Siemens 3VA1225-4EF32-0AJ0 — 250 A MCCB for Line Protection
The Siemens SENTRON 3VA1225-4EF32-0AJ0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current rating Iu of 250 A at 40 °C. This places it as a main or feeder breaker in a 400 V distribution panel, sized for loads up to that thermal threshold before derating. The 250 A rating holds flat from 40 °C through 50 °C, then steps down to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — a derating curve that matters when the breaker sits in a warm enclosure alongside other heat sources. Breaking capacity is specified across five voltage levels: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. At 415 V — the common low-voltage distribution voltage in many regions — the 75.6 kA interrupting rating gives substantial fault-current headroom for most industrial service entrances or large sub-distribution boards. The rated insulation voltage Ui is 800 V.
Physical Fit and Panel Integration
Dimensions are 70 mm depth, 105 mm width, and 158 mm height. The 105 mm width is the standard 3-pole MCCB footprint for this current class — it occupies three 35 mm DIN-rail modules, which is the expected panel layout for a 250 A frame. The 70 mm depth keeps the breaker within typical distribution board clearance, allowing front-connection cabling without forcing a deeper enclosure. The auxiliary contact configuration is listed as 2 auxiliary switches plus 1 trip alarm switch HP, which provides both status signaling and a separate trip-indication contact for remote monitoring or PLC input.