The Siemens SIRIUS 3RT1916-1CF00 is a surge suppressor built with RC elements, designed to clamp voltage transients across the coil of a contactor. It is rated for AC control supply voltage across 400 to 600 V at 50 Hz, and 600 to 400 V at 60 Hz — the reversed order on the 60 Hz line is a data presentation quirk; the part covers the same 400–600 V range at both frequencies.
The suppressor mounts directly onto SIRIUS S00 contactors — it clips onto the coil terminals, no additional wiring space needed. The RC network absorbs the inductive kick each time the contactor de-energizes, which extends the life of the coil and reduces EMI on the control circuit. For a panel builder swapping in the 3RT2916-1CF00 successor, the DIN-rail layout and terminal assignments remain identical.