What this MCCB is and where it fits
The Siemens 3VA1225-6EF32-0BC0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in industrial power distribution panels. It's a 3-pole unit rated 250 A at 40 °C, with a breaking capacity of 220 kA at 240 V AC — that's the short-circuit current it can safely interrupt without welding or exploding, which matters when you're protecting a main feeder or a high-fault bus. The 800 V rated insulation voltage tells you it's built for 690 V distribution systems with margin.
Key ratings and what they mean for your panel
The 250 A rating holds flat from 40 °C through 50 °C, then derates to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C (–). If your panel ambient runs hot — say, next to a furnace or in a non-climate-controlled enclosure — you need to factor that derating. The 220 kA at 240 V is the headline interrupting rating; it drops to 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V (–). That's a steep voltage-dependent curve, so verify the available fault current at your system voltage, not just the 240 V number. Power loss at rated load is 59.5 W — that's heat that goes into the enclosure, so account for it in your thermal budget if you're packing multiple breakers in a small panel. The breaker ships with an undervoltage release (UVR) and two auxiliary switches HQ, which means it can trip on loss of control voltage and report status back to a PLC or annunciator without adding external relays.
Integration notes
Dimensions are 105 mm wide, 158 mm tall, 70 mm deep — standard SENTRON 3VA form factor for a 250 A frame. It's a panel-mount MCCB, not DIN-rail, so plan for bolt-on bus connections and a cutout that clears the 105 mm width. The 70 mm depth includes the arc chamber and terminals; leave clearance for cable bending radius below the breaker.