Siemens SIRIUS 3RT2045-1AD04 — Power Contactor, Size S3, 77 A at 480 V
The Siemens SIRIUS 3RT2045-1AD04 is a size S3 power contactor rated for 77 A at 480 V in AC-3 duty, making it suitable for switching three-phase motor loads up to that current in industrial control panels. It carries screw-type terminals on the magnet coil and main contacts, with a wire range accepting 2.5 to 16 mm² solid or 6 to 70 mm² stranded on the power side. Mounting is via screw and snap-on onto a 35 mm standard rail per DIN EN 60715, with a mounting position that allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward. The contactor occupies a 70 mm width on the rail, with a 195 mm depth that must be accounted for in enclosure depth planning. An auxiliary switch is included as standard, with a main contact configuration of 10 normally open and 2 normally closed poles. The coil is 24 VDC rated at 6 A holding current, with a dropout threshold below 18 V — verify free-wheel diode polarity if the control circuit drives an inductive load.
Screw-type terminals on the coil accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded wire for control wiring. Main power terminals accept 2.5 to 16 mm² solid or 6 to 70 mm² stranded — torque values per the terminal marking on the contactor body. At 70 mm wide and 140 mm tall, it fits standard DIN-rail enclosures with typical gland-plate clearance. The 195 mm depth includes the arc chamber; allow an additional 20 mm forward clearance for arc quenching and cable bending radius.