Evolution and future of extra high voltage cables

The acceptance of extruded high voltage (HV) and extra high voltage cables (EHV) has increased significantly in the industry over the last 15 years. The first EHV cables in Berlin and Copenhagen were very carefully monitored and reported on in the press, but nowadays projects like this are only followed up by the experts and recording every project would be impossible. This paper will outline the improvements that have been made producing compounds for extra high voltage application including the jacketing. It will show the understanding of identifying the contaminants and reducing these in the insulation and semiconductive compounds. Today pre-qualification tests are required to produce high stress high voltage cables and extra high voltage cables. Only after this one-year test is a customer qualified to produce these cables. There are also guidelines from Cigre on what has to be tested if certain parameters in the composition of a cable have changed. We will outline the parameters that are important for a polymer producer to ensure a trouble free production of a long high voltage cables.