The sum of the harmonics vs Some of the harmonics
Harmonics in power systems are a growing problem that can have serious and costly consequences. A key step to controlling and mitigating this problem is to trace harmonics to their source. Julian Grant of Chauvin Arnoux explains how this can be done, after giving a brief overview of what harmonics are, how they are produced, and how they affect electrical installations and equipment.
Much has been written about harmonics in power systems, not least in earlier articles in this series. However, they are such an important issue that it’s worth providing a brief refresher, especially as this will lay the foundations for the second part of the article which discusses how to trace the sources of harmonics.
Electricity supplies to consumers are, almost without exception, AC supplies with a nominally sinusoidal waveform of a fixed frequency. If you were to use an oscilloscope to look at the supply waveform, you would probably see that it really is quite close to being a sine wave; if no harmonics were present, it would be a perfect sine wave.