The Siemens 3RT2926-1CE00-ZX90 is a SIRIUS surge suppressor with RC elements, designed to clip onto size S0 contactors. It suppresses voltage spikes across the AC coil when the contactor de-energizes — without it, the inductive kick can weld auxiliary contacts or take out the PLC output driving the coil.
Voltage range and frequency — what it actually handles
Rated for AC control supply voltage, it covers 240-400V at 50 Hz and 400-240V at 60 Hz. That reversed-looking 60 Hz range (400 down to 240) is typical for RC suppressors — the impedance shifts with frequency, so the voltage rating flips. If your control transformer is tapped at 400V 50 Hz or 240V 60 Hz, this unit matches.
Physical fit — panel integration
Clip-on fastening to the contactor face — no DIN rail space consumed. Dimensions are 12 mm deep, 30 mm wide, 19 mm high. That 12 mm depth means it sits flush with the S0 contactor body; no extra clearance needed behind the panel door.
Temperature tolerance
The storage range exceeds operating — that limit governs handling and shipping, not running.