SIRIUS S3 Power Contactor — 45 kW at 500 V
The Siemens SIRIUS 3RT1045-3AR60 is a Size S3 power contactor rated for 45 kW at 500 V and 21.1 kW at 690 V, covering 50/60 Hz motor loads in standard industrial control panels. Screw-type terminals accept 2x (10... 50 mm²) stranded on the main circuit, with solid wire down to 2x (0.25... 2.5 mm²) on the auxiliary.
The 45 kW rating at 500 V (AC-3 duty) tells you this contactor is sized for a 55–60 A motor load at that voltage — the real-world figure that decides the BOM line, not the AC-1 resistive current. At 690 V it carries 21.1 kW, which is the higher-voltage limit for applications like 690 V delta-connected motors in European or mining installations. Switching frequency at AC-3 is rated at 1000 operations per hour, so it handles frequent start/stop cycles on conveyors or pumps without derating for thermal accumulation.
Installation and Wiring Notes
Main circuit screw terminals accept 2x (10... 50 mm²) stranded; auxiliary terminals take 2x (0.25... 2.5 mm²) solid. The solid/stranded range on the main circuit also covers 2x (2.5... 16 mm²) for mixed wire sizes. Snap-on mounting to 35 mm or 75 mm DIN rail is tool-less; the screw-and-snap combination also allows bolting to a backplate if vibration is a concern. Side-by-side mounting is allowed — no derating for zero-gap packing at rated current.