What it is and what it does
The Siemens 4EP3700-7US00 is a three-phase mains choke (line reactor) designed for use with variable frequency drives. It reduces harmonic distortion and limits inrush current on the input side of the drive, protecting both the drive and upstream equipment. Rated for 400/480 V AC at 50/60 Hz, it carries a maximum continuous current of 18 A and a rated operational current of 16.2 A. The inductance is 1.6 mH, and the relative inductive voltage drop is 4% at rated conditions. This is a standard-duty choke for general-purpose drive applications — sized for a 3-phase motor drive pulling up to about 7.5 kW at 400 V, depending on the drive's input current profile. The 4% voltage drop is typical for a line reactor intended to smooth the drive's rectifier stage without excessive voltage sag.
Mounting and integration
The choke is IP00 rated — open frame, no enclosure. It mounts inside a panel or cabinet, not on a DIN rail. Dimensions are 0.178 m wide by 0.153 m tall by 0.105 m deep. Allow clearance around it for airflow; the combined copper and iron losses total 60.6 W at full load, which must be dissipated within the enclosure. Terminals are screw-type for the main circuit, accepting standard power wiring. Verify the terminal size against your cable gauge before panel layout. Thermal class B insulation per IEC 60085 means the winding temperature rise is limited to 80 K over a 40 °C ambient — adequate for most industrial panel environments.
Lifecycle and sourcing
This part carries UL/CSA recognition per EN 61558-2-20, so it is accepted for panel builds shipped into North American markets without additional agency review.