What it is and what it does
The Siemens 4EP3700-0DS00 is a three-phase commutating choke (line reactor) designed for use with power converters and drives. It smooths the DC link current and limits current rise rates, protecting the converter's semiconductors and reducing harmonic distortion. Rated for 28.35 A continuous current with a maximum of 31.5 A, the choke provides 0.00089 H inductance per phase at 400 V AC, 50 Hz. The relative inductive voltage drop is 4%. The DC-rated current is 38.6 A, which is relevant if the choke is used in the DC link rather than the AC input — a configuration sometimes seen in regenerative or common-bus drive systems.
Thermal and environmental ratings
Total power loss is 64.8 W (53 W in the coil, 11.8 W in the iron core) at the rated operating point of 40 °C ambient. The thermal class is B per IEC 60085, meaning the winding insulation is rated for a 130 °C hot-spot temperature — adequate for standard industrial enclosure conditions without forced cooling. Protection class IP00 means the choke has no enclosure; it must be mounted inside a panel or cabinet that provides the required ingress protection. The screw-type terminals accept standard power wiring.
Dimensions and mounting
The choke measures 0.178 m wide, 0.153 m high, and 0.105 m deep. These are the external dimensions of the core and coil assembly; allow additional clearance for the screw terminals and for air circulation around the unit.