The Siemens SENTRON 3VA1120-5EF36-0AC0 is a 3-pole molded case circuit breaker rated 20 A continuous at 40 °C, with a TM240 thermal-magnetic trip unit. Two built-in auxiliary switches HQ come standard, saving a slot on the DIN rail for the next breaker.
At 440 V it still breaks 75.6 kA, and at 500 V or 690 V it holds 17 kA. That means this breaker can be the main disconnect on a 415 V switchboard with a transformer-fed fault current up to 121 kA — no need to cascade a current-limiting fuse upstream. The TM240 thermal-magnetic release handles overloads and short-circuits in one package; no electronic trip unit to program or battery to maintain.
Thermal derating — it holds 20 A through 55 °C
That gives you headroom in a hot panel — no need to oversize the breaker for a 50 °C ambient. Power loss is 12 W at full load, which matters for heat buildup in a sealed enclosure.
It clips onto the DIN rail or mounts via rear screw terminals.
Auxiliary switches and options
Comes with two auxiliary switches HQ (high-qualified) built in — no separate order for a signal contact. It's a bare line-protection breaker with the aux contacts as the only add-on. If you need shunt trip or UVR, that's a different order code in the 3VA family.