The Siemens SIRIUS 3RT1647-1AG61 is a 3-pole capacitor contactor in Size S3, purpose-rated for AC-6 duty at 50 kVAr / 400 V. That AC-6 rating is the key spec here — it means the contactor is designed for switching capacitor banks, where the inrush current can be many times the steady-state current. A standard AC-3 motor contactor would weld its contacts on that surge; this part handles it. Coil is AC-operated, accepting 100 V at 50 Hz or 100...110 V at 60 Hz. That covers most European and Asian line voltages at 50 Hz, plus the North American 110 V 60 Hz standard. The 50/60 Hz frequency range on the control circuit means the same coil works across both mains frequencies without a change.
Termination and Protection
Main and auxiliary circuits both terminate at screw-type terminals. One normally-open auxiliary contact is built in (1 NO).