Siemens SENTRON 3VA1120-5EF36-0JA0 — 20 A MCCB with TM240 Release
The Siemens SENTRON 3VA1120-5EF36-0JA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 20 A and a rated insulation voltage of 800 V. 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. The breaker is fitted with a shunt trip (STL) auxiliary release (order code 3VA9688-0BL32) for remote tripping, and has no auxiliary contacts, undervoltage release, communication function, or phase failure detection. 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. Those numbers mean this MCCB can safely interrupt fault currents up to those levels at the respective system voltages — critical for high-fault installations like transformer secondaries or large motor control centers where available fault current can exceed 100 kA. 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. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. 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.