Successful Localization of Core Materials for Ultra-High Voltage Transmission and Transformation Equipment... 'Eco-Friendly and High Performance'

[Reference Photo 1] Vacuum interrupter (back) jointly developed by Saenggiwon and Bitsro EM, and domestically produced contact material (front)
[Reference Photo 2] The contact plays a role in cutting off power through the gap when an arc occurs. (Inside view of the vacuum interrupter)

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[Asia Economy Reporter Kim Bong-su] The Korea Institute of Industrial Technology announced on the 24th that it has succeeded in domesticating core components of ultra-high voltage power transmission and transformation equipment, expecting effects such as import substitution and reverse exports.

The institute, in collaboration with the small and medium-sized enterprise Bitsro EM, succeeded in domesticating the electrical contact material of the vacuum interrupter (VI), a core component of the 72.5kV-class ultra-high voltage vacuum circuit breaker (VCB). A circuit breaker is a mechanical device that normally conducts heat well to supply power smoothly but quickly interrupts (insulates) the current during overload or short-circuit (when wires touch each other) accidents to extinguish the arc (spark).

In existing ultra-high voltage circuit breakers of 72.5kV and above, sulfur hexafluoride (SF?) was used as the medium for arc extinction. Although sulfur hexafluoride has excellent insulation performance, its global warming potential is 23,900 times higher than that of CO₂. Therefore, there is a trend to replace it with vacuum switching devices that rapidly diffuse and extinguish arcs in a vacuum that fundamentally blocks greenhouse gas use.

Bitsro EM, a small and medium-sized enterprise, had secured vacuum circuit breaker design technology but was entirely dependent on imports for the core contact material, making domestication urgent.

Accordingly, the senior research team led by Park Kyung-tae at the Korea Rare Metal Industry Technology Center developed a contact material that can maximize breaking performance at 72.5kV ultra-high voltage. Contacts are parts that open and close to interrupt power when an arc occurs. Generally, materials with good conductivity and high heat resistance and strength are used to prevent the contacts from melting and sticking due to heat.

The research team noted that advanced overseas products use Cu-Cr (chromium copper), an alloy of Cu (copper) and Cr (chromium), as the base metal and started developing a new material based on Cu-Cr. After about a year of research, they found the optimal alloy ratio by adding Mo (molybdenum). Although chromium content was reduced by 30% compared to existing materials, hardness improved more than twice, and conductivity increased by about 20-30%. Adding about 1% of ZrO₂ (zirconia) and Al₂O₃ (alumina) further improved structure, density, electrical conductivity, and hardness. This led to the successful development of a new material that minimizes contact damage while maximizing breaking performance.

The research team optimized process conditions such as temperature, time, and pressure for commercialization and completed internal design and analysis feasibility verification to secure insulation performance. They also completed certified institution evaluations of breaking performance, including vacuum degree, resistance, and insulation performance of vacuum interrupters applying the new material.

Senior researcher Park Kyung-tae of the institute said, “Since it can replace electrical contacts with performance superior to existing foreign products, if commercialization succeeds, opportunities for reverse exports overseas as well as domestic use are expected,” adding, “Although this technology is ultra-precision, we completed research that usually takes more than five years in just over a year.”

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