A line reactor: Is usually just an inductor, which resists the flow of high frequency harmonics and thus causes harmonic currents to decrease when it is applied. Line reactors serve to suppress current spikes and limit peak currents that flow through them, because of their impedance. These are typically used in variable frequency, DC, SCR, and rectifier drives.
Feedback electronic filter: Is a complex device that detects the presence of voltage and current harmonics and generates counteracting harmonics to remove harmonic distortions. The electronic filter uses feedback mechanisms, and monitors voltage and current constantly. It thus effectively reduces harmonics and provides voltage regulation.
Selection of the harmonic filter
The selection of a harmonic filter must be based on the following:
1. kVA requirements of the load
2. Harmonic profile of the load current
3. Harmonic factor of the neutral current
4. Configuration of the existing or proposed system