HD Hyundai Electric has developed Korea's first 420-kilovolt (kV) SF6-free high-voltage circuit breaker, strengthening its push into Europe's growing market for environmentally friendly power equipment. The company said Monday that it had completed development of the 420kV-class circuit breaker, becoming the first Korean company to do so and the third company globally. The eco-friendly circuit breaker replaces sulfur hexafluoride (SF6), a potent greenhouse gas widely used in high-voltage equipment, with a C4-based gas mixture. The change requires the insulation and interruption systems to be redesigned to accommodate the properties of the alternative gas. The 420kV-class product is designed for ultra-high-voltage transmission networks and must demonstrate stable, long-term performance under extreme operating conditions, making its development particularly challenging, the company said. HD Hyundai Electric has independently developed SF6-free circuit breakers since 2021, beginning with a 170kV-class product and later adding 145kV- and 72.5kV-class products. The latest development expands