What it is and what it does
The Siemens 5SU1353-7KK10 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 single-phase final subcircuit against overload, short-circuit, and earth leakage. Rated 10 A at 30 °C with a C tripping characteristic, it handles moderate inrush loads like small motors, lighting banks, or control transformers. Breaking capacity is 4.5 kA per EN 60898 and 15 kA per IEC 60947-2, so it clears faults up to those levels without welding contacts.
Ratings and what they mean for fit
The C-curve means magnetic trip occurs at 5 to 10 times rated current — typical for circuits with motor or transformer inrush. At 10 A, that's 50 to 100 A instantaneous trip. The unit is 1P+N (switched phase, switched neutral), so it disconnects both conductors on fault. Rated insulation voltage is 264 V, surge voltage resistance 4 kV, overvoltage category III — suitable for fixed-installation distribution boards. Operating frequency is 50 Hz only. Temperature derating is published: at 40 °C the rating drops to 9.5 A, at 50 °C to 9 A, at 60 °C to 8.5 A. If the panel ambient runs hot, size up accordingly.
Mounting and integration
Snaps onto 35 mm DIN rail. Width is 2 modular units (36 mm), depth 77 mm, installation depth 70 mm. Mounting position any — no derating for upside-down or horizontal. Supply can enter from top or bottom. IP20 with conductors connected and distribution board installed. Pollution degree 2, so it's fine for normal dry indoor environments. Halogen-free and silicon-free construction matters for clean-room or high-reliability panels where outgassing can't be tolerated.