What it is and what it does
The Siemens 3RT1017-1KB42-0LA0 is a SIRIUS power contactor in size S00, built for switching motor loads in control panels. It carries a 24 V DC coil with an integrated varistor surge suppressor, so you don't need to add a separate snubber for coil suppression. The AC-3 rating at 400 V is 5.5 kW — that's the figure to size against your motor nameplate, not the AC-1 resistive current.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm standard rail per DIN EN 50022. The 45 mm width and 60 mm height fit a standard 45 mm-wide modular device footprint; depth is 123 mm, which matters when you're routing wires behind the rail. Side-by-side mounting is allowed — no mandatory gap — but the spec calls for 6 mm clearance at the side for heat dissipation when you pack multiple units. Pollution degree 3 means it's rated for the conductive-dust environment typical in industrial panels.
Terminal wiring and conductor range
Main circuit terminals are screw-type, accepting 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²) stranded, or up to 2x (0.75 to 4 mm²) max. AWG equivalents are 2x (20–16), 2x (18–14), and 1x 12. That covers most panel wiring up to 4 mm² without needing a terminal adapter. Coil terminals share the same range.
Switching ratings and coordination
AC-3 motor switching at 400 V delivers 5.5 kW; at 500 V and 690 V it also holds 5.5 kW, so the contactor is current-limited, not voltage-limited, in that band. AC-4 (reversing / inching) at 400 V is rated 8.5 A. For the auxiliary contact circuit, AC-15 ratings drop with voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V. Type 2 coordination requires a 20 A gL/gG fuse; Type 1 allows a 35 A fuse. Mechanical life is typical 30 million operations.
Environmental and operating limits
Operating temperature range is -40 to +70 °C, which covers most heated and unheated enclosures. Maximum operating altitude is 2 000 m without derating. The coil pull-in voltage is 0.7 x rated (16.8 V DC) and drop-out is 1.25 x rated (30 V DC) — so it holds in during dips but releases on overvoltage. Front and terminal protection is IP20, finger-safe for panel installation.