What the ratings mean for your panel
The Siemens 3VA1125-5EF36-0AF0 is a SENTRON molded case circuit breaker (MCCB) rated for 25 A continuous at 40 °C with a TM240 thermal-magnetic release — that fixed trip unit means the breaker is sized for a specific load and not field-adjustable, so confirm your continuous load is at or under 25 A before committing the BOM line. Three-pole construction, so it switches all phases in a three-phase circuit. The interrupting rating hits 187 kA at 240 V and still holds 121 kA at 415 V — that's high enough for most industrial service-entrance or feeder applications where fault current is stiff. The breaker carries a built-in auxiliary switch and trip alarm switch (1 each, HQ design), which gives you remote status indication without adding a separate accessory module. That saves a DIN slot and a wiring step. Power loss maxes at 8.5 W — negligible for thermal budgeting inside a sealed enclosure, but worth noting if you're packing multiple breakers in a small panel.
Panel fit and integration
The 3VA1125-5EF36-0AF0 measures 70 mm deep, 76.2 mm wide, and 130 mm tall — a standard MCCB footprint that drops into SENTRON mounting bases or DIN-rail adapters without panel rework. Rated insulation voltage is 800 V. Operating range is -25 °C to 70 °C; storage from -40 °C to 80 °C.