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. 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.
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.
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.