The Siemens 3VA9137-0FK45 is a SENTRON door-coupling rotary operating mechanism — a door-mounted rotary operator for emergency-off (E-stop) applications, designed for 3VA4 and 3VA5 molded-case circuit breakers in the 125 A frame size. It includes a door interlock and a door-open position accessory, so the enclosure door stays locked while the breaker is ON, and the operator can still be padlocked in the OFF position for LOTO compliance. Rated IP65 and NEMA 4/4X, meaning the mechanism seals against hose-directed water and corrosion — suited for washdown environments, outdoor enclosures, and food-processing or chemical plant panels where a standard IP20 operator would fail.
The operator body measures 77 mm wide by 70 mm high — a compact footprint that fits the cutout pattern for the 3VA4/5 125 frame. Verify the door thickness and handle projection against your enclosure before ordering; the door interlock mechanism needs the correct back-of-door clearance to engage the breaker toggle.