What it is and what it carries
The Siemens 3VA1150-4GE42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection — 50 A continuous on all four poles, with a TM220 thermal-magnetic trip unit that handles overload and short-circuit curves without external power. Breaking capacity is 121 kA at 240 VAC, dropping to 75.6 kA at 415 VAC and 52.5 kA at 440 VAC; at 500 V and 690 V it holds 11.9 kA — enough for most industrial distribution panels fed by a transformer of moderate impedance.
Thermal derating and panel fit
The 50 A rating holds flat from 40 °C up to 50 °C ambient; above that it derates linearly to 45 A at 70 °C. If the panel runs hot near the top of the enclosure, account for that 5 A drop before sizing the downstream load. Footprint is 101.6 mm wide by 130 mm tall by 70 mm deep — a standard 4-pole MCCB envelope that fits DIN-rail or screw-mounted backplates. IP40 on the front face keeps dust out of the mechanism; no IP rating on the terminals, so keep the enclosure sealed against washdown.
Lifecycle and compliance
Rated insulation voltage is 800 V, operating range -25 °C to +70 °C, storage from -40 °C to +80 °C. Power loss at full load is 14.6 W maximum — negligible for panel thermal budgeting but worth noting if the breaker sits in a sealed enclosure with other high-current devices.