The Siemens 4EU3921-1CA00-0A is a three-phase commutating choke (line reactor) designed for use with converter drives. It sits between the converter and the supply — or on the DC link — to limit current rise rates, reduce harmonics, and protect the converter's semiconductor switches from commutation notches. Rated for 450 A continuous (500 A maximum) with a peak current capability of 625 A, it handles the full rated load of a large drive without saturating. The 87 µH inductance (0.000087 H) at 50 Hz produces a 4% relative inductive voltage drop at rated current and voltage — a standard impedance level that coordinates with most six-pulse converter front ends without excessive voltage loss. The 750 V AC rated operating voltage covers 400 V, 480 V, and 690 V class drives with headroom.
Thermal and mounting constraints
This is an IP00 open-frame component — no enclosure, no finger-safe guarding. Total power dissipation is roughly 600 W (380 W coil loss plus 218 W iron-core loss) at full load, so forced-air ventilation or a properly sized cabinet is necessary to stay within the 40 °C rated ambient temperature. Thermal class H per IEC 60085 means the insulation system is rated for 180 °C hot-spot temperature — suitable for the high thermal stress inside a converter cabinet where ambient temperatures can climb. Main current connections use flat-type terminals (busbar or bolted lug), not screw-clamp or spring-cage; plan for busbar routing or crimp lugs with the correct hole pattern. Physical footprint: 0.41 m wide × 0.385 m high × 0.229 m deep.