Siemens SIRIUS 3RT2045-1NP34 — Power Contactor, Size S3
The Siemens 3RT2045-1NP34 is a SIRIUS power contactor in size S3, designed for switching motor loads and resistive loads in industrial control panels. It carries a rated control supply voltage of 175... 280 V at 50/60 Hz, with a coil inrush peak of 65 A and a holding power draw of 3.5 VA at both 50 Hz and 60 Hz. The pick-up threshold is 0.8 times the rated value, and the drop-out threshold is 1.1 times the full-scale value — meaning the coil reliably picks at 140 V and drops out at 308 V, giving a clean hysteresis band for noisy line conditions. Main contacts are rated for 10 poles normally open and 2 poles normally closed (10-2 configuration), with an auxiliary switch built in. The contactor mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 60715, and the mounting position allows +/-180° rotation on a vertical surface plus +/-22.5° tilt forward/backward — useful when panel layout forces an unconventional orientation.
Switching Rates and Duty Cycles
Maximum switching rates are duty-dependent: 900 operations per hour under AC-1 (resistive), 400/h under AC-2 (slip-ring motors), 1000/h under AC-3 (squirrel-cage motors — standard starting), and 300/h under AC-4 (plugging/reversing/inching). The AC-3e rating matches the AC-3 maximum at 1000/h. These rates govern thermal rise in the coil and arc chamber; exceeding them in a high-duty application will shorten contact life. Operating time is 38... 57 ms for both AC and DC coil supplies, with an arcing time of 10... 20 ms.
Termination and Clearance
Main circuit terminals accept solid conductors of 2.5... 16 mm² and stranded conductors of 6... 70 mm² — the stranded range covers the heavier cable typically run for motor feeders at this contactor size. Auxiliary circuit terminals accept 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²) solid or stranded. All terminals are screw-type. Minimum clearance to adjacent components: 10 mm upwards, 10 mm downwards, 10 mm at the side, and 20 mm forwards. The contactor body measures 70 mm wide by 140 mm high by 195 mm deep — the 195 mm depth is the dimension that matters most when sizing a shallow enclosure depth.