What the ratings mean for fit
The 3RT2045-1CP04 is a SIRIUS Size S3 power contactor rated 77 A at 480 V — that's the AC-3 motor-switching current, so it handles a 3-phase motor load up to that current without welding the main contacts. The 480 V figure tells you it's sized for 480 V line-to-line systems common in North American industrial panels; the same contactor also carries a 15 hp rating at 230 V, confirming its motor-duty capability across common voltage levels. Mechanical life is listed at 10 million operations typical, and the maximum switching frequency hits 1 000 cycles per hour in AC-3 duty — that's about one cycle every 3.6 seconds, which covers most conveyor, pump, and fan cycling without derating. The arcing time sits between 10 and 21 ms, meaning the arc extinguishes fast enough to avoid nuisance tripping of upstream protection on moderate inductive loads. The contactor mounts on a 35 mm DIN rail per DIN EN 60715, with screw and snap-on fastening. Clearance requirements are tight: 10 mm upwards, 10 mm downwards, 10 mm at the side, and 20 mm forwards — so it fits into a standard 200 mm deep enclosure with room for wiring. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, which helps when the panel layout is cramped.
Wiring and terminal details
Main power terminals accept solid conductors from 2.5 to 16 mm² and stranded conductors from 6 to 70 mm² — the stranded range covers the 77 A rating with a 16 mm² or 25 mm² cable, while the solid range handles smaller control wiring. The coil terminals are screw-type, accepting 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded. An auxiliary switch is built in, so you don't need a separate add-on block for status feedback.
Environmental and compliance
Operating temperature range is -25 to +60 °C, which covers most indoor panel environments; storage range extends from -55 to +80 °C, so it can sit in a warehouse or truck without damage. The contactor is part of the SIRIUS family, which carries IEC and UL certifications — compliance documentation (RoHS, REACH, UL, IEC) is available from the manufacturer on request.