What it is and what it does
The Siemens 3VA2140-6KQ32-0KF0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It's a 3-pole unit rated at 40 A continuous current, with a full-scale value of 40 A and an adjustable initial value of 16 A. The breaker carries a massive 242 kA breaking capacity at 240 V AC, dropping to 187 kA at 415 V and 440 V, then 121 kA at 500 V, and 3.7 kA at 690 V. That 242 kA at 240 V means it can safely interrupt a fault current up to that level without the arc flashing over or damaging upstream gear — critical for high-fault installations like large transformer secondaries or industrial switchboards where the available fault current is sky-high.
Physical fit and panel integration
Dimensions are 181 mm high, 105 mm wide, 86 mm deep. That 86 mm depth is the critical number for enclosure selection — it's shallow enough to fit a standard 200 mm deep wall-mount panel with room for wiring gutters. The 105 mm width means it takes up three pole spaces on a DIN rail or bolted bus. No special cutout; it mounts on the standard MCCB footprint. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C, so it's fine for unheated electrical rooms or outdoor enclosures in moderate climates.
Thermal performance and derating
One thing that stands out: the rated current holds at 40 A from 40 °C all the way up to 70 °C ambient. No derating curve to chase across the typical panel temperature range — that's unusual for an MCCB and simplifies the panel builder's thermal budget. Max power loss is 1.6 W, which is negligible for heat buildup in a multi-breaker enclosure.