The Siemens 4EP3905-0BK00 is a three-phase mains choke designed for the input side of a variable-frequency drive (VFD). It smooths the line current, limits harmonic distortion, and provides a measure of protection against line transients — the kind of component you bolt between the supply and the drive to keep the drive's DC bus from eating every spike on the line. Rated for 460 V AC, it handles a continuous 19.8 A (22 A maximum) with a 1.6 mH inductance and a 5 % relative inductive voltage drop at rated current.
What the ratings mean for fit
The headline numbers here are the current and inductance. The 19.8 A rated current (22 A max) tells you this choke is sized for a drive drawing roughly that much line current — think a 7.5 to 11 kW motor on a 400 V class drive, depending on drive efficiency and load profile. The 1.6 mH inductance at 5 % voltage drop is a typical value for a 3 % impedance line reactor; it's enough to knock the edge off the drive's input current harmonics to meet basic IEEE 519 limits without over-attenuating the drive's available torque. The IP00 rating means this is an open-frame component — no enclosure. It's meant to live inside a panel, bolted to a mounting plate or DIN rail, with the panel's own IP rating providing the environmental seal. The screw terminals accept standard power wiring; you'll land the line and load conductors directly on the choke's terminals, no special connectors needed. Thermal class B (130 °C rise) with a 40 °C ambient means the choke is rated for a 90 K temperature rise above a 40 °C room — standard for industrial panel gear. If your panel ambient runs hotter, you'll need to derate the continuous current; no derating curve is published here, so plan on a 10-15 % margin if the panel hits 50 °C.
Where it goes in the panel
This choke mounts between the incoming line power and the VFD's input terminals. In a typical panel layout, it sits after the main disconnect and fusing but before the drive's input — physically close to the drive to keep the un-filtered line from coupling into other circuits. The 0.219 m width and 0.179 m height mean it'll fit on a standard backplate without crowding, but the 0.123 m depth may require a deeper-than-minimum enclosure if you're mounting it flush against a door or another component. Operating frequency range is 0 to 60 Hz, so it works on 50 Hz and 60 Hz line supplies without issue. The 5 % voltage drop at rated current is a design parameter — the drive's DC bus voltage will be about 5 % lower than without the choke, so factor that into your motor torque calculations at the far end of a long cable run.