The second part of this series of tutorials deals with the measurement and calculation of distortion in power systems. The measurement of harmonic distortion in power systems is almost always a compromise between the desirable and the possible. In an ideal world it would be possible to use calibrated voltage dividers with a well established frequency response connected to the higher voltage system busbars and current transformers with good response in each of the three phases. The reality, however, is different, as the only access given will be to existing voltage transformers and current transformers. The choice of how to calculate harmonics in a power system is also often a compromise which depends on the system information available to the designer and also the purpose for which the calculations are being made. The author discusses the voltage transducers and measurement instruments for harmonics measurement. Calculations in the frequency domain and the time domain are discussed.
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