What do harmonics in electrical systems refer to?

Harmonics in electrical systems specifically refer to voltage or current waveforms that have frequencies which are integer multiples of the fundamental frequency. In most electrical systems, the fundamental frequency is typically 50 Hz or 60 Hz, depending on geographic location. When harmonics are present, they can distort the waveform from a perfect sine wave, leading to various issues including overheating of equipment, increased losses, and interference with communication lines.

Each harmonic has a frequency that is a whole number multiple of the fundamental frequency. For example, if the fundamental frequency is 60 Hz, the second harmonic would be 120 Hz, the third harmonic would be 180 Hz, and so forth. Understanding harmonics is critical for ensuring the stability and efficiency of electrical systems, especially in applications involving non-linear loads such as computers, LED lighting, and variable frequency drives.

The other options do not accurately describe harmonics; they either pertain to different electrical phenomena or components, which highlights the importance of correctly identifying harmonics in the context of electrical engineering and system performance.