Detuned Harmonic Filters
In some cases Total Harmonics Distortion (THD) is in a dangerous level to capacitor bank. It means that existing harmonics may result resonance in LC circuit and this phenomena causes serious damage to the capacitor bank over time.
Detuned reactor in series with capacitor bank has two effects; it limits inrush current and prevents resonance in circuit.
Depends of different configuration, detuning factor can be 6% or 7%.