What this MCCB is and where it fits
The Siemens SENTRON 3VA2340-5HL42-0BH0 is a 4-pole molded case circuit breaker rated for 400 A continuous current, with an adjustable thermal-magnetic trip unit covering 600 A to 4 000 A. It is designed for line protection in main distribution panels and large sub-feeders where high fault current capacity is required. The interrupting ratings are what make this breaker stand out: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V. That SCCR headroom means it can be installed upstream of smaller breakers without worrying about cascading failure during a fault — the breaker clears the arc before the fault energy damages downstream gear. The 400 A rating holds steady from 40 °C up to 50 °C, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs hot — say, near a transformer or in a non-climate-controlled enclosure — that derating curve is the real-world limit, not the nameplate 400 A.
Integration and mounting
The breaker measures 184 mm wide, 248 mm high, and 110 mm deep. It mounts on a DIN rail or directly to a panel backplate via the base mounting points. The 4-pole footprint occupies roughly 7.24 inches of rail width — plan the enclosure fill factor accordingly. Maximum power loss is 98.5 W at rated load. Manage heat inside the enclosure per standard derating rules. The breaker ships with an undervoltage release (UVR) fitted, plus 2 auxiliary switches and 1 trip alarm switch (HQ design). The UVR ensures the breaker trips if control voltage drops below the dropout threshold — a standard requirement for safety disconnects on motor feeders and emergency-stop circuits.