The Siemens 3VA1120-4EF32-0AG0 is a SENTRON molded case circuit breaker (MCCB) for line protection, rated 20 A continuous at 40 °C across a 3-pole configuration. Its TM240 thermal-magnetic release handles overload and short-circuit trip curves without undervoltage or shunt-trip add-ons — that's another SKU I don't need on the shelf. Interrupting capacity hits 121 kA at 240 V AC and still delivers 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V — enough headroom for most industrial service-entrance or feeder panels without cascading upstream breakers. Rated insulation voltage is 800 V, so it's comfortable on 480/277 V or 600 V systems with margin. Power dissipation maxes at 12 W — negligible in a ventilated enclosure but worth noting for sealed, high-density layouts.
Physical fit and panel integration
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — standard 3-pole MCCB footprint for DIN-rail or screw-mount panel integration. The 70 mm depth keeps it clear of shallow backpanels and leaves room for rear bus connections. Comes with one auxiliary switch and one trip alarm switch (HP design) factory-fitted — no separate order for status feedback to the PLC or alarm annunciator. Trip indicator is present, so a quick visual scan tells you which breaker opened.
Lifecycle and sourcing
The base switch part number is 3VA11204EF320AA0 — useful for cross-referencing internal BOMs or ordering the switching mechanism separately if the trip unit is field-replaceable.