250 A, 4-pole, TM240 — what the ratings mean for fit
The Siemens SENTRON 3VA1225-4GF42-0BA0 is a 4-pole molded case circuit breaker rated 250 A continuous, with a TM240 thermal-magnetic release designed for line protection. The 250 A frame carries the full current at ambient temperatures up to 50 °C without derating; above that, the thermal curve steps down to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — so if this breaker lives in a warm enclosure, the actual trip threshold shifts, and you size the load accordingly. Interrupting capacity is given at five voltage levels: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. The 415 V figure is the one most panel builders will check first for 400 V three-phase distribution — 75.6 kA gives solid headroom for high-fault installations without cascading upstream. Rated insulation voltage is 800 V, and the breaker includes an undervoltage release (UVR) as standard — the auxiliary release design is listed as undervoltage release (UVR). That means it drops the breaker on loss of control voltage, which is useful for safety circuits or coordinated shutdown sequences. No communication function, no ground-fault monitoring, no voltage trigger — this is a straightforward thermal-magnetic line protection device.
Sourcing and lifecycle
Power loss at rated current is 59.5 W maximum — a figure worth noting for enclosure thermal calculations, especially if multiple breakers are ganged in a small panel.
Panel integration and dimensions
Dimensions are 70 mm depth, 140 mm width, 158 mm height. The 70 mm depth is the dimension that matters most for enclosure clearance — it fits standard 200 mm deep enclosures with room for wiring and lug access. Width at 140 mm is the 4-pole footprint; verify the mounting base matches existing busbar or DIN-rail cutouts before ordering.