The Siemens SENTRON 3VA1150-3EF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) from the 3VA line-protection family, sized for a 50 A continuous load at 40 °C ambient. The TM240 thermal-magnetic release handles overloads and short-circuits without external trip units — a fixed-release design that keeps the BOM simple and eliminates setup errors on the panel floor.
Breaking capacity across voltages
This MCCB delivers 75.6 kA at 240 V AC, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at both 500 V and 690 V. The steep drop above 440 V means the 3VA1150-3EF42-0AA0 is best suited for 240 V delta or 400/415 V wye distribution panels where fault currents stay under 50 kA — at 690 V the 11.9 kA figure still covers most industrial transformer secondaries, but verify the available fault current on the line side before committing the BOM.
Thermal derating and panel fit
Rated current holds at 50 A from 40 °C through 50 °C, then drops to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. In a sealed enclosure with multiple breakers ganged, the 45 A floor at 70 °C is the number to design to — the 50 A label applies only when ambient inside the panel stays at or below 50 °C. The 70 mm depth and 101.6 mm width fit standard 4-pole MCCB mounting footprints; IP40 on the front means the breaker face is protected against tools and wires but the enclosure itself must handle splash or dust.