What this MCCB rating means for your panel
The Siemens SENTRON 3VA2340-7HN32-0AB0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. Its interrupting capacity hits 330 kA at 240 VAC and 242 kA at both 415 V and 440 V — that's the fault current it can safely clear without welding contacts or venting plasma. At 690 V it drops to 7.5 kA, so verify your system voltage against that curve before committing the BOM line.
Thermal derating — the real continuous current
The 400 A rating holds flat from 40 °C up to 50 °C. Above that, derate linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your enclosure runs hot — say a packed MCC section with other breakers radiating — that 340 A at 70 °C is the number to design for, not the catalog 400 A. Maximum power loss is 96 W, which matters for ventilation planning in sealed enclosures.
Panel fit — dimensions and auxiliaries
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep. It carries two factory-fitted auxiliary switches (HP design) and no undervoltage release, no ground-fault monitoring, and no communication module. The supplied basic switch variant is 3VA2340-7HN32-0AA0. If your panel spec calls for shunt trip or ground-fault, this base variant won't have it — you'd need a different suffix.