SENTRON RCBO — a combined residual-current circuit breaker and miniature circuit breaker in one 2-module-wide (36 mm) package. It protects a 1P+N final subcircuit against overload, short-circuit, and earth leakage, with a Type A residual-current sensor that catches pulsating DC fault currents as well as sinusoidal AC. The tripping characteristic is C (magnetic release between 5 and 10× In), and the unit is rated 13 A at 30 °C ambient, derating to 10.01 A at 70 °C. Short-circuit breaking capacity is 10 kA per EN 60898 and 20 kA per IEC 60947-2, so it handles fault currents up to those levels without rupturing — enough for most commercial and light industrial distribution boards.
What the ratings mean for fit
The 13 A rating at 30 °C is the headline current; at 40 °C it drops to 12.48 A, at 50 °C to 11.96 A, and at 70 °C to 10.01 A. If the panel ambient runs hot — say a crowded enclosure near a furnace line — size the load to the derated figure, not the 30 °C number. The 10 kA per EN 60898 covers the standard domestic/commercial fault level; the 20 kA per IEC 60947-2 applies when the RCBO is used in an industrial distribution board with higher prospective short-circuit current. The Type A residual-current sensor means it trips on AC faults and on pulsating DC up to 6 mA — essential for circuits feeding single-phase rectified loads like switched-mode power supplies, LED drivers, or variable-speed drives with small front ends.
Mounting and integration
Snaps onto standard 35 mm DIN rail, occupies 2 module widths (36 mm wide, 77 mm deep, 90 mm tall). Installation depth is 70 mm — the extra 7 mm is the front projection of the toggle and test button. Supply can enter from top or bottom, which saves a busbar re-run when retrofitting into an existing board. The IP20 rating means it's protected against solid objects larger than 12 mm (fingers) but not against moisture — it lives inside a distribution board, not in a washdown zone. Pollution degree 2 and overvoltage category III are standard for fixed-installation final circuits. Mounting position is any, so horizontal DIN-rail orientation in a shallow enclosure is fine.