When electric current waveforms deviate from a standard sinewave shape with a duration of less than one cycle, they contain what are known as harmonics. These current harmonics distort the voltage waveform and create distortion in the power system which can cause various electrical problems.
Harmonics can be best described as the shape or characteristics of a voltage or current waveform relative to its fundamental frequency. The ideal power source for all power systems is smooth sinewaves. These perfect sinewaves do not contain harmonics.
When waveforms deviate from a sinewave shape they contain harmonics. These electric current harmonics distort the voltage waveform and create distortion in the power system which can cause many problems.
Destructive Effects of Harmonic Distortion
A power system’s ability to perform at optimal levels is compromised when harmonic distortion enters the system. It creates inefficiencies in equipment operations due to the increased need for power consumption.
Two Types of Loads
A power system can contain one of two different kinds of loads: a linear load, or a non-linear load.
Linear Loads have an electrical current waveform that is proportional to the amount of voltage applied. If the voltage doubles, the current doubles as well, maintaining a near-perfect sinewave, creating no
harmonics. Examples of the types of linear loads are incandescent lamps, heaters, and resistors.
When electrical current is not proportional to the voltage, the load is classified as non-linear which is most associated with modern electronic equipment that often relies on line-operated switching power supplies. These loads create harmonic distortion that can have adverse effects on your equipment.