The Siemens 4EP3900-1DS00 is a commutating choke (line reactor) designed for converter applications — specifically to limit di/dt and smooth the DC-link current in variable-speed drives and rectifier front-ends. It handles 3-phase AC at 500 V, rated 36 A continuous with a 40 A maximum, and delivers 0.92 mH inductance per phase.
IP00 means it's an open-frame component — no enclosure, no finger-safe protection. It mounts inside a cabinet, typically on a base plate or chassis, not on a DIN rail. The 0.219 m width, 0.179 m height, and 0.123 m depth define the space you need to allocate in the panel layout; allow extra clearance for airflow and the screw-type terminals on the main circuit connections. The thermal class B insulation per IEC 60085 means the winding can sustain 130 °C hot-spot temperature continuously — adequate for a 40 °C ambient with the 70 W coil loss and 22.3 W iron-core loss dissipated through natural convection. If your ambient exceeds 40 °C, derate current or force air.
DC-link and converter duty
The same choke also carries a DC rated value of 49 A, which means it can be used on the DC side of a converter — for example, as a smoothing reactor in the DC link of a 6-pulse rectifier. The 0.92 mH inductance at 50 Hz is typical for a 36 A drive input reactor; it provides enough impedance to limit peak currents during commutation and reduce the harmonic content drawn from the supply. The 4 % voltage drop is a standard figure for line reactors in this class — high enough to be effective, low enough not to starve the drive of voltage under load.