Abstract
Most of LV customer have applied the 3-phase four wire system distribution system because it has advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But voltage unbalance more commonly emerges in individual customer loads due to phase load unbalance, especially where, single-phase power loads are used. Voltage unbalance factor(VUF) represents the loss of symmetry in the supply(magnitude and angle). It leads some problems such as de-rating or power losses. In this paper, voltage and current waveform in the actual fields have been measured and analyzed in relation with internationally allowable voltage unbalance limits.