The Siemens 3RT1926-1ER00 is a SIRIUS surge suppressor designed for DC-operated contactor coils. It uses a diode assembly to clamp the inductive flyback voltage when the coil de-energizes, protecting the control-circuit contacts and extending their electrical life. This unit is sized for S0-frame contactors and plugs onto the top of the device.
Rated for 24 V DC control supply voltage, this suppressor matches the coil voltage of the SIRIUS contactor it protects. The diode design means it is polarity-sensitive — verify the DC supply orientation before plugging it in. It mounts directly onto the top of an S0-size contactor, occupying no additional DIN-rail space. The IP20 finger-safe enclosure on the front is standard for control-panel environments.