Analysis of Deterioration Characteristics of Service-Aged XLPE Cables According to Installation Location of Combined Heat and Power Plant

Abstract

The number of XLPE cables being used near or beyond their design life is increasing. The importance of timely cable replacement is necessary. Therefore, research is actively being conducted using VLF Tan δ diagnostic technology to assess the insulation condition of cables. Present studies lack in measuring and analyzing the VLF Tan δ of service-aged XLPE cables. Additionally, there is a research gap considering the operating environment. Therefore, it is needed to diagnose and analyze the insulation condition of the same service-aged cable when it is operated in a different environment. This paper assesses and analyzes the insulation condition of cables installed in the BFP, cooling tower, and deaerator booster pump of a combined heat and power plant. Each cable was evaluated by measuring the VLF Tan δ, the dielectric breakdown test of the cable, and the tensile strength, elongation at break, crystallinity, and dielectric strength of the XLPE specimens. Additionally, the correlation between the VLF Tan δ and other characteristics was also analyzed. It was found that degradation progressed in the order of the BFP, the cooling tower, and the deaerator booster pump. Therefore, it was confirmed that even for the same cable, deterioration varies depending on the installation location.