What it is and what the AC-3 rating means
The Siemens 3RT2023-1CC20-ZX95 is a 3-pole SIRIUS contactor in size S0, with a 24 V AC coil rated for 50/60 Hz and a built-in 1NO+1NC auxiliary contact block. Its AC-3 rating of 4 kW at 400 V defines the motor-switching capacity — this is the category for starting and stopping squirrel-cage induction motors under load, so the contactor is sized for a 4 kW three-phase motor on a 400 V line. The screw terminals on this variant match standard panel wiring practice; the S0 frame is a common footprint across the 3RT2 family.
Panel integration notes
Size S0 mounts on a DIN rail per the standard SIRIUS rail profile. The AC coil draws its rated holding current at 24 V, 50/60 Hz — verify the control transformer sizing if multiple contactors share the same AC supply, because inrush at pick-up can dip the rail below the dropout threshold. The 1NO+1NC auxiliary is wired directly to the contactor; no add-on block needed for basic feedback or interlock.