The Siemens 3RT2017-2LB42 is a SIRIUS coupling contactor in the size S00 frame, designed for switching loads where the coil circuit must be electrically isolated from the main contact circuit — typical in PLC-to-motor or safety-relay-to-contactor interfaces where you need to break the control side without dropping the main power. Rated coil voltage is 24 VDC, and the main contacts switch up to 10 A at that same 24 V — enough for small motor starters, solenoid banks, or signal-level power distribution inside a control panel. Termination is spring-type (cage clamp), accepting solid or stranded wire from 0.5 to 4 mm², which speeds panel wiring and eliminates the torque-check step of screw terminals.
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, with a 45 mm width that fits standard S00 contactor spacing. Mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward — useful when the panel layout forces an odd angle. Clearance distances: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side — standard for this frame size, no special derating for tight enclosures if those gaps are maintained.
Switching performance and operating conditions
Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C — suitable for unheated plant floors and warehouse environments. Arcing time is 10 to 15 ms, and DC dropout time is 7 to 20 ms — relevant for timing-critical interlock circuits where the contactor must open before a downstream device sees the loss of power. Switching frequency varies by duty: up to 1,000 operations/hour at AC-1 (resistive loads), 750/h at AC-3 (motor starting), and 250/h at AC-4 (plugging/inching) — the AC-4 figure is the one to watch if the application does frequent reversing or jogging.