What this MCCB delivers in the panel
The Siemens SENTRON 3VA4120-5ED24-0AA0 is a 2-pole molded-case circuit breaker rated 20 A at 40 °C ambient, with a TM210 thermal-magnetic overcurrent release. Its interrupting rating hits 85 kA at 240 V AC and 35 kA at 480 V AC — figures that govern fault-clearing capability in a distribution panel, not just a label. At 600 Y/347 V it still holds 18 kA, so it handles common North American wye configurations without derating the SCCR. The TM210 release is a fixed thermal-magnetic trip unit — no interchangeable rating plugs, no electronic adjustment. That simplifies specification: what you see on the nameplate is the continuous current, and the magnetic pickup is factory-set. For a system-protection role (per the product design), this is intentional — fewer variables in a coordination study.
Thermal derating and ambient conditions
The 20 A rating holds at 40 °C and 45 °C. At 50 °C it derates to 19 A, at 60 °C to 18 A, and at 70 °C to 17 A. If your panel ambient runs above 40 °C — common in a crowded enclosure or near a heat source — size the load accordingly. The operating range spans -25 °C to +70 °C, storage from -40 °C to +80 °C. Power loss at full load is 5.6 W maximum, which matters for thermal budgeting inside a sealed cabinet.
Physical fit and panel integration
Dimensions: 50.8 mm wide (2 in), 129.4 mm high (5.09 in), 75.1 mm deep (2.96 in). The 2-pole width matches a standard 2-module DIN-rail footprint. Front IP40 protection means tools or fingers won't contact live parts through the cover, but the breaker is not sealed against dust ingress — mount it inside a rated enclosure for washdown or outdoor duty.