A Comparative Analysis of the Impact of the Roughness of MV Cable Insulation Surface on MV Cable Joint Performance Based on Impulse Testing

Nowadays a significant number of MV cable joints are based on cold shrink technology. This paper investigates the comparative performance of MV cold shrink joints based on strippable outer semiconducting layer and those based on bonded semiconducting layer, removed using tools leaving a relatively rough surface. The comparative performance of cold shrink joints with and without grease is also analysed. The performance comparison is based on impulse breakdown testing results. The test results indicate that MV cold shrink cable joints with rough and smooth surfaces give equivalent performance when greased. However, if grease is omitted or migrates out of the interfacial region, rougher surfaces show significantly poorer interfacial strength, while smooth surfaces without grease maintain their good initial impulse breakdown strength performance.