400 A MCCB with ETU850 — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-8KP32-0AA0 is a 3-pole molded case circuit breaker rated 400 A continuous at 40 °C, built around the ETU850 electronic trip unit. That 400 A holds flat through 50 °C — you only start derating above 55 °C, dropping to 300 A at 70 °C. For a 400 A feeder in a warm enclosure, that thermal headroom matters more than the raw number. Interrupting capacity is 440 kA at 240 V, 330 kA at 415 V, and still 52.5 kA at 690 V. That puts it in the high-fault tier — suitable for main service-entrance or large feeder duty where available fault current is substantial. The 800 V rated insulation voltage confirms it's built for 690 V line-to-line systems without derating the dielectric. The ETU850 trip unit supports communication, so this breaker can report status and trip events over the plant network — useful for a maintenance team that wants to know which feeder cleared without walking the panel. No undervoltage release and no ground-fault monitoring are fitted as standard; those are add-on options if your coordination study calls for them.
Physical fit and panel integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width is a 3-pole frame — it occupies three modular 45 mm slots on a standard DIN rail or panel-mount footprint. The IP40 front protection means it's suitable for enclosed distribution boards where the front face is behind a door; not rated for washdown environments. Maximum power loss is 96 W. In a sealed enclosure with multiple breakers, that heat needs to be factored into the thermal calculation — especially if you're running near the 70 °C upper operating limit.