What it is and where it fits
The Siemens 3RT5046-1BF40 is a SIRIUS S3 power contactor rated for 110 VDC coil supply, designed for switching motor loads in industrial control panels. It mounts on 35 mm or 75 mm standard DIN rail via screw or snap-on fastening, with ±180° rotation and ±22.5° tilt possible on a vertical surface — useful when panel layout forces an unconventional orientation. Frame size S3 and a 70 mm width mean it occupies two standard 35 mm DIN-rail slots side by side, and side-by-side mounting is explicitly permitted — no derating gap required between units.
Key ratings and what they mean for your BOM
Motor power ratings at 60 °C ambient: 38 kW at 230 V, 66 kW at 400 V, and 114 kW at 690 V — these are the numbers that govern real motor sizing, not the lower 25.4 kW at 690 V figure which applies under a different condition. At 40 °C the conductor cross-section minimum is 50 mm²; at 60 °C it drops to 35 mm², reflecting the thermal derating curve. Switching frequency limits: 900 operations/hour under AC-1 resistive load, 850/h under AC-3 motor starting, 250/h under AC-4 plugging/reversing, and 1,000/h for DC loads. Mechanical service life is 10 million operations typical — so the wear limit is almost always electrical, not mechanical, for motor-duty applications. Coil consumption is 15 W for both closing and holding at DC — no inrush spike to design around. The control supply accepts 110 VDC nominal; at that voltage the coil draws 1 A. At 24 VDC it draws 6 A, at 220 VDC 0.3 A, and at 230 VDC 6 A. Rated insulation voltage is 1,000 V, and pollution degree 3 means it's rated for industrial environments with conductive dust or condensation — no need for additional conformal coating in a typical panel.
Termination and protection
Main and control circuits use screw-type terminals. Main contacts accept 2x (2.5...16 mm²) solid or stranded, or 2x (10...1/0) AWG. The recommended short-circuit protection is a gL/gG fuse rated 160 A — that's the fuse size to coordinate with upstream selectivity. The contactor supports auxiliary switch extension (product extension auxiliary switch: yes), so you can add feedback contacts or status indication without replacing the base unit.