What it is and what it does
The Siemens 4EP3700-1US00 is a 3-phase mains choke (line reactor) designed for installation ahead of a frequency converter (FU). It limits harmonic distortion, reduces peak currents, and protects the drive from line-side transients. Rated for 500 V AC at 50 Hz with a maximum continuous current of 35.5 A, it presents an inductance of 0.52 mH and a relative inductive voltage drop of 2% at rated conditions. The IP00 open-frame construction means it is intended for mounting inside an enclosure — no touch protection on the part itself. Connection is via screw-type terminals, which simplifies wiring in a panel compared to busbar-style chokes.
Ratings and what they mean for your panel
The 35.5 A maximum current (ITHMAX 1) is the thermal current rating at 40 °C ambient — the choke can carry this continuously without exceeding Class B insulation temperature limits per IEC 60085. The rated operational current is 31.95 A, which is the current at which the 2% voltage drop and 0.52 mH inductance are guaranteed. For motor drive applications, size the upstream protection such that the drive's input current does not exceed 35.5 A under worst-case load. Total power loss splits between the coil (49.6 W) and iron core (9.74 W), summing to about 59 W. This heat must be considered in the enclosure thermal design — at IP00, natural convection is expected, so adequate ventilation or forced airflow around the choke is necessary.
Compliance and approvals
The 4EP3700-1US00 is UL and CSA recognized, designed to EN 61558-2-20 (safety of transformers, reactors, and power supply units). The product lifecycle status is active — this is a current-production part, not a discontinued or NRND item. For RoHS, REACH, and CE documentation, the manufacturer provides declarations on request.
Physical fit and panel integration
Dimensions: 0.178 m wide × 0.153 m tall × 0.105 m deep. The open-frame design means it mounts via its core or a bracket — no DIN-rail clip. Plan for screw-terminal access on the main circuit connections. The 0.105 m depth is the choke body only; allow additional clearance for cable bending radius and airflow.