What the ratings mean for fit
The Siemens 4EP3901-4DS00 is a 3-phase commutating choke (line reactor) for converter applications, rated 400 V AC at 50 Hz. Its 56 A maximum continuous current and 50.4 A rated current define the thermal limit for the load side — size the upstream converter and cabling for at least this continuous current. The 0.4 mH inductance with a 4% relative inductive voltage drop means this choke limits di/dt and reduces harmonic distortion on the converter's DC link; the 4% drop is typical for moderate smoothing without excessive voltage sag under load. The 70 A peak current rating handles short-duration inrush or transient events without saturating the core.
Deployment context
This is an open-frame (IP00) component — no enclosure, so it mounts inside a panel or cabinet where the ambient temperature stays at or below 40 °C. The flat-type terminals accept busbar or cable lugs; plan for panel wiring with adequate clearance around the 0.219 m width and 0.123 m depth. Thermal class B insulation per IEC 60085 means the winding withstands 130 °C hot-spot temperature — adequate for continuous duty in a ventilated enclosure. The 70.6 W coil power loss plus 15.7 W iron-core loss total about 86 W of heat to vent; factor that into the cabinet's thermal budget.