What it is and where it fits
The Siemens 4EM5212-8CB00 is a single-phase commutating choke (line reactor) designed for converter front ends. It sits between the AC supply and the converter input to limit current rise rates, reduce harmonics, and protect the DC link from line transients. Rated for 400V AC at 50 Hz, it carries 35.5 A maximum AC current and 31.95 A rated operational current in continuous duty. The 4% relative inductive voltage drop at rated conditions is the design target — it limits inrush without dropping too much voltage across the choke under load.
Mounting and connection
This choke is IP00 — no enclosure, no drip shield. It's intended for a clean, dry cabinet where it can be bolted down and wired via its screw-type terminals. Dimensions are 0.121 m wide by 0.131 m tall by 0.128 m deep, so it'll fit in a standard 200 mm deep enclosure with room for cable bends. The screw terminals accept common power wiring; no special lugs or crimp tools needed for field replacement.
Thermal and electrical limits
Thermal class B per IEC 60085 means the insulation system is rated for 130 °C hot-spot. At 40 °C ambient, total power loss splits 22 W in the coil and 36 W in the iron core — 58 W to vent inside the cabinet. The DC-rated current of 43.5 A is higher than the AC rating because DC doesn't induce the same skin and proximity losses; use that figure if the choke sits on the DC bus side of a converter.