The Siemens 4EU4521-3AA00 is a commutating choke (line reactor) designed for converter duty — it sits between the drive and the line to limit current rise, reduce harmonics, and protect the DC bus from line notching. Rated 910 A continuous at 750 V AC, three-phase, 50/60 Hz, with an inductance of 0.06 mH and a 4% relative inductive voltage drop at rated conditions. That 4% drop is the standard sizing for most drive applications — enough to smooth commutation without dragging down the bus voltage under load.
The 910 A rating is the thermal continuous current (Ith) at 40 °C ambient — that's the current the choke can carry indefinitely without exceeding its thermal class H (180 °C) insulation. If your drive's line current is lower, the choke still works; if it's higher, you need a larger reactor. The DC rating is even higher at 1,115.1 A, which matters if you're using the choke on the DC link side of a converter. IP00 means it's an open-frame component — no enclosure. It's designed for mounting inside a cabinet where the panel provides the environmental protection. The flat-type terminals accept busbar or large cable lugs, typical for high-current power connections. Dimensions are 0.46 m wide × 0.435 m tall × 0.293 m deep — plan your gland plate and busbar clearance accordingly.