The Siemens SIRIUS 3RT1936-1CF00-ZX90 is an RC-type surge suppressor — a resistor-capacitor snubber — rated for 400 to 600 V AC, designed to bolt onto SIRIUS contactors in frame sizes S2 and S3. It suppresses voltage spikes from inductive loads (coils, solenoids) that would otherwise arc across the contactor's auxiliary or main contacts, extending electrical life. The part ships in a multi-unit pack of five, which matters for MRO planners stocking a line: one bag covers five contactors on a panel layout.
Lifecycle reality — phased out, successor named
The 3RT1936-1CF00-ZX90 carries a current lifecycle stage but is explicitly marked as a phased-out product. The official successor is the SIRIUS 3RT2 series — same function, same S2/S3 frame fit, updated design. If the panel spec allows a drop-in swap, the 3RT2 successor is the cleaner long-term path.
This suppressor mounts directly onto the contactor's coil terminals — no DIN-rail footprint, no extra wiring space needed beyond the contactor itself. For a panel OEM wireman: the suppressor's pigtails land on the same A1/A2 terminals as the coil supply; verify the RC element's voltage rating (400-600 V AC) matches the line voltage feeding the contactor coil.
Sourcing posture for this order code
Because this is a phased-out line with a named successor, the procurement decision splits: buy the exact 3RT1936-1CF00-ZX90 for a legacy BOM that cannot be re-qualified, or migrate to the 3RT2 successor for new builds. Either path runs through an RFQ — we source both the legacy order code and the 3RT2 equivalent through independent channels, with pricing and lead time confirmed per inquiry.