The Siemens 3RT1265-6AB36 is a SIRIUS vacuum contactor in size S10. Vacuum contactors use a sealed vacuum interrupter to extinguish the arc, so the switching chamber is maintenance-free and the contact erosion is minimal — a good fit for high-cycle applications like compressor or conveyor drives where mechanical wear on conventional air-break contacts would drive early replacement. The operating coil is rated 23...26 V with screw-type terminals.
Sizing and integration
The main power circuit accepts stranded wire from 70 mm² up to 240 mm² — that is a heavy cable range, sized for load currents that justify the S10 frame. The auxiliary circuit uses separate screw terminals accepting 0.5...4 mm² solid or stranded. Dimensions are 210 mm high × 145 mm wide × 206 mm deep. It mounts via screw fixing with two 11 mm holes.
The contactor is rated for different switching duties, each with a maximum operations-per-hour limit. For AC-1 (resistive loads) and AC-3 (squirrel-cage motor starting, running disconnect) you get up to 750 cycles/hour. For AC-2 (slip-ring motor starting) and AC-4 (plugging, inching, reversing) the limit drops to 250 cycles/hour. On the auxiliary contacts, at 24 V rated value it switches 10 A; at 48 V and 60 V rated value it switches 2 A; at 110 V rated value it switches 1 A. Coil pickup is at 80% of rated voltage, dropout at 110% — so the coil holds in reliably down to about 18.4 V on a 23 V nominal supply, and drops out above about 28.6 V. The power factor is 0.9 at 50 Hz and 60 Hz.