Electrical Loading Assessment of Commonly Used Transformers for Feeder 21 of Pampanga Distribution Utility

Abstract

Transformer plays a vital part in the process of utilization of electricity. In power distribution, the most widely used equipment is the distribution transformer (DT) and function to transform the primary voltage of 13200 volts to the utilization level voltage of 230 volts. In a distribution system, transformers are installed serving commercial, industrial, irrigation, street lights and residential consumers. Distribution transformers were classified as sole-used and commonly-used distribution transformers. The study focuses on assessing the commonly-used distribution transformer of Feeder 21 of Pampanga Distribution Utility. Microsoft Excel 2013 was used to evaluate the percent loading, core and copper losses of each DT's installed in the feeder. The DTs were classified according to their percent loading: Overloaded Above 71%, Normal Loaded 40% to 70%, and Under Loaded Below 40%. From the data from 2017-2018, 104 units commonly-used DT's were installed in the feeder. From the results obtained, 30 units were overloaded distribution transformers while 31 units were under loaded distribution transformers. Out of 104 distribution transformers 61 of which are not in the normal loading conditions. The total Core loss in MWh of the distribution transformer in under loaded and overloaded conditions were 34.37 and 38.04, while the copper loss in under loaded and overloaded conditions was 7.46 MWh and 199.76 MWh respectively. The study also shows the implication if the percent loading was maintained to 70%, 110.21MWh will be saved by the electric utility. The researchers find that there is a need in uprating or downrating of transformer and quantifying the consumer connected in each distribution transformers for proper transformer loading may be considered by the Distribution Utility.