Siemens 3VA1050-4ED36-0BH0 SENTRON MCCB, 50 A, 121 kA at 240

The 50 A rating holds flat from 40 °C through 50 °C, then derates to 48 A at 55 °C and 45 A at 70 °C — so in a warm enclosure you lose about 10 % at the top end. Breaking capacity runs 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. The UVR means the breaker drops open if control voltage falls below the dropout threshold — common on safety circuits or E-stop strings where loss of control power should also kill the load. The trip alarm switch gives a separate signal when the breaker trips on fault, not just when manually opened, which is useful for remote annunciation or PLC fault-logging.