Impacts of harmonics caused by Personal Computers on distribution transformers

Personal computers (PC´s) being electronic load draw non-sinusoidal current. When this non-sinusoidal current passes through the impedance of the line/cable, it causes considerable distortion in voltage. This distorted voltage in a parallel connection scheme appears at the LT/HT sides of distribution transformer and causes significant effects on equipment performance which are designed to operate at sinusoidal voltage and current only. In this research paper, the complete distribution network of Rachna College of Engineering & Technology (RCET), Pk has been simulated using electrical transient analyzer program (ETAP) software. For this purpose an experiment has been performed in which current waveform drawn by a PC along with its spectrum has been recorded using oscilloscope at RCET Research Lab as prototype. This model of a single PC is injected into the harmonic library of ETAP for simulation of RCET distribution network. The impacts of harmonics caused by PC´s on distribution transformers have been completely analyzed in this research work. Moreover, the trend of total harmonic distortion (THD) with variation in different types of loads has been analyzed mathematically & graphically.