The Siemens SIRIUS 3RT1317-2BF40 is a size S00 power contactor with a 110 VDC magnet coil, four normally-open main contacts, and spring-loaded terminals for the main circuit. It's rated for 5.5 kW motor switching at AC-2 duty, 400 V — that's the operating curve for slip-ring motors or moderate inductive loads, not just resistive heating. The coil pulls 3.3 W on both pick-up and hold, so the DC supply doesn't need a separate economy resistor. Drop-out is clean; no residual magnetism issues at this power level. Mounting is screw or snap-on onto 35 mm DIN rail per EN 50022. The 45 mm width means it occupies one standard modular slot — panel layout is straightforward.
Ratings and what they mean for fit
The AC-2 rating of 5.5 kW at 400 V is the headline motor-switching number. AC-2 covers starting and plugging of slip-ring motors; if your load is a standard squirrel-cage motor, you'd typically use the AC-3 rating instead, but this contactor's AC-3 data isn't listed here. The AC-12 maximum operating current is 10 A — that's the resistive/control circuit limit, not the motor contact rating. Auxiliary contact ratings span the common control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 110 V. The 110 V figure is the one that matches the coil voltage — verify your control transformer sizing against the full load of all aux contacts in the circuit. For short-circuit protection, Type 1 coordination calls for a 35 A gL/gG fuse; Type 2 requires 20 A. That's the difference between allowing the contactor to be damaged vs. protecting it for reuse after a fault — specify Type 2 if downtime for replacement matters. Operating temperature range is -25 to +60 °C, with pollution degree 3 — suitable for industrial control panels where conductive dust or humidity is present. IP20 on the front and terminals means finger-safe but not washdown-rated. Mechanical service life is 30 million operations typical — that's the mechanical endurance, not electrical. Electrical life will be lower and depends on the switching load and frequency.
Sourcing and lifecycle
Physical dimensions are 45 mm wide, 60 mm high, 72 mm deep — fits the standard S00 footprint. The spring-loaded terminals accept 2x (0.25 to 2.5 mm²) solid or stranded, or 2x (0.25 to 1.5 mm²) with ferrules. AWG equivalent is 2x (24 to 14).