What this RCBO is and what it does
The Siemens SENTRON 5SV9316-7NK25 is a 2-pole residual-current-operated circuit breaker (RCBO) combining overcurrent protection and earth leakage protection in a single 18 mm wide module. Rated at 25 A with a 30 mA residual trip threshold, Type A detection, and a C tripping characteristic, it handles both sinusoidal AC and pulsating DC fault currents — the standard choice for mixed-load final circuits in commercial and industrial distribution boards. Breaking capacity is 6 kA per EN 60898 and IEC 60947-2, sufficient for most sub-distribution applications where the prospective short-circuit current at the board is under that limit. The 4 kV surge voltage rating (overvoltage category III) means it's designed for fixed installation downstream of the main distribution board, not for equipment-level protection.
Sizing and derating — the real current rating
The 25 A rating holds at 30 °C ambient. At 40 °C it derates to 23.75 A, at 45 °C to 23 A, at 50 °C to 22.25 A, and at 55 °C to 21.5 A. If the distribution board runs warm — common in densely packed enclosures — the effective continuous current drops. Size the upstream protective device and cable accordingly. The RCBO occupies 1 modular width unit (18 mm) on a DIN rail, with an installation depth of 70 mm and overall depth of 77 mm. Mounting position is unrestricted; supply can enter from top or bottom. Pollution degree 2 (non-conductive, occasional condensation) covers typical indoor panel environments.
Lifecycle and sourcing reality
Halogen-free and silicon-free construction suits environments where outgassing or contamination must be minimized — clean rooms, medical equipment, or sealed enclosures near sensitive electronics.
Panel integration notes
Snap-on DIN-rail mount, 18 mm width (1 MW). IP20 rating applies only when installed in a distribution board with connected conductors — not for standalone open-panel use. The RCBO is designed for fixed wiring; the spring-loaded terminal accepts copper conductors typical of final circuits. Operating temperature range spans -40 °C to 75 °C, covering unheated storage and hot panel conditions. The energy limitation class 3 indicates fast arc extinction, limiting let-through energy to protect downstream equipment.