What it is and what it does
The Siemens 3RT1055-6NB36 is a SIRIUS power contactor, size S6, designed for switching motor loads and resistive loads in industrial control panels. Its main power circuit accepts stranded conductors from 25 mm² up to 120 mm², so it handles the full current path for large motors or heavy feeder circuits without needing an external terminal adapter. Coil termination is screw-type, and the auxiliary switch block is included as standard, which simplifies wiring for interlocking or status feedback.
Mounting and integration
Mounting is by screw fixing onto a vertical surface, with the contactor rotatable ±90° and tiltable ±22.5° front-to-back. That flexibility helps when retrofitting into existing enclosures where the backplate is already drilled. Clearance requirements: 10 mm upward, 10 mm downward, 20 mm forward, 10 mm at the side — tight enough for most standard panel layouts. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C, so it can sit in an unheated warehouse or a warm cabinet without derating concerns.