What this MCCB is and what it does
The Siemens 3VA2340-5HN42-0AD0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current across a 4-pole configuration, designed for line protection in distribution panels and switchboards. Its interrupting capacity reaches 187 kA at 240 V AC, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — figures that cover high-fault utility feeds and industrial transformer secondaries without cascading upstream. The breaker carries no trip indicator, no undervoltage release, no communication module, and no ground-fault monitoring — it is a plain line-protection device, not a multifunction power breaker.
Thermal derating and mounting footprint
Full 400 A rating holds from 40 °C through 50 °C ambient; above that it derates linearly to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C — the operating temperature ceiling. Dimensions are 248 mm high, 184 mm wide, 110 mm deep — a 4-pole frame that fits standard switchboard cubicle mounting plates; the 110 mm depth leaves clearance for rear-connected busbars or cable ladders behind the panel door. Maximum power dissipation is 96 W at rated load — account for that heat in the enclosure ventilation calculation, especially when grouping multiple breakers in a single section.