The Siemens SIRIUS 3RT6025-1KF40 is a coupling contactor — size S0 — designed for switching motor loads in control panels. Its 110 V coil and AC-3 rating up to 690 V mean it handles a 23 kW motor at 400 V or 40 kW at 690 V in standard three-phase duty. The built-in varistor surge suppressor protects the coil circuit from voltage spikes, so you don't need an external snubber on the control side.
Mounting and panel fit
Fastens with screw and snap-on onto 35 mm DIN rail per DIN EN 50022. The 45 mm width and 107 mm depth fit a standard S0 footprint. Side-by-side mounting is allowed, so you can gang multiple contactors without extra spacing — useful when packing a dense motor control center. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, giving flexibility in tight enclosures.
Termination and wiring
Main current circuit and auxiliary/control circuit both use screw-type terminals. Accepts 2x (0.5…1.5 mm²) solid or stranded on the control side, and 2x (16…12 AWG) or 2x (14…8 AWG) for the main contacts. Minimum permissible conductor cross-section at 40 °C and 60 °C is 10 mm². Pollution degree 3 means it's rated for industrial environments with conductive contamination — no special conformal coating needed for typical panel conditions.