What this MCCB carries and where it fits
The Siemens SENTRON 3VA1225-6EF32-0KA0 is a 3-pole molded case circuit breaker (MCCB) rated 250 A continuous at 40 °C, with a TM240 thermal-magnetic overcurrent release and an integrated shunt trip (STL) auxiliary release. It is designed for line protection in distribution panels and switchboards, sized for the 3VA platform's 105 mm width and 158 mm height — a standard footprint that drops into SENTRON mounting bases and busbar systems without adapter plates. Breaking capacity is the headline number that governs fault-current coordination: 220 kA at 240 V AC, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That 220 kA at 240 V places it in the high-interrupting category for North American 240/277 V distribution — it clears a bolted fault upstream of the main without cascading, so downstream breakers can be rated lower. The 154 kA at 415 V covers most European 400 V industrial feeds with headroom for transformer-backed installations.
Thermal derating and continuous current
The 250 A rating holds flat from 40 °C through 50 °C ambient — no derating needed in a typical 40 °C panel. At 55 °C it drops to 243 A, at 60 °C to 237 A, at 65 °C to 230 A, and at 70 °C to 223 A. If the breaker sits in a high-ambient enclosure (near a transformer or in a non-ventilated cabinet), use the 55 °C column for sizing. The TM240 release is factory-set for 250 A at 40 °C; the thermal element tracks the derating curve, so no field adjustment compensates for ambient — the breaker self-derates.
Shunt trip and auxiliary release configuration
This variant ships with a shunt trip (STL) auxiliary release. The breaker can be remotely tripped by energizing the shunt coil, standard for emergency-stop circuits or fire-alarm shunt-down. There is no undervoltage release on this unit. Power loss at rated current is 57 W maximum — relevant for enclosure thermal calculations in a multi-breaker panel. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Rated insulation voltage is 800 V, which covers 690 V systems with margin.