Detuned filter are designed to used for power factor correction in systems where harmonics are generated by nonlinear loads, each step of detuned filters consists of a capacitor and a series reactor connected in series. These two from a series resonant circuit tuned at a frequency below the lowest harmonics frequency present in the system normally the 5th (250Hz) . Detuned filter also removes lower order harmonics from the system to some extent. This will helps to offset the Resonance effect for longer trouble free operation.