Construction of high-voltage lines in China is a massive market,the largest in the world and dominated by two state-owned giants that ensure its development.What is not known outside of a small circle of industry insiders is that the performance of these lines,essential for the growth of China's economy and,above all,for facilitating the energy transition,depends on components of marginal value,which include tempered glass insulators produced by an Italian-French company.
"These glass insulators at first glance are not very noticeable when observing pylons and cables in midair,but they are actually strategic because 60 percent of the issues in energy transmission operations can stem from them if the quality does not meet the required standards,"explained Paolo Daneu,CEO of Sediver China and a Ligurian with a degree in electrical engineering who has 20 years of experience in China after working at Italimpianti,ABB,and Techint Group.
"It might seem paradoxical that insulators account for merely 5 percent of the total investment cost,yet they are indispensable.They serve a dual function:mechanically supporting the cables and electrically insulating them from the tower structure."
Sediver was formed from the combination of Seves,formerly known as Vetroarredo,a Florence-based company that produces glass blocks worldwide,and Dielve,located in Nusco,in the province of Avellino.
Seves then acquired the French company Sediver,a company specialized in the production of tempered glass insulators,in 2002.Maintaining the Sediver name,the company continued the journey in the Chinese market that Sediver had started in 1994.
"There is an increasing need for energy,and as a result,the need for energy transmission across the world is becoming more urgent and unavoidable,"continued the CEO."If we look at the general demand,we're talking about projects that can cover distances of up to 2,000 kilometers with a line operating voltage of 1,000 kV in alternating current(AC)and 800 kV in direct current."
In recent years,China's 1,000-kilovolt ultra-high voltage(UHV)AC power transmission projects have experienced rapid growth nationwide.
In 2024,the first 1,000-kilovolt UHV AC project for the country's Southwest region was completed and put in operation.In March 2025,another 1,000-kilovolt UHV AC project commenced construction.It starts from Datong,North China's Shanxi Province and terminates in Tianjin.
A large part of Sediver's success lies in its ability to anticipate innovations and organize itself with very high production standards.
The Shanghai plant,which supplies not only China but also 77 other countries and regions,began actual production in 2004 on a total area of 66,000 square meters.It includes a natural gas-powered glass furnace,two glass production lines,and two insulator assembly lines,all robotic and utilizing the most advanced technologies.The workforce consists of a total of 450 employees,with an annual production capacity of up to 9 million insulators.
