Harmonic pollution refers to the distortion of normal electrical voltage and current sine waves caused by unwanted high-frequency currents. 

In an ideal power distribution system, voltage flows as a clean, continuous sine wave operating at a fundamental frequency (typically 50 Hz or 60 Hz). However, modern non-linear devices —  such as variable-speed drives, computers, LED drivers, and electronic ballasts — don’t draw power smoothly. Instead, they absorb current in abrupt, uneven pulses. These high-frequency current pulses distort the fundamental waveform, injecting electrical "noise" or pollution into the power network. In other words, properly operating power generators create clean sine waves. It’s the things that we plug into the system that create harmonic distortion.

While non-linear loads primarily create harmonic currents, this current distortion transforms into voltage distortion across the impedance of the system, which affects the entire electrical ecosystem. Just as Ohm’s Law (V = I x Z) applies at fundamental frequencies, it also governs harmonic frequencies. When harmonic currents flow through the natural impedance of conductors, transformers, and power distribution equipment, they generate corresponding harmonic voltages. Because electrical impedance typically increases alongside higher harmonic frequencies, even relatively small harmonic currents can produce disproportionately large, disruptive harmonic voltage drops across a facility depending on the impedance. 

This widespread voltage and current pollution creates operational challenges for industrial and commercial facilities. Harmonic pollution causes equipment to overheat, leads to premature failures, trips circuit breakers without an obvious overload, and causes false readings in monitoring devices. Ultimately, unmanaged harmonic pollution wastes energy, degrades power quality, and risks sudden uptime interruptions by exposing sensitive connected equipment to polluted power.