A power-quality event is a disturbance in electrical service, such as a voltage sag, surge, frequency deviation, or waveform instability. Unlike a long outage, it is often brief, but even short transients can disrupt sensitive equipment, trigger resets, or cause control systems to behave unpredictably.
In cyber security, power-quality events matter because modern attacks can create physical effects. Fast-changing GPU workloads, for example, may produce sharp load ramps that stress local power conditioning or upstream infrastructure. Defenders watch for these events with power monitors, uninterruptible power supplies, and facility telemetry, then correlate electrical behavior with workload scheduling, cooling, and capacity planning. Treating power as part of the attack surface helps teams spot cyber-physical risks before they become equipment faults or service degradation.