What the ratings mean for fit
The Siemens SIRIUS 3RT1045-1AV60 is a size S3 power contactor rated for motor switching duty. The AC-2 rating at 400 V is 37 kW — that's the figure that governs switching wound-rotor or slip-ring motors where the load current stays near the starting current throughout the cycle. The AC-4 rating at 400 V is 66 A, which covers reversing or inching applications where the contactor makes and breaks the stalled-rotor current. For a panel builder, the screw-type terminals on the main circuit accept stranded conductors up to 2x 50 mm², so no crimping tool change for the power feed.
Mounting and integration
Mounts via screw or snap-on onto 35 mm or 75 mm standard DIN rails. The 70 mm width and 146 mm height fit a standard S3 footprint; side-by-side mounting is permitted without derating, which keeps the panel fill factor tight. The front face carries IP20 protection with the cover or box terminal installed; the terminal area itself is IP00, so live parts are exposed during wiring — standard practice for panel-mounted contactors. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C, which covers most enclosure environments without forced cooling.