The Siemens 3VM1125-3ED32-0AA0 is a SENTRON molded case circuit breaker (MCCB) built for line protection in distribution panels. It's a 3-pole unit rated 25 A continuous at 40 °C, using a TM210 thermal-magnetic trip unit — fixed thermal and magnetic settings, no field-adjustable dials. That keeps it simple for a feeder or branch circuit where you don't need tuning. Breaking capacity is the headline here: 76 kA at 240 V AC, 53 kA at 415 V, 32 kA at 440 V, and 12 kA at 500 V. For a 25 A frame, that's serious fault-interruption headroom — it'll clear a high-energy arc flash without upstream fuses having to open, which matters for selective coordination in a multi-level panel. Rated insulation voltage is 800 V, and max operating voltage is 690 V AC or 500 V DC. The front face carries IP40 protection — fine for a dry indoor panel, but not for washdown or outdoor use without an enclosure.
Current derating — what the numbers mean for your panel
This breaker holds 25 A from 40 °C all the way to 50 °C, then drops to 24 A at 55–60 °C, and 23 A at 65–70 °C. That's a shallow derating curve — you lose only 2 A over a 30 °C rise. In a packed panel where ambient hits 50 °C, you still get full 25 A. At 70 °C, you're at 23 A, which is still 92% of the base rating. Most MCCBs in this class start derating sooner. Maximum power loss is 9 W — low enough that you don't need to factor much heat into the enclosure's thermal budget, even with several breakers ganged together.
Physical fit — panel integration notes
Dimensions: 130 mm tall, 76.2 mm wide, 70 mm deep. That 70 mm depth is the body only — add a bit more for the handle throw and rear terminals. It's a standard MCCB footprint for a 3-pole 25 A frame; no oddball cutout needed. Mounts on a DIN rail or panel-mount plate. The IP40 front means it's sealed against tools and fingers from the front, but the back and sides are open to the enclosure interior — typical for a panelboard install.