The Siemens 3RT1264-6AF36 is a SIRIUS-branded vacuum contactor in the S10 frame size. Vacuum contactors are built for high-cycle, high-voltage switching where arc extinction in open air is a problem — think mining conveyors, mill drives, or any 3-phase motor circuit where contactor life matters more than a few dollars saved on a standard air-break unit. Main circuit accepts stranded cable from 70 mm² up to 240 mm², so this is sized for heavy feeder or large motor duty — not a 5 hp pump starter. The coil is screw-type terminals, 110–127 V rated, with pickup at 80% of rated voltage and dropout at 1.1× full-scale, which is a standard industrial control-voltage range across North American and European panels.
Mounting and clearances — what the panel needs
Fastening is screw fixing — no DIN-rail clip on this frame size. Four holes, 11 mm diameter, on a 210 mm height by 145 mm width footprint. Depth is 206 mm, so factor that into your enclosure depth before you cut the gland plate. That's minimal — the vacuum bottle does the arc quenching inside, so you don't need the big phase-to-phase air gaps an open-air contactor demands.
Switching frequencies and mechanical life
Rated switching rates: 800 operations per hour at AC-1 (resistive), 750 at AC-3 (squirrel-cage motor start/run), 300 at AC-2 (slip-ring motor), 250 at AC-4 (plugging/inching). The AC-3e rating also sits at 750 ops/h. Mechanical life is a typical 10 million operations — that's the vacuum advantage: no contact erosion from arcing in air, so the mechanical wear is the limiting factor, not the electrical wear.