The Siemens 4EU3921-5AA00-0A is a 3-phase commutating choke (also called a line reactor) for use with a converter or drive. It limits current rise and harmonics on the input side, protecting the rectifier and smoothing the DC bus. Rated 405 A continuous (450 A maximum) at 690 V AC, 50 Hz, it's sized for medium-power drive systems in industrial panels. The 0.00011 H inductance and 4% relative inductive voltage drop provide line impedance for the converter. The flat-type connectors are heavy-duty bus-bar style terminals, common for this current class.
Thermal rating and duty cycle
Thermal class H per IEC 60085 means the insulation system withstands 180°C hot-spot temperature — standard for high-ambient or overload-prone drive applications. The 40°C ambient rating is the baseline; above that, derate the continuous current. Copper loss is 378 W, iron loss 277 W, so total heat dissipation is about 655 W at full load — factor that into cabinet ventilation.