An Approach for Evaluating VLF Tanδ Factor Combination for MV Cable Diagnosis

Since the 1980s, industrialization in Korea has led to a significant increase in cable installations, emphasizing the importance of maintaining these cables. Underground distribution cables use VLF (very low frequency) tanδ, a nondestructive test, to inspect insulation defects. This test can detect early-stage insulation degradation and offers consistent measurements. Test values are processed into determination factors to determine the degree of degradation, set re-diagnosis periods, or predict remaining life. However, if a selected combination has a blank value, judgment becomes difficult. Using all determination factors is inefficient and may lead to inaccurate predictions. Therefore, this paper conducted a validity analysis of each combination to prioritize effective factor combinations for determining degradation.