Contactor selection for motor switching
The Siemens 3RT1015-1HB42-ZW95 is a SIRIUS contactor rated for AC-3 duty at 3 kW / 400 V, meaning it is sized for switching three-phase induction motors up to that power. The DC 24V coil with a control range of 0.7 to 1.25 times the rated control supply voltage gives a consistent pick-up margin even if the panel supply sags. One normally-closed auxiliary contact is built in, which is often used as a feedback interlock or for a status signal to the PLC.
Panel integration and form factor
Size S00 is the smallest frame in the SIRIUS 3RT1 series, designed for snap-on mounting onto a 35 mm DIN rail. The screw terminals accept standard ferruled or solid copper conductors, and the compact footprint leaves room for auxiliary contact blocks or a solid-state overload relay alongside it in the panel.