What this 40 A SENTRON MCCB delivers
The Siemens 3VA2140-5KQ42-0AA0 is a 4-pole molded case circuit breaker from the SENTRON 3VA2 series, rated at 40 A continuous current (Iu) across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. It carries the ETU860 electronic trip unit, which gives you adjustable overload and short-circuit protection curves plus integral ground-fault monitoring via summation current sensing on the L + N conductor. Breaking capacity hits 121 kA at 415 V and 440 V, and 187 kA at 240 V, so it handles high-fault utility feeds and transformer secondaries without cascading upstream. This is a line-protection device — it guards distribution feeders and large branch circuits, not motor starters. The communication function lets it talk to a higher-level monitoring system for power-quality data and trip-event logging, which is useful if you're tracking arc-flash incident energy or doing selective coordination studies. Insulation voltage is rated at 800 V (Ui), so it's comfortable on 480/277 V and 600 V systems with headroom.
Mounting and panel fit
Dimensions are 181 mm high, 140 mm wide, and 86 mm deep. That's a standard 4-pole MCCB footprint for the 3VA2 frame — it bolts into the panel via the rear mounting plate or optional DIN-rail adapter. Front IP40 protection means it's sealed against tools and fingers but not washdown; keep it inside the enclosure. The optional motor drive lets you remote-trip or remote-reset the breaker for unattended restart schemes.