Analysis of the Effect of Unbalanced Load on Neutral Current, Power Losses and Efficiency in Distribution Transformer

Hartono, Hartono
Sudjoko, Rifdian Indrianto
Hariyadi, Slamet
Sukomardojo, Tekat
Julaihah, Siti

Journal of Research in Social Science and Humanities
Vol 5, No 1 (2025)

630 kVA, 20 kV/400 Volt transformer is a distribution transformer that supplies electrical loads at the Aviation Polytechnic of Surabaya. In a distribution transformer if the inter phase load is unbalanced there will be a neutral current flowing in the neutral wire.  This load imbalance is caused by single-phase loads on a 220 Volt low voltage network. The current flowing in the neutral of this transformer causes losses, namely due to the presence of neutral current in the neutral conductor of the transformer and losses due to neutral current flowing to the ground. After analyzing the peak load during the day of 79.92% and load imbalance during the day of 12.23%, then there is a neutral current of 181 Amperes and losses due to neutral currents flowing to the ground of 7, 26%, and transformer efficiency  at the day of 88.5 %.