tion, thermoplastic PE was very popular, compared to paper insulation, as insulation for cables because of its low cost, electrical properties, processability, moisture and chemical resistance, and low temperature flexibility. A significant design issue with PE [5], in its thermoplastic state, was that its temperature of operation was limited to 70°C. Consequently, it could not match the temperature rating of paper-oil insulated cables. This problem was solved with the advent of crosslinked polyethylene (XLPE), which had the ability to match the thermal rating of paper-oil insulated cables and provide the freedom from the

On-site partial discharge (PD) measurement is required to ensure proper installation of extra high voltage (EHV) cable systems accessories. To achieve high sensitivity and good localization, two problems have to be overcome. First, the strong high frequency attenuation in long XLPE cables requires that the sensors be located along the cable, preferably directly at the accessories. Secondly, the detection system must be able to distinguish internal PD from other pulses. This paper describes a solution based on directional coupling sensors and a data visualization system, which displays phase-amplitude diagrams for individual PD sources which are identified by the direction of pulse propagation. It has been applied to on-site measurements, type and routine testing of HV cable joints and stress cones. Due to the reliable discrimination between internal PD from the accessory measured and from other pulses, testing can be done in unshielded rooms even using terminations with internal PCI and corona. The method works independently well on line voltage, resonance sources, oscil1,ating voltages and 0.1 Hz. cosine-square voltage. It has been used to verify the cable accessories installed in the 6.3 km long 380 kV cable system in Berlin, Germany

No abstract

No abstract

No abstract