Siemens SENTRON 3VA2440-6HN32-0AA0 — 400 A MCCB with ETU350
The Siemens SENTRON 3VA2440-6HN32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current across the full 40 °C to 70 °C ambient range — no derating needed as the panel warms up. The 4800 A rated uninterrupted current (Iu) sets the breaker's frame size; the ETU350 electronic trip unit handles the overcurrent protection curve. This is a line-protection design (not motor-protection), so it's sized for feeder or main breaker duty in a distribution panel.
What the interrupting ratings mean for coordination
At 240 V the breaker interrupts 242 kA — that's utility-transformer-level fault current, so it's suited for service-entrance or main-tie applications where available fault current is high. At 415 V and 440 V it holds 187 kA; at 500 V it drops to 121 kA; at 690 V it's 9 kA. The steep drop above 500 V means you need to verify the SCCR at your system voltage before committing the BOM line — at 690 V the 9 kA rating may force an upstream current-limiting device if your fault current exceeds that.
Panel fit and thermal budget
Footprint is 138 mm wide by 248 mm tall by 110 mm deep — standard SENTRON 3VA frame size for a 400 A MCCB. Plan for 63.5 W maximum power loss at full load; that heat has to be vented inside the enclosure. The ETU350 is electronic (not thermal-magnetic), so it draws its own operating power from the line side and doesn't rely on bimetal heating — that helps with trip accuracy but means the breaker needs control power to trip on undervoltage or shunt-tap events (no undervoltage release fitted on this variant).