What this 3VA1120-5EF32-0HH0 is and what it does
The Siemens 3VA1120-5EF32-0HH0 is a SENTRON molded case circuit breaker (MCCB) set up for line protection — it's the main disconnect and fault interrupter in a distribution panel, not a motor starter or a feeder for sensitive electronics. Rated 20 A continuous current (Iu) with a TM240 thermal-magnetic release, it holds full load at 20 A up to 50 °C ambient, then derates to 18 A at 70 °C — so in a hot panel or next to a drive, you need to check the actual ambient before you commit the BOM line. The interrupting ratings are the headline: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V — these tell you the breaker can safely clear a fault up to those levels without welding contacts or bursting the case, which means it handles high-fault-current industrial service without cascading upstream.
Fit and integration
Three-pole, 70 mm deep, 76.2 mm wide, 130 mm tall — it mounts on a DIN rail or panel base in a standard distribution enclosure, with IP40 protection on the front face. It carries 2 auxiliary switches plus 1 trip alarm switch (HQ type) for remote status, and a shunt trip release (STL) is built in — no undervoltage release, no communication module, no ground-fault monitoring, so if you need those functions you spec a different variant or add external modules. The integrated auxiliary trip order code is 3VA9688-0BL30 — that's the factory-matched accessory, not a generic substitute.
What the ratings mean for the buyer's decision
The 187 kA at 240 V is the highest short-circuit current this breaker can interrupt — if your facility's available fault current at the panel is 200 kA, this breaker isn't rated for it, and you'd need a current-limiting upstream device or a higher-rated frame. Rated insulation voltage is 800 V, which means it's suitable for 690 V line-to-line systems (common in heavy industrial) — the 17 kA at 690 V confirms it handles faults at that voltage level. Latching endurance is 15,000 operations — mechanical life, not electrical load-switching life.