What this part is and where it lands
The Siemens 3RT1055-7AB36-0SF1 is a SIRIUS power contactor in Size S6, designed for switching motor loads in industrial control panels. It is a current-production part, so it remains a standard BOM line for new builds and replacements alike.
Key ratings and what they mean for fit
The contactor is rated for AC-3 switching at up to 750 operations per hour, which covers the duty cycle of most conveyor, pump, and fan applications. AC-4 duty is lower at 130 ops/h, reflecting the heavier arc stress of reversing or plugging service. The auxiliary contact block carries 10 A at 24 V, 2 A at 48/60 V, and 0.3 A at 220 V — enough for PLC inputs or relay coils in the control circuit. The coil is terminated with spring-type terminals, which speeds wiring and resists loosening under vibration. The main power terminals accept stranded conductors from 16 to 70 mm², sized for the S6 frame's current capacity.
Mounting and integration
Fastening is by screw fixing, not DIN-rail snap-on, so plan for a drilled backplate or mounting channel. The mounting position is flexible: the contactor can be rotated ±90° on a vertical surface and tilted ±22.5° forward or back, which helps when fitting into tight enclosure layouts. Minimum clearances are 10 mm upward, downward, and to the side, and 20 mm forward — factor these into your gland-plate and bus-bar planning. Dimensions are 172 mm high by 120 mm wide by 170 mm deep.