Record-breaking power line: the world's largest HVDC project with Durostone® EPX-M

Roechling Industrial electrical oil filled transformer shield end ring web

Shield end rings made of the material Durostone® EPX-M, which demonstrates exceptional dimensional stability, serve as spacers between the coil windings inside transformers.

World record power line: The most powerful high-voltage direct current transmission (HVDC) in the world

More than a billion people in China need electricity – and it is not always produced where it is used. That is why a world-record power line is being put into operation in China. It spans 3284 kilometers across the country, from the metropolis Changji in northwestern China to Guquan in the far east. A leading transformer manufacturer developed the newest generation of HVDC transformers for this project. It involves shield end rings made of Durostone® EPX-M from Röchling.

High-voltage direct current transmission (HVDC transmission) is a process of transmitting electric energy with high DC voltage. It requires special transformers which are used to transform direct current into alternating current and vice versa at the beginning and end of a power line. This is necessary because the transmission of alternating current, which is used every day across the world, across such large distances results in high losses. Losses experienced during the transmission of direct current are much smaller.

The highest-capacity HVDC transmission in the world, which has now been put into operation in China, has a capacity of twelve gigawatts, more than six times the capacity of a modern nuclear power plant. With 1000 kilovolts (kV) and 587.1 megavolt amperes (MVA), the HVDC transformers developed for this project have the highest capacities in the world. Shield end rings made of Durostone® EPX-M from Röchling are part of these new transformers.

In 2014, Röchling introduced shield end rings made from glass fibre reinforced resin-based materials onto the market for the first time. Compared to traditional materials like pressboard and laminated densified wood, the rings made of Durostone® EPX-M do not shrink after being subject to so-called Vapour-Phase Drying. During this process, insulation materials are freed of humidity and other impurities. That makes it easier for designers to plan component dimensioning and installation because they can calculate using exact tolerances.

Rings of Durostone® EPX-M are produced using a special winding process and consist of glass fiber reinforcement and a resin matrix on the basis of epoxy resins. With insulating class H (180 °C), the material has also an extreme strength, even at higher temperatures.

Röchling offers an extensive range of construction and insulation components for use in oil-filled power transformers.