The 3RT1066-6NB36: The coil is rated 21-27.3 VDC — a narrow band that matches standard 24 VDC control buses in industrial panels, but the 0.8 initial pickup ratio means the coil draws inrush at 80% of rated voltage, so a sagging 24 V rail below about 19 V may fail to pull the contactor in.
Switching duty and endurance — AC-1 through AC-4
Operating frequency varies sharply by duty class: 750 cycles/hour in AC-1 (resistive), 500 in AC-3 (squirrel-cage motor start/run), 250 in AC-2 (slip-ring motor), and 130 in AC-4 (plugging/inching). For a conveyor drive cycling every 7 seconds in AC-3, the 500 cycles/hour ceiling is the limit — pushing past it shortens contact life fast. The mechanical endurance is 10 million operations typical, so the contactor outlasts most application lifetimes at moderate switching rates. Arcing time is 10-15 ms, and opening time is 80-100 ms for both AC and DC — this matters for selectivity coordination with upstream breakers: the contactor clears fast enough that a downstream fault won't cascade if the breaker trip curve is set above 100 ms.