Description

Passive Harmonic Filter (PHF) is a cost-effective and reliable solution for reducing harmonic distortion in electrical power systems. It is designed using tuned combinations of capacitors, reactors, and resistors that absorb specific harmonic frequencies generated by nonlinear loads such as VFDs, rectifiers, and industrial power converters. By diverting harmonic currents away from the supply, PHF improves overall power quality and system efficiency.

Passive harmonic filters are commonly used in industrial plants, power distribution panels, DG sets, and heavy-duty applications where harmonic levels are predictable and relatively stable. In addition to harmonic mitigation, PHF also provides reactive power compensation and power factor improvement, helping reduce transformer losses, cable heating, and utility penalties.

Operating Principle

The passive harmonic filter is tuned to targeted harmonic orders (such as 5th, 7th, or 11th). When harmonic currents flow in the system, the filter presents a low-impedance path at these frequencies, allowing harmonics to be absorbed by the filter instead of flowing back into the grid. Compared to active solutions, PHF offers simple design, high reliability, and lower initial cost, making it suitable for applications with steady load profiles. However, unlike AHF, passive filters have limited adaptability and must be carefully engineered to avoid resonance with the power network.

Applications: Cement, textile, and steel industries with fixed nonlinear loads.