The Siemens SENTRON 5SM9623-0 is a 2-pole residual current (RC) unit designed to snap onto the side of a 5SL4 miniature circuit breaker, forming a combined RCBO assembly. It's rated for 40 A continuous current and trips on AC fault currents at 300 mA, with a supply voltage of 230/400 V AC. This is a type AC device — it detects sinusoidal AC residual currents only. For pulsating DC or smooth DC fault currents, you'd need a type A or type B unit. The 300 mA trip threshold is typical for fire protection or high-leakage industrial circuits rather than personal shock protection (which usually calls for 30 mA). The unit mounts on standard DIN rail, occupies 2 width units (36 mm), and installs in any position. Its IP20 rating applies only when the distribution board is closed with conductors connected — so it's strictly for inside a panel, not exposed to washdown or dust.
Sourcing & Lifecycle
The mechanical service life is rated at 10,000 switching cycles typical, which is standard for this class of residual current device. The surge current resistance is 3 kA, so it can handle the inrush from a downstream short circuit without nuisance tripping or damage.
Terminal & Wiring
Screw-type terminals accept solid conductors from 0.75 to 35 mm² and stranded from 0.75 to 25 mm². Tightening torque is 2.5 to 3 N·m — a standard screwdriver setting, no special tooling needed. The supply cord connects at the top, above the miniature circuit breaker. Installation depth is 70 mm, matching the 5SL4 breaker it pairs with. That's a common depth for DIN-rail residential and light commercial panels; no extra enclosure depth required.
Environmental & Compliance
Operating ambient temperature range is -25 to +55 °C, with storage from -40 to +75 °C. Overvoltage category III means it's suitable for fixed installation downstream of the main distribution board. The unit is silicon-free.