What this part is and where it fits
The Siemens 3RT2936-1BF00 is a surge suppressor with a built-in varistor, designed to clip directly onto SIRIUS contactors in sizes S2 and S3 (3RT2.3 and 3RT2.4 series). It suppresses voltage transients across the coil terminals during switching, protecting the contactor coil and extending relay life in repetitive cycling applications.
Electrical ratings — what the numbers mean for your panel
Rated for 400-600 V AC at both 50 Hz and 60 Hz — this covers the common industrial control voltages across European (400 V) and North American (480/600 V) distribution without needing a different suppressor variant. The varistor design clamps the peak voltage to a safe level for the coil insulation; unlike RC snubbers, it handles higher energy pulses but has a finite life limited by the number of surge events.
Mechanical fit — DIN rail and panel integration
Clip-on fastening method means it snaps onto the contactor without tools — no additional DIN rail footprint or wiring space needed beyond the contactor itself. Dimensions are 30 mm wide, 30 mm high, and only 14.5 mm deep — it sits flush against the contactor side, so the overall panel depth is unchanged. Mountable in any position, with an operating temperature range of -25 to +60 °C and storage range of -40 to +80 °C, covering most indoor panel environments.
Lifecycle and sourcing reality
Sourced and quoted to order against your BOM quantity; availability and current pricing confirmed at RFQ time through independent distribution channels.