SIRIUS S00 power contactor, 24 V DC coil — what fits
The Siemens 3RT1017-1KB41 is a SIRIUS S00 power contactor with a 24 V DC coil, rated for motor switching up to 5.5 kW in AC-2 duty at 400 V. The 24 V DC coil pulls 2.3 W on closing and holds at the same 2.3 W — a steady-state draw that matters for control-transformer sizing and DC supply headroom in a panel. The contactor carries a 10 A rated operational current at 24 V, so it also handles resistive or light inductive loads at that voltage without derating the main poles. It snaps onto 35 mm DIN rail per DIN EN 50022, or screws directly to a backplate. The 45 mm width and 57.5 mm height mean it occupies a standard S00 footprint — three units side-by-side fit a 135 mm DIN section, and side-by-side mounting is explicitly allowed, so no derating for zero-gap packing in a dense panel.
Terminal specs and wiring reality
Both main and auxiliary circuits use screw-type terminals. The main contacts accept 2x (0.5 … 1.5 mm²), 2x (0.75 … 2.5 mm²), or max 2x (0.75 … 4 mm²) solid or stranded; AWG equivalents are 2x (20 … 16), 2x (18 … 14), and 1x 12. That covers the common motor-circuit wire sizes up to 4 mm² — no need for ferrule adapters on standard builds, though a ferrule helps on the 0.5 mm² end if the wire is fine-stranded. Auxiliary terminals share the same AWG range. The contactor ships with a varistor-type surge suppressor across the coil — that handles the DC coil's flyback voltage internally, so you don't need an external free-wheel diode unless the PLC output card has a very low off-state leakage spec.
Coordination and protection
For type 2 coordination (no weld after fault), the required upstream fuse is gL/gG 20 A. For type 1 coordination (welding allowed, but no fire or shock), it's gL/gG 35 A. That's the fuse size to spec on the line side of the motor branch circuit — the contactor itself is pollution degree 3 rated, so it's fine in a typical industrial enclosure without sealed climate control.