What this 400 A MCCB does on your line
The Siemens 3VA2440-7KP32-0AA0 is a 3-pole SENTRON molded case circuit breaker rated for a continuous current Iu of 400 A, with an ETU850 electronic trip unit for adjustable line protection. At 240 V it can interrupt up to 330 kA of fault current; at 415 V and 440 V that drops to 242 kA, at 500 V to 187 kA, and at 690 V to 9 kA — so the voltage class of your distribution board determines which interrupting rating governs your coordination study. The ETU850 release gives you adjustable time-current curves (tr max 25 s) and a ground-fault detection option — though this specific variant ships without ground-fault monitoring. Communication and other measurement functions are built in, so it can talk to a higher-level control system for energy monitoring or remote trip indication.
Temperature derating — don't spec the 400 A number alone
The 400 A rating holds from 40 °C through 50 °C ambient. Above that it derates linearly: 376 A at 55 °C, 352 A at 60 °C, 324 A at 65 °C, and 300 A at 70 °C. If your panel sits near a heat source or in a non-climate-controlled enclosure, use the derated figure — not the 400 A nameplate — for your load schedule. Maximum power loss is 63.3 W, so factor that into your enclosure ventilation. The breaker itself can operate between -40 °C and 70 °C ambient, and survive storage down to -40 °C and up to 80 °C.
Panel fit and footprint
The case measures 248 mm high by 138 mm wide by 110 mm deep (9.8 × 5.4 × 4.3 inches). That's a standard 3-pole MCCB footprint — it'll drop into most DIN-rail or panel-mount arrangements without re-drilling the gland plate. Front IP40 protection means it's fine in a clean indoor enclosure but not for washdown areas.