What this 40 A MCCB brings to the panel
The Siemens SENTRON 3VA2140-5KP42-0AA0 is a 4-pole molded case circuit breaker rated for 40 A continuous current. That 40 A holds steady from 40 °C all the way up to 70 °C — no derating curve to chase in a hot enclosure. The interrupting rating at 240 V is 187 kA, which drops to 121 kA at 415 V and 440 V, then 76 kA at 500 V, and 3.8 kA at 690 V. That spread tells you this breaker is sized for high-fault commercial and light industrial distribution, not for a 690 V motor branch circuit. It carries the ETU850 electronic trip unit — that's the adjustable-release version, not a fixed thermal-magnetic. The N-conductor protection is adjustable from OFF through 40 % to 160 %, and the response time tr is settable from 0.5 s up to 25 s. That kind of adjustability matters when you're coordinating selectivity downstream or protecting a feeder that feeds mixed loads.
Fit and footprint
The case measures 181 mm high by 140 mm wide and 86 mm deep. That depth is the critical dimension for enclosure clearance — 86 mm (3.4 in) means it fits standard 200 mm deep enclosures without the cover bumping the door. The IP40 rating on the front means it's protected against tools and wires over 1 mm, but it's not sealed against moisture; keep it in a dry indoor panel.