Analytical Evaluation of Voltage Drop along 11/0.415KV Distribution Lines and Within Agu-Awka Injection Substation Distribution Network

Abstract

Electrical distribution system is becoming more complex because of rapid and continuous increase in electricity demand. The quality of power reaching electricity consumers through distribution networks is poor. This work involves investigation, evaluation and analysis of voltage drop in power distribution network in Nigeria with reference to Agu-Awka injection substation distribution network in Anambra State. The work includes studying the hourly load readings of the feeders so as to ascertain their load profile, determine the peak and off-peak loading periods and finally take the following voltage readings from 11/0.415KV distribution transformers within one of the station’s feeders - Ifite feeder during the peak and off-peak periods respectively. The readings taken were as follows; voltage values from various 11/0.415KV transformers (bus voltages) and received voltages at consumers’ houses were taken using Avo-meter, the distance of each consumer’s house to the transformer supplying it was also taken with a measuring tape. After evaluating and analyzing the various readings, it was observed that, with radial distribution system being operational in network under review, that as the length of the distribution line (distributor) increases, the voltage drop along the same line increases too and as such, the received voltages at consumers’ houses decreases. For consumers to receive optimal voltage values that is within the statutory limit of voltage variations of ±10% of rated value as stated by American National Standards Institute (ANSI C84.1), the distribution transformers during network planning stage should be properly positioned and that the size and length of distribution line should be such that the voltage at consumer’s terminals is within the permissible limits of 90% ˂ V ˂ 106%.