REDUCTION OF HARMONICS IN MULTI TAP AUTOTRANSFORMER USING LOW PASS FILTER

Abstract

The purpose of this research work, is to reduce harmonics in the autotransformer and improve the efficiency rate of the autotransformer. This research work aims at serving the industries needs of multi tap transformer with just a single transformer with good efficiency. The major problems of autotransformers are harmonics disturbance due to poor techniques or poor designs. The method used in reducing harmonics in this research work, is known as the passive low pass filter with a resistor and a capacitor. The low pass filter resists the flow of high harmonics and attenuate it to the ground through the capacitor. It was noted that the results of the output voltages of the three taps of the auto transformers are 48 volts, 24 volts and 12 volts respectively. The results also show that the harmonics when not filtered was 120dB and when filtered became 6dB. The result also shows that the reactive power of the autotransformer was low and out of phase with the apparent and real power of the autotransformer. The research work evaluated the voltage and current relationships of the primary and secondary autotransformer, designed the low pass filter, evaluated the apparent power of the autotransformer, and also after evaluation the efficiency of the autotransformer was increased from 94.13% to 97.4%. However, this research work is therefore recommended for further improvement on the efficiency, reduced harmonics and improve the number of taps with good efficiency to meet the industrial standard.