The Siemens 3RT2936-1CF00-ZX90 is a SIRIUS surge suppressor built as an RC element, designed specifically for size S2 contactors. It clips onto the contactor to suppress voltage spikes from the AC coil when de-energized — that RC snubber network absorbs the inductive kick that would otherwise arc across auxiliary contacts or radiate noise into nearby control wiring. Rated for 400 to 600 V AC at 50 Hz and 600 to 400 V AC at 60 Hz, it covers the common 400 V and 480 V industrial line voltages across both mains frequencies.
Mounting and footprint
Clip-on fastening method — no wiring or tools needed. It snaps directly onto the S2 contactor's coil terminals. Dimensions are 30 mm wide, 30 mm high, and only 14.5 mm deep, so it adds negligible depth to the contactor assembly.