Next generation xlpe insulation reaching extra high voltage dc performance Loyens Wendy, Englund Villgot, Hagstrand Per-Ola Borealis AB, Sweden Online published on 20 April, 2019. Abstract The use of extruded HVDC cables for energy transmission has increased significantly over the last two decades. Additionally, extruded (crosslinked polyethylene) XLPE HVDC cables are being used at continuously higher voltage levels to facilitate the demand of increased energy transportation. This obviously puts high demands on the insulation systems both in terms of electrical and mechanical characteristics as well as long term performance. Various material design parameters need to be considered of which DC conductivity has been identified as the most important electrical property when aiming to reach higher transmission voltages compared to the in service level to date. For this development of insulating materials to be used in cables for HVDC transmission above 320 kV, an innovative way forward in terms of contaminants was developed focusing on the need for high chemical cleanliness which is the key enabler for the envisioned performance. Chemical cleanliness stands for the minimization to the molecular level of species that can contribute negatively to the DC conductivity. In order to control the level of conductivity it is vital to limit the number of charge carriers available in the material. This paper will discuss the property profile of this next generation of HVDC XLPE material which has beenachieved by balancing the electrical and mechanical properties. The material solution is based on a known and mature technology platform, building on the extensive experience in producing specialized compounds for the highest requirements. A cable based on the insulation system presented in this paper has passed both type test and pre-qualification tests according to Cigre TB 496 at a voltage level of 640 kV. Top Keywords HVDC, Insulation, Insulation system, XLPE, Conductivity, Space charge, Extruded cable. Top |