The application of capacitors in circuits with harmonic components must be done with discretion avoiding to cause problems for the life of the capacitor and for the system as a whole. Every circuit that acts with devices that alter the waveform of the current and the fundamental voltage of power, has harmonic components. The amplitude and frequency of these harmonics will depend on the type of equipment used, its power and the essential values of the circuit and equipment connected to it.
We can conclude that their impedance will be smaller the greater the frequency of the network, since the impedance is inversely proportional to the frequency. Such an effect will make the capacitor a “low impedance” path for harmonic circulation, causing a large part of the harmonic currents generated to pass through the capacitor.
It should be remembered that the capacitors “do not generate” harmonics, but they are victims of their effects. It is also observed that certain circuits may have their harmonic values increased in intensity after the installation of capacitors in them, since these tend to decrease the general impedance of the circuit for frequencies above the fundamental.