400 A MCCB for main feeder or large subfeed — 187 kA SCCR at 240 V
The Siemens SENTRON 3VA2340-5JQ42-0BL0 is a 4-pole molded case circuit breaker rated 400 A continuous at 40 °C, designed for line protection in main distribution boards and large subfeed applications. Its 187 kA interrupting capacity at 240 V AC means it can safely clear bolted-fault currents up to that level without cascading failure upstream — a critical selectivity figure for high-fault utility feeds. The breaker carries a communication function for integration into plant monitoring systems and includes an undervoltage release (UVR) as the auxiliary release, which trips the breaker when supply voltage drops below a threshold, protecting downstream equipment from brownout damage.
Breaking capacity across voltages — where it fits
The interrupting rating drops as line voltage rises: 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V. That 690 V figure is the one to watch if you are specifying for a 690 V industrial network — 7.5 kA is modest, so confirm the available fault current at the installation point. The 400 A rating holds from 40 °C through 50 °C ambient; above that it derates linearly to 300 A at 70 °C. Max power loss is 98.5 W, which matters for heat buildup in a sealed enclosure.
Panel fit — dimensions and mounting
The breaker measures 248 mm high, 184 mm wide, and 110 mm deep (9.76 × 7.24 × 4.33 in). That 184 mm width for a 4-pole frame is standard for SENTRON 3VA2 fixed-mounted breakers — it bolts directly to a mounting plate or busbar system; no DIN-rail adapter. Verify the gland plate cutout and phase barrier clearance before panel layout.