SENTRON 3VA1225-5FF42-0JC0 — 125 A MCCB with shunt trip
The Siemens SENTRON 3VA1225-5FF42-0JC0 is a 4-pole molded case circuit breaker rated at 125 A continuous, built for line protection in distribution panels. Breaking capacity hits 187 kA at 240 V AC and still delivers 121 kA at 415 V — enough headroom for high-fault industrial services without cascading upstream breakers. The 800 V rated insulation voltage means it handles 690 V line-to-line systems comfortably. This variant ships with a factory-fitted shunt trip (STL) release and two auxiliary switches HQ, so you get remote trip capability and status feedback without extra wiring. No undervoltage release, no ground-fault module — it's a straight line-protection breaker with a trip coil for emergency or remote shutdown.
Breaking capacity and thermal derating
The 125 A frame carries a 187 kA interrupting rating at 240 V, dropping to 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That's a strong short-circuit curve — useful for panels fed from large transformers or generator paralleling where fault currents run high. Thermal derating is flat at 250 A from 40 °C through 50 °C, then steps down: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, 223 A at 70 °C. If your panel ambient runs hot, the 125 A rating holds without a frame bump — the breaker's thermal calibration handles it.
Lifecycle and sourcing
Power loss is 57 W maximum at rated load — factor that into enclosure thermal calculations if you're packing several breakers in a small cabinet.
Mounting and integration
Dimensions are 70 mm deep, 140 mm wide, 158 mm high — a standard 4-pole MCCB footprint for DIN-rail or panel-mount installation. The 2.76 in × 5.51 in × 6.22 in translates cleanly into existing cutouts if you're swapping an older frame. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C. If the breaker lives in an unheated enclosure in a cold climate, the -25 °C floor is fine for most industrial sites.