The 3RT1034-3AL20: Rated for 50/60 Hz operation with a coil pick-up range of 0.8–1.1 at 50 Hz and 0.85–1.1 at 60 Hz, so it holds in on marginal supply conditions.
The AC-3 motor-switching rating is the one that decides fit for most conveyor, pump, and fan loads: 15 kW at 400 V AC-2, and at AC-3 the contactor is sized for the 18.5 kW / 500 V and 10 kW / 690 V marks. That puts it in the sweet spot for a 20–25 hp motor at 400 V three-phase. Auxiliary contact ratings cover the usual control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V — enough for direct pilot-duty control of smaller contactors or PLC inputs. The auxiliary contacts share the same coil suppression as the main poles, so verify free-wheel diode polarity if you're driving inductive loads downstream. Mechanical life is rated at 10 million operations typical, with maximum switching frequencies of 1,200 cycles/hour at AC-1, 1,000 at AC-3, and 250 at AC-4 — the AC-4 figure governs plugging or inching duty, where you'll see contact wear accelerate.