The Siemens SENTRON 3VA1225-6FF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 125 A continuous, designed for line protection in industrial power distribution panels. Its TM240 thermal-magnetic trip unit provides fixed overload and short-circuit protection without undervoltage or ground-fault monitoring — a straightforward fit for main or feeder breaker duty where selectivity coordination is the priority.
Interrupting capacity and selectivity headroom
At 240 V the breaker clears 220 kA, dropping to 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. These figures exceed typical utility fault levels in most low-voltage networks, giving the site electrical engineer headroom for selective coordination with downstream breakers — the high 240 V rating in particular suits transformer secondary applications where available fault current can exceed 100 kA.
Thermal derating and panel integration
The breaker carries 250 A through 50 °C ambient, then derates to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. The 57 W maximum power loss at full load must be dissipated within the enclosure; for a panel OEM, this means checking the gland plate and fill factor against the switchgear manufacturer's heat rise calculation. The 70 mm depth, 140 mm width, and 158 mm height fit standard Siemens SENTRON mounting footprints — verify the existing bus-bar drill pattern if retrofitting into a third-party panel.
Environmental and compliance range
Operating temperature spans -25 °C to 70 °C; storage range extends from -40 °C to 80 °C. The front face carries IP40 protection — suitable for dry indoor panel mounting, not washdown or outdoor exposure. Rated insulation voltage is 800 V, and for DC network applications the manufacturer directs to the 3VA MCCB device manual for switching power values.