Analyzing Effects of Current Harmonics on Distribution Transformers

With the increasing presence of nonlinear loads in modern power systems, current harmonics have become a significant issue, particularly for distribution transformers. These harmonics distort the sinusoidal waveform of current, leading to increased electrical losses, overheating, and accelerated aging of insulation materials, which collectively compromise transformer performance and reliability. Furthermore, the effects of harmonics—such as electromagnetic interference, magnetic saturation, and mechanical vibrations—pose additional risks to system stability. This study investigates how varying levels of current harmonics affect transformer temperature and losses through an experimental study conducted on an 800 kVA, 10-0.4 kV Dyn5 distribution transformer under controlled harmonic distortion conditions. The results reveal that higher harmonic content leads to a notable rise in thermal stress and power losses in transformers. These findings highlight the importance of considering harmonic impacts in transformer design to ensure reliable and efficient operation in today’s evolving energy systems.