S10 vacuum contactor, 70-240 mm² main power
The Siemens 3RT1265-6AF36 is a SIRIUS vacuum contactor in the S10 frame size. It switches loads in the main power path — the main pole wiring accepts stranded conductors from 70 mm² up to 240 mm², so this is sized for high-current motor or transformer circuits where a standard air-break contactor would arc excessively.
Physical fit: 206 x 145 x 210 mm, screw-fixed
Mounting is by screw fixing through an 11 mm hole — not a DIN-rail snap-on.
Coil and auxiliary contact ratings
Pick-up is 0.8 × rated value; drop-out is 0.9 × rated value at 50 Hz and 60 Hz.
Switching frequency and duty cycles
Maximum switching rates: 750 operations per hour in AC-1 (resistive), AC-3 (squirrel-cage motor starting), and AC-3e duty; 250 operations per hour in AC-2 (slip-ring motor) and AC-4 (plugging/inching). The arcing time is 10-15 ms, and the opening/closing times are 40-80 ms for both AC and DC. These limits matter when the contactor cycles frequently — a conveyor or pump with short start/stop intervals will hit the 250 ops/hr ceiling in AC-4.
Vacuum technology and mechanical life
This is a vacuum contactor — the contacts are sealed in a vacuum bottle, which suppresses the arc that forms when switching high currents. Typical mechanical life is 10,000,000 operations. The 10 million-cycle rating reflects the absence of contact erosion in vacuum switching, making this a candidate for applications where maintenance access is limited.