What this contactor is and what it does
The Siemens 3RT2045-1AV00 is a SIRIUS power contactor in size S3, designed for switching motor loads and resistive loads in industrial control panels. It carries a 77 A rating at 480 V in AC-3 duty, which means it handles full motor starting current up to that level — the rating that actually decides whether it holds on a conveyor or pump start. At 230 V it's rated 15 hp, so it covers a common three-phase motor range in North American panels. The screw-type coil terminals are a field-serviceable detail: you can swap the coil on site with a headlamp and a screwdriver, no shop bench needed.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The depth is 152 mm — that's the dimension that matters when you're laying out gland plates or door clearance. Width is 70 mm, height 140 mm. Clearance around the contactor: 10 mm upwards, 10 mm downwards, 20 mm forwards, 10 mm at the side. Mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward, so you can shoehorn it into tight enclosures without re-drilling the backplate.
Wiring terminals
Main circuit terminals accept solid conductors 2.5 to 16 mm² or stranded 6 to 70 mm² — that's a wide clamping range that covers most motor feeder cables without adapters. Auxiliary switch terminals take 2x (0.5 to 1.5 mm²) solid/stranded or 2x (0.75 to 2.5 mm²). The screw-type coil terminals are standard across the SIRIUS line, so a panel-builder can keep the same screwdriver bit for the whole cabinet.
Switching performance and mechanical life
Rated for 10 million mechanical operations typical. Switching frequency at AC-3 is 1,000 cycles per hour; at AC-1 (resistive) it's 900 cycles per hour; AC-4 (plugging/inching) is 300 cycles per hour. Arcing time is 10 to 20 ms at 50 Hz. The 0.38 value at 50 Hz likely refers to power factor at rated current — a typical motor-load power factor that confirms the AC-3 rating is genuine, not a resistive-only number.
Environmental and auxiliary specs
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The auxiliary switch is included. Coil operating current at 24 V is 10 A (likely the contact rating, not the coil draw — verify against your control transformer sizing). At 400 V the auxiliary contacts are rated 3 A.