Investigation of electrical breakdown strength of interfaces. Study of interfaces between electrical insulation materials used in high voltage products exposed to electrical AC and DC fields

Usage of cable systems has increased during the last decades both for AC and DC\nsolutions. To make the cable system functional cable accessories is needed used for\nexample when connecting or terminating a cable. When an accessory is installed to a\ncable an interface is created between the insulation of the cable and the insulation of the\naccessory. This interface is exposed to an electric field stressing the interface both radial\nand tangential.\nThis master thesis has focused on finding the electrical breakdown strength of above\nmentioned interface when exposed to an electric field directed tangential to the interface.\nExperiments have been performed on small samples, imitating interfaces in high voltage\naccessories. The samples has been tested with interfaces of different material\ncombinations, with varying surface structures and when stressed to either a DC or AC\nfield. All samples had an interfacial pressure of 0.5 Bar.\nThe results of the experiments show no difference in breakdown strength when\ncomparing the two tested types of surface structure, simulating a cut and grinded surface.\nThe material combination of XLPE/EPDM has proven to have a stronger interface in\ncomparison with the material combination of XLPE/SiR. Finally the samples stressed to\nalternating electric field broke down at lower field intensities in comparison to the\nsamples stressed with DC-electric field.\n\n