On the 26th, at the LS ELECTRIC manufacturing facility in the Hwa-jeon district of Gangseo, Busan, there were two thick hoses connected to another device outside the tank of a 154 kilovolt (kV) ultra-high voltage transformer, which stands 4 meters tall and weighs 100 tons. This work involves using a vacuum hose to suck the moisture from the transformer inside the tank to dry it.

The oil-filling transformer uses a lot of wood for insulation to eliminate explosion risks. While wood has excellent insulation properties and stability, it retains a lot of moisture due to its characteristics, making the moisture extraction process crucial. Choi Hyung-seok, Head of Team of the HVTR (High Voltage Transformer) manufacturing team at LS ELECTRIC's Busan facility, noted, "Moisture damages the insulating function, which can be deadly to the transformer, so transformer manufacturing is a battle against water."

An employee is working on the winding of a transformer at the Busan facility, Production Building 1 of LS ELECTRIC. /Courtesy of Kim Nam-hee

The manufacturing process for ultra-high voltage transformers consists mainly of winding (the process of winding copper wire to allow electrical current to flow), iron core lamination (cutting silicon steel into specified dimensions and stacking), assembly of the main body (inserting the winding into the laminated iron core and configuring the electrical circuit), vacuum drying (removing moisture from the main body), tank insertion (putting the dried main body into the tank and welding), and final assembly (filling with insulating oil and installing various equipment outside the tank), followed by a final testing phase. Among these, the moisture removal process is performed twice: once during vacuum drying and again after tank insertion.

Vacuum drying is conducted for five days by placing the assembled transformer into a facility known as Vapor Phase Drying (VPD). This process removes moisture by repeatedly cycling heat and vacuum under a vacuum state. In the case of a 154 kV transformer, after VPD vacuum drying, 100 liters of moisture is removed. Team Leader Choi said, "VPD is the most important facility to determine the ability to engage in the ultra-high voltage transformer business, and currently, we have two units at the Busan facility."

After the VPD vacuum drying, when the transformer is placed into the tank, it absorbs moisture again. At this point, the vacuum hose is connected to further remove moisture from inside the tank. Then, after adding insulating oil and assembling external equipment, the transformer is completed.

A transformer under production is placed in front of the vacuum drying room (VPD·Vapor Phase Drying) with the orange door down at the Busan facility, Production Building 1 of LS ELECTRIC. /Courtesy of Kim Nam-hee

Currently, the production capacity for ultra-high voltage transformers at the first production building is approximately 200 billion won per year. LS ELECTRIC decided to invest in expanding the Busan facility last year to strengthen its presence in the ultra-high voltage transformer market. Construction is underway for a new second production building on a 13,223 square meter site next to the first production building. On that day, concrete pouring was taking place under the hot sun. The second production building is expected to be equipped with two VPD units, an assembly area, a testing laboratory, and a welding area, among other facilities. Once completed in September, LS ELECTRIC's ultra-high voltage transformer production capacity will double to 400 billion won, combining the capacities of both the first and second production buildings.

Work is being done to stack the cores for transformer production at the Busan facility, Production Building 1 of LS ELECTRIC. /Courtesy of Kim Nam-hee

LS ELECTRIC is expanding its portfolio, which was heavily focused on medium and low voltage transformers, into ultra-high voltage transformers. This shift has been largely influenced by investments in artificial intelligence (AI) data centers, particularly in the United States, where power consumption has increased significantly. AI is an energy-intensive industry, consuming power on a large scale. In particular, generative AI applications, such as OpenAI's ChatGPT, consume even more power. The increasing power demand from AI data centers is expected to lead to a boom in the power infrastructure and system market, including ultra-high voltage transformers, distribution boards (electrical distribution devices), and wires for several years.

The high-voltage transformer testing facility at LS POWER SOLUTION's Ulsan plant. /Courtesy of Kim Nam-hee

To increase its production capacity for ultra-high voltage transformers, LS ELECTRIC acquired KOC Electric in April of last year. It was subsequently renamed LS Power Solutions. LS Power Solutions' Ulsan plant is located about an hour's drive from the LS ELECTRIC Busan facility. LS Power Solutions is the only small and medium-sized enterprise in South Korea that produces 154 kV ultra-high voltage transformers and supplies them to the Korea Electric Power Corporation.

LS POWER SOLUTION is in the process of producing a high-voltage transformer at the Ulsan plant. /Courtesy of Kim Nam-hee

LS Power Solutions completed the expansion of its Ulsan plant in December last year, increasing its annual production capacity for ultra-high voltage transformers to 100 billion won, a three-fold increase. Kim Hyun-il, Executive Director of LS Power Solutions, said, "Before we developed ultra-high voltage transformers, we primarily produced products for large companies through OEM (Original Equipment Manufacturer) methods, which has given us a solid understanding of the strengths and weaknesses of other large companies, making this our competitive advantage."