The Siemens 3RV6021-4AA10 is a SIRIUS motor protection circuit breaker in the S0 frame size — a three-pole thermal-magnetic device rated 16 A operational current at 690 V, 50/60 Hz. That 16 A at AC-3 duty (400 V) means it directly protects a motor drawing that full-load current; the 7 W typical power loss tells you it's not a power hog in a crowded panel.
The S0 frame footprint is 45 mm wide by 97 mm tall by 96 mm deep. That 0 mm forward clearance means it can sit flush against a panel door or busbar cover without extra breathing. Screw-type terminals on top and bottom accept 2×(1…2.5 mm²) solid/stranded or 2×(2.5…10 mm²) — torque to 2…2.5 N·m.
Rated 16 A at AC-3 (400 V) — that's the motor-switching current, not a resistive load. Shock-rated to 25 g / 11 ms per IEC 60068-2-27, so it holds up in mobile or high-vibration installations. Operating temperature -20 to +60 °C, 10-95% RH non-condensing.
