What the ratings mean for fit
The Siemens SENTRON 3VA1120-4EF36-0HH0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection in distribution panels. Its 20 A continuous rating holds across 40 °C to 50 °C without derating; above that it drops to 19.2 A at 55 °C and 18 A at 70 °C — a curve that matters when the breaker shares a warm enclosure with other heat sources. Breaking capacity is 121 kA at 240 V AC, 75.6 kA at 415 V, and 52.5 kA at 440 V, so it handles high-fault industrial mains without cascading upstream. Rated insulation voltage is 800 V, covering 480 V and 600 V class systems. The TM240 thermal-magnetic release provides fixed overload and short-circuit protection; a shunt trip (STL) is built in for remote tripping. Auxiliary contacts include two form-C switches plus a separate trip alarm contact (HQ configuration), giving the PLC or BMS a dedicated fault signal without sharing the aux stack.
Panel integration and mounting
The breaker measures 76.2 mm wide, 130 mm high, and 70 mm deep — a standard 3-pole MCCB footprint that fits most Siemens SENTRON distribution boards and third-party enclosures with 25 mm busbar centers. Front protection is IP40, so it is suited for indoor panel installation where tools or fingers are the main concern; no washdown rating. The integrated auxiliary trip (order code 3VA9688-0BL30) is factory-fitted, saving a wiring step at the panel builder. Latching endurance is rated at 15,000 cycles, which covers routine switching in process or building power distribution.