The Siemens SIRIUS 3RT1017-1KF42-0LA0 is a Size S00 power contactor with a 110 V DC coil and an integrated varistor surge suppressor across the coil terminals. It is designed for screw and snap-on mounting onto 35 mm standard mounting rail per DIN EN 50022, making it a direct panel fit for any S00-footprint rail assembly. The 45 mm width and 60 mm height keep the DIN density tight — three of these fit in a standard 145 mm section alongside a motor starter.
Coil and switching ratings
The 110 V DC coil draws 11 W closing power and 4 W holding power. For DC switching at the coil rated voltage, the contactor is rated 1 A at 110 V, 0.3 A at 220 V. On the AC side for motor loads, it delivers 5.5 kW at 400 V under AC-2 duty and 8.5 A at 400 V under AC-4 duty. The main circuit screw terminals accept 2x (0.5…1.5 mm²), 2x (0.75…2.5 mm²), or max 2x (0.75…4 mm²) solid/stranded, with AWG equivalents 2x (20…16), 2x (18…14), 1x 12. The auxiliary and control circuit terminals are also screw-type.
Sourcing posture
This is a current-production Siemens SIRIUS contactor, sourced through independent distribution channels. Availability and current pricing are confirmed at quote time against an RFQ. For a BOM line that calls out 3RT1017-1KF42-0LA0, the fit is direct — same Size S00 footprint, 110 V coil, varistor suppression, and screw terminals as the order code specifies.