What this 400 A MCCB carries and where it fits
The Siemens SENTRON 3VA2340-7JQ32-0AA0 is a 3-pole molded case circuit breaker rated 400 A continuous (Iu) with an ETU560 electronic trip unit. It's built for line protection in main distribution boards, switchgear, and industrial feeder circuits where high fault current capacity is non-negotiable. Breaking capacity hits 330 kA at 240 V and 242 kA at 415 V, dropping to 7.5 kA at 690 V — that SCCR headroom covers transformer secondaries and large motor branch circuits without cascading upstream breakers. Rated insulation voltage is 800 V. The ETU560 release supports adjustable N-conductor protection (OFF, 20% to 160%).
Thermal derating and panel fit
Full 400 A rating holds through 50 °C ambient; above that it derates linearly to 300 A at 70 °C. For a 40 °C panel, no derating needed — but if the enclosure runs hot from adjacent drives or transformers, factor the curve. Dimensions are 248 mm high, 138 mm wide, 110 mm deep. The 3-pole frame mounts on a standard backplate or DIN rail adapter; front IP40 keeps out tools and dust in a closed cabinet. Maximum power loss is 96 W at rated current — budget that heat into the enclosure ventilation. Operating range spans -25 °C to 70 °C; storage from -40 °C to 80 °C.