What this contactor is and where it fits
The Siemens 3RT2645-1NP35 is a SIRIUS contactor with a screw-type magnet coil accepting AC or DC control voltage. It mounts onto 35 mm DIN rail per DIN EN 50022 via screw and snap-on fastening, so it integrates into a standard control panel without adapters. Rated for 6 A at 230 V AC and 3 A at 400 V AC, this contactor handles motor loads and resistive circuits within those limits. The 80 mm width and 140 mm height give it a compact footprint for a contactor of this rating class.
What the key ratings mean for your panel
The 6 A at 230 V AC rating defines the maximum continuous current for a resistive or general-purpose load at that voltage. For motor duty, the AC-3 switching current is typically lower — the 3 A at 400 V AC gives a better indication of motor-switching capability at a common three-phase voltage. The 0 A at 690 V AC means this contactor is not rated for switching at that voltage; keep it below 690 V. The coil accepts AC or DC control voltage with a rated range of 175 to 280 V AC at 50/60 Hz and an initial pickup of 0.8 times nominal. This simplifies panel wiring because you don't need separate coil types for AC or DC control circuits. Operating temperature spans -25 to +60 °C, which covers most indoor industrial environments. Storage range is -55 to +80 °C, so it tolerates warehouse extremes without damage.
Wiring and conductor sizing
The screw-type terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². For stranded wire, the range is 2x (10 to 70 mm²) or 1x (10 to 70 mm²). At 40 °C ambient, a single 50 mm² conductor is allowed; at 60 °C, two 35 mm² conductors.