The Siemens 3RT2045-1AP04 is a SIRIUS power contactor, size S3, rated 77 A at 480 V for AC-3 motor switching duty. That 77 A figure at 480 V is the load-breaking current under motor starting conditions — the rating that governs whether this contactor holds on a 40–60 hp motor at 480 V three-phase. Screw-type terminals on the magnet coil and main contacts; the coil draws 6 A at 24 V rated value, so verify your control transformer sizing if you're running multiple contactors off one 24 VDC supply.
Mounting and integration
Fastens via screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715. Mounting position is flexible: +/-180° rotation on a vertical surface, and can be tilted forward/backward by +/-22.5° on a vertical surface — useful when you're fitting into a tight gland plate or existing wireway layout. Keep the specified clearances: 10 mm upwards, 10 mm downwards, 20 mm forwards, 10 mm at the side. Depth is 195 mm, width 70 mm, height 140 mm.
Thermal and operational limits
Operates from -25 to +60 °C; storage range is -55 to +80 °C. That storage ceiling matters if this sits in a warehouse or unheated container before commissioning — it's fine down to -55 °C in storage, but don't attempt to switch loads below -25 °C ambient. Main contacts rated for 10 million typical mechanical operations; electrical life depends on load and switching frequency: 1,000 cycles/hour at AC-3 maximum, 300 at AC-4 maximum. Arcing time runs 10–20 ms at 50 Hz.