What it is and what it does
The Siemens 3RT1016-1HB42-ZW96 is a 3-pole coupling relay in the SIRIUS 3RT series, size S00. It switches motor loads up to 4 kW at 400 V under AC-3 duty — that's the standard induction-motor switching category per IEC 60947-4-1, so it handles the locked-rotor inrush and breaking current of a typical three-phase motor. The coil is DC 24 V with a pick-up range of 0.7 to 1.25 times the rated control supply voltage, meaning it pulls in reliably even if the 24 V bus sags to about 17 V.
Where it fits in the panel
Size S00 is the smallest frame in the 3RT contactor family — it snaps onto a DIN rail and takes up about 45 mm of width. The single NC auxiliary contact is built in, so you get a feedback or status signal without adding a separate block. Screw terminals are standard for this variant; the ZW96 suffix flags the multi-unit packing of 90 pieces in a 2x2 layer carton, which is a storeroom consideration if you're stocking spares for a line of identical panels.