Ghana: GRIDCo Commissions 145MVA Transformer

Ghana’s power transmission company, GRIDCo, has successfully installed and commissioned a new 120/145MVA Siemens Energy power transformer at the Afienya Substation in the Tema Region to boost power supply in the area.

This milestone project is a major upgrade from the previous 66MVA transformer, effectively more than doubling the station’s capacity and positioning the grid to meet increasing load demands across Accra, Dawhenya, and surrounding communities.

Commenting on the project, Ing. Dr Benefit E.A.K. Patu, Supervisor for Electrical Maintenance at GRIDCo, said the initiative was driven by the urgent need to address overloading challenges in the area.

He explained, “The capacity of the original transformer (50/66MVA) was nearing its limit due to increasing demand from ECG’s extended distribution lines. With the new 120/145MVA transformer, we now have the capacity to accommodate more load and extend reliable power supply to more communities.”

This upgrade doubles the capacity at the Afienya Substation and also strengthens the National Interconnected Transmission System (NITS), ensuring a stable and efficient power supply for both current and future needs.

The installation involved a series of critical steps, beginning with positioning the transformer on its foundation, followed by the full assembly of its components and accessories.

The team then carried out oil filtration to ensure proper filling of the transformer core and conservator, while also preparing the OLTC unit with oil to support efficient operation and overall system performance.

During the oil treatment process, the team focused on reducing the moisture content in the transformer oil to acceptable levels (measured in PPM). Continuous monitoring showed single-digit PPM results, indicating very good quality.

The results were subsequently submitted to the technical service team for validation and were successfully approved. The Protection and Control (P&C) team also played a critical role in ensuring the transformer’s safe operation.

Ing. Francis Koomson led the team in decommissioning old cables, installing new wiring, and conducting comprehensive protection tests, including trip testing to confirm that the system responds correctly under fault conditions.

“Our responsibility was to ensure the transformer operates safely. We verified that in the event of a fault, the system will trip as expected,” he stated.

After comprehensive testing and thorough technical validation, the transformer was deemed ready for commissioning.

The transformer replacement and installation work was carried out entirely by GRIDCo engineers, led by Ing. Dr Benefit E.A.K. Patu, Supervisor for Electrical Maintenance.