Publication: Analysis of power system harmonic effect on power distribution transformer
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Date
2010-04-01
Authors
Hayon, Nor Halim
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Abstract
The increases use of non – linear load has increased the level of harmonics in electrical power system. The increases of harmonics cause the reducing of the transformers life expectancy. The used of rating system called K – Factor is to ensure that the transformer can operate safely when supplying non-sinusoidal load current. The effect of harmonic on distribution transformer is reported in this thesis. The experiment was conducted at three phase transformer with capacity of 500 VA. The effect of harmonics on distribution transformer has been investigated by connecting non – linear load to the output of transformer. The load used in the experiment are resistance and rectifier. In addition, the effect of harmonic to the transformer such as losses, power rating, power factor and temperature rise. The analyzing the derating method also introduced to reduce the harmonic effect on transformer. The derating method is suggested accordance to BS7821 standard. The results show that the temperature increased linearly when total harmonic distortion increases. The power loss also increased linearly when total harmonic distortion increased. The power factor of transformer decreased linearly when total harmonic distortion increased. For %THDi 24.3%, 38.8%, 64.3%, 70.8% and 80.7%, the percentage of derating transformer is 92.59%, 89.91%, 86.82% , 85.51% and 85.40%.