What this MCCB is and what the ratings mean for your panel
The Siemens 3VA1150-6EE42-0AA0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated for 50 A continuous current, with a TM220 thermal-magnetic release. That 50 A is the sustained load it can carry at 45 °C ambient without derating — at 70 °C it still holds 45 A, so it's a solid pick for a warm enclosure where you need headroom on a 40 A motor or feeder circuit. The interrupting capacity is where this breaker earns its keep: 220 kA at 240 V, 154 kA at 415 V, and 121 kA at 440 V. That's high-fault-duty territory — think transformer secondaries, large capacitor banks, or industrial feeders where a downstream fault could dump serious energy. At 690 V it still clears 17 kA, which covers most 690 V motor circuits.
Panel fit and integration notes
The breaker measures 70 mm deep by 101.6 mm wide by 130 mm tall — a standard 4-pole MCCB footprint that drops onto a DIN rail or mounts directly in a panel. Front face is IP40, so it's fine for a clean indoor enclosure but not washdown zones. The TM220 release is adjustable: the magnetic trip (li) goes up to 500 A, giving you some selectivity tuning against downstream branch breakers.