The 3RT2017-2KG42: This is a Siemens SIRIUS coupling contactor, size S00, designated for switching loads in 24 V DC control circuits — 10 A at 24 V DC rated value. The contactor sits in the SIRIUS modular system, so it integrates with overload relays and other SIRIUS components on the same DIN rail.
The 45 mm width (3 width units on a standard DIN rail) is compact — you can pack several of these in a row. That matters when you're fitting into a tight enclosure or a swing-panel layout. Spacing clearances: 10 mm upwards, downwards, and forwards; 6 mm at the sides.
For a coupling contactor, the mechanical life is typical 30 million operations — that's a long service interval before you're swapping it out on a PM schedule.
Ratings across voltages
The contactor carries a range of DC-13 rated currents depending on the control voltage: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V. At 400 V AC it's rated 3 A. At 230 V it's rated 2 hp. No auxiliary switch is built in — if you need aux contacts, you add them separately from the SIRIUS system.