What this breaker is and what it carries
The Siemens 3VA1225-6EF32-0DA0 is a 3-pole SENTRON molded case circuit breaker rated for line protection, with a TM240 thermal-magnetic overcurrent release and an integrated undervoltage release (UVR). Rated 250 A continuously at 40 °C, it holds that full rating through 50 °C before starting a gradual derating — 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — so in a warm panel you still get most of the capacity. Breaking capacity is 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V — enough to clear high-fault scenarios downstream of a large transformer without cascading upstream. Rated insulation voltage is 800 V.
What the TM240 release and UVR mean for fit
The TM240 thermal-magnetic release combines a thermal bimetal for overload protection (inverse-time curve) with a magnetic coil for short-circuit instantaneous trip — no electronic adjustment, so it's a fixed-curve breaker suited to standard feeder or distribution duty where coordination studies are already done. The undervoltage release (UVR) trips the breaker when control voltage drops below a threshold — common in emergency-stop chains or where you need the breaker to drop out on loss of control power.
Panel fit and dimensions
Measures 105 mm wide by 158 mm tall by 70 mm deep — standard SENTRON 3VA form factor for a 250 A frame, mounts on a DIN rail or panel-mount baseplate. Power loss at full load is 59.5 W — factor that into enclosure heat rise calculations if the panel is sealed.