What this contactor is and what it does
The Siemens 3RT1046-1AL20-ZX95 is a SIRIUS power contactor in frame size S3, designed for switching motor loads and resistive loads in industrial control panels. It carries a rated power of 55 kW at 500 V in AC-3 duty — the standard motor-switching category per IEC 60947-4-1 — meaning it handles the inrush and break current of a 55 kW induction motor at that voltage. For AC-1 (resistive) duty the mechanical life is rated at 10,000,000 operations typical, and the electrical endurance at AC-1 is 900 operations per hour maximum. The contactor mounts via screw or snap-on onto 35 mm and 75 mm standard mounting rail, which is the dominant DIN-rail profile in European panels and increasingly common in North American enclosures.
Terminal capacity and wiring constraints
Main circuit terminals are screw-type, accepting solid conductors of 2x (0.5... 1.5 mm²), 2x (0.75... 2.5 mm²), and up to 2x (0.75... 4 mm²). Stranded conductors on the main circuit can be 2x (10... 50 mm²) — a wide range that covers everything from control-circuit pigtails to heavy motor feeders. The auxiliary/control circuit accepts solid or stranded 2x (2.5... 16 mm²). All terminals are rated IP00 for the terminal body, while the front face (with cover or box terminal) is protected to IP20. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive due to condensation) is the rated environment: typical for industrial control panels without sealed enclosures.
Environmental and mounting specs
Operating ambient temperature range is -25 to +60 °C; storage range is -55 to +80 °C. Side-by-side mounting is permitted without derating for the mechanical endurance, though the electrical switching frequency limits (AC-1 900/h, AC-3 850/h, AC-4 250/h) should be observed. The contactor dimensions are 146 mm height, 70 mm width, 139 mm depth — this depth keeps it within the typical 200 mm deep enclosure profile used for motor control centers.