The Siemens 3RT1916-1CD00 is a SIRIUS RC-type surge suppressor designed to clip voltage transients across the coil of a contactor. It mounts directly onto S00-frame contactors — the smallest in the SIRIUS family — and handles control supply voltages of 127...240 V AC (50/60 Hz) or 150...250 V DC. The RC element (resistor-capacitor network) dampens the inductive kick when the coil de-energizes, protecting nearby PLC outputs and extending contact life.
The voltage range — 127...240 V AC and 150...250 V DC — tells you this suppressor works on coils rated anywhere inside that band. On a 230 V AC contactor coil, the RC element sees the full line voltage and clamps the turn-off spike. The dual AC/DC rating is useful: a DC-supplied contactor coil (common in 24 VDC control systems stepped up through a DC-DC converter or a separate 220 VDC supply) gets the same protection as an AC coil. The S00 size restriction is absolute — this suppressor physically clips onto the front of S00 contactors only; S0 or S2 frames need a different suppressor.
Deployment context
Snaps onto the front of a SIRIUS S00 contactor — no tools, no extra wiring beyond the two coil terminals. In a typical panel, you'd fit one per contactor driving a motor starter or resistive load. The RC element is polarity-insensitive for AC, but on DC circuits verify the suppressor's orientation matches the coil polarity (the datasheet marking is usually clear).