What it is and what it does
The Siemens 5SV4347-0MB is a 4-pole residual current circuit breaker (RCCB) from the SENTRON family, designed for DIN-rail mounting in distribution boards. It is a Type AC device — meaning it detects sinusoidal AC residual currents only — with a rated tripping residual current of 30 mA and a rated operational current of 80 A at 40 °C. The instantaneous design means it trips without intentional delay when the residual current exceeds the threshold.
Key ratings and what they mean for fit
The 80 A rating at 40 °C is the baseline; the device derates linearly as ambient temperature rises — 77.57 A at 45 °C, 74.59 A at 50 °C, down to 48.84 A at 70 °C. If the distribution board runs warm, the continuous load must be checked against the derated value, not the 80 A headline. The 30 mA trip threshold is the standard for personal protection against direct contact in residential and commercial installations. The 10 kA short-circuit current rating (SCCR) means the device can safely interrupt a fault up to that level without external fusing, provided the upstream overcurrent device is coordinated per the manufacturer's selectivity tables.
Mounting and panel integration
The 5SV4347-0MB occupies 4 width units (72 mm) on a DIN rail (REG) and can be mounted in any position. Depth is 70 mm, matching the standard installation depth for SENTRON modular devices. The supply cable can enter from the top or bottom. The IP20 rating applies when installed in a distribution board with conductors connected — standard for enclosed panels; no washdown rating.
Compliance and approvals
The device is silicon-free, which matters for applications where silicone outgassing can contaminate contacts or optics. Overvoltage category III suits fixed installation downstream of the main distribution board. The protection against electric shock is rated as finger and back-of-hand safe per the design standard.