[Power Industry Transformation]②From Ultra-High-Voltage Transmission to Switchboards and DC Equipment... Paradigm Shift in the Power Grid

While Large-Scale Transmission Investments Were Common,
the Importance of Medium-Voltage Distribution Networks Is Rising
AC-Centered Power Grids Shift Toward DC,
Emergence of DC Circuit Breakers and Contactors

Editor's NoteThe power industry is emerging as a major driver of Korea's economy, following the automotive and semiconductor sectors. For a long time, electricity played only a supporting role in industry. However, with the explosive increase in demand driven by artificial intelligence (AI) data centers, electric vehicles, and the expansion of renewable energy, electricity has now become a core pillar of the K-industry sought after worldwide. The four leading domestic power equipment companies, including LS Electric, have secured orders worth a combined 33 trillion won. The industry has established itself as a growth engine, contributing to exports and job creation. The power sector is now focused on how to establish a virtuous cycle. Securing direct current (DC) technology for more efficient power transmission has become a key challenge. We examine the issues Korean companies are facing in this era of major transformation in the power industry.

From the moment electricity is generated at a power plant to the point it reaches homes, businesses, and data centers, countless pieces of power equipment work together in precise coordination. At each stage, transformers raise and lower voltage, circuit breakers interrupt current, switchboards distribute power, and protection and measurement devices detect abnormal signals, all meticulously arranged to ensure the stability of the power grid.

Recently, the very nature of electricity demand has been changing. The rapid increase in AI data centers and the expansion of renewables such as solar and wind power have made the flow of electricity more complex than ever before. In addition, as DC distribution technology advances within what was previously an AC-focused power infrastructure, the power equipment ecosystem is being rapidly restructured.

On February 12, visitors are viewing LS Electric's data center solutions at 'Elex Korea 2025' held at COEX in Gangnam-gu, Seoul. Photo by Kang Jinhyung

The power industry sees this shift not as a simple equipment replacement, but as a "paradigm shift in the power grid." It is a period in which nearly every layer of the grid-from ultra-high voltage transmission to switchboards and DC-based equipment-is expanding simultaneously.

Power Equipment Used at Every Stage, from Transmission to Consumption

After electricity is generated at a power plant, it is first stepped up to ultra-high voltage (345-765 kV) at a transmission substation. Because the voltage produced at the plant is too low for long-distance transmission, it is multiplied several times at this initial stage. The equipment used here is the "ultra-high voltage transformer," the most expensive piece of grid equipment, weighing tens of tons and costing billions of won.

The transmission lines that run along towers carry this ultra-high voltage electricity over long distances to cities and industrial complexes. To prevent accidents in these high-voltage environments, vacuum circuit breakers (VCBs), power fuses (PFs), and high-voltage switchgear (RMUs) are also installed. This area is the core of the nation's key infrastructure.

Once the electricity has traveled along the transmission lines, it is stepped down to 154 kV at a distribution substation, entering the "medium voltage (MV)" range. This is the stage where electricity begins to reach actual end users. While large-scale investments in transmission infrastructure were common in the past, the recent increase in new site development and the attraction of data centers have heightened the importance of the medium voltage distribution grid.

After passing through the distribution substation, the electricity is further reduced to 22.9 kV via pole-mounted transformers, and then converted again to 220-380V for supply to homes, businesses, and data centers. This is the "low voltage (LV)" range. A single data center can require thousands of low-voltage circuit breakers and contactors. Most of the key components that make up switchboards and distribution panels are these low-voltage devices. This year, the market for low-voltage distribution equipment has seen the fastest growth in both domestic and overseas orders.

The Era of Direct Current: Newly Emerging Equipment

The recent focus on direct current is closely tied to the increasing presence of DC-based devices such as solar power, batteries, and electric vehicles. The power grid, once centered on AC, is beginning to shift toward DC. In the past, converting DC voltage was difficult, but with advancements in power semiconductors, stepwise DC transmission and conversion-ranging from high-voltage direct current (HVDC) to medium-voltage (MVDC) and low-voltage (LVDC)-has become possible. Lee Jin-oh, professor at Korea Institute of Energy Technology (KENTECH), stated, "HVDC is already commercialized, and MVDC is an area where Korea has an opportunity to lead standardization."

With the expansion of DC systems, demand for DC circuit breakers is also surging. Because DC maintains a constant polarity and the current never reaches zero, arcs are much harder to extinguish during faults, requiring high-speed interruption technology that is completely different from AC. Korean companies are also accelerating the development of products such as DC circuit breakers and contactors.

Professor Kim Heetae of KENTECH describes the changes in the power grid as "entering a complex system." He explained, "We are now in an era where generation sources are fragmented, as with solar and wind power, and consumers also become producers. To operate these distributed resources stably, the role of power equipment has become even more important."

This content was produced with the assistance of AI translation services.