The Siemens SIRIUS 3RT6018-1BG42 is a size S00 power contactor rated for 7.5 kW at 400 V in AC-3 duty and 4 kW at 230 V, with a DC 125 V coil. It switches three main poles and carries one normally-closed auxiliary contact — the 1NC in the order code.
Switching frequency and duty
Rated for 750 operations per hour in AC-3 and AC-3e duty, this contactor handles frequent motor starts typical of conveyor sections or pump cycling. That 750 1/h figure governs the thermal load on the coil and arc chamber — exceed it and the contactor overheats, shortening life. For less demanding resistive loads (AC-1) the permissible rate is higher, but for motor switching this is the number to respect in the PLC cycle time.
Size S00 means 45 mm wide, 57.5 mm tall, 73 mm deep — a compact footprint that leaves room on the DIN rail for an overload relay or auxiliary contact block. The screw terminals accept 2x (0.5 to 2.5 mm²) solid or stranded, or 2x 4 mm² for the main circuit.