What it is and what it does
The Siemens SENTRON 3VA1020-4ED42-0AA0 is a 4-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 20 A rating at 40 °C, with a TM210 thermal-magnetic overcurrent release that handles both overload and short-circuit conditions without undervoltage or ground-fault monitoring. The breaker's 121 kA interrupting capacity at 240 V AC means it can safely clear high-fault currents in a 240 V system without cascading upstream — critical for selectivity in a main or feeder position. At 415 V the breaking capacity drops to 75.6 kA, still enough for most industrial service-entrance applications.
Key ratings and what they mean for fit
Rated current holds at 20 A from 40 °C up to 55 °C, then derates to 19 A at 60 °C through 70 °C — no surprise for a panel-mounted breaker, but worth noting if the enclosure runs hot. The insulation voltage is rated 800 V, so the breaker is suitable for 690 V systems as well, where it still interrupts 11.9 kA. Front IP40 protection keeps dust out of the operator interface; the body is open to the panel interior, so overall enclosure IP rating depends on the cabinet. Dimensions are 101.6 mm wide, 130 mm high, 70 mm deep — a standard 4-pole MCCB footprint that fits SENTRON panelboards and most DIN-rail adapters.