Voltage Calculation of Distribution Line Using Modified Equivalent Resistance Method with no Angle θ Terms

Abstract

The ‘Equivalent resistance method’ has been used in the field for a very long time to calculate the voltages in distribution power systems. IEC 60364 standard also recommends this method because it yields an approximate but a fairly reliable solution using a scientific calculator. Cosθ and sinθ terms of the complex line current are included in the ‘Equivalent resistance method’, however, the authors found out that there is an overlapping calculation between the magnitude of line current and its values of cosθ, sinθ. This paper proposes a modified formula in which the cosθ and sinθ terms included in the conventional formula are eliminated. An example calculation for a distribution line with two load points is illustrated to compare the results by modified formula with those by conventional formula, by which we can see the effectiveness of the proposed formula. It is expected that the simplified formula with no θ terms could help electrical engineers calculate the voltages of distribution power systems in a more convenient way using a scientific calculator.