What it is and what the ratings mean
The Siemens 5SU1324-1RC63 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — rated 63 A, 2-pole, with a C tripping characteristic and 30 mA Type AC residual-current sensitivity. The C-curve means the thermal-magnetic trip holds up to 5–10× rated current for short overloads, so it's sized for motor-starting or transformer inrush loads that would nuisance-trip a B-curve. The 30 mA AC residual-current element catches line-to-ground faults on sinusoidal AC circuits only — not pulsed DC or smooth DC, so it's the standard choice for general-purpose final circuits in residential and commercial distribution boards where no variable-speed drives or electronic loads are downstream. Breaking capacity is 10 kA per EN 60898 and 15 kA per IEC 60947-2. The higher IEC figure applies when the RCBO is used as a distribution-board component in an industrial installation with a known prospective fault level; the EN number governs residential/commercial certification. Either way, it clears a bolted fault up to that level without welding the contacts or cascading upstream — the energy-limitation Class 3 keeps let-through energy low enough to protect downstream wiring. Rated insulation voltage (Ui) is 440 V AC, overvoltage category III, pollution degree 2 — standard for fixed-installation final circuits in a distribution board. Operating frequency is 50 Hz only; this is not a 50/60 Hz dual-rated unit, so confirm mains frequency before specifying.
Panel fit and mounting
Occupies 4 modular width units (72 mm wide) on a DIN rail, with a depth of 70 mm and height of 90 mm. Supply can enter from top or bottom — no fixed orientation — and the RCBO can be mounted in any position. The IP20 rating applies only once the distribution board is installed and conductors are connected; the device itself is not sealed against dust ingress before panel closure. Ambient temperature range is -40 °C to +75 °C, with max 95% humidity. That -40 °C floor matters for unheated enclosures in cold climates — the thermal-magnetic trip element stays within calibration down to that limit.