What this contactor is and what it switches
The Siemens SIRIUS 3RT1017-1HB42 is a Size S00 power contactor designed for switching motor loads and resistive loads in industrial control panels. The 24 VDC coil draws 2.3 W closing and holding, so the control transformer or PLC output must supply that continuously — no coil economizer on this DC variant. Rated operational current at AC-12 (resistive) is 10 A; for motor duty, the AC-3 rating at 400 V is 5.5 kW, and at 690 V also 5.5 kW. The AC-4 (reversing/inching) rating at 400 V is 8.5 A — important if the application requires frequent plugging or jogging. Auxiliary contact switching capacity is given at several voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V DC, which governs what pilot loads it can handle directly.
Mounting and integration into a panel
Fastens by screw or snap-on onto a 35 mm DIN rail per EN 50022. Dimensions are 45 mm wide, 57.5 mm high, 72 mm deep — fits a standard 45 mm module slot. Side-by-side mounting is permitted without derating, which saves rail space in multi-contactor groups. Terminals are screw-type for both main and auxiliary circuits; the main circuit accepts 2x (0.5…1.5 mm²), 2x (0.75…2.5 mm²), or max. 2x (0.75…4 mm²) solid/stranded, or 2x (20…16), 2x (18…14), 1x 12 AWG. Degree of pollution 3 means it's rated for industrial environments with conductive pollution. IP20 on the front and terminals — protected against finger contact, not against water ingress, so keep it inside a closed panel.
Coordination and protection
For type of coordination 1 (no damage to the contactor under short circuit), the required fuse is gL/gG 35 A. For type of coordination 2 (limited damage permissible), the fuse is gL/gG 20 A. This matters when designing the branch circuit — the fuse size governs the SCCR contribution and the selectivity with upstream breakers. The 3RT1017-1HB42 carries no integrated overload relay; it is a bare contactor intended to be paired with a separate SIRIUS overload or motor starter.