In most cases it is necessary to reduce the effects of the harmonic currents. One way
of reducing harmonic currents is to install an inductance (filter reactor) in series with the
capacitor.
The filter reactors protect the electrical installations and equipment but it does not
eliminate the harmonics.
The reactor value should be calculated and designed in order to reduce the resonant
frequency of the circuit to a value lower than that of the lowest harmonic in the system.
A capacitor equipped with a filter reactor is protected from harmonics regardless of the
layout of the network to which it is connected. Except in some cases when switching in
steps the inductance and capacitance values