What it is and where it fits
The Siemens SENTRON 3VA1125-4ED22-0AA0 is a 2-pole molded case circuit breaker (MCCB) rated 25 A at 40 °C, with a TM210 thermal-magnetic trip unit and a maximum interrupting capacity of 121 kA at 240 V AC, 75.6 kA at 415 V AC. It's designed for line protection in distribution panels, sized for a 50.8 mm wide by 130 mm tall by 70 mm deep footprint — a standard 2-pole MCCB slot on most DIN-rail or panel-mount assemblies.
Ratings that matter for fit
The 25 A rating holds steady across 40 °C to 50 °C ambient, then derates to 24 A at 55–60 °C and 23 A at 65–70 °C. That means in a warm panel — say 55 °C internal — you still get 24 A continuous, not a forced down-rate. The 121 kA at 240 V AC is the short-circuit breaking capacity; at 415 V AC it's still 75.6 kA, which covers most industrial service-entrance or feeder applications without needing an upstream current-limiting fuse. Rated insulation voltage is 500 V, and the front face carries IP40 protection — fine for a dry indoor panel, but not for washdown areas. Maximum power loss is 5.66 W, so heat buildup in a densely packed enclosure is manageable.
Panel integration notes
At 50.8 mm wide and 70 mm deep, it fits a standard 2-pole MCCB cutout. The TM210 trip unit is thermal-magnetic — no electronic adjustments, no communication function, no undervoltage release. That makes it a straight swap for older fixed-trip MCCBs in line-protection duty. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.