What the ratings mean for your panel
The Siemens 3VA2450-6KP42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 500 A continuous current at 40 °C, with full 500 A hold through 50 °C before derating to 477 A at 55 °C, 455 A at 60 °C, 432 A at 65 °C, and 410 A at 70 °C — so in a warm enclosure you lose about 5 % per 5 °C above 50 °C. The 4-pole design with adjustable N-conductor protection (OFF, 20 % to 100 %) means it handles both 3-phase and 3-phase-plus-neutral distribution without a separate neutral breaker. Breaking capacity is the headline: 242 kA at 240 V, 187 kA at 415 V, 85 kA at 440 V, 55 kA at 500 V, and 9 kA at 690 V. That 187 kA at 415 V puts it in the high-fault tier for industrial mains — it safely interrupts a bolted fault up to that level without cascading upstream, which is the number your arc-flash study and SCCR label will reference. The ETU850 electronic trip unit gives you LSIG or LSI curves (adjustable long-time, short-time, instantaneous, and ground-fault if enabled — though this variant ships without ground-fault monitoring). Mechanical endurance is 15,000 operations, which is typical for a 500 A frame in distribution duty — not a frequent-switching motor-starting role. Communication function is onboard (the 6KP42-0AA0 suffix signals the communication-ready variant), so it can report status and trip events to a higher-level system without an external module. IP40 on the front means it's protected against solid objects larger than 1 mm but not against water ingress — standard for indoor switchgear.
Panel fit and mounting
Dimensions: 248 mm high, 184 mm wide, 110 mm deep (9.8 x 7.2 x 4.3 inches). The 184 mm width is the 4-pole frame — three poles plus switched neutral — so it occupies the same panel cutout as other 3VA2 4-pole breakers. Mounting is via four screws to the rear panel or onto a mounting plate; no DIN-rail clip on this frame size. Leave clearance above and below for arc-chute exhaust and cable bending radius. Power loss is 99 W maximum at rated current. Storage range is -40 °C to 80 °C; operating range is -40 °C to 70 °C.