MCCB with ETU350 — what the ratings mean for the panel
The Siemens SENTRON 3VA2340-5HN32-0KG0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu) at 40 °C, with the ETU350 electronic trip unit configured for line protection. The interrupting ratings tell you where this breaker fits: 187 kA at 240 V AC, 121 kA at 415 V, 55 kA at 440 V, 36 kA at 500 V, and 7.5 kA at 690 V — so at typical 400 V class distribution voltages it handles high fault currents without cascading upstream. The ETU350 release gives adjustable short-time delay (tsd) from 0.02 s to 0.4 s and adjustable response time (tr) from 0.5 to 17 s, which lets you coordinate selectively with downstream breakers on a feeder or main. Thermal derating is published: the breaker holds 400 A through 50 °C, then drops to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs above 50 °C, size the load accordingly or provide additional ventilation. The 96 W maximum power loss at rated current matters for enclosure heat rise calculations — a sealed IP40 front panel needs that dissipation accounted for in the thermal budget.
Panel fit and integration
Dimensions: 138 mm wide (5.4 in), 248 mm high (9.8 in), 110 mm deep. The 138 mm width is a standard 3-pole MCCB footprint for this class — it fits the common cutout and bus-bar spacing in SENTRON distribution panels and switchboards. The 110 mm depth includes the case body; verify clearance for the ETU wiring and any auxiliary contact blocks behind the front cover.