The Siemens 3RT2936-1CC00 is a SIRIUS-brand RC-element surge suppressor sized for the S2 contactor frame — specifically the 3RT2.3 series. It clips onto the contactor coil terminals, no wiring required, and handles both AC and DC control voltages: 48–127 V at 50/60 Hz and 70–150 V DC. The 15 mm depth keeps it flush with the contactor body, so it doesn't steal rail space from adjacent devices.
Mounting is clip-on — no screwdriver, no torque spec. The suppressor snaps directly onto the coil terminals of a 3RT2.3 contactor. It occupies any mounting position and fits within the S2 contactor's envelope, so panel layout stays tight. The RC element suppresses voltage spikes from the coil when it de-energizes, protecting nearby PLC outputs and reducing EMI on the control wiring.
That's standard for cabinet-mounted control gear; no derating needed for most industrial environments.