Integrator's first look
The Siemens 3RT1046-3BW44 is a SIRIUS power contactor in size S3, designed for switching motor loads and resistive loads in control panels. The 48 VDC coil is the primary control voltage — rated value is 48 V, with a pickup voltage of 0.8 x rated value and a dropout of 0.1 x rated value. Coil holds at 48 VDC nominal; the arcing time at DC is 14 to 20 ms. AC-3 rating at 500 V is 55 kW, which is the figure that governs motor switching for a 3-phase induction motor at that voltage — the contactor is sized for that load, not the higher AC-1 resistive current. Screw-type terminals on the main circuit accept stranded conductors up to 2x 50 mm², so it handles the cable size for a 55 kW motor at 500 V without needing lug adapters.
Mounting and integration
Mounts via screw or snap-on onto 35 mm and 75 mm standard mounting rail. Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without spacing — useful for compact motor control centers. Dimensions: 146 mm height, 70 mm width, 201 mm depth. The depth of 201 mm is the full body depth including terminals; plan for that clearance behind the panel door. IP20 on the front with the cover or box terminal installed; the terminal itself is IP00, so the panel enclosure provides the overall protection. Pollution degree 3 means it's rated for industrial environments with conductive pollution — no additional conformal coating required for most factory-floor conditions.
Switching performance and duty cycles
Maximum operating frequency varies by duty class: AC-1 (resistive) at 900 operations per hour, AC-3 (motor start/run) at 850 ops/h, AC-2 (slip-ring motor) at 350 ops/h, and AC-4 (plugging/inching) at 250 ops/h. The AC-4 rating at 400 V is 80 A — this is the current the contactor can interrupt during the most severe switching duty, so if your application requires frequent reversing or inching of a motor, that 80 A at 400 V is the hard limit. Mechanical life is typical 10 million operations; electrical life depends on the switching current and duty class. The contactor also carries DC switching ratings: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, 3 A at 400 V, and 37 W at 1000 V — useful for switching DC loads like solenoids or DC motor fields.