Recently we have seen more and more sites starting to see harmonic issues. Harmonics result in poor quality of supply, which can cause failure of sensitive equipment on site. Power factor correction units contain capacitors which may be damaged by quality of supply problems such as harmonics, and as such should be protected if needed.
What are harmonics?
Harmonics are created when the normal electrical current waveform is distorted, typically by nonlinear loads. The main cause of this is switched-mode power supplies, such as those found variable speed drives, some types of lighting and computers.
Harmonics may be generated in your own grid, or be present in the supply side from your supply authority.
How do I know I have harmonic issues?
Constant sensitive equipment failure may indicate harmonic problems, but the only way to really know is through quality of supply measurement with high-resolution measurement equipment. A good quality of supply investigation will show the probable cause and magnitude of any harmonic issues.
How do I protect the power factor correction system?
Following a quality of supply measurement exercise the system should be designed with appropriate harmonic de-tuned reactors. This will protect the power factor correction system and ensure a long system life