S3 power contactor for motor and resistive loads
The Siemens 3RT1045-1AR04 is a SIRIUS power contactor in frame size S3, designed for switching motors and resistive loads in industrial control panels. It mounts via screw or snap-on onto 35 mm and 75 mm standard DIN rails, with a 70 mm width footprint that fits alongside other SIRIUS components in a crowded enclosure. Rated at 66 A in AC-4 duty at 400 V, it handles the high inrush and frequent switching of reversing or plugging motor applications. For AC-2 duty — typical for slip-ring motors — it delivers 37 kW at 400 V. The AC-3 rating supports 45 kW at 500 V and 21.1 kW at 690 V, covering standard squirrel-cage motor starts across common European supply voltages.
Wiring and environmental limits
Main power circuit uses screw-type terminals accepting stranded conductors up to 2x (10... 50 mm²). Auxiliary/control wiring takes solid conductors from 0.5 mm² up to 4 mm² per terminal. The front face carries an IP20 rating with the cover or box terminal installed; the terminal body itself is IP00, so panel builders must maintain safe clearance distances inside the enclosure. Operating ambient range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 rating means it tolerates conductive pollution typical in industrial environments — no special sealing required for most factory-floor panels. Side-by-side mounting is permitted without derating, simplifying multi-contactor assemblies.