Cables are one of the main assets in the power grid particularly for distribution network where the loads are widely spaced, this is a vital issue in oil and gas power grid. Monitoring cables on-line is an impossible task due to the cost and the excessive number of distributed cables. In most of oil and gas production countries the ambient temperature hits 56 degree Celsius that adds to the failures of power cables and shorten the cables lifecycle and the hour to hour capacity. This paper presents the results of estimating the maximum operating temperature of the cable during different operating load and under different ambient temperature, it is anticipating its impacts on the cables lifecycle. This is compared to the cable manufacturer design specification associated with the normal operating temperature. The results identify the factors contribute significantly to the degradation of the physical insulation property of the cables. In this paper the response time in the thermal transient model is used to identify the remaining useful life (RUL) of the cable. The model is used as a diagnostic procedure to detect the degree of aging, the results show that RUL of underground cables is7.5 years and for overhead cables is13.3 years under ambient temperature of 47°C and maximum load current.

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