What this 400 A MCCB is and where it fits
The Siemens 3VA2440-5KQ42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current, designed for line protection in main or feeder distribution panels. Its 4-pole configuration handles three-phase plus neutral, common in North American and IEC installations where a switched neutral is required. The 187 kA interrupting capacity at 240 V gives it the headroom for high-fault service-entrance or large sub-feed applications without needing a current-limiting upstream device.
Breaking capacity across the voltage range
This breaker's interrupting rating drops as voltage rises: 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. The 9 kA at 690 V is the limiting figure for 600 V class systems — verify the available fault current at the point of installation against that value, especially on 690 V marine or industrial grids.
Thermal performance and continuous rating
The 400 A rating holds flat from 40 °C through 70 °C ambient — no derating needed across that range, which simplifies panel layout in warm enclosures or near other heat sources. Maximum power loss is 63.5 W, so ventilation planning should account for that dissipation at full load. The adjustable thermal-magnetic trip unit has a full-scale value of 400 A and an initial setting of 80 A, with a short-time withstand of 5 kA limited to 1 second.
Physical fit and panel integration
Dimensions are 248 mm high, 184 mm wide, 110 mm deep — a standard SENTRON 3VA frame size for 400 A class. The 184 mm width (7.24 in) is the key constraint for multi-breaker lineup spacing on a DIN rail or panel-mount backplate. Verify the gland plate knockout pattern against your enclosure; the 110 mm depth (4.33 in) leaves clearance behind the door for wiring and accessory modules.
Communication and monitoring features
This MCCB includes a communication function for integration into a plant-wide energy management or monitoring system. It also supports ground-fault monitoring via summation current formation on the L + N conductors, which allows detection of leakage without a separate core-balance transformer. No undervoltage release or voltage-triggered trip is fitted as standard.