The Siemens SENTRON 3VA1225-4GF42-0CH0 is a 4-pole molded case circuit breaker rated 250 A continuous, with a breaking capacity of 121 kA at 240 V — enough to handle high-fault utility feeds or transformer secondaries without cascading upstream. It is designed for line protection (not motor or generator protection), so the trip curve is shaped for cable and busbar thermal limits rather than inrush. The breaker ships with an undervoltage release (UVR) and a complement of two auxiliary switches plus one trip alarm switch (HQ type), meaning it can report its status to a PLC or annunciator panel without an add-on module. The UVR will trip the breaker if control voltage drops below its dropout threshold — a common requirement for emergency-stop circuits that need a hard mechanical break on loss of control power.
Breaking capacity across voltages
This MCCB delivers 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. That spread tells you the part is sized for 400–480 V distribution panels in industrial plants — at 690 V the interrupting rating drops below what most high-voltage motor feeds require, so keep it on the low-voltage side of the transformer.
Thermal derating and ambient limits
Rated 250 A up to 50 °C ambient; above that it 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 runs hot — near a VFD cabinet or a roof-mounted enclosure in summer — size the load at the 60 °C column, not the nameplate. The operating range is -25 °C to 70 °C, storage from -40 °C to 80 °C.