Siemens 3RT2518-1BB40 is a SIRIUS contactor in the compact S00 frame, with a 24 V magnet coil terminated via screw-type terminals. It's a current-production unit, so no end-of-life surprise for a lineside spare.
Mounting and panel fit
Snaps onto 35 mm DIN rail per EN 50022, or screws directly to a mounting plate. Dimensions: 45 mm wide, 57.5 mm tall, 73 mm deep. Side-by-side contactors need 6 mm spacing between units – no extra gap at top, bottom, front, or back (zero clearance for those planes). Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/back – useful when fitting into tight enclosures. Wire range for main and auxiliary circuits: 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or 2x 4 mm² solid/stranded.
Comparison to 3RT2028-1BB40
Both are S00-frame SIRIUS contactors with 24 V screw terminals. The 3RT2518-1BB40 is the newer-generation offering; the 3RT2028-1BB40 is its direct predecessor. Mounting, wire range, and auxiliary contact capacity are identical per the published specs. If your BOM calls the older code, this one drops into the same panel slot without rewiring – but confirm the auxiliary switch count (this one includes a built-in auxiliary, the earlier may have been ordered without).