Harmonics are unwanted distortions in an electrical waveform, usually created by non-linear loads such as switch-mode power supplies, UPS systems, variable-speed drives, and dense GPU servers. Instead of drawing current as a smooth sine wave, these devices pull power in pulses that add extra frequency components to the line.
In cyber security, harmonics matter because availability depends on more than keeping the lights on. Distorted power can overheat equipment, reduce power factor, trigger nuisance alarms, and make telemetry harder to trust. In AI datacenters and other cyber-physical environments, a noisy waveform can look like a software problem or hide the real cause of throttling, resets, or instability. Defenders monitor harmonics alongside voltage, frequency, UPS behavior, and hardware telemetry so they can spot failing equipment, overloaded circuits, or unsafe operating conditions before they become outages.