What this MCCB delivers — and where the ratings matter
The Siemens 3VA2225-5KP32-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current at 40 °C, with an interrupting capacity of 187 kA at 240 VAC — that is the headline number for fault-clearing duty on a 240 V service entrance or large feeder. At 415 V and 440 V it still holds 121 kA, dropping to 75.6 kA at 500 V and 4.5 kA at 690 V. The ETU850 electronic trip unit provides adjustable long-time, short-time, instantaneous, and ground-fault protection curves — line protection design, so it is sized for distribution feeders, not motor-starting duty. Three poles, IP40 on the front face, with a communication function onboard for integration into a monitored power system.
Thermal derating — the real continuous current at your panel ambient
Rated 250 A continuous up to 50 °C ambient. Above that, the ETU850 begins to thermally limit: 238 A at 55 °C, 225 A at 60 °C, 213 A at 65 °C, and 200 A at 70 °C. If your panel internal ambient runs at 60 °C, you have 225 A available — not the full 250 A. The 48 W maximum power loss at rated current matters for enclosure heat buildup; factor it into your thermal budget.
Physical fit and panel integration
Dimensions: 105 mm wide, 181 mm tall, 86 mm deep. Three-pole footprint matches standard SENTRON 3VA2 panel cutouts. IP40 on the front — suitable for enclosed distribution boards; not rated for washdown or outdoor exposure without an additional enclosure.