The Siemens SIDAC 4EU2531-2UA00-0A is a 3-phase output reactor (output choke) rated for 47 A AC maximum at 300 Hz, with an inductance of 0.34 mH. It sits between a variable-frequency drive and the motor to limit dv/dt, reduce motor bearing currents, and attenuate reflected-wave voltage spikes on long cable runs. The 0–300 Hz range covers the full output spectrum of most PWM drives, including high-speed spindle applications.
The 47 A AC maximum current and 42.3 A operational current rating size this reactor for 30–40 hp (22–30 kW) 400 V drives in typical AC-3 duty. The 0.34 mH inductance gives a 9.1 % voltage drop at rated current, which is a standard impedance for output reactors — it smooths edges without stealing too much torque from the motor. The 123 W coil loss plus 98.5 W iron-core loss means about 220 W total heat to vent in the enclosure; at 40 °C ambient it stays within thermal class H (180 °C) insulation, so it can run hot in a crowded panel as long as airflow is adequate.
The flat-type terminals accept bus bars or large-gauge ring lugs.