A scheme for the Health Index and residual life of cables based on measurement and monitoring of diagnostic quantities

Defining a methodology providing an objective assessment of the health conditions of electrical apparatus is a must for an effective asset management approach, which can provide the most appropriate Return of Investment (ROI) keeping the asset at the desired reliability level. At present, diagnostic and monitoring techniques are available to evaluate electrical apparatus conditions, but too often the output is made by patterns, values and subjective indications which are not able to provide a real clue to help asset and maintenance manager decisions. This paper proposes an algorithm for the estimation of a health index, HI, for polymeric cable systems based on off-line and on-line measurement of diagnostic markers. The health index is a number ranging between 0 (worst condition, indicating imminent failure) and 1 (unaged cable, potentially able to provide the design life), which can allow a functional estimation of residual life to be obtained. An example of HI and residual life calculation for a cable system is provided, which shows feasibility and potentiality of the algorithm.