What this MCCB brings to a panel
The Siemens SENTRON 3VA2440-6HL32-0DH0 is a 3-pole molded case circuit breaker rated for 400 A continuous current, with an ETU320 electronic trip unit that gives you adjustable overload and short-circuit protection curves — no need to swap the whole breaker if the load profile shifts. Breaking capacity hits 242 kA at 240 V, 187 kA at 415 V, and still 40 kA at 690 V — that's enough to handle high-fault utility feeds or transformer secondaries without cascading upstream. An undervoltage release (UVR) is built in, so if the control voltage drops, the breaker opens automatically — a common requirement for safety circuits on conveyor or pump lines. The auxiliary contact set includes two auxiliary switches plus a separate trip alarm switch (HQ), letting the PLC know exactly when the breaker tripped on a fault versus a manual open.
Thermal derating — what the 400 A rating really means
The 400 A rating holds flat from 40 °C up to 50 °C, then derates gradually: 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. If your panel runs hot near the top of that range, you lose about 10 % of the headroom — factor that into your load schedule. Operating ambient spans -25 °C to 70 °C; storage range goes -40 °C to 80 °C. That storage floor matters if the spare sits in an unheated warehouse over winter.
Panel fit and dimensions
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep — a standard MCCB footprint that drops into most existing SENTRON or third-party panel cutouts without re-drilling the gland plate. Rated insulation voltage is 800 V, so it's comfortable on 480 V or 600 V class systems with plenty of margin.
What the ETU320 release gives you
The ETU320 is an electronic trip unit with adjustable long-time pickup, short-time pickup, and instantaneous settings — you can fine-tune coordination with downstream breakers without changing the breaker itself. Maximum power loss is 66 W at full load — that's heat that stays inside the enclosure, so check your panel's thermal budget if you're packing multiple breakers in a sealed cabinet.