The Siemens SENTRON 3VA2450-5MN32-0AJ0 is a 3-pole molded case circuit breaker (MCCB) rated for 500 A continuous at 40 °C, with no derating needed up to 50 °C — it holds 500 A flat through that range. That means you can size the bus and terminations for a solid 500 A without worrying about ambient temperature creep in a typical enclosed panel. Above 50 °C it derates linearly to 480 A at 70 °C, which is the maximum operating ambient. The interrupting ratings tell the real story: 187 kA at 240 V, 121 kA at 415/440 V, and 75.6 kA at 500 V.
Motor protection design — what that means in practice
The product designation is motor protection, which means the trip curve and thermal memory are tuned for induction motor starting inrush and locked-rotor conditions. It includes phase failure detection — if one phase drops out, the breaker trips before single-phasing cooks the winding. That's a standard feature on this design, not an add-on. No undervoltage release is fitted; if you need UVR for a safety circuit, that's a separate order.
The 138 mm width is for a 3-pole frame; if you're replacing an existing MCCB, check the mounting hole pattern and bus bar spacing against the cutout. This is a standard SENTRON 3VA2 frame size, so panel layouts designed for that family accept it without modification.
Environmental limits and power loss
Maximum power loss is 99 W at full rated current — that's heat that must be ventilated or conducted out of the enclosure. In a sealed panel with multiple breakers, the cumulative heat load matters; plan for forced ventilation if ambient inside the enclosure approaches 50 °C.