Contactor for motor switching — SIRIUS 3RT2 series
The Siemens 3RT2015-1BG42-0CC0 is a 3-pole contactor from the SIRIUS 3RT2 series, rated AC-3 for motor switching at 3 kW on a 400 V three-phase supply. The coil is DC 125 V, and the built-in auxiliary is 1 NC. The size S00 frame keeps the panel footprint compact — roughly the width of a 45 mm terminal block — and the screw terminals accept standard power and control wiring without special tooling.
What the AC-3 rating means for your motor load
AC-3 duty covers starting and switching off squirrel-cage motors under load. The 3 kW at 400 V figure means this contactor handles a typical 4 HP induction motor on a 400 V line — common for small pumps, fans, and conveyors. The DC 125 V coil is worth noting: it draws a steady holding current with no AC hum, but the coil suppression circuit must match the DC polarity. Verify the free-wheel diode or varistor orientation on the control board before wiring.
Panel integration — size S00 screw terminals
The S00 frame snaps onto a DIN rail (EN 60715) and occupies a single 45 mm width unit. Screw terminals accept 1.5 to 4 mm² stranded or solid wire. The 1 NC auxiliary is factory-fitted on the left side; if you need additional auxiliary contacts, the 3RT2 series accepts add-on blocks that clip onto the front without increasing the panel width. The DC coil draws about 2.5 W holding power — negligible for the control transformer budget.