Ratings and fit
The 3RT2018-2BG42-0CC0: The AC-3 rating of 7.5 kW at 400 V governs motor switching — that is the load a standard 400 V induction motor draws under starting and running conditions. The 125 VDC coil suits control circuits common in North American and some European DC-powered PLC or relay panels. Size S00 is the smallest SIRIUS frame; it occupies roughly 45 mm of DIN-rail width, which matters when packing multiple contactors into a compact panel. Spring-loaded terminals accept solid or ferruled stranded wire without routine re-torquing — a time-saver during panel build and a reliability gain under vibration. The single NC auxiliary is built in; if your circuit needs more than one auxiliary contact or an NO, you add a side-mount block from the 3RT29 series.