The Siemens 5SM9636-6 is a SENTRON residual current unit (RC unit) designed as a companion device for the 5SL4 miniature circuit breaker series. It is a 3-pole, type A instantaneous RCD rated at 63 A with a 300 mA residual tripping current, operating on a 230/400 V AC supply at 50 Hz. This is the electronic variant — the DI unit, type A, covering the 0.3...63 A range in a 3-pole, 300 mA configuration.
What the ratings mean for fit
The 63 A rated current at AC and 300 mA residual current define the load and protection envelope: this unit handles circuits up to 63 A and trips on ground faults above 300 mA. Type A detection means it responds to sinusoidal AC residual currents and pulsating DC residual currents — the standard for circuits with single-phase rectifiers, switching power supplies, or electronic loads. The 3 kA surge current resistance tells you it can withstand transient overvoltages without nuisance tripping, which matters on lines with motor starts or capacitor switching. Overvoltage category III confirms it is rated for fixed-installation downstream of the main distribution board.
Mounting and integration
Standard rail mounting — snaps onto a DIN rail in the distribution board. Occupies 3 width units, so at 54 mm wide it fits a standard 3-module slot. Depth is 70 mm, installation depth the same, height 100 mm. Mounting position is any, which gives flexibility in tight enclosures. The supply connects at the top, above the miniature circuit breaker. Terminal accepts solid conductors from 0.75 to 35 mm² and stranded from 0.75 to 25 mm²; tighten to 2.5...3 N·m. IP20 rating — protected against finger contact only when installed in a distribution board with conductors connected. Ambient operating range -25 to +55 °C; storage from -40 to +75 °C.
Compliance and documentation
Designed to DIN EN 61346-2 and DIN EN 81346-2 (function designation F). Overvoltage category III per IEC. The product is silicon-free. Mechanical service life is 10 000 switching cycles typical. The unit is the electronic RC companion for the 5SL4 MCB series — it is not a standalone RCCB; it mounts mechanically and electrically to the 5SL4 breaker. The 5SM9 design designation identifies this as the second-generation RC unit platform.