Managing and controlling voltage unbalance in power systems due to economic issues and satisfying customers is crucial. Any changes in quantities of voltage, current and frequency which result in damage or incorrect performance of equipment is called power quality. Regarding this definition, it is actually voltage quality that is expressed in definition of power quality. Therefore, this study is to analyze a radial distribution feeder and present a comprehensive formulation in order to determine portion of each effective factors including existing loads in the system, lines among buses, and voltage source. Regarding the required information from extracted formulas and information of radial distribution system of lines impedance, load power or load impedance is from specifications and specific information of the system. MATLAB and Power Factory Dgsilent were used in order to validate the relations from analysis of unbalance load distribution. Such a structure can provide more research opportunities for statistical techniques in international standards about managing voltage unbalance factor.