The Siemens 4EU4551-0AF10-0B is a three-phase mains choke (line reactor) designed for the input of a variable frequency drive. It is rated for 350 A continuous at 400 V AC, 60 Hz, with an inductance of 0.17 mH and a relative inductive voltage drop of 9.7% at rated current. That 9.7% drop is the key figure for sizing: it tells you how much voltage the choke consumes under load, which directly affects the DC bus voltage available to the drive. A higher drop gives better harmonic attenuation but reduces the voltage headroom for the motor.
Thermal and mechanical fit
The choke is rated for a 40 °C ambient with Class H insulation (180 °C thermal class per IEC 60085), which means the winding can handle sustained high temperatures without degrading — important when the reactor is mounted inside a cabinet with other heat sources. Total power loss is 970 W (600 W in the coil, 370 W in the iron core), so plan for that heat rejection in your enclosure ventilation. Connections are flat-type terminals for the main circuit, sized for the 350 A buswork.