What the 250 A rating and interrupting capacity mean for your panel
The Siemens SENTRON 3VA1225-6GF42-0AF0 is a 4-pole molded case circuit breaker rated 250 A continuous at 40 °C, with a TM240 thermal-magnetic release sized for line protection. That 250 A holds flat through 50 °C — above that, the thermal curve derates to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If your panel ambient runs warm, the 60 °C figure (237 A) is the one to check against your load current. Interrupting capacity is the headline number for fault coordination. This breaker delivers 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That 220 kA at 240 V covers high-fault utility feeds; the 154 kA at 415 V handles most European industrial distribution. The 690 V figure (17 kA) is lower — verify it against your transformer's prospective fault current if you're on a 690 V system.
Physical fit and integration
Dimensions are 158 mm high, 140 mm wide, 70 mm deep. The 70 mm depth is shallow enough for most standard distribution panels — it won't force a deeper enclosure than the rest of the gear. Four-pole construction means it switches all three phases plus neutral; verify your panel's neutral bus routing if you're swapping a 3-pole unit.
Key specs at a glance
Rated insulation voltage is 800 V. Maximum power loss is 57 W. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The breaker includes one auxiliary switch and one trip alarm switch (HQ design). No undervoltage release, no ground-fault monitoring, no communication function — this is a straight thermal-magnetic line-protection breaker.