The Siemens SENTRON 3VA1120-5EF32-0CC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current Iu of 20 A at 40 °C through 50 °C. That flat thermal curve means no derating in a typical 50 °C panel interior — a real advantage when the enclosure runs warm. Above 55 °C it steps down: 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. The TM240 overcurrent release handles the thermal-magnetic trip curve for this frame size. Breaking capacity is the headline number here: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. Those are the interrupting ratings at the respective system voltages — critical for fault-current coordination studies. At 415 V, 121 kA covers most industrial secondary-distribution scenarios with high transformer kVA.
Mounting and integration — DIN-rail footprint and panel fill
That 76.2 mm width is 3 x 25.4 mm — a standard 3-pole MCCB module pitch, so it fits a 3-module DIN-rail cutout. The 15,000 mechanical endurance cycles (latching operations) are typical for this class — adequate for a distribution panel that sees infrequent switching; not a contactor duty cycle.