It's the full-size S3 frame (70 mm wide, 148 mm tall, 139 mm deep), so it takes up a standard contactor slot on the DIN rail. The front face carries IP20 finger protection; the terminals are IP00, meaning the wiring zone expects enclosure protection from the panel itself.
AC-3 switching up to 690 V — that's the motor-duty rating for starting and disconnecting squirrel-cage induction motors under load. The 3RT7045-1AC20 carries no DC-3 or AC-4 numbers in the spec, but the AC-3 max operating voltage at 690 V tells you it handles 400 V and 480 V line-ups without derating the voltage side. The mechanical switching frequency tops out at 800 operations per hour under AC-3, 250 per hour under AC-4 — the AC-4 figure governs plugging and inching duty, so if your application does frequent reversing or jogging, that's the number that limits cycle life. Coil draw is modest: 0.62 W closing power, 0.27 W holding — that keeps the control transformer small and the heat inside the panel down. Pollution degree 3 suits it for industrial enclosures where conductive dust or humidity is present.
That means you can orient it to fit tight cable entries or gland plates without worrying about derating the coil or contacts. Side-by-side mounting is allowed — no gap needed between units — which saves rail space in multi-contactor groups. Terminals accept 2x 0.5 to 1.5 mm² solid/stranded, or 2x 0.75 to 2.5 mm² — fine for control wiring on the aux side and main power cables up to 2.5 mm². The screw-type terminals are field-serviceable with a standard Pozidriv bit; no special torque tool required. The product extension allows an auxiliary switch block to be added on top if you need extra N/O or N/C contacts beyond the three main poles. Operating temperature range is -10 to +55 °C, storage from -25 to +70 °C — fine for most indoor panel environments. If the panel sits in a non-conditioned space that hits 55 °C ambient, the contactor is still within its operating band without derating.