ANALISA PENGARUH HARMONISA TERHADAP BESARNYA PENURUNAN KAPASITAS DAYA (kVA) TRAFO TERPASANG

DI PLN ULP DENPASAR

Abstract

Modern electrical equipment such as computers, printers, energy-saving lamps, and motor speed controllers are classified as non-linear loads that generate harmonics in the power system. These harmonics may cause heating, derating, and even damage to distribution transformers, which in PLN’s network are generally not designed for harmonic loads. This study uses a quantitative descriptive method to analyze the effect of harmonics on transformer capacity derating. Measurements were carried out on two distribution transformers at PLN ULP Denpasar over two days using a Hioki 3286-20 Power Quality Analyzer, between 17:00–21:00 WITA. Data were compared with IEEE-519 standards, and transformer derating was calculated using the THDF method. Results show transformer DB1034 (160 kVA) experienced a THDi of 14.36%, leading to a 10.7% derating (142.89 kVA). Transformer DS1225 had a THDi of 13.55% with an 8.39% derating (146.57 kVA). Higher THDi corresponds to greater capacity loss, with third-order harmonics exceeding IEEE-519 limits. Routine harmonic monitoring is therefore essential.