What it is and what it does
The Siemens 3RT2035-3NB30-Z W97 is a size S2 power contactor from the SIRIUS family, rated for AC-3e and AC-3 duty at 41 A and 18.5 kW at 400 V. The AC-3e rating means it is tested for switching three-phase motor loads up to that current — the standard category for squirrel-cage motors during starting and running. The 20-33 V AC/DC coil with an integrated varistor gives you a wide control-voltage tolerance and built-in surge suppression, so you do not need an external RC snubber across the coil. The contactor has three main poles for switching power circuits and comes with one normally-open plus one normally-closed auxiliary contact. Main circuit wiring uses screw terminals; the control and auxiliary circuit connections use spring-loaded terminals, which speeds up panel wiring and eliminates periodic retorquing on low-current circuits.