What this contactor is and what it does
The Siemens 3RT2017-2BG42-0CC0 is a SIRIUS 3RT2 contactor rated for AC-3 duty at 5.5 kW at 400 V, with a DC 125 V coil and one normally-closed auxiliary contact. The S00 frame size and spring-loaded terminals suit it for compact control panels where fast wiring without screwdrivers is the norm — common on packaging lines and conveyor sections that see frequent changeovers.
AC-3 rating and what it means for motor loads
The AC-3 rating of 5.5 kW at 400 V means this contactor is designed to switch three-phase induction motors on and off under full load — starting and stopping a motor up to that power. The DC 125 V coil allows direct connection to a 125 VDC control circuit without an intermediate relay, simplifying the control panel wiring.
Panel integration notes
The S00 frame size snaps onto a DIN rail (EN 60715) and accepts spring-loaded terminals for 0.2–2.5 mm² solid or ferruled stranded wire. The 1NC auxiliary contact is built in; additional auxiliary contact blocks can be front-mounted without tools. Verify coil polarity on the DC 125 V coil — the free-wheel diode is internal, but reverse polarity will not energize.