电气系统中的补偿和干扰滤除
In general, new computer and electrical units perform better on today's processes and tasks.
Example of an installation with equipment that generate electrical harmonics on the grid
Yet these devices are more complex internally and include components such as switching power supplies, rectifiers or other elements that typically consume a current wave shape that is distorted and deformed rather than being sinusoidal.
Ideal wave shape and distorted wave shape
We can thus say that these units have improved our quality of life, but at the cost of greater contamination of our electrical systems, causing them to exhibit unusual behaviour.
All regular non-sinusoidal wave shapes may be represented as a sum of sinusoidal waves whose frequencies are integer multiples of the fundamental frequency, which we call harmonics.
Distorted wave shape decomposition
These harmonics mainly affect the quality of the voltage wave shape, and can negatively disrupt many machines and units, as well as the installation itself.
Harmonics are produced by non-linear loads that absorb non-sinusoidal current. The most common loads that generate harmonics, in both industrial and domestic environments, are the following:
- Variable speed drivers
- Discharge lamps (mercury vapour, sodium, energy-saving, fluorescent, etc.)
- Rectifiers
- AC/DC transducers
- Arc welding
- Induction furnaces
- UPS
- Computers
- etc.
In turn, the harmonic currents generated when they pass through linear loads generate distortion in the voltage wave shape, which will depend on both the nature of the harmonic currents and the grid and loads themselves.
Sometimes harmonic distortion is not originated inside our installation, but we can notice its impact due to an outside source that is generating it, such as a neighbouring installation. In the following chapter we will learn how to measure and trace these disturbances so we can then treat them correctly.
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