What it is and what it does
The Siemens 4EP3700-4DS00 is a 3-phase commutating choke (line reactor) designed for converter front-ends. It limits current rise and harmonics on the AC side of a variable-frequency drive or DC drive converter, protecting the rectifier diodes and smoothing the DC bus. Rated 45 A AC maximum, 0.31 mH inductance, and 400 V AC at 50 Hz.
Key ratings and what they mean for fit
The 45 A AC maximum current and 40.5 A AC rated operational current define the continuous load this choke can carry without saturating the core. For a 400 V, 50 Hz converter input, the 2% relative inductive voltage drop means the choke will drop about 8 V at rated current — negligible for most drive applications but worth confirming the drive's undervoltage tolerance. The 0.31 mH inductance sets the dv/dt and harmonic attenuation; per the datasheet, this value is measured at rated current, frequency, and voltage. Thermal class B insulation per IEC 60085 means the winding can sustain 130 °C hot-spot temperature. The 49 W copper loss plus 12 W iron loss sum to 61 W total dissipation at rated load — this heat must be ventilated from the enclosure. The 40 °C ambient rating is the reference; derate above that per the thermal curve in the full datasheet. IP00 protection means the choke has no enclosure — it is an open-frame component intended for mounting inside a panel or drive cabinet. Screw-type terminals accept ring or fork lugs; the 0.105 m depth, 0.178 m width, and 0.153 m height define the mounting footprint. Allow clearance for airflow and terminal access.
Where it is used
This choke mounts on the AC input of a 3-phase converter drive — typically between the mains supply and the drive's rectifier section. It reduces harmonic distortion, limits inrush current, and protects the drive's input diodes from commutation notches. Common in motor control panels for pumps, fans, conveyors, and compressors where the drive is fed from a stiff supply or where multiple drives share a common bus.