Improving MV underground cable performance: Experience of TNB Malaysia

MV underground cable failures have been contributing to some 60% of annualized SAIDI for a number of years. Bulk of the reliability issues originated from MV underground cable joint failures. Special programs focused on skilled development of jointer and VLF Testing of cables were implemented over the last few years. Despite some early success, this approach is increasingly seen as being not sustainable as the fundamental issue of cable joint reliability and subsequent choice of cable joint technology is still unresolved. The choice of joint technology for MV underground cables has been a subject of much debate in the local industry in the midst of the growing evidence that the existing cable joint design is not performing well enough under the local operating environment. The approach towards seeking the long-term solution to the choice of cable joint technology is to conduct special performance-based laboratory testing. The methodology and tests are so designed as to expose the selected cable joints to extreme operational conditions and environment. Identified cable joint technologies and respective brands will later be further exposed to “extended field trials” before any standardization decision is made. This paper discusses the approach, methodologies and initiative in managing improvement effort of MV underground cable joint