What the ratings mean for fit
The Siemens SENTRON 3VA2340-5KP32-0HC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu) at up to 50 °C ambient — no derating needed in a typical 40 °C panel. Above 50 °C it steps down: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. That thermal curve is the one to check if your enclosure runs hot; the 400 A rating holds only within the standard range. Breaking capacity is the headline: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. For a 400 A frame, those numbers mean it can interrupt a bolted fault at the main distribution board without upstream fuses — the 121 kA at 415 V covers most industrial low-voltage networks in Europe and Asia. The 17 kA at 690 V is lower but still adequate for most 690 V motor control centers. The ETU850 electronic trip unit provides line protection with communication capability (the order code suffix -0HC0 includes the communication function). It ships with a shunt trip (STL) and two HQ auxiliary switches. No undervoltage release, no ground-fault monitoring, no phase-failure detection — this is a straight overcurrent + shunt-trip package for feeder protection.
Lifecycle and sourcing reality
The basic switch (the breaker without the electronic trip) is order code 3VA2340-5KP32-0AA0; the integrated auxiliary trip is 3VA9688-0BL30. Those are the sub-assembly references if you ever need to replace just the trip unit or the switch body separately.
Panel integration notes
Dimensions: 138 mm wide, 248 mm high, 110 mm deep. That 138 mm width is the standard 3-pole MCCB footprint for a 400 A frame — it fits the same cutout as other SENTRON 3VA2 breakers. The 110 mm depth includes the arc chamber and terminals; verify clearance behind the panel door for the shunt trip wiring. Maximum power loss is 96 W at rated current. That heat has to be vented — in a sealed enclosure with other high-current devices, factor the dissipation into your thermal budget. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.