SIRIUS S3 Power Contactor — 3RT2045-1SF30
The Siemens 3RT2045-1SF30 is a SIRIUS S3 power contactor, size S3, designed for switching motor loads and resistive loads in industrial control panels. It carries an integrated auxiliary switch and uses screw-type terminals for the magnet coil and main contacts. The coil accepts 83-150 V AC/DC, with a dropout threshold at 80% of rated voltage — meaning it holds in reliably down to about 66 V on a 83 V nominal supply, a useful margin for brownout ride-through. Mounting is screw-fixed or snap-on onto 35 mm DIN rail per EN 60715. The 70 mm width and 152 mm depth fit standard S3 panel cutouts; clearance requirements are 10 mm upward/downward, 20 mm forward, and 10 mm at the sides. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, giving flexibility in dense enclosures.
Duty Ratings and Switching Frequency
The contactor is rated for multiple duty classes with corresponding maximum switching rates: AC-1 (resistive) at 900 operations/hour, AC-2 (slip-ring motor) at 400/h, AC-3 (squirrel-cage motor starting) at 1 000/h, AC-3e at 1 000/h, and AC-4 (plugging/inching) at 300/h. The AC-3 and AC-3e rates are identical, so the part handles standard motor starting and high-efficiency motor profiles at the same cycle rate. Arcing time is 10-20 ms, and the make/close times for both AC and DC coils are 38-57 ms. Typical mechanical endurance is 5 000 000 operations. The MTBF is listed at 52 years — a reliability figure that reflects the contactor's mechanical and electrical design life under normal operating conditions, not a warranty period. For the auxiliary contact set, ratings are 10 A at 24 V, 2 A at 48 V, and 2 A at 60 V; the inrush peak is 20 A.
Wire and Terminal Specifications
Main contact terminals accept solid conductors from 2.5 to 16 mm² and stranded conductors from 6 to 70 mm². The auxiliary contact terminals accept 2x (0.5-1.5 mm²) solid or stranded, or 2x (0.75-2.5 mm²). All terminals are screw-type, requiring a screwdriver for termination — no spring-cage option on this variant. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C.