What it is and what it does
The Siemens SENTRON 3VA1125-4EF32-0KC0 is a 3-pole molded case circuit breaker (MCCB) rated 25 A at 40 °C, designed for line protection in distribution panels. Its 121 kA breaking capacity at 240 V handles high-fault utility feeds; at 415 V it still interrupts 75.6 kA, and at 690 V it holds 11.9 kA — enough for most industrial service-entrance or feeder applications. The 800 V rated insulation voltage covers 480/600 V class systems with margin.
Ratings and what they mean for fit
The 25 A current rating holds flat from 40 °C to 50 °C (–), then derates to 24 A at 55 °C and 23 A at 70 °C (–). That means a panel at 50 °C ambient still gets full 25 A continuous; above that, you need to account for the drop. The 3-pole frame handles three-phase loads — motor feeders, lighting, or general distribution — and the shunt trip plus two auxiliary switches allow remote tripping and status feedback without an external control relay. Maximum power loss is 8.5 W — low enough that ventilation in a standard IP2X enclosure is adequate. The 70 mm depth, 76.2 mm width, and 130 mm height (–) fit the standard SENTRON 3VA mounting footprint, so it swaps into existing panel layouts without re-drilling.
Integration notes
Mounts on a DIN rail or directly to a backplate via the standard SENTRON 3VA base. The shunt trip (STL) requires a separate control voltage — verify polarity and timing per the wiring diagram. The two auxiliary switches (HQ) are pre-installed; they change state with the breaker mechanism, not the handle, so they report true contact position.