What the 250 A rating means for your panel
The Siemens 3VA2225-6KP32-0AC0 is a SENTRON molded case circuit breaker rated for 250 A continuous current at ambient temperatures up to 50 °C — it holds that full 250 A from 40 °C through 50 °C without derating, which is where most MCCBs start to lose capacity. Above 55 °C it steps down: 238 A at 55 °C, 225 A at 60 °C, 213 A at 65 °C, and 200 A at 70 °C. That thermal curve is the one you care about when the breaker sits in a hot switchgear lineup or next to a transformer. Interrupting capacity is 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 6 kA at 690 V. Those numbers mean it can clear a fault at the full available short-circuit current of a large transformer secondary — no need for a current-limiting fuse upstream in most industrial distributions. The ETU850 electronic trip unit gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves, so selectivity with downstream breakers is programmable, not fixed.
Physical fit and panel integration
The breaker measures 105 mm wide, 181 mm tall, and 86 mm deep. That 86 mm depth is the dimension that matters for enclosure clearance — it fits standard 200 mm deep panels with room for wiring gutters. The 105 mm width is the 3-pole footprint; mount it on a DIN rail or bolt it to a mounting plate with the SENTRON accessories. IP40 on the front means it is protected against tools and wires larger than 1 mm — standard for a panel-mounted breaker. The 2 HQ auxiliary switches (form C) give you remote status feedback without an add-on module. Maximum power dissipation is 48 W at full load, so account for that heat in your panel ventilation calculation.
Approvals and documentation
Rated insulation voltage is 800 V, so it is suitable for 690 V systems with margin. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The ETU850 trip unit includes communication and other measurement functions — it can report current, power, and energy data over the SENTRON communication bus.