The Siemens SIRIUS 3RT1016-1AN02-1AA0 is a size S00 power contactor with a 24 VDC coil, rated to switch 10 A at 24 V and 3 A at 400 V in AC-3 duty.
For motor starting (AC-3), the 400 V rating of 3 A governs the load it can handle cycle after cycle. The 690 V rating of 5.5 kW covers higher-voltage motor circuits common in European industrial panels. The screw terminals accept solid or stranded conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²). For AWG, that's 2x (20 to 16), 2x (18 to 14), and 1x 12. The IP20 finger protection on the front and terminals means it's safe for open-panel mounting inside an enclosure.
