Mobile substation. Zest Energy
Mobile substation unit. Pic credit Zest Energy
The company worked closely with Eskom to assist with the unit’s operation. Pic credit: Zest Energy

In South Africa, energy and electrical solutions company Zest Energy, announced that it was responsible for bringing mobile substation technology to the African continent.

Since the first mobile substation units were supplied to Eskom in South Africa, the company has expanded its solutions to include a wide range of mobile substation units and mobile switching stations, the company said.

Coenraad Vrey, managing director of Zest Energy, says that the first mobile substation units engineered by the company in South Africa were mobile diesel generators.

The company used this experience, together with the application of WEG’s technology, to engineer a mobile substation solution suitable for the harsh and demanding African conditions.

Vrey added: “What is particularly significant is that, with this mobile substation technology, it is possible to move these units to wherever they are required.

“This provides optimum flexibility, not just to power utilities, but also to other operations such as mines, quarries and rural areas.”

Mobile substation specifications

Zest Energy leveraged WEG’s 20 years of experience in engineering transformers to develop a transformer that has significant weight reduction.

"This re-engineering was necessary to minimise both the weight and the physical size of the transformers. One way that we were able to achieve this requirement was by employing ODAF (oil direct air force) cooling,” says Vrey.

He explains that an intimate understanding and knowledge of various applications means that the company is able to meet very specific requirements.

Customised mobile substation

Vrey explained: “As an example, for a particular mobile substation for Eskom, we engineered a transformer with a low impedance value to comply with the project specifications.

“This was done while still ensuring that the overall substation weight remained within the South African road ordinance requirements.”

The company worked closely with the utility and in an effort to assist with the unit’s operation made use of offload selector switches to select the primary and secondary ratios.

According to Vrey, this was essential as previous technologies in place required that the transformer be opened and the links manually changed inside the transformer.

“Our solutions resulted in savings in time and enhanced safety, with increased ease of operation," said Vrey.

Voltage selection at mobile substation

Due to the units being multi ratio and connecting to different network operational voltages, technology was built into the control system to ensure the correct voltage is selected.

Vrey explains: “The equipment has a comprehensive earthing system incorporating copper bars with connectors. This provides Eskom with different earthing interfacing points to which connections to the local earth system can be made.

“Similar, customised mobile substation solutions can be developed for utilities throughout Africa, all with an emphasis on fit for purpose practicality and safety."