SIRIUS S0 power contactor — 3RT1023-3AP00
The Siemens 3RT1023-3AP00 is a SIRIUS S0-frame power contactor with three normally-open main contacts, a 230 V 50 Hz coil, and screw-type terminals. It's rated for motor switching up to 4 kW at 400 V in AC-2 duty (slip-ring motors) and 8.5 A in AC-4 duty (reversing or inching). The S0 frame keeps it at 45 mm wide, 85 mm tall, and 90 mm deep — a standard DIN-rail footprint that snaps onto 35 mm rail per DIN EN 50022.
The AC-4 rating of 8.5 A at 400 V governs plugging and reversing cycles — that's the real-world limit for frequent motor reversals, not the higher AC-3 figure you'd see on a standard contactor. For slip-ring or wound-rotor motors, the AC-2 rating of 4 kW at 400 V applies. The coil holds at 230 V 50 Hz with an operating range of 0.8 to 1.1 times rated voltage, so it drops out below about 184 V. The IP20 front face protects against finger contact; the IP00 terminals are exposed — panel builders should plan for terminal shrouding or clearance.
The screw-type main terminals accept 2x (0.25 to 2.5 mm²) solid or 2x (1 to 2.5 mm²) stranded, up to 2x 10 mm² max. For type 1 coordination, use a 63 A gL/gG fuse; for type 2 coordination, a 25 A gL/gG fuse.