400 A MCCB with ETU350 — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-6HN32-0DC0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current (Iu) with an ETU350 electronic trip unit. The 242 kA breaking capacity at 240 V means it can safely interrupt fault currents up to that level without upstream cascading — sized for high-fault installations like transformer secondaries or large motor control centers. At 415 V and 440 V it still holds 187 kA, dropping to 40 kA at 690 V, so verify the available fault current at your system voltage. The 400 A rating holds flat from 40 °C through 50 °C ambient; above that it derates to 385 A at 55 °C and 340 A at 70 °C, which matters for sealed enclosures or high-ambient machine bays.
Line protection version — what it guards
This is the line protection variant, meaning the ETU350 is configured for cable and busbar protection rather than motor or generator protection. It ships with an undervoltage release (UVR) integrated and two HQ auxiliary switches for status feedback to a PLC or annunciator panel. No communication function, no ground fault monitoring, no phase failure detection — it's a straightforward thermal-magnetic + electronic trip breaker for distribution feeder duty.
Panel integration — footprint and auxiliaries
At 138 mm wide, 248 mm tall, and 110 mm deep, this MCCB fits standard SENTRON 3VA drawout or fixed-mount footprints. The two HQ auxiliary switches provide form-C contacts for remote status — one for open/closed, one for tripped, typical for a distribution breaker. The undervoltage release will drop the breaker on loss of control voltage; if your application doesn't require UVR, factor that into the control wiring because the release coil draws continuously when the breaker is closed. Maximum power loss is 98.5 W — account for that heat in a sealed enclosure derating calculation.