What this SIRIUS S3 contactor does in a panel
The Siemens SIRIUS 3RT1045-3AV60 is a size S3 power contactor — the middle frame in the SIRIUS family, sized for motor loads up to 37 kW under AC-2 duty at 400 V. That AC-2 rating covers slip-ring motor starting and reversing, where the contactor sees moderate inrush and makes/breaks under load. For the tougher AC-4 duty — plugging, inching, jogging — it's rated 66 A at 400 V, so it handles the higher switching frequency and arcing those cycles demand. Mounts on standard 35 mm or 75 mm DIN rail with a screw-and-snap action, or you can bolt it to a backplate. Main terminals are screw-type, accepting solid conductors 2x 0.25...2.5 mm² and stranded 2x 10...50 mm².
Where the ratings matter for selection
The AC-2 37 kW at 400 V tells you this contactor is specced for wound-rotor motors, not the standard squirrel-cage AC-3 duty. If your motor is a standard induction type, you'd size off the AC-3 rating instead — but that figure isn't listed here, so check the motor's duty cycle against the AC-2 or AC-4 curves. That's a real constraint for a conveyor or hoist application — don't overshoot that cycle rate.
Dimensions: 146 mm high, 70 mm wide, 139 mm deep. That depth matters when you're laying out a shallow enclosure — 139 mm is the body depth, not including projection of screw terminals or wiring loops. IP20 on the front with the cover or box terminal installed; the terminal itself is IP00, so it's not sealed against dust ingress into the connection area.