400 A, 4-pole MCCB with ETU330 — what the ratings mean for your panel
The Siemens 3VA2340-6HM42-0AA0 is a SENTRON molded case circuit breaker rated 400 A continuous (Iu) at 40 °C through 50 °C, with a 4-pole configuration and an ETU330 electronic overcurrent release. That 400 A holds flat across the 40–50 °C band; above 50 °C it derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C — so if your enclosure runs hot, the continuous current you can actually carry drops, and the trip unit settings need to reflect that. The interrupting ratings are substantial: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 7.5 kA at 690 V. At typical 400 V-class distribution voltages, that 187 kA gives you headroom for high-fault installations without cascading upstream breakers. The ETU330 release is electronic, adjustable for long-time, short-time, instantaneous, and ground-fault protection — the N-conductor protection is configurable to OFF, 50%, or 100% of the phase current.
Panel integration and physical fit
The breaker measures 184 mm wide, 248 mm high, and 110 mm deep — a 4-pole frame that occupies roughly 7.24 × 9.76 inches of panel face. Front IP40 rating means it is protected against tools and wires >1 mm but not against water ingress; mount it inside a rated enclosure if washdown or outdoor exposure is expected. The ETU330 is front-accessible for adjustment without removing the cover. Power loss at full rated current is 96 W maximum — factor that into enclosure thermal calculations, especially if the panel is densely packed.
Selectivity and coordination notes
The 187 kA interrupting capacity at 415 V and 440 V means this MCCB can be used as a main or feeder breaker in high-fault installations without requiring a current-limiting upstream device — useful for transformer secondaries or large motor control centers. The ETU330's adjustable short-time delay (typically 0.1–0.5 s) allows zone-selective interlocking with downstream breakers, keeping the faulted branch isolated while the main stays closed. The 800 V rated insulation voltage (Ui) confirms it is suitable for 690 V systems with proper clearance and creepage distances.