The Siemens 4EU4321-3DA00-0A is a commutating choke (line reactor) for converter applications, designed to limit current rise and reduce harmonics on the AC side of a drive or rectifier. It's a 3-phase, 690V AC, 50Hz choke rated at 900A continuous (1000A max) with a peak current capability of 1250A.
Rated 900A continuous, 1000A max, 1250A peak. 690V AC, 50Hz, IP00, flat-type terminals.
Thermal and power loss considerations
That's significant heat to manage inside a cabinet — plan for forced ventilation or a larger enclosure to keep ambient below the 40°C rating. The thermal class H insulation (IEC 60085) means the winding can handle 180°C hot-spot temperature, so the choke itself is robust, but the surrounding components and cabinet air need to stay within limits. Mounting dimensions: 0.435m high, 0.46m wide, 0.265m deep — a substantial footprint; verify panel door clearance and busbar routing before committing the layout.