What the ratings mean for your panel
The Siemens SENTRON 3VA1120-3EF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 20 A continuous at 40 °C, with the TM240 thermal-magnetic release providing fixed overload and short-circuit protection. The 75.6 kA interrupting rating at 240 V AC means it can safely clear a fault of that magnitude — high enough for most secondary distribution panels without needing a current-limiting upstream device. At 415 V the rating drops to 52.5 kA, and at 690 V to 11.9 kA, so verify the available fault current at your service voltage before committing the BOM line. The IP40 protection on the front means the breaker face is sealed against tools and small solids but not against moisture — suitable for a dry indoor panel. The 12 W maximum power loss is the heat it dumps into the enclosure; factor that into your thermal budget if the panel is densely packed.
Physical fit and integration
Dimensions: 70 mm deep, 101.6 mm wide, 130 mm tall. The 4-pole body occupies the same DIN-rail footprint as other SENTRON 3VA breakers of this frame size. No undervoltage release, no communication function, no ground-fault monitoring — it is a straight thermal-magnetic line-protection breaker with the TM240 release. If your BOM calls for a shunt trip or aux contact, order the accessory separately.