Condition Assessment of MV Cable Systems Successfully Implementing Experience Knowledge into Strategy Processing

A comprehensive cable diagnosis opens new possibilities for energy supply companies to manage the compromise between operational safety, investment, and cost pressure. Cable diagnosis is more than just performing diagnostic measurements. A key factor for success is the implementation of a defined workflow that includes the diagnostic measurement procedure and a comprehensive evaluation logic with a clear, cable network-specific action plan. Experience accumulated from intensive collaboration with many large energy suppliers shows that fundamental diagnostic methodology and evaluation approaches must be considered uniformly. It is particularly noteworthy that partial discharge measurement with its many individual parameters and dissipation factor measurement with very meaningful pattern types should be considered and evaluated simultaneously. This allows weak points to be clearly classified by measurement parameters and limits and backed up with an action plan. Experience is particularly crucial in mixed cable routes to arrive at the correct aging assessment from the complex evaluation of measurement parameters and to implement targeted actions. Cable diagnosis based on Very Low Frequency (VLF) dissipation factor and VLF partial discharge measurement is recognized worldwide as the basis for the comprehensive condition assessment of medium-voltage cables. Huge savings potentials are realistic if underground medium- voltage cables can be operated until their optimal service life while significantly increasing network reliability. Cable diagnosis has undergone profound development in recent years. In addition to detecting and evaluating defects with subsequent replacement of weak points, the diagnosis aims at the aging assessment of cable insulation. From diagnostic measurements, coupled with statistical analysis, the aging index of cable insulation is formed. An important tool calculates the statistical remaining life of the cable based on the data statistics of over 100,000 measurement data. Estimating the remaining life of the cable is an important basis for investment planning for the asset manager while significantly improving the reliability of a cable network. The article shows how successful the proven cable diagnostic technology, coupled with data statistics and tremendous experience, has matured into a solution for a frequently encountered asset manager problem.