Scaling Up from LV to MV Cable Splice Design Through the Innovative Three-Leg Approach: PD-Free and Life-Compliant Design

Reliability of medium-voltage (MV) cable systems, for distribution to industrial and renewable plants, is becoming an issue for various reasons, among which are increased global aging, unconventional voltage waveforms, and insufficient commissioning tests. The major component undergoing premature failures is splices, and most of those failures can be associated with flaws in installation, commissioning and, in general, workmanship. One of the topics of an ongoing Department of Energy (DOE) Advanced Research Projects Agency-Energy (ARPA-E) project, GOPHURRS, is, indeed, to increase splice reliability through simpler design and installation procedures, which can minimize assembly and aging risks. This paper deals with design and testing techniques, which can allow scaling up to MV, a type of splice design and assembly that has been successful in low-voltage (LV) applications. A new design paradigm, the three-leg approach, is applied for the first time to LV splices to evaluate their operation likelihood and reliability up to 30 kV nominal voltage, allowing intrinsic life to reach the specified target (e.g., 30 years at a failure probability of 5%) and preventing extrinsic aging, namely, partial discharge occurrence. Design principles and validation, including accelerated aging and forensic observations, are presented and discussed.