The Siemens 3RT1276-6AB36 is a SIRIUS-branded vacuum contactor in Size S12, designed for switching motor loads in industrial control panels where arc suppression and long mechanical life matter — 10 000 000 typical cycles on the contactor. Vacuum interrupters mean the arc quenches inside a sealed bottle, so this contactor suits environments with frequent switching or where contact erosion from arcing in air is a concern. The S12 frame carries stranded power wiring from 70 up to 240 mm², and the auxiliary switch is included — no separate add-on needed for basic status feedback.
Mounting and panel fit — screw fixing, generous clearances
Fastening is by screw fixing through a single 11 mm hole. Mounting position is flexible: ±22.5° rotation on a vertical surface, can tilt forward/backward by the same angle, and can stand on a horizontal mounting surface. That 225 mm depth plus 20 mm forward clearance means the panel depth needs at least 245 mm from the mounting plate to the door. Overall dimensions: 214 mm height, 160 mm width. The screw terminals on the magnet coil accept solid or stranded wire: 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², max 2x 0.75–4 mm².
Coil rated value is 23–26 V, with a pick-up factor of 0.8 x rated and a drop-out factor of 1.1 x full-scale. Switching frequency limits: 700 ops/h at AC-1 (resistive), 250 ops/h at AC-2 and AC-4, and 750 ops/h at AC-3 and AC-3e. Auxiliary contact ratings: 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V. These are the switching limits for the control circuit — stay under these for reliable signal feedback. Power factor at 50 Hz and 60 Hz is 0.9.