What this varistor suppressor does on an S0 contactor
The 3RT2926-1BC00-ZX90 is a varistor-type surge suppressor designed for Siemens SIRIUS S0-size contactors. It clips onto the contactor coil terminals and limits voltage transients when the coil de-energizes — without it, the inductive kick from the contactor coil can exceed the rated impulse withstand of the PLC output or relay driving it. The control supply voltage range covers AC 48...127V at 50/60 Hz and DC 70...150V, with the AC/DC designation meaning the same unit handles both supply types across those bands. This is a single voltage-range variant — confirm your coil voltage falls within these windows before fitting.
Panel fit and mounting constraints
The suppressor measures 12 mm deep, 30 mm wide, and 19 mm tall — it adds negligible depth to the contactor assembly. The clip-on fastening method means it snaps directly onto the S0 contactor's coil terminals without additional hardware or DIN-rail space. Mounting position is any orientation, which simplifies panel layout when the contactor is installed sideways or upside-down. The operating temperature range is -25 to +60 °C, storage -40 to +80 °C — adequate for most indoor industrial cabinets but check if your enclosure sees sustained heat near the upper limit.
Sourcing and lifecycle status
Sourced and quoted to order against your BOM quantity through independent industrial distribution.