The Siemens SIRIUS 3RT2936-1BD00-ZX90 is a surge suppressor with varistor, designed to clip onto contactors of size S2 or S3. It suppresses voltage spikes across the coil terminals, protecting the contactor coil and nearby control electronics from inductive kickback when the coil de-energizes. Rated for 127-240V AC at 50 Hz and 150-250V DC, it covers the common control voltage ranges in European and North American panels. The varistor clamps the transient, not a series RC snubber — so it handles both AC and DC coils without the polarity sensitivity of a diode.
At 14.5 mm deep, 30 mm wide, and 30 mm tall, this suppressor takes minimal DIN-rail space. It clips directly onto the contactor's front side — no separate mounting rail needed. The any-position mounting means it works in tight enclosures where orientation is constrained. The clip-on fastening method matches the SIRIUS S2 and S3 contactor frames.
Environmental limits and sourcing posture
The AC/DC voltage type means one part number covers both supply types — simplifies BOM management.