Rating and fit — what the numbers mean for the panel
The Siemens 3VA2225-5JQ32-0BA0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection in distribution panels. Its headline rating is 250 A at 40 °C, which means it carries that current continuously without tripping in a 40 °C ambient — the standard thermal benchmark for panel design. The 3-pole configuration suits it for three-phase feeders, motor branch circuits, or main incoming protection on 400 V / 480 V systems. Breaking capacity is the real fit gate: 187 kA at 240 V and 121 kA at 415 V tell you this breaker handles high-fault-current scenarios typical of large transformer-fed panels. At 690 V it still interrupts 4.5 kA — enough for most industrial motor circuits but not for high-fault 690 V distribution. The 250 A frame covers feeder sizes from 375 A minimum up to 2 500 A maximum via the electronic trip unit range, so the same chassis can be re-specced for a different amp rating by swapping the trip block.
Thermal derating and power loss — panel integration reality
The breaker holds a flat 250 A from 40 °C through 50 °C (–), then derates linearly to 200 A at 70 °C. For a panel with multiple breakers side-by-side, the 50.5 W maximum power loss adds up — factor that into the enclosure's thermal budget. Dimensions are 105 mm wide × 181 mm tall × 86 mm deep, which is a standard SENTRON 3VA2 frame footprint; it mounts on a DIN rail or directly to a backplate with the supplied screws.