MCCB for main feeder or large branch protection
The Siemens 3VA1225-6EF42-0BH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. Four poles, line-protection version — no ground-fault or N-conductor protection built in. The breaking capacity hits 220 kA at 240 V and 154 kA at 415 V, so it handles high-fault utility feeds or transformer secondaries without cascading upstream. Undervoltage release (UVR) is included; auxiliary contacts are 2 NO/NC plus a separate trip-alarm switch (HQ). Panel-mount footprint: 140 mm wide, 158 mm tall, 70 mm deep.
Current rating holds to 50 °C; derate above
The 250 A rating is flat from 40 °C through 50 °C. At 55 °C it drops to 243.3 A, at 60 °C to 236.5 A, at 65 °C to 229 A, and at 70 °C to 223 A. If your panel ambient runs above 50 °C, size the load accordingly — the breaker doesn't trip early, but the continuous current limit shifts. The 800 V rated insulation voltage (Ui) covers 480 V and 600 V class systems with margin.
Panel fit and aux contact layout
Mounts in a standard switchboard or enclosure cutout. The 140 mm width and 158 mm height match typical SENTRON 3VA frame spacing. Auxiliary contact block (2 auxiliary switches + 1 trip alarm switch HQ) is integrated; the undervoltage release (UVR) is factory-fitted. Front face carries a trip indicator and is rated IP40 — suitable for indoor panel environments, not washdown zones.