The Siemens SENTRON 3VA1120-6EF32-0KA0 is a 3-pole molded case circuit breaker (MCCB) rated for 20 A continuous current at 40 °C, with a massive 220 kA breaking capacity at 240 V AC — that's the SCCR headroom you need for high-fault utility feeds or transformer secondaries where a standard 65 kA breaker would cascade upstream. It's designed for line protection, meaning it's the main incoming breaker in a distribution panel, not a motor-protective device. The shunt trip release (STL) built into this variant allows remote tripping from a fire alarm, E-stop, or PLC output — essential for emergency-off circuits or load-shedding schemes where you need to kill the main feed without walking to the panel. The TM240 overcurrent release gives thermal-magnetic protection with a fixed 20 A rating and adjustable magnetic pickup (not detailed here, but typical for the SENTRON TM series).
Thermal derating and panel integration
Rated 20 A from 40 °C through 55 °C, then derates to 19 A at 60 °C through 70 °C. That's a clean thermal curve — no derating step until 60 °C, which simplifies panel design for most industrial environments. The 70 mm depth and 76.2 mm width fit standard Siemens SENTRON mounting feet; it snaps onto the DIN rail or bolts to the backplate. At 130 mm tall, it leaves room for auxiliary contacts above or below in a typical distribution board. Maximum power loss is 12 W — negligible for panel thermal budgeting, but worth noting if you're packing multiple breakers in a sealed enclosure. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.