Zesa power lines
Martin Kadzere and Tinashe Makichi
POWER utility, Zesa Holdings has refurbished part of its power evacuation system at Kariba Power Station at a cost of about $14 million, spokesperson Fullard Gwasira has said. Power evacuation is a critical function that allows generated power to be immediately evacuated from the WPP to the grid for distribution. Zesa, through its power transmission subsidiary ZETDC contracted Helcraw, a local firm to undertake the project.“The Zimbabwe Electricity Transmission and Distribution Company in partnership with Helcrow — the implementing contractor — embarked on a project to refurbish transformers at the Kariba Power Station complex during the period 2014-16 at a cost of $13,7 million.
“The project, funded by Afrochin, involved replacement of old cables and the associated equipment to increase off-take of electricity from the power station and to make the assets insurable as well as to eliminate the risk of fire to the assets.”
“We are happy the project has been successfully completed. This will result in greater efficiency, greater reliability and stability in the evacuation of power,” he added.
Kariba has six generators, two of which supply power to a single transformer. The other three generators have a voltage of 18 Kilovolt that is stepped up to 330Kv (grid voltage) as they feed power to the national grid. The 330Kv is then linked to the national grid through a set of cables of an inter-distance of 600 metres. The generator transformer belongs to Zimbabwe Power Company, the power generation subsidiary of Zesa and the cables belong to the transmission section of ZETDC.
Out of the three transformers, ZETDC has done work on one and commissioned the new set with the second transformer being expected to be completed by June.
The target completion date of the remaining transformer is October this year. The work encompass the replacement of the old technology called the Paper Insulated Filter cables that had been serving the system since 1960. The old technology is being replaced by the Cross-Linked Polyethylene technology that is real-time. Mr Gwasira said the renewed assets were expected to efficiently supply power for another 50 years.
He added that ZPC has upgraded generator transformers from 240 MVA to 315 MVA to increase capacity, with the upgraded and renewed cables being expected to improve the uptake of power from Kariba as the entire system has been given a fresh lease of life.
In an interview, Helcraw managing director Farai Jere said the successful completion of the project was a major milestone particularly for a local company.
“This was a very complicated project and everyone was looking at the company to see how Helcraw was going to execute that project” said Mr Jere.
“Even when the project was awarded to Helcraw it was hugely contested and it was said that as a local company it was not going to perform. It is a $14 million project; small but in terms of execution, it is one of the most complicated projects to undertake. This project has since been done.
“The complication of the project was that the tunnel was severely damaged and the shaft was also damaged by water coming from the dam.
“We had to repair that and then find ways to stop the water using latest technology when we were repairing the shaft and the tunnel. The other complication was to remove the existing cables because the cables that were there were installed about 50 years ago.”
He said his company had to partner a South Korean company, LS Cables, and a South African company which had previously done a similar project with Eskom, SA power utility.
The project was managed by a Norwegian company. Mr Gwasira said the power utility was still doing apex progammes to ensure reliability of power generation and distribution.
It is estimated that the country could be losing significant amount of power due to ageing infrastructure.