400 A MCCB with ETU320 — selectivity and SCCR headroom
The Siemens SENTRON 3VA2440-6HL32-0CC0 is a 3-pole molded case circuit breaker rated for a continuous current Iu of 400 A, with a maximum breaking capacity of 242 kA at 240 V AC. That 242 kA figure at 240 V is the headline interrupting rating — it tells you this breaker can safely clear a fault up to that level without cascading upstream, which is the figure you need for the SCCR (short-circuit current rating) declaration on the panel nameplate. At 415 V and 440 V it still holds 187 kA, and at 690 V it drops to 40 kA, so the voltage-dependent curve governs where you place it in the distribution. The overcurrent release is an ETU320, a microprocessor-based trip unit that supports LSIG (long-time, short-time, instantaneous, ground-fault) protection profiles — though this particular variant ships without ground-fault monitoring. The breaker also includes an undervoltage release (UVR) as the auxiliary release design, which means it will trip if the control voltage drops below a set threshold, a common requirement for emergency-stop circuits or undervoltage protection schemes in motor control centers.
Thermal derating and panel integration
The 400 A rating holds flat from 40 °C to 50 °C ambient. Above that, it derates: 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. If your enclosure runs hot — say a packed MCC lineup or a NEMA 12 panel with limited airflow — use the 55 °C or 60 °C column for your load calculation, not the 40 °C number. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Dimensions are 248 mm high, 138 mm wide, 110 mm deep. The 110 mm depth is the body depth behind the panel — relevant when you're checking clearance to the rear gland plate or a back-mounted busbar system. The 138 mm width is the standard 3-pole MCCB footprint for this SENTRON frame size; it will fit the same mounting cutout and busbar adapter pattern as other 3VA2-series breakers of the same frame. Maximum power loss is 66 W, which matters for thermal rise calculations in a sealed enclosure.
Lifecycle and sourcing reality
The auxiliary contact block fitted is a 2-changeover HQ type (order code 3VA9608-0BB24), and the basic switch assembly carries the code 3VA2440-6HL32-0AA0. If you're replacing the trip unit or the aux block separately, those are the service-part order codes to reference.