What it is and what it does
The Siemens SENTRON 3VA1150-3EF36-0AC0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a continuous current rating of 50 A at 40 °C, with the TM240 thermal-magnetic release providing overload and short-circuit protection. The interrupting capacity reaches 75.6 kA at 240 V, dropping to 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at 500 V and 690 V — so it handles high-fault conditions on the secondary side of a distribution transformer or at a service entrance.
Thermal derating and real-world current
The 50 A rating holds steady from 40 °C up to 50 °C, then derates 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, uncooled enclosure near other heat sources, expect to apply that derating curve — the 45 A floor at 70 °C is the safe continuous limit. Operating ambient range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.
Physical fit and mounting
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard 3-pole MCCB footprint that fits most DIN-rail or panel-mount enclosures with the appropriate mounting base. It ships with two auxiliary switches (HQ design) pre-configured; no undervoltage release or ground-fault monitoring is included. Power loss at rated load is 14.6 W, which factors into enclosure thermal calculations.