The Siemens SIRIUS 3RT2017-2KB42 is a size S00 coupling contactor with a 24 VDC coil and spring-type terminals. It's a current-production part, so no lifecycle surprises for a BOM freeze. Rated for DC switching: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 3 A at 400 V. That covers the common control-voltage taps you'll find in a panel — 24 VDC gets the full 10 A, and the derating at higher voltages is clean. Mechanical life is typical at 30,000,000 operations. Switching frequency: 1,000 cycles/hour for AC-1, 750 for AC-2 and AC-3, 250 for AC-4.
Mounting and wiring in the panel
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The S00 footprint is compact: 45 mm wide, 70 mm tall, 73 mm deep. Mounting position is flexible — ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward. That's useful when you're squeezing it into a tight enclosure corner. Spring-type terminals accept solid or stranded wire 0.5 to 4 mm², or 2x (0.5 to 4 mm²). No screwdriver torque to worry about — just strip and push. Clearance to adjacent gear: 10 mm upward, 10 mm forward, 10 mm downward, 6 mm to the side. That's tight enough for a dense DIN-rail layout. Main contacts are configured as 20... 12. No built-in auxiliary switch.
Environmental and operating limits
Operates from -25 to +60 °C; storage range is -55 to +80 °C. Coil pickup threshold is 0.7 x rated value. Dropout time at DC is 7 to 20 ms; arcing time 10 to 15 ms.