What this MCB is and where it fits
The Siemens 5SJ4140-8HG41 is a 1-pole miniature circuit breaker from the SENTRON 5SJ4 series, designed for branch-circuit protection in industrial control panels and mechanical-engineering installations. Its D-tripping characteristic handles high inrush loads — motor starters, transformers, solenoid banks — without nuisance trips, while the 10 kA breaking capacity per EN 60898 and 15 kA per IEC 60947-2 cover typical industrial fault levels. The 18 mm width occupies one modular unit on standard DIN rail, and the IP20 enclosure with IP40 in the handle range suits enclosed panel use.
Key ratings and what they mean for fit
Rated at 400 V AC and 60 V DC, this MCB covers single-phase AC loads and low-voltage DC control circuits. The D-curve trips between 10× and 20× In, so it clears fast on hard shorts but rides through the magnetizing inrush of a small transformer or a DC solenoid. The 10 kA (EN 60898) and 15 kA (IEC 60947-2) ratings mean it can interrupt faults up to those levels without upstream coordination — a 10 kA SCCR is typical for a panel fed from a 100 kVA transformer; the 15 kA IEC rating gives headroom for higher-fault points. Insulation voltage of 440 V AC confirms the internal creepage distances are sized for 400 V line-to-line panels.