What it is and what it does
The Siemens SIRIUS 3RT1016-1HB42 is a size S00 power contactor with a 24 VDC coil, screw-type terminals on both main and auxiliary circuits, and a 45 mm wide footprint that snaps onto 35 mm DIN rail per DIN EN 50022. Its AC-2 rating at 400 V is 4 kW, covering slip-ring motor switching; the AC-4 rating at 400 V is 8.5 A for reversing or inching duty. For resistive loads (AC-12) it carries 10 A. The DC coil draws 2.3 W during both closing and holding, so the control transformer or power supply must deliver that continuously — no inrush spike to size for.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. Side-by-side mounting is permitted, so you can gang multiple contactors without spacing gaps — useful when packing into a shallow enclosure. The 45 mm width and 72 mm depth fit standard panel layouts; the IP20 front enclosure means it's protected against finger contact but not washdown — keep it inside a cabinet. Wire range for main and auxiliary terminals accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²) solid/stranded, plus AWG equivalents 2x (20 to 16), 2x (18 to 14), or 1x 12. That covers most control and small power circuits without lug adapters.
Coordination and protection
For type 2 coordination (no damage to the contactor after a short circuit), the required upstream fuse is gL/gG 20 A. For type 1 coordination (contactor may need replacement after fault), use gL/gG 35 A. Pollution degree 3 rating means it's suitable for industrial environments with conductive pollution or dry non-conductive pollution that becomes conductive due to condensation — typical for unsealed control panels. Operating temperature range is -25 to +60 °C, so it handles both cold storage areas and warm cabinet interiors without derating the coil.