What it is and what it does
The Siemens 3RT1317-2BD40 is a SIRIUS power contactor in size S00, with 4 normally-open main contacts and spring-loaded terminals for the main current circuit. It is rated for 5.5 kW at 400 V in AC-2 duty, which covers slip-ring motor starting and reversing — the kind of load you see on a winder or a reel drum drive where the machine speed and tension need controlled reversal without unplanned downtime.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022. At 45 mm wide and 72 mm deep, it fits a standard S00 footprint — no surprises on the gland plate. Side-by-side mounting is permitted, so you can gang several contactors in a motor control centre without extra spacing, though you'll want to check the thermal derating if the ambient inside the enclosure climbs above 40 °C.
Coil and control circuit
The DC magnet coil draws 3.3 W on closing and holds at the same 3.3 W — a constant-hold design that simplifies the control transformer sizing. Rated control supply voltage is 42 V DC. The pick-up threshold is 0.85 x rated voltage (about 35.7 V), and the drop-out is not explicitly stated but typical for this class is around 0.6 x rated. Operating temperature range is -25 to +60 °C, which keeps the machine running even in an unventilated mill enclosure during a summer outage.
Switching capacity and coordination
Switching capacity at 24 V DC is 10 A, dropping to 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — the inductive load curve typical for DC coils and solenoids. For AC-12 (resistive) use, the maximum operating current is 10 A. Short-circuit protection: with type 2 coordination, use a gL/gG fuse rated 20 A; with type 1, a 35 A fuse. The contactor is rated for pollution degree 3, so it survives the steam and the chemicals in a pulp mill environment without creeping failures.