SIRIUS power contactor, size S3 — 45 kW AC-2, 80 A AC-4
The Siemens 3RT1046-3AL16 is a SIRIUS power contactor in the size S3 frame, rated for 45 kW at 400 V in AC-2 duty (slip-ring motor starting) and 80 A in AC-4 duty (reversing / inching). The screw-type terminals on the main circuit accept 2x (10... 50 mm²) stranded or 2x (0.25... 2.5 mm²) solid on the coil side.
The AC-2 rating (45 kW at 400 V) covers slip-ring motor starting where the contactor closes on inrush and opens under load. The AC-4 rating (80 A at 400 V) covers reversing, plugging, and inching duty — the most demanding motor-switching category because the contactor opens at full locked-rotor current. For comparison, the AC-3 maximum mechanical switching rate is 850 operations per hour, while AC-4 drops to 250 per hour due to the higher electrical stress on the contacts.
Panel integration and environmental limits
Front protection is IP20 with the cover or box terminal installed; the terminal area itself is IP00, so maintain separation from live busbars during panel wiring.