What it is and what it does
The Siemens 3VA1225-4GF42-0CC0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current with a 4-pole configuration, designed for line protection in distribution panels. Its TM240 thermal-magnetic trip unit handles overload and short-circuit protection without electronic adjustments — set it and forget it, which is exactly what a field-service tech wants when swapping a failed breaker on a live line. Interrupting capacity is 121 kA at 240 V AC and 75.6 kA at 415 V AC, so it can clear high-fault currents upstream without cascading to other gear. That 121 kA number means it's sized for a main breaker position near a large transformer — not a downstream feeder. At 440 V it still handles 25 kA, and at 690 V it's 11.9 kA.
Ratings and what they mean for fit
Continuous current holds at 250 A from 40 °C up to 50 °C ambient; above that it derates to 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel runs hot — say near a drive cabinet or in a non-conditioned electrical room — check the derating curve against your load. The thermal-magnetic trip is fixed at 250 A (TM240 designation means the thermal element is calibrated for 240 A frame, but the continuous rating Iu is 250 A). Dimensions are 158 mm high, 140 mm wide, 70 mm deep. The 140 mm width is a 4-pole footprint — three phases plus 100 % rated neutral (N-conductor protection designed for 100 %). That matters when you're laying out a panel: it takes up the same width as four single-pole breakers side by side, but in one molded case. Front protection is IP40 — fine for a dry indoor enclosure, but keep it behind a door or cover if there's any chance of tools or debris dropping in.
Built-in auxiliary and undervoltage release
This unit ships with 2 auxiliary switches (HQ type) and an undervoltage release (UVR) already integrated. The UVR trips the breaker when control voltage drops below a threshold — common in safety circuits or emergency-stop chains where loss of control power must open the main contacts. The auxiliary switches give you status feedback (open/closed) to a PLC or indicator light without adding an external contact block. The integrated auxiliary trip is order code 3VA9608-0BB24, so if you need a spare or replacement, that's the part number. No voltage trigger, no communication function, no phase failure detection, no ground fault monitoring — this is a straightforward thermal-magnetic breaker with no electronics. If you need remote tripping or ground-fault protection, you'd step up to an electronic-trip version in the same 3VA family.