What it is and what it does
The Siemens SENTRON 3VA1050-3ED42-0BC0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection. It carries 50 A continuously at 40 °C and derates to 45 A at 70 °C, so the thermal curve stays predictable across a warm panel interior. Breaking capacity hits 75.6 kA at 240 V AC and 52.5 kA at 415 V — enough for high-fault utility feeds or transformer secondaries where the available short-circuit current is substantial. An integrated undervoltage release (UVR) trips the breaker when control voltage drops, and two auxiliary switches HQ provide status feedback to a PLC or indication lamp.
Sizing and selectivity
At 50 A rated current and 4 poles, this MCCB fits as a main or feeder breaker in a 3-phase + N panel. The 800 V rated insulation voltage gives headroom for 690 V systems without derating the insulation path. This 50 A unit does not drop in for a panel originally specified with the higher-rated 3VA1110-5ED36-0AC0 without re-calculating load and cable sizing.
Panel integration
Dimensions are 130 mm high, 101.6 mm wide, 70 mm deep — fits standard MCCB panel cutouts and busbar spacing. The 4-pole width matches a 100 mm grid. Maximum power loss is 17.1 W at rated load, so ventilation in a sealed enclosure should account for that dissipation.