The Siemens 4EP3900-0DS00 is a commutating choke (line reactor) designed for converter input circuits. Its job is to limit current rise, reduce harmonics, and protect the DC link from line-side transients — essential for keeping variable-frequency drives and DC drives running reliably in a high-bay AS/RS or any automated line. Rated 45 A continuous (50 A maximum) on a 3-phase, 400 V AC, 50 Hz system, with an inductance of 0.56 mH and a relative inductive voltage drop of 4% at rated conditions. That 4% drop is the design target for most standard drive applications — it smooths the current waveform without pulling down the bus voltage enough to trip undervoltage on the drive. The DC-rated current is 61.2 A, which covers the higher RMS current typical in DC-link applications. Thermal class B (130 °C rise) per IEC 60085, with a total power loss of 65 W in the coil plus 21 W in the iron core at rated load — that heat must be considered in enclosure sizing, especially given the IP00 open-frame construction.
The 0.123 m depth, 0.219 m width, and 0.179 m height occupy a moderate footprint. The choke is UL/CSA recognized per EN 61558-2-20, which covers the safety isolation and thermal performance for North American installations.