The Siemens SIRIUS 3RT1046-3KF44-0LA0 is a size S3 power contactor with a 110 V AC coil, screw-type terminals for the main current circuit, and a rated operational power of 55 kW at 500 V. It's designed for motor switching in industrial control panels, with a mechanical life of 10,000,000 operating cycles typical.
What the ratings mean for fit
The 55 kW at 500 V (AC-3 duty) is the motor-switching rating that governs the real-world load — it's the figure you size against your motor nameplate. At 690 V the same contactor delivers 25.4 kW, so the voltage derating is significant; don't assume the 500 V number holds at higher line voltages. The AC-4 rating at 400 V is 80 A, which covers reversing or inching duty where the contactor makes and breaks stalled-rotor current.
Panel integration and mounting
Mounts via screw or snap-on onto 35 mm and 75 mm DIN rail — the snap-on feature speeds panel assembly. Side-by-side mounting is supported, so you can gang multiple contactors without spacing gaps. Dimensions are 145 mm high, 95 mm wide, 191 mm deep; the depth is the dimension that extends into the enclosure, so check your gland-plate clearance if the panel is shallow. Pollution degree 3 means it's rated for industrial environments with conductive pollution.
Termination and wiring
Main current circuit uses screw-type terminals. Solid wire accepts 2x (0.25 to 2.5 mm²); stranded accepts 2x (10 to 50 mm²) for the larger power connections, with an intermediate range of 2x (2.5 to 16 mm²) for mixed gauges. The IP00 rating on the front and terminals means this is an open-device contactor — it relies on the enclosure for environmental protection.
Switching frequency and coil data
Maximum switching frequency varies by duty: 900 cycles/hour at AC-1 (resistive), 850 at AC-3 (motor running), 350 at AC-2 (slip-ring motor), and 250 at AC-4 (reversing/plugging). The coil holds at 110 V rated value; arcing time is 10 to 15 ms at AC and 14 to 20 ms at DC. Operating temperature range is -40 to +70 °C; storage range is -55 to +80 °C.
Compliance documentation
RoHS compliance date is 05/01/2012, meaning it meets the EU RoHS directive as of that date. The SIRIUS series carries CE marking and is designed to IEC/EN 60947-4-1 standards. No UL or CSA listing is stated in the evidence; verify with your local Siemens representative if UL recognition is required for your panel.