The Siemens 3RA1317-8XB11-1BB4 is a pre-assembled reversing contactor from the SIRIUS 3RA1 family, Size S00, designed to switch the direction of a three-phase motor by mechanically interlocking two contactors so both cannot close simultaneously. Rated at 12 A operational current in AC-3 duty at 400 V, it handles a 5.5 kW motor load — the AC-3 rating is the one that matters for squirrel-cage induction motors with starting currents up to 8x rated; the 12 A figure governs the actual motor FLA it can switch, not a resistive-heater curve. The coil is 24 V DC, which means it pulls in cleanly on a DC supply without the hum or dropout issues an AC coil can exhibit in low-voltage conditions; holding power is inherently lower than an AC coil, reducing heat inside the panel.
Fastens by screw or snaps onto 35 mm DIN rail per DIN EN 50022 — the S00 footprint (90 mm wide, 67 mm tall, 72 mm deep) fits standard enclosure backplates and leaves room for an overload relay or auxiliary contact block alongside.
Lifecycle status and sourcing reality
The successor 3RA2317-8XB11-1BB4 is the direct drop-in replacement for new designs or BOM updates; it shares the same S00 frame, 24 V DC coil, AC-3 rating, and screw-terminal configuration.