Harmonics are the by-products of modern electronics. They are produced by any non-linear loads such as:

• Variable Speed Drives (AC and DC),
• Switch mode power supplies from personal computers,
• Uninterruptible Power Supplies (UPS),
• Most low-energy lighting systems, or
• Any electronic device using solid-state power switching supplies to convert incoming AC to DC.

Non-linear loads generate harmonics by drawing current in abrupt short pulses, rather than in a smooth sinusoidal manner.

Harmonics can be a very costly overhead. Its effect can range from spurious operation of equipment to a complete shutdown of important plant equipment, such as machines or assembly lines.

Harmonic Filters and Reactors

With the advent of power electronics and proliferation of non-linear loads in industrial applications, power harmonics and their effects on power quality are a topic of concern. Effects of three-phase harmonics on circuits are similar to effects of stress and high blood pressure on human body. High level of stress or harmonic distortion can lead to problems for the utility’s distribution system, plant distribution system and any other equipment serviced by that distribution system. Harmonics can lead to power system inefficiency and affects plant equipment operation.