What this 250 A MCCB delivers in the panel
The Siemens SENTRON 3VA2225-5HN42-0CH0 is a 4-pole molded case circuit breaker rated for 250 A continuous current at 40 °C ambient, with a line protection design that handles fault currents up to 187 kA at 240 V and 121 kA at 415 V or 440 V. At 500 V the interrupting rating drops to 75.6 kA, and at 690 V it holds 4.5 kA — so the SCCR you need at your system voltage is the one that governs the fit, not the headline 187 kA figure. The breaker ships with an undervoltage release (UVR) and a complement of 2 auxiliary switches plus 1 trip alarm switch (HQ). The basic switch variant is 3VA2225-5HN42-0AA0, which means the UVR and aux-switch package are factory-integrated — no field retrofit required.
Thermal derating — the real continuous current in a warm cabinet
The 250 A rating holds flat from 40 °C through 50 °C. Above that, the breaker derates: 241 A at 55 °C, 232 A at 60 °C, 222 A at 65 °C, and 213 A at 70 °C. If your panel ambient sits at 55 °C, you lose 9 A — small, but enough to trip a fully loaded feeder on a hot day. The maximum power loss is 50.5 W, which matters for enclosure thermal calculations when grouping multiple breakers.
Physical fit and mounting
The breaker measures 140 mm wide by 181 mm tall by 86 mm deep. That 86 mm depth is the dimension to check against your gland plate clearance or enclosure door clearance — it's not a shallow unit. The 140 mm width for a 4-pole frame is standard for this class, but verify your DIN-rail or mounting-plate spacing if you're retrofitting into an existing panel.