What it is and what it does
The Siemens 5SU1354-6LB10 is a SENTRON RCBO (residual current circuit breaker with overcurrent protection) combining a 2-pole (1P+N) miniature circuit breaker with a Type A residual current device in a single 2-module-width (36 mm) package. Rated at 10 A with a B-curve tripping characteristic, it protects final circuits against overload and short-circuit while the integrated residual current element detects sinusoidal AC and pulsating DC fault currents (Type A). Breaking capacity is 10 kA per EN 60898 and 20 kA per IEC 60947-2, giving the part headroom for high-fault installations — the IEC 60947-2 rating is the one to use when coordinating with upstream devices in an industrial panel.
Thermal derating — the real-world current rating
The 10 A rating holds at 30 °C ambient. Above that, derate linearly: 9.5 A at 40 °C, 9 A at 50 °C, 8.5 A at 60 °C, and 7.7 A at 70 °C. In a warm enclosure (50 °C+), the effective continuous current is closer to 9 A — factor that into the load calculation.
Mounting and integration
Snaps onto DIN rail, 2 MW wide (36 mm). Mounting position is unrestricted — vertical, horizontal, or inverted — and the supply can enter from top or bottom. Installation depth is 70 mm, overall depth 77 mm. IP20 rated (with distribution board installed and conductors connected), so it belongs inside a closed panel — not exposed to washdown or outdoor weather.
Construction and compliance
Halogen-free and silicon-free construction, overvoltage category III, pollution degree 2. Energy limitation class 3 — meaning it limits let-through energy to a low level during a fault, protecting downstream equipment.