400 A MCCB with ETU560 — what the ratings mean for fit
The Siemens SENTRON 3VA2440-8JQ42-0AA0 is a 4-pole molded case circuit breaker rated for 400 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. That flat thermal curve is unusual; most MCCBs start to derate above 40 °C, so this one simplifies panel sizing in warm enclosures or near other heat sources. Breaking capacity reaches 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 53 kA at 690 V — figures that place it well above typical distribution-level fault currents. The ETU560 electronic trip unit provides adjustable long-time pickup (lg) from 0.8 s to 400 A and short-time pickup (li) from 600 A to 4400 A, giving selectivity tuning for downstream feeders. It includes ground-fault monitoring via summation current formation on L + N conductor and supports communication functions, so it can report status and trip events to a higher-level control system. The front face carries IP40 protection; the enclosure dimensions are 248 mm high, 184 mm wide, 110 mm deep.
Mounting and integration notes
Mounts on a DIN rail or directly to a panel backplate. The 184 mm width occupies four 45 mm pole spaces; the 110 mm depth fits standard 200 mm deep enclosures with clearance for rear-mounted busbars. An optional motor drive is available for remote switching.