What this MCCB is and what it does
The Siemens 3VA2440-5MN32-0JL0 is a SENTRON molded case circuit breaker (MCCB) designed specifically for motor protection, with a continuous current rating of 400 A across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. That means it handles the full thermal load of a large motor feeder without tripping early on a hot panel day. Three poles, phase failure detection built in, and a short-circuit breaking capacity of 187 kA at 240 V — enough to clear a fault on a high-capacity distribution transformer without cascading upstream. At 415 V it still holds 121 kA, dropping to 9 kA at 690 V.
What the ratings mean for fit
The 400 A rating is flat from 40 °C to 70 °C, which is unusual — most MCCBs start derating above 40 °C. If your panel ambient runs hot, this breaker holds its full ampacity without a larger frame. The interrupting ratings (187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 500 V) tell you where it can be installed in the fault-current hierarchy; 187 kA is main-breaker territory on a large low-voltage switchboard. Motor protection design means the trip curve is shaped to handle inrush without nuisance trips while still clearing a locked-rotor condition. Phase failure detection is integrated — no need for a separate voltage relay on the motor starter. The auxiliary switch complement (2 auxiliary + 1 trip alarm + 1 electrical alarm switch HQ) and a shunt trip release (STL) are factory-fitted, so remote tripping and status feedback are wired out of the box. Power loss at full load is 63.5 W — plan for heat dissipation in the enclosure.
Mounting and integration
Dimensions are 110 mm deep × 138 mm wide × 248 mm high. The 138 mm width is a standard 3-pole MCCB footprint — it fits most panel-mounted or DIN-rail adapter bases without re-drilling the backplate. Depth of 110 mm leaves room for rear-connected busbars or cable lugs inside a 400 mm deep enclosure.