S10 vacuum contactor built for heavy switching
The Siemens 3RT1266-6LA06 is a SIRIUS vacuum contactor in the S10 frame size, designed for motor switching and resistive loads where the arc needs to be extinguished fast and cleanly — the vacuum bottle does that in 10-15 ms arcing time. Rated 302 A at 480 V in AC-3 duty, this contactor handles the full-load current of a 200-250 hp motor at 480 V without derating the main poles.
Power terminations and wiring constraints
Main power conductors land on screw-type terminals that accept stranded cable from 70 mm² up to 240 mm² — that is a 2/0 AWG to 500 kcmil range, sized for the full 302 A without needing parallel runs. The magnet coil has its own screw-type terminals, separate from the main power lugs, so the control wiring stays isolated from the high-current path.
Mounting and panel clearance
Fastening is by screw fixing through a single 11 mm diameter hole — no DIN rail clip on the S10 frame, so budget for a drilled backplate or mounting bracket. The contactor measures 210 mm high, 145 mm wide, and 206 mm deep, including the arc chute and coil housing. Minimum clearances: 10 mm above and below, 10 mm to the sides, and 20 mm forward of the arc chamber — respect these to keep the arc flash from tracking to adjacent gear.
Mechanical endurance is 10 million cycles typical — the vacuum interrupter contacts do not erode the way air-break contacts do, so the rated life is effectively the coil and mechanism wear limit. Maximum switching rates: 750 operations per hour in AC-1 and AC-3 duty, 250 ops/h in AC-2 and AC-4 — the heavier the load make/break, the more thermal recovery time the contactor needs between operations.
Temperature range and auxiliary contact ratings
An auxiliary switch block is built in.