Effect of harmonics current on the performance of current transformers
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Date
2019-06
Authors
Muhammad Syarifuddin Bin Sha’ari
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Abstract
Determination of harmonic emission level is becoming a serious task in power distribution systems. Harmonic currents or voltages are generated from a non-linear load when it is connected to the main supply. Many problems caused by harmonic that can influence the efficiency of a system[1]. Voltage transformer and current transformer are widely used and are more exposed to the effect of harmonics. A methodology is proposed to carry out the analysis of the effect of harmonics current on the performance of current transformers. A laboratory method is implemented to determine the emission level of harmonic current with the presence of current transformers. Current transformer is been used for this analysis and some test are been conducted to ensure proper current transformers operation. The harmonics level are measured using the power analyser (fluke). Each current transformers are tested with several stages of harmonic until it is saturated. It is found that the current transformers have a point called the knee point or also known as the saturation level of the transformers. The graph shows a linear increase and then at one point it will start to loss its linearity properties and the current transformers start to saturate. The usual amount of harmonic level in the system is around 48% and this experiment is carried out near to 48% so that a better understanding of the harmonic behaviour on the current transformers can be obtained. The output of the current transformers should be synchronise with its ratio. A ratio of 7.5/1A are the smallest ratio that can be obtain from the lab and the output should obey the ratio given because the some test have been conduct to ensure proper operation of the current transformer. So, if the output gain is different from the ratio, harmonics are present in the system.