What it is and what it does
The Siemens 3RT1055-6AS36 is a SIRIUS power contactor in Size S6, designed for switching motor loads and resistive loads in industrial control panels. It is a screw-fixed device rated for a vertical mounting surface, rotatable ±90° and tiltable ±22.5° front-to-back, which gives panel builders flexibility in enclosure layout. The main power terminals accept stranded conductors from 25 to 120 mm², while the auxiliary circuit terminals accept solid or stranded wire from 0.5 to 4 mm². The magnet coil uses screw-type terminals, and the contactor includes an auxiliary switch as standard.
Key ratings and what they mean for selection
The AC-3 switching rate is 750 operations per hour maximum, and the AC-3e rating matches that figure — this is the duty cycle for standard squirrel-cage motor starting. For resistive loads (AC-1), the rate is 800 ops/h. For the most severe duty, AC-4 (plugging, inching, reversing), the rate drops to 130 ops/h, reflecting the higher thermal stress on the contacts during those operations. The auxiliary contact is rated for 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, and 1 A at 110 V — these are the switching capacities for the control circuit, not the main power path. The opening time is 40 to 60 ms for both AC and DC coil supply, with an arcing time of 10 to 15 ms. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C. The rated coil voltage is 500 to 550 V, and the power factor at both 50 Hz and 60 Hz is 0.8.
Physical fit and panel integration
Dimensions are 120 mm width, 172 mm height, and 170 mm depth. The contactor is screw-fixed, not DIN-rail mounted. Clearance requirements around the device are 10 mm upwards, 10 mm downwards, 10 mm at the sides, and 20 mm forwards. A single 9 mm diameter mounting hole is provided. The Size S6 frame means this is a physically large contactor — verify the enclosure depth can accommodate the 170 mm projection plus the 20 mm forward clearance before panel layout is finalized.