Siemens SENTRON 5SN6140-7CN — 1-pole C-curve MCB at 40 A
The Siemens 5SN6140-7CN is a SENTRON miniature circuit breaker rated 40 A with a C tripping characteristic, single-pole construction, and a 6 kA breaking capacity per EN 60898 at 230/400 V AC.
Breaking capacity of 6 kA per EN 60898 at 230/400 V AC tells you this MCB can safely interrupt a fault current up to 6,000 A symmetrical. For industrial panels with higher fault capacity, you'd step to the IEC 60947-2 rating on a sibling like the 5SL series. Single-pole switching (1P) with no neutral conductor switching — the neutral is either a solid bus or a separate terminal block. Rated operational voltage covers 250 V AC single-phase and 440 V AC multi-phase, with a DC maximum of 72 V. That DC rating is low — this is an AC-optimized breaker; for DC circuits above 72 V, you need a DC-rated MCB. In a densely populated enclosure, that heat adds up — account for it in your thermal derating calculation, especially if ambient inside the panel exceeds 40 °C. Vibration resistance per IEC 60068-2-6 at 50 m/s² over 25 to 150 Hz means it holds calibration and contact stability under moderate vibration — fine for wall-mounted panels near rotating machinery, but not rated for direct mounting on a motor or compressor frame without additional damping.
Deployment context
Snap-on DIN-rail mounting in any position (vertical, horizontal, upside-down — the breaker operates identically). Accepts solid conductors up to 25 mm², which is generous for a 40 A circuit — typically you'd terminate 6 or 10 mm², but the larger terminal accommodates parallel feeds or looping through. The sealable feature allows the panel builder to lock the toggle position after commissioning — useful for critical circuits where unauthorized reset must be prevented.
Rated for overvoltage category III (distribution board level) and pollution degree 2 (non-conductive pollution with occasional condensation). The manufacturer provides IEC/EN 60898 certification documentation; RoHS and REACH declarations are available through the standard Siemens documentation portal.