Active harmonic filters are the most powerful, fast and advanced technology in harmonic mitigation. The active filter senses the current harmonics and injects the opposites of them into the system. The harmonics and their opposites cancel each other and the harmonics are filtered out of the system. Benefits of Active Filters: * Independent operation of network parameters * Can be used for harmonic filtering, power factor correction and both of them * The neutral current can be filtered by using a 3 phase 4 wire device * The harmonic suppression ratio is very high * Very fast response to load changes (<1ms) * No risk of resonance with the utility * No risk of overloading. * The filter current can be increased by using parallel units.