MCCB for high-fault panel builds
The Siemens 3VA2340-5HN42-0DA0 is a SENTRON molded case circuit breaker sized for 400 A continuous duty in a 4-pole configuration, designed for line protection. Its interrupting ratings hit 187 kA at 240 V and 121 kA at 415 V, which means it can clear high-fault currents on the secondary side of a large distribution transformer without cascading upstream — the kind of SCCR headroom a site electrical engineer needs for selectivity coordination studies. The 110 mm depth and 184 mm width fit standard panel footprints, and the built-in undervoltage release (UVR) lets safety circuits drop the breaker on loss of control voltage.
Thermal reality check
This breaker holds its full 400 A rating up to 50 °C ambient. Above that, it derates linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. For a panel OEM wireman packing breakers into a closed enclosure, that derating curve is the real limit — not the label. The 98.5 W maximum power loss at rated current drives heat into the enclosure; factor that into your thermal rise calculation if the panel is sealed or has limited venting.
Sourcing and fit
This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time. The 184 mm width and 248 mm height are standard for the 3VA2 frame family; if you are replacing a 3VA2116-5JP32-0AE0 or similar, the physical footprint and mounting pattern are the same — no panel rework needed. The undervoltage release is wired separately; verify your control voltage matches the release coil rating before installation.