The Siemens 3VA1050-3ED42-0DA0 is a SENTRON molded case circuit breaker (MCCB) rated for 50 A continuous current at 40 °C ambient, with no derating needed up to 50 °C — it holds 50 A flat through that range, then steps down to 49 A at 55 °C and 45 A at 70 °C. That thermal curve means you can load it to nameplate in a warm enclosure without recalculating. The 4-pole configuration with a TM210 thermal-magnetic release handles line protection duty, and the integrated undervoltage release (UVR) lets you drop the breaker on a control signal or safety interlock. Breaking capacity is 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at both 500 V and 690 V. Those numbers cover most industrial distribution panels where fault current is high at the transformer secondary but drops as you move downstream.
Dimensions: 130 mm height, 101.6 mm width, 70 mm depth. 4-pole width is 101.6 mm. UVR adds a control-wire connection.