The Siemens SENTRON 5SJ3620-7 is a 20 A miniature circuit breaker with a C tripping characteristic, designed for 3P+N (4-pole) 400 V AC circuits. Its 4.5 kA breaking capacity per EN 60898 covers most commercial and light industrial distribution panels — adequate for sub-distribution where the upstream device limits the fault current. The C-curve (5–10× In magnetic trip) suits moderate inrush loads like small motor groups, lighting banks, or transformer primaries where you need the breaker to hold through the start surge but still trip fast on a hard fault.
What the ratings mean for your panel
Rated 20 A at 400 V AC, this breaker handles a 3-phase+N load up to roughly 13.8 kW resistive. The C-curve means the magnetic trip fires between 100 A and 200 A — right-sized for motor starting or capacitor bank inrush without nuisance trips. Breaking capacity of 4.5 kA per both EN 60898 and IEC 60947-2 tells you the breaker can safely interrupt a fault up to that level; if your available fault current at the panel exceeds 4.5 kA, you need an upstream current-limiting device or a higher-rated breaker. Insulation voltage rated 440 V AC gives headroom on 400 V systems. The 3P+N design switches all three phases and switches the neutral, which is required for TN-S or TT systems where you want the neutral isolated on a fault. Wire range accepts solid or stranded conductors from 0.75 mm² up to 25 mm² — covers everything from a 1.5 mm² lighting circuit to a 6 mm² sub-feed. The terminals are sealable, which matters for utility-metering or revenue-grade installations where the meter seal must stay intact. Touch protection is built in (IP20 with conductors connected), so the busbar area is finger-safe once the breaker is snapped onto the DIN rail.
Integration notes
Mounts on standard 35 mm DIN rail in any orientation — the 4 width units (roughly 72 mm) occupy four module spaces in the enclosure. Installation depth is 70 mm, so it fits most 100 mm deep distribution boards. Ambient temperature range of -20 to +45 °C covers unheated electrical rooms and outdoor enclosures in temperate climates; storage range extends to -40 to +75 °C. Vibration resistance tested to 50 m/s² at 25–150 Hz and 60 m/s² at 10–150 Hz per IEC 60068-2-6 — suitable for installation near rotating machinery or on shipboard panels. Mechanical endurance is rated for 20 000 switching cycles, which is typical for this class of MCB in distribution duty.