What it is and what it handles
The 3RT1045-1AV00: The headline number that matters for motor duty: 37 kW at 400 V in AC-2 use (slip-ring motors, soft-start applications). That's the rating that governs the real load, not the AC-3 figure. If you're switching standard squirrel-cage motors, the AC-3 curve is the one to check — this contactor delivers 45 kW at 500 V and 21.1 kW at 690 V, so it covers a wide voltage band without derating surprises. For heavy inching or plugging duty (AC-4), it's rated 66 A at 400 V. That's the worst-case thermal stress number — if your application cycles hard, that's the current limit to respect.
Panel fit and wiring
Mounts via screw and snap-on onto 35 mm or 75 mm standard DIN rail. The S3 frame footprint is 70 mm wide by 146 mm tall by 139 mm deep. Main power terminals are screw-type, accepting solid conductors up to 2x 4 mm² (or 2x 2.5 mm² stranded) and stranded up to 2x 50 mm². That's generous for a contactor this size — you can land a 50 mm² cable without a ferrule adapter. The IP20 front cover with box terminal keeps live parts behind a tool-removed shield, which satisfies most panel-build requirements for finger-safe wiring.
Environmental and compliance
Operates from -25 °C to +60 °C, stores from -55 °C to +80 °C. Pollution degree 3 means it's rated for conductive environments — typical in industrial panels without climate control. The side-by-side mounting allowance (no derating gap needed) saves rail space when ganging multiple contactors. RoHS compliance date is 05/01/2012, so it's been fully RoHS-compliant for over a decade. No REACH or UL mark is explicitly listed in the spec record, but as a Siemens SIRIUS product it carries CE and typically UL/CSA — confirm with the full datasheet for your specific certification requirement.