What it is and what it does
The Siemens 3VA1120-4ED32-0AA0 is a SENTRON-series molded case circuit breaker (MCCB) for line protection, built around a TM210 thermal-magnetic overcurrent release. Three poles, rated 20 A continuously at 40 °C ambient — derate to 19 A above 60 °C per the thermal curve. Breaking capacity is the headline number here: 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 500/690 V. That is a high-interrupting rating for a 20 A frame — it sits comfortably ahead of most panelboard MCCBs in the same current class, which means it can be used as a main or branch device where fault current is substantial. The TM210 release is a fixed thermal-magnetic type — no interchangeable trip units, no electronic adjustments. For a line-protection role (cable/feeder protection) that is usually fine; you set the application at 20 A and leave it. Insulation voltage rated 800 V, IP40 on the front face — suitable for enclosed panel mounting, not open washdown areas.
Panel fit and dimensions
The 3VA1120-4ED32-0AA0 measures 130 mm high, 76.2 mm wide, 70 mm deep. That is a standard 3-pole MCCB footprint for the SENTRON 3VA platform — it occupies three 18 mm pole spaces on the DIN rail, same as other 3VA three-pole breakers. No undervoltage release, no shunt trip, no communication module on this variant — it is a straight thermal-magnetic breaker with no auxiliary electronics. Operating temperature range -25 °C to +70 °C; storage from -40 °C to +80 °C. Maximum power loss 12 W at rated load — negligible for panel thermal budgeting, but worth noting if you are packing several breakers in a sealed enclosure.