What it is and what it does
The Siemens SENTRON 5SV4617-0KL is a 2-pole residual current circuit breaker (RCCB) designed for AC fault currents, rated at 80 A and 300 mA tripping sensitivity. It's built for DIN-rail mounting in distribution boards — the kind of thing you'd put on a lighting or general-power submain where you need earth-leakage protection but don't want nuisance trips from motor inrush. Rated 230/400 V AC, overvoltage category III, with a 10 kA short-circuit current rating (SCCR) — that means it's rated to break a fault up to 10 kA without welding its contacts or blowing up the panel. The 300 mA trip threshold is an instantaneous design (no intentional delay), so it clears ground faults fast. The 80 A rating holds at 40 °C ambient; above that you need to derate. At 45 °C it's 77.87 A, at 50 °C it's 74.77 A, and it drops to 48.19 A at 70 °C. That derating curve matters if this RCCB sits in a hot enclosure near transformers or drives — the real-world ampacity is the temperature-corrected number, not the sticker.
Panel fit and wiring
The 5SV4617-0KL takes up 2 width units (36 mm) on the DIN rail, with a 70 mm installation depth — standard for a 2-pole RCCB in this class. Mounting position is any, so you can flip it upside down if the busbar layout demands it. Supply can come from top or bottom; the design is marked 'N left' per the SENTRON convention. Terminals accept solid or stranded copper from 0.75 mm² up to 35 mm² — that covers everything from a 2.5 mm² lighting circuit tail to a 35 mm² subfeed. The I²t withstand is 110,000 A²s, so it coordinates with most downstream MCBs without the RCCB being the weak link in the fault chain. IP20 rating applies when installed in a distribution board with conductors connected — normal for enclosed panels. The housing is finger and back-of-hand safe per the standard, so you're not getting a shock if you brush the terminals with the cover off.