Siemens SENTRON 3VA1120-5EF36-0JA0 — 20 A MCCB with TM240 Release
It uses a TM240 thermal-magnetic overcurrent release — a fixed-trip design that combines a thermal bimetal for overloads and a magnetic coil for short-circuits, with no adjustable trip settings. Breaking capacity is the headline figure here: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. The 187 kA at 240 V rating is especially relevant for North American 240 V split-phase or 240/120 V center-tapped services. Thermal derating is documented across the ambient temperature range: the breaker holds its full 20 A rating from 40 °C up to 50 °C, then begins to derate — 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. For a panel that runs hot (say 55 °C inside the enclosure), you must size the load to 19.2 A or less, not the nameplate 20 A. Physical footprint: 70 mm deep, 76.2 mm wide, 130 mm high — a standard 3-pole MCCB width for panel-mounted or DIN-rail installations. Front protection is IP40 (tool-accessible terminals are protected against solid objects over 1 mm; no water ingress protection on the front face). The breaker has no trip indicator and no ground-fault monitoring version.