The Siemens SENTRON 3VA1120-5EF36-0AH0 is a 3-pole molded case circuit breaker (MCCB) rated 20 A at 40 °C with a TM240 thermal-magnetic release. It carries 2 auxiliary switches plus a trip alarm switch HQ, so it can signal its state back to a PLC or SCADA without an add-on module.
The 3VA1120-5EF36-0AH0 measures 76.2 mm wide, 130 mm tall, and 70 mm deep. The 76.2 mm width (3 inches) is the standard 3-pole MCCB footprint — it occupies three 25.4 mm module positions on the rail.
Rated current holds at 20 A from 40 °C up to 55 °C ambient, then derates to 19 A at 60 °C through 70 °C. That's a flat thermal curve — no derating step until 60 °C, which is unusual for a compact MCCB. The insulation voltage is rated 800 V, and the breaking capacity drops from 187 kA at 240 V to 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. Maximum power loss is 12 W.