What this MCCB carries
The Siemens SENTRON 3VA1225-5GF42-0DH0 is a 4-pole molded case circuit breaker rated 250 A continuous, with a breaking capacity of 187 kA at 240 V AC — that's the short-circuit current it can safely interrupt at that voltage level, which matters for high-fault-capacity panels near transformers or large motor banks. Breaking capacity drops across the voltage curve: 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V — so the voltage class of your distribution system determines which figure governs the fault rating. Rated insulation voltage is 800 V, which covers 690 V systems with margin.
Thermal derating and panel fit
At 40 °C, 45 °C, and 50 °C the breaker holds full 250 A rating. Derating starts at 55 °C (243 A), then 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — so if the panel ambient runs above 50 °C, you need to account for the reduced continuous current. Dimensions: 158 mm high, 140 mm wide, 70 mm deep — a standard MCCB footprint for a 250 A frame. The 70 mm depth means it fits typical distribution panelboards without crowding the gland plate.
Integrated accessories
Factory-fitted with an undervoltage release (UVR) and a set of 2 auxiliary switches plus 1 trip alarm switch (HQ configuration) — so it arrives ready for status feedback and undervoltage protection without separate add-on modules. Line protection design, no ground-fault monitoring, no communication function — a straightforward main or feeder breaker for standard distribution.