The Siemens SENTRON 3VA1225-5EF32-0KA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 250 A at 40 °C ambient. It uses a TM240 thermal-magnetic release — the thermal element handles overloads, the magnetic element clears short-circuits. The interrupting capacity hits 187 kA at 240 V, which gives solid headroom for high-fault panels where you need selectivity without cascading upstream.
Breaking capacity and thermal derating
Breaking capacity drops as voltage rises: 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That means this breaker is sized for 400 V-class distribution where the fault current stays under 120 kA; at 690 V the 17 kA limit still covers most industrial motor-control panels. The continuous rating holds at 250 A from 40 °C up to 50 °C, then derates to 243 A at 55 °C and 223 A at 70 °C. If the panel ambient runs hot, you lose about 11 % at 70 °C — factor that into the busbar sizing.
Integration notes
Dimensions: 105 mm wide, 158 mm high, 70 mm deep. That's a standard 3-pole MCCB footprint for a 250 A frame — it fits a typical DIN-rail or panel-mount enclosure with a 105 mm cutout. Rated insulation voltage is 800 V, so it's fine for 480/600 V systems with margin. Max power loss at rated current is 57 W — that's the heat to vent in a sealed enclosure; don't stack it tight against other high-loss devices without a thermal calculation. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.