What It Is and Where It Lands
The Siemens SIRIUS 3RT2518-1BW40 is a Size S00 contactor with a 24 VDC coil, screw-type terminals for the main circuit, and a 45 mm width that snaps onto a standard 35 mm DIN rail per DIN EN 50022. Rated for a 24 VDC coil, it switches DC loads up to 10 A at 24 V, 2 A at 48 V or 60 V, and handles 10 A at 230 V AC — so it's suited for control transformers, small motor loads, and resistive heating elements in a panel. The S00 frame keeps the footprint tight at 57.5 mm high and 73 mm deep, leaving room for auxiliary contact blocks alongside.
What the Ratings Mean for Fit
The DC switching table tells you the real story: at 24 V it's good for 10 A, but at 220 V DC that drops to 0.3 A, and at 600 V DC it's only 0.1 A. That's the arc-quenching limit of a contactor this size — don't expect it to break a 600 VDC motor circuit at full current. The operating temperature range of -25 to +60 °C means it'll sit fine in a non-conditioned cabinet on a factory floor, but keep it out of direct steam or oven exhaust. Mechanical life is rated at 30,000,000 switching cycles typical, so it's built for high-cycle applications like conveyor indexing or packaging machinery.
Panel Integration Notes
Snap it onto a 35 mm DIN rail or screw-mount it directly. The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward or backward, so you can orient it to fit tight enclosures. Side-by-side mounting is allowed with zero clearance on all sides except 6 mm sideways spacing for heat dissipation. Terminals accept solid or stranded wire: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm² — covers most control wiring you'll run in a panel.