What this MCCB carries
The Siemens 3VA1225-5GE42-0AA0 is a SENTRON molded case circuit breaker (MCCB) sized for line protection — 250 A frame, 4-pole, with a TM220 thermal-magnetic trip unit. The 250 A rating holds continuously at 40 °C through 50 °C without derating; at 55 °C it steps down to 243 A, and at 70 °C it's still good for 223 A, so it handles warm enclosures without a frame-size jump. Breaking capacity is the headline number for this class: 121 kA at 415 V, 187 kA at 240 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That 121 kA at 415 V means it safely clears a bolted fault up to that level without cascading upstream — critical for high-fault panels where the transformer is close and the available short-circuit current is well above 50 kA. Rated insulation voltage is 800 V, so it's comfortable on 690 V line-to-line systems with margin. Power loss maxes at 57 W — factor that into enclosure thermal calculations if the panel is densely packed.
Integration and footprint
The 3VA1225-5GE42-0AA0 measures 158 mm high, 140 mm wide, 70 mm deep — a 4-pole MCCB that fits standard panel-mount cutouts. IP40 on the front keeps dust out of the toggle and trip-indicator area; the rest of the body is open to the enclosure for heat shedding. No undervoltage release, no shunt trip, no communication function, no ground-fault monitoring on this variant — it's a straight thermal-magnetic line-protection breaker. If you need those auxiliaries, you're looking at a different 3VA order code with the appropriate suffix.