What this 3VA2440-5MN32-0AB0 is and what it does
The Siemens 3VA2440-5MN32-0AB0 is a SENTRON molded case circuit breaker (MCCB) in a motor protection variant, rated for a continuous current Iu of 400 A across the full 40 °C to 70 °C ambient range — no derating needed up to the maximum operating temperature. It is a 3-pole device with a supplied basic switch order code of 3VA2440-5MN32-0AA0, meaning this is the assembled, ready-to-install unit with the internal switching mechanism pre-integrated. The breaking capacity tells you where this breaker can safely interrupt a fault: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 9 kA at 690 V. For a motor protection MCCB, those numbers mean it handles high-fault-current industrial feeds without cascading upstream — the 121 kA at 415 V covers most European 400 V distribution panels with headroom to spare. This is the motor protection version, so it includes phase failure detection built in — no separate phase-monitoring relay needed for that function. It ships with 2 auxiliary switches (HP type) for status feedback to a PLC or indication lamp. The auxiliary release slot is empty, so if you need an undervoltage or shunt trip, that gets added separately.
Panel fit and integration — dimensions and mounting
The 3VA2440-5MN32-0AB0 measures 248 mm high, 138 mm wide, and 110 mm deep. That 110 mm depth is the dimension that matters most for shallow enclosures — it fits standard 250 mm deep panels with room for wiring gutters. The 138 mm width is the 3-pole footprint; if you are replacing an existing MCCB in a SENTRON or similar platform, check the mounting hole pattern against the existing base plate.
Power dissipation and thermal management
Maximum power loss is 63.5 W at rated current. For a 400 A breaker in a closed panel, that heat needs to be considered in the enclosure thermal calculation — it is not a trivial loss, and adjacent devices should not be packed tight without derating or forced ventilation.