The Siemens 5SU1324-6KX20 is a SENTRON RCBO — a combined residual-current device and miniature circuit breaker in one 2-pole unit, rated 20 A at 110/120 V AC, 50 Hz. It trips on both overcurrent (B-curve, 10 kA breaking capacity per EN 60898) and earth leakage (30 mA, Type A, 20 kA per IEC 60947-2). The 30 mA Type A rating means it detects sinusoidal AC fault currents plus pulsating DC fault currents — the kind a single-phase rectifier load or a switched-mode supply can produce. That makes it a fit for circuits feeding electronics, appliances, or lighting ballasts where a plain AC-only RCD might miss a fault.
Panel fit and wiring
The 5SU1324-6KX20 occupies 3 modular width units (54 mm) on a DIN rail, with a depth of 77 mm and an installation depth of 70 mm. It accepts supply from either the top or bottom terminals, and the neutral conductor is switched internally — no separate neutral bar needed downstream. The IP20 rating applies once the distribution board is installed with connected conductors; the unit itself is touch-protected. Mounting position is unrestricted, so it can sit horizontally or inverted in a tight enclosure without derating.