The Siemens 3RU1126-1HB0-ZW97 is a SIRIUS overload relay in Size S0, rated for a current range of 5.5...8 A with Class 10 trip characteristic. The 1NO+1NC auxiliary contact set provides one normally-open signal for the control circuit and one normally-closed for the safety chain, which is the standard configuration for a motor feeder in a panel. Size S0 is the compact frame in the SIRIUS modular system, designed for direct mounting onto Siemens contactors of matching frame size. The multiunit packing of 22 pieces per package is a production-line or large-MRO convenience — the relay itself is the same single unit as the individually-boxed variant, just bulk-packed for volume builds.
This relay snaps directly onto the matching SIRIUS contactor (Size S0) without additional wiring between the two — the power connections pass through the relay's integral bus bars. That keeps the motor feeder compact on the DIN rail and reduces wiring errors. For a panel builder, the S0 footprint means the relay occupies roughly 45 mm of rail width, leaving room for the contactor and a downstream terminal block in a standard 600 mm enclosure depth.