What this SIRIUS S0 contactor is and where it lands
The Siemens 3RT1023-1AU60 is a SIRIUS S0 power contactor with three normally-open main contacts and screw-type terminals, rated for motor switching in control panels and industrial machinery. It mounts via screw or snap-on onto 35 mm DIN rail per EN 50022, so it drops into any standard panel rail without adapter plates. The S0 frame is the compact workhorse in the SIRIUS lineup — 45 mm wide, 85 mm tall, 91 mm deep — fitting tight enclosures where every millimeter counts. The front face carries IP20 protection; the terminal area is IP00, meaning the wiring zone expects enclosure-level guarding.
Motor-duty ratings that decide the fit
The headline motor-switching number is 8.5 A in AC-4 duty at 400 V — that's the reversing / plugging / inching current, not the steady-run rating. For AC-2 (slip-ring motor starting) the same contactor carries 4 kW at 400 V. The difference matters: if your application cycles the motor direction under load, the AC-4 figure governs the contactor's life; if it's a simple start/run, the AC-2 rating is the one to size against. Auxiliary contact ratings cover a wide control-voltage spread: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V DC. The DC curve drops fast — verify your pilot-duty load against the 220 V DC figure if you're switching DC solenoids or relays.
Integration and wiring notes
Screw terminals accept solid or stranded copper: main circuit wires from 1 to 10 mm² (2x 1–2.5 mm² or 2x 2.5–6 mm², max 2x 10 mm²), auxiliary circuits from 0.5 to 4 mm². Strip length and torque follow standard Siemens practice for S0 frames. Side-by-side mounting is allowed with no derating gap — the 6 mm side clearance is for air circulation, not mandatory spacing. For type 2 coordination (no-weld) the required upstream fuse is gL/gG 25 A; for type 1 coordination (allow weld but clear fault) it's 63 A. Pollution degree 3 means the contactor is rated for conductive environments typical of industrial panels — no additional conformal coating needed for normal factory air.