What this MCCB delivers — and what the ratings actually mean
The Siemens SENTRON 3VA2040-5KQ42-0AA0 is a 4-pole molded case circuit breaker 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. That flat thermal curve simplifies panel design: you don't have to oversize for a hot enclosure. Breaking capacity is the headline here: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3 kA at 690 V. Those numbers mean this breaker can safely interrupt a fault current up to those levels without welding contacts or cascading upstream — critical for high-fault installations like transformer secondaries or large motor control centers. It carries the ETU860 electronic overcurrent release, which gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves. The ground-fault monitoring uses summation current formation on L+N, so it catches leakage without a separate core-balance CT. Rated insulation voltage Ui is 800 V, and the front face is IP40 — fine for a clean indoor panel, but not for washdown zones. Communication function is built in, and an optional motor drive is available for remote tripping or re-closing.
Panel fit and integration
Dimensions: 181 mm high, 140 mm wide, 86 mm deep — a standard 4-pole MCCB footprint. Optional motor drive and communication function mean it can be integrated into a remote-controlled or monitored distribution system without a separate contactor or RTU.