Determination of Overhead Conductors Curves with Quadratic Approach Based

Abstract

Transmission line conductor supported by towers will cause sag in the conductor span. Sag is an unavoidable condition related with the weight and the limited tensile strength of the high voltage overhead conductor. Sag is also influenced by elevation angle, span distance , wind speed, and temperature. The main purpose of sag determination is to obtain a safe distance (free area) of the object under the overhead conductor and to determine the conductor length and tower height. This paper proposes a calculation method with the quadratic approach that is influenced by elevation angles, distance ranges, wind speed, and temperature. The methodology is based on mathematical derivation to obtain the formulations clearly. This method has been tested by simulation to understand the effect of elevation angle, wind speed, and temperature on the sag. The simulation results show that the proposed method has been able to determine the conductor curve along the span distance for various angles of height. From this conductor curve, the clearance area under the conductor can be determined precisely. A small increase in the conductor due to the temperature rise leads to a significant increase in sag (2.80m) compared to the influence of the wind with a pressure of 40kg/m2 (sag increases 1.18m). Increased elevation angle will reduce the sag to the lowest tower and will increase the sag to the highest tower. When the angle is 1.374° and span distance 350m, the obtained sag for the lowest tower is zero and for the highest tower obtained the same height difference between the two towers (tower 1 and tower 2). This elevation angle also affects the length of the conductor, for the elevation angle changes from 1° to 5° and the lenght of the conductor rises linearly