Phase unbalance in low-voltage distribution systems

An analytical study by statistical methods is made of the unbalance in l.v. distribution systems caused by unequal loads on the different phases of the supply network. It is shown that the current in the neutral conductor is statistically distributed according to the X2 distribution on two degrees of freedom and that the probability distribution of the voltage across the consumer´s terminals is closely approximated by the normal distribution. The results confirm the conclusions that have been derived from field data and that have previously been used as the basis for estimating the unbalanced voltage regulation in l.v. distribution systems for new housing estates. Correction factors are given in graphical form, which can be used to correct the balanced regulation for the effects of phase unbalance at different risk levels.