What it is and where it fits
The Siemens 3RT1017-1BP42 is a SIRIUS S00 power contactor with a 230 V AC coil, screw-type terminals for the main current circuit, and a 45 mm wide housing that snaps onto a 35 mm DIN rail per EN 50022. The S00 frame size keeps it compact at 57.5 mm tall and 72 mm deep, so it fits tight panel layouts where every millimeter counts. Rated for pollution degree 3 and an operating temperature range of -25 to +60 °C, it handles the typical conditions inside an industrial control cabinet without derating.
What the ratings mean for your motor load
At AC-4 duty (plugging, inching, reversing) at 400 V, the contactor is rated for 8.5 A — that is the switching current for severe motor starts, not the steady running load. For AC-12 duty (resistive loads like heater banks), it handles up to 10 A maximum operating current. The magnet coil draws 3.3 W both on closing and holding, so the thermal load on the control transformer is predictable — no inrush spike to size for.
Short-circuit coordination and wiring
With type 2 coordination (no damage to the contactor after a fault), the upstream fuse must be gL/gG 20 A. With type 1 coordination (contactor may need replacement), a 35 A gL/gG fuse is allowed. The screw terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or up to 2x (0.75 to 4 mm²) — solid or stranded — and AWG equivalents from 2x 20 to 1x 12. Side-by-side mounting is permitted with a 6 mm clearance at the side, so you can pack multiple contactors on the same DIN rail without derating.
Lifecycle and sourcing reality
The IP20 rating on the front and at the terminals means it is finger-safe for panel installation but not rated for washdown or outdoor exposure.