What it is and what the ratings mean
The Siemens 3RT1023-1AP80-0KR0-ZW97 is a Size S0 power contactor from the SIRIUS 3RT1 series, rated for AC-3 duty at 9 A and 4 kW at 400 V. The AC-3 rating means it is specified for starting and stopping squirrel-cage induction motors under load — the standard motor-switching category per IEC 60947-4-1. The 9 A AC-3 figure governs real motor sizing, not the higher AC-1 resistive rating. The coil pulls in at 230-240 V AC, 50/60 Hz, so it drops into any European-standard control voltage circuit without a transformer tap change.
Deployment context
Size S0 mounts on a standard DIN rail inside a control panel. The screw terminals accept up to 2.5 mm² conductors, typical for motor branch circuits at this rating. The 3-pole configuration handles three-phase motor loads up to 4 kW at 400 V — common for small pumps, fans, and conveyors in industrial panels.