Electric stress management of high voltage cable accessories based on the refractive stress control method

Abstract:
Today, almost every new energy cable system in medium and high voltage networks is projected with power cables based on extruded insulation and consequently the technology of the corresponding cable accessories has changed from oil/paper to dry materials as well. The key factor of these intensively developed and specially adapted products is lifetime expectancy. This is commonly more than 30 years as requested today. To achieve this, an appropriate electric field management system must be provided within the cable accessories. The requirements on those are increasing since the electrical insulation is facing different stress conditions such as DC, AC and operation at abnormal frequencies. This article presents a methodology of how a refractive electric stress management system could be used inside a cold applied or heat shrink cable accessory. Typical parameters of refractive stress management systems like their material properties at different frequencies, magnitude of electrical stress inside of cable accessories and the impact of the electrically stressed volume on the life expectancy are highlighted and discussed. This will be shown based on theoretical models, simulations as well as practical results. It is shown that it’s possible to design cable accessories for voltages up to 123 kV based on the refractive stress control method.