The Siemens SIDAC 4EU3021-2EB00-0A is a 3-phase output reactor rated for 120A maximum continuous current at 400V AC, with a rated switching frequency of 7000Hz and 0.24mH inductance. It's designed to sit between a variable-frequency drive and the motor, smoothing the PWM waveform and limiting voltage spikes that would otherwise stress motor windings on long cable runs. Thermal class H (180°C insulation system) tells you the core and coil can run hot under full load without degrading the magnet wire varnish.
At 0.3m wide, 0.26m tall, and 0.21m deep, this reactor takes up a noticeable footprint on the backplate — not something you drop into a crowded DIN-rail section. The free cable endings (no terminal blocks) mean you'll land the power conductors directly, typically with ring lugs or ferrules. The 120A rating covers most 37–45 kW drives at 400V, but the 7000Hz switching frequency is specific to higher-carrier-frequency IGBT stages; if your drive runs at 4kHz or 16kHz, the core losses and temperature rise change. Total power loss sums to 369W (210W coil + 159W iron) at rated conditions — that's real heat that needs to leave the enclosure, so factor it into your thermal budget.
Installation notes
Mount the reactor as close to the drive output as practical — long unshielded cable between drive and reactor defeats the purpose. The IP00 rating means no drip shield or dust seal; keep it inside a clean, dry enclosure. Ambient temperature rated at 40°C; above that, derate the current or add forced airflow. The free cable endings accept conductor sizes appropriate for 120A — typically 35–50 mm² copper. Thermal class H allows a 180°C hot-spot temperature, but the surrounding panel components (wiring, terminal blocks, adjacent devices) must be rated for the radiated heat.