What it is and where it fits
The Siemens 3RT1016-2BF42 is a SIRIUS power contactor in size S00, designed for switching motor loads in control panels. It mounts on a 35 mm DIN rail per EN 50022 — screw or snap-on — and uses spring-loaded terminals for the main circuit, which speeds wiring and holds up better under vibration than screw clamps. The coil is 110 V DC, drawing 3.3 W to close and 3.3 W to hold — a DC coil means no hum, and the steady holding power simplifies the control transformer sizing.
Key ratings and what they mean for your motor
Rated for AC-2 duty at 400 V — 4 kW — that covers slip-ring motor starting and stopping, where the contactor makes and breaks under load each cycle. For AC-4 inching or plugging at 400 V, it handles 8.5 A, enough for frequent reversals on a small conveyor or hoist. Short-circuit coordination is specified: type 2 requires a 20 A gL/gG fuse upstream; type 1 allows a 35 A gL/gG fuse. Type 2 means the contactor stays functional after a fault — no welded contacts — so it matters on lines where downtime for a swap costs more than the fuse. Mechanical life is typical 30 million operations — that's the contactor body, not the contacts under load. For a machine cycling once every 10 seconds, that's roughly 8.5 years of continuous running before the mechanism wears out.
Panel integration details
Dimensions: 45 mm wide, 60 mm tall, 73 mm deep — fits a standard 45 mm slot on the DIN rail. Side-by-side mounting is allowed, with 6 mm clearance at the side for heat dissipation. IP20 on the front and terminals — protected against finger contact, but not washdown; keep it inside the enclosure. Wire range for main contacts: 2x (0.25 to 2.5 mm²) solid or stranded, or 2x (24 to 14 AWG). Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation — standard for an unsealed panel. Operating temperature range -25 to +60 °C, with altitude limit 2000 m. No derating needed for most indoor industrial spaces.