Representing line voltage unbalance

Abstract

Representing the degree of voltage unbalance with the voltage unbalance factor (VUF) derived from symmetrical transformation requires complex phasor manipulations. This paper investigates various ways of representing VUF to facilitate the calculation in field applications. A formula for VUF with readily available line-to-line voltage magnitudes is derived and a straightforward graphical way of determining VUF is proposed. Various approximate methods are examined and it is shown that some alternative measures can be more effective in approximating VUF than conventional ones.