The Siemens 4EM5000-0KB00 is a single-phase commutating choke (line reactor) for a converter — it sits between the AC line and the converter's input rectifier to limit current rise, reduce harmonics, and protect the DC bus from line notching. You'll find it in a drive cabinet or power supply section, bolted in with screw terminals and no enclosure (IP00), so it's meant for inside a panel where the cabinet provides the real protection.
Rated at 250 V AC and 50 Hz — standard European line voltage. The maximum continuous current is 26 A with a rated (nominal) current of 23.4 A. At DC the rated current is higher at 31.8 A, which matters if you're using this on the output side of a converter or in a DC link application. Inductance is 1.2 mH with a relative inductive voltage drop of 4% at rated current — that's a typical impedance for a commutating choke, enough to smooth the current waveform without dropping excessive voltage across the reactor. Power losses split between the coil (12.4 W) and iron core (22.8 W), totaling about 35 W of heat to dissipate inside the panel. Thermal class B per IEC 60085 means the insulation system is good for a 130 °C hot-spot temperature, and the ambient rating is 50 °C — fine for most ventilated cabinets but derate if you're cramming it into a sealed box.
Dimensions are 0.115 m deep, 0.097 m wide, 0.111 m high — about 115 × 97 × 111 mm. That's a compact footprint for a 26 A choke; it'll fit on a backplate or DIN-rail adapter plate. The screw-type terminals accept standard ring or fork lugs, so no special crimping tools needed. IP00 means no built-in touch protection — the panel builder needs to provide finger-safe covers or a locked cabinet door.