The Siemens 3RT1266-6NF36 is a SIRIUS vacuum contactor in Size S10. Vacuum contactors use sealed vacuum interrupters, making the switching chamber maintenance-free with minimal contact erosion over the rated mechanical life of 10,000,000 operations typical for this contactor size. The coil is rated for 96-127 V, covering both AC and DC control circuits within that window.
Power circuit and termination
The main power terminals accept stranded conductors from 70 mm² up to 240 mm², sized for the high currents this contactor class switches. Auxiliary control wiring uses screw-type terminals on the magnet coil, accepting solid or stranded conductors: 2x (0.5-1.5 mm²), 2x (0.75-2.5 mm²), or max 2x (0.75-4 mm²). Fastening is by screw fixing through a single 11 mm diameter hole. The contactor footprint measures 210 mm high, 145 mm wide, 206 mm deep — confirm the backplate layout against these dimensions before committing the panel layout. These are the minimum free-air gaps around the contactor body for proper arc quenching and heat dissipation.
The vacuum contactor is built for high-cycling applications. Maximum operating rates: 750 operations per hour at AC-1 (resistive) and AC-3 (motor starting) duty, and 250 ops/hour at AC-2 (slip-ring motor) and AC-4 (plugging/inching) duty. The arcing time is 10-15 ms, and the arc is contained within the vacuum bottle — no ionized gas vented into the enclosure. The auxiliary switch is present (yes), and the contactor includes an integrated surge suppressor with a rated value of 1.1 times the coil voltage and an initial value of 0.8 times — this limits voltage spikes during coil dropout without needing an external RC snubber in most installations.