Line protection MCCB, 50 A frame, 4-pole, TM220 trip
The Siemens SENTRON 3VA1150-5GE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous 50 A at 40 °C and derating to 45 A at 70 °C. The TM220 thermal-magnetic trip unit handles overload and short-circuit response without external control power — it's self-powered, so it clears faults even if the control voltage drops. Interrupting capacity is 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V, which covers most industrial distribution panels where high fault current is expected downstream of a transformer.
Panel fit and thermal considerations
Dimensions are 130 mm height, 101.6 mm width, 70 mm depth — a 4-pole frame that occupies roughly four module spaces on a DIN rail or panel-mount base. The thermal derating curve is flat from 40 °C to 50 °C (50 A), then drops to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. Maximum power loss is 14.6 W at rated current — modest for a 50 A frame, but in a sealed cabinet with multiple breakers the cumulative heat matters.