The Siemens 3RT2017-2KB42-0LA0 is a SIRIUS power contactor in the compact Size S00 frame (45 mm wide, 70 mm tall, 121 mm deep). The spring-type terminals on the coil side accept solid or stranded wire up to 4 mm². This contactor is a standard building block for DC control circuits in industrial panels — think conveyor brakes, solenoid valves, or DC motor contactors in a 24 VDC control architecture.
The key spec for a DC contactor is the current it can break at a given voltage, because DC arcs are harder to extinguish than AC. At 24 VDC, the 3RT2017-2KB42-0LA0 is rated for 10 A. At 48 V and 60 V, that drops to 2 A; at 110 V it's 1 A; at 220 V it's 0.3 A. These are the DC-1 (resistive load) ratings — if you're switching inductive loads (DC-3 or DC-5), expect to derate further or add a snubber. The contactor also carries AC ratings for motor starting: 3 A at 400 V AC-3, 11 A at 480 V, and 11 A at 600 V. That 11 A at 480 V is the figure to watch if you're using this on a 480 VAC motor branch — it's the AC-3 rating that governs contactor life under motor switching.
Coil terminals are spring-type, accepting 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid or stranded. No screwdriver needed for the coil connection — just strip to 8 mm and push in.
If you're stocking spares for a panel that uses the 3RT2326-1BK80 (a larger frame), this won't drop in without rewiring — different footprint and coil voltage. This is the part to order when the BOM says 3RT2017-2KB42-0LA0.