SIRIUS Size S6 Power Contactor — 200-277 V Coil, Screw Fixing
The Siemens SIRIUS 3RT1055-6NP36-3PA0 is a Size S6 power contactor built for motor switching and resistive load control in industrial panels. The coil is rated 200-277 V AC, so it lands squarely on standard three-phase control transformers without needing an intermediate relay. Screw fixing to the mounting plate and screw-type coil terminals keep wiring straightforward for panel builders. Main power circuit accepts stranded conductors from 25 to 120 mm², sized for the S6 frame's typical motor currents. Auxiliary switch is included on the unit, with its own screw terminals accepting 2x (0.5-1.5 mm²) solid, 2x (0.75-2.5 mm²) solid, or up to 2x (0.75-4 mm²) stranded — enough for control-wire terminations without a separate terminal block.
Duty Ratings and Switching Frequency
The contactor's operating life and thermal limits depend on the duty class. At AC-3 (squirrel-cage motor starting) it manages up to 750 switching cycles per hour; at AC-4 (plugging/reversing/inching) that drops to 130 cycles per hour. AC-1 resistive loads allow 800 cycles per hour. Mechanical life is rated at 10 million operations — the figure that governs replacement intervals in high-cycle applications like conveyor sortation or compressor cycling. Operate time is 80-90 ms on both AC and DC coil supplies, and arcing time runs 10-15 ms. The power factor at 50 Hz and 60 Hz is 0.6, which matters when sizing control transformers for a bank of contactors.
Mounting and Clearance
Mounting position is flexible: vertical surface with ±90° rotation and ±22.5° tilt forward/back. Clearance to adjacent components: 10 mm upwards, 10 mm downwards, 10 mm at the side, and 20 mm forwards — tight enough for dense panel layouts but the forward clearance is the one to watch when the panel door has a gland plate or busbar shroud. Dimensions are 172 mm height, 120 mm width, 170 mm depth. Four mounting holes at 9 mm diameter on a single-hole pattern per pole. Operating temperature range is -25 to +60 °C; storage range extends to -55 to +80 °C.
Auxiliary Contact Ratings
The built-in auxiliary switch is rated 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, and 1 A at 110 V. These are the figures to check when the auxiliary feeds a PLC input or a pilot light — the 24 V rating is generous, but the 110 V rating drops to 1 A, so a multi-lamp indication circuit could exceed it.