What this MCB is and where it fits
The Siemens 5SY7313-7 is a 3-pole miniature circuit breaker from the SENTRON 5SY7 series, rated 13 A with a C tripping characteristic. It occupies 3 modular width units (54 mm) on a DIN rail and installs at a 70 mm depth behind the panel face, with an overall depth of 76 mm. The C-curve means it trips between 5 and 10 times rated current — the standard choice for motor-starter and lighting circuits where inrush isn't extreme but you still want some tolerance for short-duration starting currents. Rated for AC supply at 50/60 Hz, it carries a breaking capacity of 15 kA per EN 60898 and 25 kA per IEC 60947-2. The higher IEC figure matters when the MCB sits downstream of a transformer or in an industrial panel where the prospective fault current can exceed the domestic standard. Overvoltage category III and pollution degree 3 mean it's rated for fixed installations inside a distribution board or control panel — not for outdoor or wet locations (IP20 only, with conductors connected).
Thermal derating — the real-world current
The 13 A rating holds at 35 °C ambient. Above that, the bimetallic strip starts to shift: 12.38 A at 40 °C, 12.05 A at 45 °C, 11.73 A at 50 °C, 11.38 A at 55 °C, and 11.02 A at 60 °C. If your panel runs hot — say, a sealed enclosure with drives — size the load to the derated figure at your expected ambient, not the nameplate 13 A. The breaker itself can be mounted in any position, which helps with airflow routing inside a crowded cabinet.