The Siemens 4EU3921-6AA00-0A is a 3-phase commutating choke for converter applications, rated 450 A continuous with a maximum of 500 A at 690 V AC, 50 Hz. The 0.000094 H inductance limits the rate of current rise during thyristor commutation, which reduces di/dt stress on the converter's semiconductors and suppresses line notching.
The 450 A rated current and 690 V AC operating voltage define the continuous thermal load. That heat must be removed from the enclosure; IP00 means no ingress protection, so the choke is intended for mounting inside a clean, ventilated cabinet where convection or forced air handles the thermal budget. The DC rated current of 612.7 A is higher than the AC rating because the RMS current in a DC link is lower for the same copper loss — a detail that matters when the choke is used on the DC side of a 6-pulse or 12-pulse rectifier.
Deployment context
This choke mounts inside a converter cabinet via its flat-type terminals — no DIN rail, no snap-on. Thermal class H insulation (180 °C hot-spot) per IEC 60085 gives headroom for overload cycles common in drive and rectifier applications.