The Siemens 3RT2017-2UW42 is a SIRIUS coupling contactor — a relay interface between a PLC output and a motor or resistive load, built in the compact Size S00 frame at 45 mm wide and 73 mm deep. It carries a 24 V DC coil, so it drops right onto a standard 24 V control bus without an extra power supply tap. The coil connection uses spring-type terminals — no screwdriver needed for the control wiring, which speeds up panel build and field swap-out.
These are the numbers to check when packing multiple contactors side-by-side on a rail. Wire range accepts 0.5 to 4 mm² solid or stranded, and 2x (0.5 to 4 mm²) for looping through — covers typical control and power tails without adapters.
Switching ratings and mechanical life
Rated for 10 A at 24 V DC and 3 A at 400 V AC — the AC-3 maximum operating frequency is 750 switching cycles per hour, dropping to 250 cycles/hour under AC-4 (plugging/inching) duty. Mechanical life is typical 30 million operations — the contactor itself will outlast most panel refreshes, but the coil arcing time runs 10–15 ms and DC dropout is 7–13 ms, so factor that into your PLC timing if you're sequencing fast.
It carries an auxiliary switch contact built in, and the spring-clamp terminals make field replacement straightforward: no loose screws to drop inside a live panel.