What this 250 A MCCB carries
The Siemens 3VA2225-6KP42-0AA0 is a SENTRON 3VA2 molded case circuit breaker rated for 250 A continuous current at 40 °C, built on a 4-pole frame with an ETU850 electronic trip unit. It's a line-protection breaker — no voltage trip, no ground-fault monitoring — so it's sized for straight feeder or main switch duty where you need adjustable long-time, short-time, instantaneous, and ground-fault protection curves (the ETU850 handles all four). The interrupting capacity at 240 V hits 242 kA; at 415 V and 440 V it holds at 187 kA, then drops to 121 kA at 500 V and 4.5 kA at 690 V. That's a lot of fault-clearing muscle for a 250 A frame — you're getting the high-interrupt version of the 3VA2 line, not the standard 50/65 kA variant.
Thermal derating and panel fit
The breaker holds its full 250 A rating up to 50 °C. At 55 °C it derates to 238 A, at 60 °C to 225 A, at 65 °C to 213 A, and at 70 °C to 200 A. If you're stuffing this into a crowded enclosure with other heat sources, those are the numbers to size against — don't plan on 250 A above 50 °C without checking the ambient inside the panel. Dimensions are 181 mm tall, 140 mm wide, and 86 mm deep — a standard 4-pole MCCB footprint for a 250 A frame. The front carries IP40 protection, so it's fine for a dry indoor panel but not for washdown or outdoor exposure.
What the ETU850 trip unit does
The ETU850 is the top-tier electronic trip unit in the 3VA2 family. It provides adjustable L (long-time), S (short-time), I (instantaneous), and G (ground-fault) protection — the G function is configurable from 20% to 100% of the sensor rating, and you can also switch the neutral protection off entirely. The insulation voltage rating is 800 V, and the operating voltage maxes out at 690 V AC. Power loss at full rated current is 48 W — that's the heat you need to vent from the enclosure. Storage temperature range is -40 °C to 80 °C; operating range is -25 °C to 70 °C.