Harmonics are generated by non-linear components and loads in the power system. They essentially consist of reactors and capacitors and usually installed close to harmonics source in order to provide low impedance path for the harmonic currents.

A parallel resonant filter has high impedance that blocks for currents of a certain frequency, while a series resonant filter has a low impedance that leads away currents of a certain frequency.

The sharp minimum in impedance which occurs is useful in tuning applications. If the filter requires fine tuning If fine tuning of the filter is required, the filter reactor may be equipped with taps for inductance adjustment.

When lower Q factor is desired, it can be achieved either by providing the resistor in filter circuit OR the “Q” factor of the reactor can be reduced by providing loss making ring, popularly known as Diminished-‘Q’ ring. Diminished –‘Q’ ring provides economical solution & requires lower space.

Desired Q factor can be achieved by providing the resistor in filter circuit. Further, Q factor of reactor can be reduced by providing loss-making ring, also called Diminished Q Ring. This ring provides an economical solution and requires lower space.