The Siemens 3RT1023-1BB40-ZX95 is a SIRIUS power contactor in size S0, with a 24 V DC coil and screw-type terminals for the main circuit. It snaps onto a 35 mm DIN rail per DIN EN 50022, occupying 45 mm of panel width. Rated for AC-3 duty at 5.5 kW / 690 V and 4.5 kW / 500 V, it handles motor loads up to those power levels. The AC-4 rating at 400 V is 8.5 A — that's the reversing or inching duty cycle, where the contacts open under full load. Coil draws 5.4 W both on closing and holding — no extra inrush to size your control transformer for.
Main circuit terminals accept solid conductors up to 2x 4 mm² or stranded up to 2x 10 mm². Control circuit wiring uses 0.5 to 1.5 mm² solid or 0.75 to 2.5 mm² stranded. Front face carries IP20 protection — safe for finger contact during panel work.