The Siemens 3RT6926-1BC00 is a varistor-type surge suppressor from the SIRIUS family, sized for S0 contactors. It clips onto the contactor coil terminals — no wiring needed — and protects the coil circuit from voltage spikes during switching. The control supply can be AC or DC, with a coil voltage range of 48... 127 V at 50 Hz, 127... 48 V at 60 Hz, and 70... 150 V DC. That dual AC/DC rating covers most global control voltages without needing a separate suppressor variant.
Clip-on fastening to the contactor coil terminals — no DIN rail space consumed. The suppressor measures 12 mm deep, 30 mm wide, and 19 mm high, so it adds negligible depth to the S0 contactor stack.