What the frame size and terminal type tell you about fit
The 3RT2017-2BE41: The magnet coil connects via spring-type terminals (cage clamp), not screw terminals — so you need a screwdriver with a small blade to push the spring, not a Pozi driver.
Auxiliary contact ratings — what switches at what voltage
At 400 V AC the auxiliary contact is rated 3 A (cites:,). The DC ratings drop fast as voltage climbs — at 220 V DC you're limited to 0.3 A, so if you're switching a 24 V DC PLC input you're fine at 10 A, but for a 125 V DC control circuit you're down to 0.9 A. That's the contact gap limitation on a size S00 frame (cites:,). At 230 V AC, the contactor is rated for 2 hp motor load — that's the typical small pump or fan motor on a single-phase 230 V supply (cites:).
Switching frequency and operating life by duty class
The AC-4 limit is the one that bites if you're doing reversing or jogging — you get a quarter of the rate of straight starting (cites:,). Electrical life is shorter and depends on the switched current and duty class (cites:).
Environmental limits and clearance
These are minimums for heat dissipation — pack them tighter and you derate the continuous current (cites:,).
Sourced through independent distribution channels against your BOM quantity.