What It Is and Where It Fits
The Siemens 3RT2018-2BM42 is a SIRIUS power contactor in the Size S00 frame, designed for switching motor loads in control panels. It mounts on a 35 mm DIN rail per DIN EN 60715, with screw and snap-on fastening, so it drops into a standard panel layout without special brackets. The 45 mm width and 73 mm depth keep the footprint tight for dense DIN-rail assemblies.
Key Ratings and What They Mean for Fit
The 220 V AC coil is rated at the control voltage; pickup happens at 0.8 times that value, dropout at 1.1 times, so the contactor stays pulled in across a reasonable sag but drops cleanly on undervoltage. For motor duty, the AC-3 switching rate is 750 operations per hour, which suits conveyor and pump cycling without overheating the coil or arc chamber. The AC-4 rate drops to 250 operations per hour — that's the inching or plugging duty cycle, so if the application does frequent reversing, the lower limit governs the selection.
Wiring and Termination
The magnet coil terminates with spring-type terminals, accepting solid or stranded wire from 0.5 to 4 mm², and can take two conductors of the same size per clamp. That saves a terminal block when daisy-chaining control voltage to multiple contactors. The main contacts also use spring terminals, so no screw torque to verify — just strip to length and push in.
Clearances and Mounting Position
Minimum clearances to adjacent metalwork: 10 mm upwards, forwards, and downwards, 6 mm to the side. The contactor can be mounted in any orientation within ±180° rotation on a vertical surface, and can be tilted forward or backward by ±22.5°. That flexibility helps when the panel layout forces a non-standard angle, but the 10 mm clearance rule still applies.
Environmental and Mechanical Endurance
Operating temperature range is -25 to +60 °C, storage range -55 to +80 °C, so it handles unheated enclosures and warehouse storage without issue. Mechanical life is rated at 30 million cycles typical, with main contact electrical life between 20 and 12 million cycles depending on load. The auxiliary switch is built in, saving an add-on block for status feedback.