50 A MCCB with TM240 release — line protection for 3-phase panels
The Siemens 3VA1150-4EF36-0AA0 is a 3-pole molded case circuit breaker from the SENTRON family, designed for line protection in distribution panels. Rated 50 A continuous at 40 °C through 50 °C, it carries a TM240 thermal-magnetic overcurrent release — meaning the thermal element is fixed at 50 A and the magnetic trip threshold is factory-set to 240 A (4.8x In), which is a standard setting for feeder protection where you want short-circuit pickup well above inrush but below cable damage curves. Breaking capacity is the headline number here: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 500 V and 690 V. That 121 kA at 240 V is unusually high for a 50 A frame — it means this breaker can sit upstream of a high-fault transformer without needing a current-limiting fuse ahead of it. At 415 V the 75.6 kA still covers most industrial service-entrance applications in IEC markets. The 11.9 kA at 690 V is the weak point; if your system runs 690 V with fault current above that, you need a different frame. Thermal derating is published across the full operating range: full 50 A up to 50 °C, then 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. That 45 A at 70 °C is the number to use if this breaker lives in a non-ventilated enclosure next to transformers or drives. The maximum power loss is 14.6 W, which is manageable for a 50 A MCCB but worth checking against your enclosure thermal budget if you're packing several in a row.
Integration — panel fit and wiring
Physical footprint: 76.2 mm wide (3 in), 130 mm tall (5.12 in), 70 mm deep (2.76 in). That is a standard 3-pole MCCB width — it occupies three 25.4 mm modular spaces on a DIN rail or panel-mount plate. The IP40 front protection means it is suitable for indoor panel installation where no water jets are present; if the panel door is open during maintenance, keep tools away from live busbars. No undervoltage release, no shunt trip, no communication module, no ground-fault monitoring — this is a bare line-protection breaker. If you need remote trip or GFCI, you step up to a different 3VA variant with the accessory slot populated. The TM240 release is non-interchangeable; the thermal and magnetic settings are fixed at the factory.