What it is and what it does
The Siemens SENTRON 3VA1050-3ED32-0BH0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a continuous rating of 50 A at 40 °C, with minimal thermal derating up to 70 °C (45 A at 70 °C). The interrupting capacity reaches 75.6 kA at 240 V AC, stepping down to 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at 500/690 V — a curve that tells you this breaker is built for high-fault locations like transformer secondaries or industrial main feeders where 240 V phase-to-neutral faults can exceed 50 kA.
Key ratings and what they mean for fit
The 50 A frame at 40 °C is the thermal benchmark. At 55 °C it still delivers 49 A, and at 60 °C it holds 48 A — so in a warm panel near a transformer or drive cabinet, you lose less than 5 % of capacity before 60 °C. The rated insulation voltage of 800 V covers 480 V and 600 V class systems with margin. The 17.1 W maximum power loss is modest for a 50 A frame, which helps keep internal panel temperature rise under control in a dense layout.
Built-in accessories and panel integration
This variant ships with an undervoltage release (UVR) and a pre-installed auxiliary switch block carrying 2 auxiliary contacts plus 1 trip alarm switch (HQ). The UVR ensures the breaker drops out on loss of control voltage — standard for safety circuits or emergency-stop chains that need the load isolated when the control supply fails. The auxiliary and alarm contacts give the PLC or BMS a clean status signal without an add-on module. The 3-pole body measures 76.2 mm wide, 130 mm tall, and 70 mm deep — a standard 3-pole MCCB footprint that fits SENTRON panelboards and most DIN-rail adapters.