The Siemens SIDAC 4EU4551-0AD18-0B is a 3-phase output reactor (choke) rated for 690 V AC, with a maximum continuous current of 740 A at 120 Hz and a rated switching frequency of 3.4 kHz. It carries 666 A rated current at the nominal inductance of 0.05 mH per phase. The IP00 enclosure means it's an open-frame component intended for installation inside a cabinet or panel — no washdown protection, so keep it away from moisture and dust ingress.
The 740 A rating at 120 Hz is the thermal limit under the rated switching frequency — this reactor is sized for high-current motor drives running at moderate output frequencies. The 3.4 kHz switching frequency matches IGBT-based drives in the common 2–4 kHz range; if your drive runs a higher carrier frequency, derate the current or look for a reactor with a higher frequency rating. The 7 % impedance (UK) provides enough line reactance to limit di/dt and reduce motor bearing currents, but it's not a heavy-duty harmonic filter — it's a standard output reactor for motor protection. Thermal class H (180 °C insulation) and a 40 °C ambient rating mean the reactor can run hot without derating at that ambient — fine for most industrial enclosures, but if your panel ambient exceeds 40 °C, you'll need to derate the current or add forced cooling. The flat-type terminals (flat connector) are common for high-current busbar connections; expect to bolt on lugs or busbars, not wire ferrules.
This reactor mounts between the drive output and the motor cable. The 0.46 m width and 0.43 m height footprint is substantial — plan for a 500 mm wide backplate section and ensure the cabinet depth (0.29 m) fits the available enclosure depth. The IP00 frame means it's not touch-safe; mount it behind a locked door or with a protective cover. The flat terminals are sized for high-current busbars — torque specs should follow the manufacturer's recommendation for the lug size you use.