Name of OHTL


Voltage of OHTL



Fondasol foundation design

Duration of assignment

08.2012 - 11.2012

Value of service

20,7 k€

The aim of the project was the detailed design of two new 33kV single circuit Overhead Lines located in Ashegoda Plato, Ethiopia, to connect a wind farm to a 220/33kV substation. The optimized tower spotting has been carried out by HECLA, thanks to the modeling of both OHLs with the OHL calculation software PLS-Cadd (POWERLINE SYSTEMS Inc.).

Load cases definition has been made from meteorological data and according to IEC 60826 standard. Electrical clearances have been determined according to EN 50341-1 and EN 50423-1. One of the main project's specificity was the altitude of 2,500m having a large influence on insulation issues.

Both OHLs are only made of existing tubular steel structures, already used for other existing OHL, whose design had to be upgraded by HECLA to strengthen larger loads due to heavier conductor cables. These towers have been modeled with PLS-Pole software (POWERLINE SYSTEMS Inc.), and their structural strength has been checked in accordance with ASCE/SEI 48-11.

Foundation design also has been modified accordingly.
The conductors used are AAC 280 and the optical cable is an ADSS SP1245 connected to the pole below the 3 conductors.

Key figures:
240 tubular steel poles, 2 lines of 7 km long, single circuit, 2,500m height.