400 A MCCB with ETU320 — what the ratings mean for fit
The Siemens 3VA2340-7HL32-0AJ0 is a SENTRON molded case circuit breaker rated for 400 A continuous current (Iu) with an ETU320 electronic trip unit, configured for line protection in a 3-pole package. The 400 A rating holds across 40 °C to 50 °C ambient without derating — at 55 °C it's still good for 385 A, and at 70 °C it carries 340 A, so it handles warm panel environments without stepping up frame size. Breaking capacity hits 330 kA at 240 V, 242 kA at 415/440 V, 187 kA at 500 V, and 52.5 kA at 690 V — that's serious fault-interruption headroom for high-capacity distribution or transformer secondary protection where available fault current is high. The ETU320 is a basic electronic trip unit — no communication, no voltage trigger, no undervoltage release, no ground-fault monitoring. It's a straight overcurrent protector with a trip indicator, suited for fixed-distribution or feeder duty where you don't need metering or remote signaling beyond the auxiliary contact block. The supplied basic switch is order code 3VA2340-7HL32-0AA0, and the auxiliary contact version ships with 2 auxiliary switches plus 1 trip alarm switch (HP type).
Panel fit and thermal budget
Mounts in a standard panel footprint at 138 mm wide, 248 mm tall, 110 mm deep — that depth is the dimension to watch when routing cables behind the breaker or fitting it into a shallow enclosure. Maximum power loss is 96 W at rated load, so adjacent devices need breathing room; don't pack it tight against heat-sensitive electronics without checking the thermal stack. IP40 on the front face keeps dust out of the trip-unit compartment, but the rest of the breaker is open-frame — install in a clean, dry enclosure.