The steady development of dry-type transformers in the African market is being driven by a series of advantages provided by this technology, and as its use becomes more and more common, its application becomes more and more extensive.
“We have seen dry-type transformers have more widespread use in Africa as they shift from niche products to more general uses,” said David Claassen, managing director of Trafo Power Solutions, a dry-type transformer expert. “The reasons are not difficult to find, including safety, reliability and low installation costs.”
A key difference is that the cells and coils in the dry device are cooled by normal air ventilation. In contrast, liquid-filled transformers are cooled by oil, silicone, or other liquids. This risk of liquid spillage is one of the main factors contributing to the increase in the use of dry-type transformers. The latter has a higher level of safety and no environmental hazards.
“This makes the dry unit more suitable for indoor use, but also for underground and marine applications,” he said. “At the same time, they are flexible enough for harsh outdoor environments.”
In order to insulate the windings and protect them from dust, moisture, corrosive fumes and conductive dust, special treatment techniques are applied. Depending on the application, one of three main insulation types is used: uncoiling, vacuum pressure impregnation (VPI) or cast coil.
One of their safety advantages is the low fire risk, the transformer insulation is made of epoxy resin and environmentally friendly quartz powder, and the windings are flame-retardant. This also means that it will not produce toxic gases when an arc occurs. The cost implication is that expensive fire extinguishing equipment becomes unnecessary.
“When the location is remote, because they are usually in African applications, the installation of dry-type transformers makes sense,” Klassen said. “This is because they are reliable and require little maintenance, and they are easier and more economical to install.”
There is no risk of oil spills, no need for concrete dikes or important civil works-saving time and money. Only air is used for cooling, no liquid test is required. At the same time, the smooth coil surface eliminates a large amount of dirt accumulation. These devices are designed to meet E2 environmental requirements and are resistant to condensation and heavy pollution.
“In terms of high reliability, the service life of cast resin transformers usually exceeds 25 years, and the failure rate has been proven to be very low,” Klassen concluded.
Post time: Oct-18-2021
