The Siemens 3RT5955-5AU31 is a SIRIUS magnet coil designed for size S6 contactors.
The 277 V rating at 50 Hz, 60 Hz, and DC means this coil operates directly on a 277 V control bus without a transformer or rectifier — common in North American 480Y/277 V panel supplies. Because it accepts AC or DC, it suits both traditional relay-logic panels and DC-switched PLC output circuits. The SIRIUS S6 contactor frame it mates with is a standard DIN-rail or screw-mounted size; verify the coil's mechanical interface matches the contactor's magnet system before specifying.