What it is — and what it does
The Siemens 3VA1120-4GF46-0AA0 is a SENTRON molded case circuit breaker (MCCB), designed for line protection in industrial distribution panels. Rated 20 A continuous through the full 40–55 °C range, it holds that current without derating in a warm cabinet — only above 60 °C does it step down to 19 A. Interrupting capacity is the headline: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That means it can safely clear a fault at high available short-circuit current without upstream coordination headaches — useful on large transformer secondaries or high-capacity busways. The overcurrent release is a TM240 thermal-magnetic type — fixed thermal curve, magnetic pickup set at 240 A (12× In). No ground-fault monitoring, no communication module, no undervoltage release on this variant. Front protection is IP40, fine for a clean panel environment.
Panel fit and mounting
Footprint is 101.6 mm wide by 130 mm tall by 70 mm deep — a compact 4-pole MCCB that bolts into standard mounting plates. No DIN-rail clip; expect screw-mount or bus-bar connection. The 70 mm depth fits most shallow gland-plate enclosures; check back-panel clearance if you're stacking multiple breakers. Power loss is 12 W maximum at rated load — negligible for thermal budgeting in a ventilated enclosure, but worth noting if the panel is sealed and densely packed.
Lifecycle and sourcing
If you're replacing a failed unit on a line-down call, the 20 A 4-pole TM240 release is the specific variant. No direct second-source with the same footprint and interrupting curve is listed; verify physical interchangeability against your existing panel layout.