400 A MCCB with ETU550M — what the ratings mean for your panel
The Siemens 3VA2440-7MP32-0AA0 is a 3-pole SENTRON molded case circuit breaker rated for motor protection duty. It carries a continuous current Iu of 400 A across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. The ETU550M electronic trip unit gives you adjustable overload and short-circuit protection curves, plus phase failure detection, which is the main reason you spec this over a thermal-magnetic breaker on a motor feeder. Interrupting capacity is the headline number here: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V. That puts it in the high-fault-current bracket — useful downstream of a large transformer or on a switchboard with stiff utility feed. At 690 V the rating drops to 9 kA, so if your line voltage is up there, verify the available fault current stays under that ceiling. The 1-second short-time withstand is 5 kA, which matters for selective coordination with downstream breakers. Physical fit: 138 mm wide, 248 mm tall, 110 mm deep. That is a standard 3-pole MCCB footprint for this current class — it lands on a DIN rail or mounts direct to a backplate. The front face carries IP40 protection, so it is fine in a typical enclosed panel but not rated for washdown environments.
Integration notes for the panel builder
The 3VA2440-7MP32-0AA0 includes a communication function — check the specific protocol variant on your order code suffix if you need fieldbus integration. Power loss at full rated current is 63.5 W max; factor that into your enclosure thermal calculation. The ETU550M release is field-adjustable, but the trip curves and settings should be coordinated with the upstream protective device before commissioning. Rated insulation voltage Ui is 800 V. Storage temperature range is -40 °C to 80 °C; operating ambient is -25 °C to 70 °C.