What it is and what it does
The Siemens SIRIUS 3RT1326-1AR60 is a size S0 power contactor with four normally-open main contacts, designed for switching motor loads in control panels. The coil is rated for 400 V at 50 Hz and 400–440 V at 60 Hz, so it's a direct line-voltage coil — no control transformer needed if your panel feeds 400 V three-phase. Its AC-2 rating at 400 V is 11 kW, which covers wound-rotor motors and moderate-duty induction motors up to that load. For AC-3 duty (squirrel-cage motors, the more common standard), the current rating will be higher — the AC-2 figure is the conservative one for slip-ring or high-inertia starts. Mounting is screw-and-snap-on onto 35 mm DIN rail per EN 50022, so it integrates into any standard panel. The S0 frame is compact at 61 mm wide, 85 mm tall, and 91 mm deep — fits a standard 8-module row with room for auxiliaries.
What the ratings mean for fit
The 4 NO main contacts handle 10 A in AC-12 duty (resistive loads like heaters) and the motor-rated currents at 400 V. The terminal block accepts up to 2x 10 mm² stranded or 1x 12 AWG, which is generous for a contactor this size — you can land two motor cables per phase without a separate distribution block. Operating temperature range is -25 to +60 °C, with a maximum altitude of 2000 m. Pollution degree 3 means it's rated for conductive pollution environments — typical industrial panels with some dust and humidity. The front face carries IP20 protection; the terminals are IP00 (finger-safe only when wired into a panel with a closed door). Type 1 coordination requires a 63 A gL/gG fuse upstream; Type 2 coordination (for reduced damage on fault) needs a 35 A fuse. That's the selectivity headroom to plan for in your distribution board.