What it is and what it does
Siemens 3RT1016-5BB44-ZW95 is a SIRIUS 3RT1 contactor rated for AC-3 duty at 4 kW on a 400 V three-phase supply. AC-3 rating certifies the contactor can make and break motor locked-rotor current. 4 kW / 400 V AC-3 fits a small pump, fan, or conveyor drive.
Deployment context
Snap-on DIN rail mounting to a standard 35 mm rail in the enclosure. The SIRIUS 3RT1 family shares a common accessory platform — same auxiliary contact blocks, same coil suppression modules, same mechanical interlock for reversing pairs — so panel integration is straightforward if you're already stocking the family.