What it is and what it does
The Siemens SENTRON 3VA1050-4ED32-0BA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection — the primary overcurrent and short-circuit safeguard in a distribution panel or motor control center. It carries 50 A continuously at 40 °C ambient, with a TM210 thermal-magnetic release that handles both overload (thermal) and short-circuit (magnetic) trip curves. The undervoltage release (UVR) built into this variant drops the breaker when supply voltage falls below a set threshold, which is useful for preventing motor re-acceleration after a brownout or for safety interlocking.
Breaking capacity — what it means for your panel
This breaker's interrupting rating is voltage-dependent, and the spread matters for selectivity studies. At 240 VAC it clears 121 kA — enough for most secondary distribution near a large transformer. At 415 VAC it's 75.6 kA, at 440 VAC 52.5 kA, and at 500 VAC and 690 VAC it holds at 11.9 kA. The 690 V figure is the one to watch if you're feeding a 690 V drive or motor; 11.9 kA is a solid interrupting rating for that voltage class but needs coordination with upstream protection. The insulation voltage is rated 800 V, so the breaker itself is built for 690 V systems.
Thermal derating and panel integration
The 50 A rating holds steady through 50 °C ambient — no derating needed in a typical 40 °C panel. Above that it drops: 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, 45 A at 70 °C. If the breaker sits in a sealed enclosure or next to heat-generating gear, use the 70 °C figure (45 A) for your continuous load calculation. Dimensions are 130 mm tall, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint that fits most Siemens SENTRON panelboards and third-party enclosures with DIN-rail or screw-mount adapters.