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.
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. 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.
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.